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Background: Complications after total hip arthroplasty (THA) are frequently the consequence of malpositioned components or leg length discrepancy after surgery. Recently, a new version of a portable, accelerometer-based hip navigation system (New HipAlign) was made available with a change in the method of measuring cup abduction and the addition of a leg length measurement function. The purposes of this study were to investigate cup positioning and to examine the accuracy of leg length measurement with New HipAlign. Methods: Cups were implanted and intraoperative leg length change was measured using New HipAlign in 60 THAs through a posterior approach in the lateral decubitus position. The cup position and radiographic leg length change were determined postoperatively on pelvic radiograph and computed tomography scans. We previously compared cup positioning with a previous version of a portable, accelerometer-based hip navigation system (Previous HipAlign) and conventional surgical techniques. Cup positioning in this study was compared with the results of out previous study using Previous HipAlign. Results: The mean cup abduction of 40.3° ± 4.9° (range, 26° to 53°) and the mean cup anteversion of 15.8° ± 5.6° (range, 6.7° to 29.5°) were found. The deviation of the postoperative measured angles from the target cup position was 3.7° ± 3.3° for cup abduction and 5.9° ± 3.6° for cup anteversion. 56/60 of the cups were inside the Lewinnek safe zone. Compared with our previous study using Previous HipAlign, there were no significant differences with regard to cup abduction, cup anteversion, the deviation from the target cup position for cup abduction, the value of deviation for cup anteversion, and the number of cups inside the Lewinnek safe zone (P = 0.218, 0.334, 0.651, 0.797, 0.592). The mean difference between the intraoperative and radiographic leg length changes was + 0.8 ± 3.4 mm. There was significant correlation between the intraoperative and radiographic leg length changes (r = 0.804, P = 0.000). Conclusions: Use of New HipAlign allowed for accurate cup placement and reliable leg length measurement during THA. Trial registration: Clinical trial is defined as ‘any research study that prospectively assigns human participants or groups of humans to one or more health-related interventions to evaluate the effects on health outcome’ by the World Health Organization (WHO). Because this study is not a clinical trial, trial registration is not needed.

DOI： 10.1186/s12891-021-04167-y

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SAGE Publications Ltd  

Background: Dislocation continues to be a common complication following total hip arthroplasty (THA). Although previous studies of computed simulation analysis investigated the range of motion (ROM), it is unclear whether the ROM before impingement simulated using computed tomography-based 3-dimensional simulation analysis (simulated ROM) is related to dislocation after THA. It is also unclear what angles are required in computed simulation analyses for stable hips after THA. In this study, we compared the simulated ROM in patients with and without dislocation. Methods: 16 patients with posterior dislocation were compared with 48 matched patients without dislocation. Risk factors including preoperative bone morphology of the hip, implant position, change of femoral offset, change of leg length, anterior aspect of the greater trochanter (GTa) length, and anterior inferior iliac spine length were also compared. Results: The mean flexion angle, internal-rotation at 90° flexion (IR) angle, cup anteversion based on the anterior pelvic plane (APP), tilt-adjusted cup anteversion and GTa length were significantly different between patients with dislocation and patients without dislocation (p = 0.033, 0.002, 0.010, 0.047, 0.046). A receiver-operating characteristic curve analysis suggested cutoff points for flexion angle, IR angle, cup anteversion based on the APP, tilt-adjusted cup anteversion and GTa length, of 114.5°, 45.5°, 19.5°, 12.0° and 15.3 mm. Conclusions: This study suggests that preoperative planning to achieve a larger simulated ROM, flexion angle and IR angle, may reduce the risk of posterior dislocation. This study also suggests that fine-tuning of cup anteversion and/or trimming of the overhanging GTa during preoperative planning may reduce the risk of posterior dislocation.

DOI： 10.1177/11207000211044807

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Churchill Livingstone Inc.  

Background: Malposition of the acetabular component during total hip arthroplasty (THA) is associated with increased risk of dislocation, reduced range of motion, and accelerated wear. The purpose of this study is to compare cup positioning with a portable, accelerometer-based hip navigation system and conventional surgical technique. Methods: In a prospective, randomized, clinical study, cups were implanted with a portable, accelerometer-based hip navigation system (navigation group
n = 55) or conventional technique (conventional group
n = 55). THA was conducted in the lateral position and through posterior approach. The cup position was determined postoperatively on pelvic radiograph and computed tomography scans. Results: An average cup abduction of 39.2° ± 4.6° (range, 27° to 50°) and an average cup anteversion of 14.6° ± 6.1° (range, 1° to 27.5°) were found in the navigation group, and an average cup abduction of 42.9° ± 8.0° (range, 23° to 73°) and an average cup anteversion of 11.6° ± 7.7° (range, −12.1° to 25°) in the conventional group. A smaller variation in the navigation group was indicated for cup abduction (P =.001). The deviations from the target cup position were significantly lower in the navigation group (P =.001,.016). While only 37 of 55 cups in the conventional group were inside the Lewinnek safe zone, 51 of 55 cups in the navigation group were placed inside this safe zone (P =.006). The navigation procedure took a mean of 10 minutes longer than the conventional technique. Conclusion: Use of the portable, accelerometer-based hip navigation system can improve cup positioning in THA.

DOI： 10.1016/j.arth.2019.08.044

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BioMed Central Ltd.  

Background: Dislocation continues to be a common complication following total hip arthroplasty (THA). A larger intraoperative range of motion (ROM) is believed to minimize dislocation risk, and intraoperative stability tests have been used to assess the ROM. However, it is not clear whether or not intraoperative stability tests can predict hip stability after THA. It is also unclear which angles are required in intraoperative stability tests. We investigated the usefulness of intraoperative stability tests, and other risk factors to predict hip stability after THA. Methods: Patients operated by single surgeon at one hospital from June 2009 to December 2013 were evaluated. This study included 185 hips with 32 mm metal femoral head. The range of internal rotation with 90° hip flexion (IR angle) was measured as an intraoperative stability test. The variables studied as risk factors included age, height, weight, gender, cerebral dysfunction, preoperative diagnosis, history of previous hip surgery, and IR angle. Results: Mean IR angle was statistically different between patients with dislocation and patients without dislocation (59.5° vs 69.6°: p = 0.006). Cerebral dysfunction and a history of previous hip surgery were statistically related with prevalence of dislocation (p = 0.021, and p = 0.011). The receiver-operating characteristic curve analysis suggested that the cutoff points for IR angle were 51° and 67°. Dislocation rate in larger IR angle group was significantly lower than the rate in smaller IR angle group when patients were divided by 51° (p = 0.002). Logistic regression analyses showed that significant risk factors were cerebral dysfunction (OR: 5.3 (95%CI 1.1-25.9)
p = 0.037), history of previous hip surgery (OR: 8.6 (95%CI 1.2-63.0)
p = 0.035), and IR angle (OR: 10.4 (95%CI 1.9-57.1)
p = 0.007). Conclusions: The results showed that intraoperative stability test, especially the IR angle, was a useful method to predict hip stability after THA, and a larger intraoperative ROM reduced the likelihood of dislocation. 51° and 67° were indicated as cutoff points for IR angle. Cerebral dysfunction and a history of previous hip surgery are also risk factors for the incidence of dislocation after THA. Trial registration: This is a retrospective study, not a clinical trial defined by the World Health Organization (WHO).

DOI： 10.1186/s12891-018-2289-y

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DOI： 10.1371/journal.pone.0201559

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DOI： 10.1371/journal.pone.0190588

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

Background: Developmental dysplasia of the hip is an important disease leading to osteoarthritis. Recently, researchers have focused on hip instability as a potentially important dynamic factor for osteoarthritis, but the detailed kinematics of dysplastic hips during weight-bearing gait have not been reported. The purpose of this research is to contrast femoral translation in contralateral healthy hips and dysplastic hips during weight-bearing stepping.
Methods: Twelve dysplastic hips and eight healthy hips were investigated. Hip joint kinematics were analyzed using 3D-2D model-image registration with dynamic fluoroscopic images of each hip during a stepping-in-place activity. Femoral translation relative to the acetabular center was quantified as instability.
Findings: Total femoral head translations were significantly different between dysplastic and contralateral healthy hips. Mean translation was 1.0 nun in dysplastic hips and 0.4 mm in contralateral healthy hips during swing-phase, and consisted of inferior translation during early swing phase with a complementary superior translation just before foot strike. Total femoral translation was significantly correlated to several radiographic indices of hip dysplasia.
Interpretation Superior translations of the femur during the end of swing phase may result in altered articular contact mechanics, abnormal stresses on the labrum and lost lubricant sealing. All of these factors may contribute to joint degeneration and osteoarthritis in dysplastic hips.

DOI： 10.1016/j.clinbiomech.2017.05.003

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DOI： 10.1177/1947603516661820

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DOI： 10.1177/1602400222

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DOI： 10.1186/s12891-016-1179-4

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DOI： 10.1007/s00586-016-4615-0

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DOI： 10.1155/2016/1496529

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DOI： 10.2188/jea.JE20140162

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER JAPAN KK  

This study proposes novel optimized stem geometry with low stress values in the cement using a finite element (FE) analysis combined with an optimization procedure and experimental measurements of cement stress in vitro. We first optimized an existing stem geometry using a three-dimensional FE analysis combined with a shape optimization technique. One of the most important factors in the cemented stem design is to reduce stress in the cement. Hence, in the optimization study, we minimized the largest tensile principal stress in the cement mantle under a physiological loading condition by changing the stem geometry. As the next step, the optimized stem and the existing stem were manufactured to validate the usefulness of the numerical models and the results of the optimization in vitro. In the experimental study, strain gauges were embedded in the cement mantle to measure the strain in the cement mantle adjacent to the stems. The overall trend of the experimental study was in good agreement with the results of the numerical study, and we were able to reduce the largest stress by more than 50 % in both shape optimization and strain gauge measurements. Thus, we could validate the usefulness of the numerical models and the results of the optimization using the experimental models. The optimization employed in this study is a useful approach for developing new stem designs.

DOI： 10.1007/s10047-014-0792-y

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DOI： 10.3109/14397595.2014.924385

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BIOMED CENTRAL LTD  

Background: It has not been shown whether accelerated rehabilitation following periacetabular osteotomy (PAO) is effective for early recovery. The purpose of this retrospective study was to compare complication rates in patients with standard and accelerated rehabilitation protocols who underwent PAO.
Methods: Between January 2002 and August 2011, patients with a lateral center-edge (CE) angle of < 20 degrees, showing good joint congruency with the hip in abduction, pre- or early stage of osteoarthritis, and age younger than 60 years were included in this study. We evaluated 156 hips in 138 patients, with a mean age at the time of surgery of 30 years. Full weight-bearing with two crutches started 2 months postoperatively in 73 patients (80 hips) with the standard rehabilitation protocol. In 65 patients (76 hips) with the accelerated rehabilitation protocol, postoperative strengthening of the hip, thigh and core musculature was begun on the day of surgery as tolerated. The exercise program included active hip range of motion, and gentle isometric hamstring and quadriceps muscle sets; these exercises were performed for 30 minutes in the morning and 30 minutes in the afternoon with a physical therapist every weekday for 6 weeks. Full weight-bearing with two axillary crutches started on the day of surgery as tolerated. Complications were evaluated for 2 years.
Results: The clinical results at the time of follow-up were similar in the two groups. The average periods between the osteotomy and full-weight-bearing walking without support were 4.2 months and 6.9 months in patients with the accelerated and standard rehabilitation protocols (P < 0.001), indicating that the accelerated rehabilitation protocol could achieve earlier recovery of patients. However, postoperative fractures of the ischial ramus and posterior column of the pelvis were more frequently found in patients with the accelerated rehabilitation protocol (8/76) than in those with the standard rehabilitation protocol (1/80) (P = 0.013).
Conclusion: The accelerated rehabilitation protocol seems to have advantages for early muscle recovery in patients undergoing PAO; however, postoperative pelvic fracture rates were unacceptably high in patients with this protocol.

DOI： 10.1186/1471-2474-15-234

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DOI： 10.12659/MSM.889704

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There have been few reports describing intermediate- to long-term results after hybrid total hip arthroplasty in patients with rheumatoid arthritis. We followed up 52 hips in 44 patients aged 5 men and 39 women, with a mean of 11.5 years (range, 5-23.5 years). Revisions had been performed in 6 hips in 6 patients: 1 both acetabular and femoral components for infection, 1 acetabular component for aseptic loosening, 3 acetabular components for recurrent dislocation, and 1 acetabular component for dislodgement of the polyethylene liner from the metal shell. None of other acetabular or femoral components were revised or found to be loose at the final follow-up. Although postoperative dislocation remains a concern, hybrid total hip arthroplasty had an acceptable result in patients with rheumatoid arthritis. © 2013 Elsevier Inc.

DOI： 10.1016/j.arth.2012.06.002

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DOI： 10.1002/jor.22200

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BRITISH EDITORIAL SOC BONE JOINT SURGERY  

We have previously described the mid- to long-term results of conventional simple varus intertrochanteric osteotomy for osteonecrosis of the femoral head, showing that 19 of the 26 hips had good or excellent results. We extended the follow-up to a mean of 18.1 years (10.5 to 26) including a total of 34 hips in 28 patients, with a mean age at surgery of 33 years (19 to 53). There were 18 men and ten women and 25 hips (74%) had a satisfactory result with a Harris hip score >= 80. In all, six hips needed total hip replacement (THR) or hemiarthroplasty. The collapse of the femoral head or narrowing of the joint space was found to have progressed in nine hips (26%). Leg shortening after osteotomy was a mean of 19 mm (8 to 36). With conversion to THR or hemiarthroplasty as the endpoint, the ten-year survival rate was 88.2% (95% confidence interval (CI) 82.7 to 93.7) and the 20-year survival rate was 79.7% (95% CI 72.1 to 87.3); four hips were converted at ten years and other two hips were converted at 20 years.
Shortening of the leg after osteotomy remains a concern; however, the conventional varus half-wedge osteotomy provides favourable long-term results in hips with less than two-thirds of the medial part of the femoral head affected by necrotic bone and with normal bone superolaterally.

DOI： 10.1302/0301-620X.94B3.27814

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The acetabular labrum is believed to have a sealing function. However, a torn labrum may not effectively prevent joint fluid from escaping a compressed joint, resulting in impaired lubrication. We aimed to understand the role of the acetabular labrum in maintaining a low friction environment in the hip joint. We did this by measuring the resistance to rotation (RTR) of the hip, which reflects the friction of the articular cartilage surface, following focal and complete labrectomy. Five cadaveric hips without evidence of osteoarthritis and impingement were tested. We measured resistance to rotation of the hip joint during 0.5, 1, 2, and 3 times body weight (BW) cyclic loading in the intact hip, and after focal and complete labrectomy. Resistance to rotation, which reflects articular cartilage friction in an intact hip was significantly increased following focal labrectomy at 1-3 BW loading, and following complete labrectomy at all load levels. The acetabular labrum appears to maintain a low friction environment, possibly by sealing the joint from fluid exudation. Even focal labrectomy may result in increased joint friction, a condition that may be detrimental to articular cartilage and lead to osteoarthritis. (C) 2011 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jbiomech.2011.11.044

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DOI： 10.1007/s00776-011-0166-8

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A 4-U hybrid total hip arthroplasty (THA) system was specifically designed for patients with developmental dysplasia of the hip (DDH). Straight stem with an appropriate offset and various size variations are advantages. We followed 128 hips in 124 patients, 13 men and 111 women, for a mean of 6.5 years (range, 5.0-7.5 years). Two acetabular and femoral components in two patients had been revised for infection, one acetabular component had been revised for recurrent dislocation, and one femoral component had been revised for periprosthetic femoral fracture. None of the acetabular or femoral components were revised for loosening or were found to be loose at follow-up. The Harris hip score increased from a preoperative average of 42 points to 88 points at the most recent follow-up. Primary THA using the 4-U system had a good mid-term result in patients with DDH. This system could be applied for all patients including those with the narrowest and deformed femurs.

DOI： 10.1007/s00264-010-1096-3

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOURNAL BONE JOINT SURGERY INC  

Background: The treatment of middle-aged patients with periacetabular osteotomy remains controversial. The goal of the present retrospective study was to analyze the intermediate to long-term functional and radiographic results of periacetabular osteotomy in patients below and above the age of forty years.
Methods: Between February 1990 and December 2004, 166 periacetabular osteotomies were performed in 146 patients. We evaluated 158 hips in 139 patients who had a mean age of thirty-two years at the time of surgery. The mean duration of follow-up was eleven years (range, five to twenty years). We compared thirty-six patients (forty-one hips) who were forty years of age or older with 103 patients (117 hips) who were younger than forty years of age at the time of surgery.
Results: The average Harris hip score increased from 70 points preoperatively to 90 points postoperatively. The mean Harris hip scores at the time of the five-year follow-up were similar in the older and younger groups (p = 0.57), although the latest follow-up scores were significantly higher in the younger group than in the older group (91 compared with 88 points; p = 0.02). The average modified Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) function score (with 0 representing the worst score and 100 representing the best score) was higher for the younger group than for the older group (92 compared with 90 points; p = 0.03). Kaplan-Meier analysis with progression of the Tonnis grade of osteoarthritis as the end point showed a ten-year survival rate of 90.8% (95% confidence interval, 88.3% to 93.3%) and a fifteen-year survival rate of 83.0% (95% confidence interval, 78.5% to 87.5%); the ten-year survival rates in the younger and older groups were 94.4% and 81.3%, respectively, and the fifteen-year survival rates were 86.9% and 71.2%, respectively (p = 0.025).
Conclusions: Periacetabular osteotomy yielded similar results for the two groups at the time of the five-year follow-up, although the results for the older group deteriorated thereafter. Decrease in physical function due to aging and increased susceptibility to the progression of osteoarthritis may be responsible for the poorer results over time in the older group.

DOI： 10.2106/JBJSJ.01059

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DOI： 10.2106/JBJS.J.00561

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We report the mid-to long-term (mean 20.3 years, 10 to 32.5) results of the Chiari pelvic osteotomy in patients with pre- to advanced stage osteoarthritis in dysplastic hips. We followed 163 Japanese patients (173 hips) with a mean age at surgery of 20 years (9 to 54). Overall, 124 hips (72%) had satisfactory results, with Harris hip scores >= 80. Satisfactory results were seen in 105 of 134 hips with pre- or early osteoarthritis (78%) and 19 of 39 hips with advanced osteoarthritis (49%). A total of 15 hips (9%) underwent a total hip replacement (THR) with a mean interval between osteotomy and THR of 16.4 years. With conversion to THR as the endpoint, the 30-year survival rate was 85.9% (95% confidence interval 82.3 to 89.5). It was 91.8% for patients with pre-or early osteoarthritis and 43.6% for those with advanced osteoarthritis (p < 0.001).
We now perform the Chiari osteotomy for patients with dysplastic hips showing poor joint congruency and who prefer a joint-conserving procedure to THR.

DOI： 10.1302/0301-620X.93B6.26178

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

There are many designs of the femoral stem of a cemented total hip arthroplasty, and mechanical failure of the stem is caused by several factors related to the cement, such as failure of the cement. Optimization of the shape of the stem, especially multiobjective optimization, is required to solve these design problems because a cement fracture is caused by multiple factors. The objective of this study was to determine a stem geometry considering multiple factors at the same time. A three-dimensional finite element model of the proximal femur was developed from a composite femur. A total of four objective functions-two objective functions, the largest maximum principal stress of proximal and distal sections in the cement mantle, for each of the two boundary conditions, walking and stair climbing-were used. The neighborhood cultivation genetic algorithm was introduced to minimize these objective functions. The results showed that the geometry that leads to a decrease in the proximal cement stress and the geometry that leads to a decrease in the distal cement stress were not the same. However, the results of the walking and the stair climbing conditions matched. Five dominant stem designs were considered to be the Pareto solution, and one design was identified as the "better design" for all objective functions. It was shown that multiobjective optimization using a genetic algorithm may be used for optimizing the shape of the femoral stem in order to avoid cement fracture.

DOI： 10.1111/j.1525-1594.2010.01117.x

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHURCHILL LIVINGSTONE INC MEDICAL PUBLISHERS  

We evaluated intermediate-term to long-term survival of cemented calcar replacement femoral components in hybrid revision total hip arthroplasty. We followed up 52 hips in 50 patients for a mean of 11.4 years. Six (12%) femoral components had been revised: 2 for aseptic loosening, 2 for periprosthetic fracture, and 2 for deep infection. One additional femoral component was definitely loose. The number of previous revision operations (P =.004), preoperatively poorer femoral bone stock (P =.005), and postoperative poor cement mantle grading (P =.003) were significant factors for failure. Kaplan-Meier analysis revealed that the 15-year survival rate was 90% with mechanical failure as the end point. This technique remains a reasonable option for the first-time revision, especially for older and less active patients.

DOI： 10.1016/j.arth.2010.02.014

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHURCHILL LIVINGSTONE INC MEDICAL PUBLISHERS  

We previously reported the average 9 3-year (range, 5-13 years) results of 74 patients (83 hips) with porous-coated acetabular components that were placed without bulk bone graft at revision surgery Since the previous report 7 patients (7 hips) died before the minimum follow-up of 10 years and 1 patient (1 hip) was lost to follow-up We now report the average 15 6-year (range, 10-20 years) results for 66 patients (75 hips) Three additional acetabular components were removed or revised again 2 for infection and 1 for dislodgement of the polyethylene liner from the metal shell Overall 7 (7%) components required removal or repeat revision No shell was revised for aseptic loosening and none was categorized as loose during the entire follow up period

DOI： 10.1016/j.arth.2009.10.012

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DOI： 10.1007/s00776-009-1412-1

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DOI： 10.1007/s00776-010-1507-8

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHURCHILL LIVINGSTONE INC MEDICAL PUBLISHERS  

The purposes of this study were to determine the spectrum of femoral head damage in patients undergoing revision total hip arthroplasty and to determine the impact of that damage on polyethylene wear. One hundred eight consecutive modular metal femoral heads were retrieved at revision surgery. The mean roughness (Ra) value was 0.18 +/- 0.18 mu m. The roughest femoral heads (mean Ra, 0.56 mu m) were from retrievals correlated with mode 2 wear (recurrent dislocation and complete wear through of the polyethylene liner). Five million cycles of wear tests were performed using retrieved femoral heads against both new conventional and highly cross-linked polyethylene. The mean wear rate of conventional polyethylene was 15.9 +/- 4.3 mg and that of highly cross-linked polyethylene was 0.04 +/- 0.14 mg per 1 million cycles (P<.001). Highly cross-linked polyethylene was more resistant to wear than conventional polyethylene, even when mated against roughened femoral heads.

DOI： 10.1016/j.arth.2009.01.010

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wichtig Publishing Srl  

Modular component exchange is one of several viable options for treating instability after total hip arthroplasty (THA). Recently, we reported that polyethylene liners retrieved from stable THAs had significantly deeper cup articular geometry than liners retrieved from dislocated THAs. Modular liner exchange with implantation of a deeper cup articulation for the treatment of THA instability may be an option in certain cases. We describe the use of modular liner exchange with implantation of a custom polyethylene liner with a deepened articular geometry for surgical treatment of recurrent dislocation after primary THA in a 70 year old patient. The patient did not feel unstable and no symptoms of subluxation or dislocation have been experienced in the 3 years of follow-up subsequent to treatment. Surgeons should consider the articular geometry of the polyethylene liner as an important design parameter, and we recommend that deeper polyethylene liners be considered for treatment of recurrent dislocation after primary THA. © 2010 Wichtig Editore.

DOI： 10.1177/112070001002000222

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The structure and function of the proximal hip joint capsule and the zona orbicularis are poorly understood. We hypothesized that the zona orbicularis is an important con tributor to hip stability in distraction. In seven cadaveric hip specimens from seven in ale donors we distracted the femur from the acetabulum in a direction parallel to the femoral shaft with the hip in the neutral position. Eight sequential conditions were assessed: (1) intact specimen (muscle and skin removed), (2) capsule vented, (3) incised iliofemoral ligament, (4) circumferentially incised capsule, (5) partially resected capsule (distal to the zona orbicularis'), (6) completely resected capsule, (7) radially incised labrum, and (8) completely resected labrum. The reduction of the distraction load was greatest between the partially resected capsule phase and completely resected capsule phase at 1, 3, and 5 mm joint distraction (p = 0.018). The proximal to middle part of the capsule, Which includes the zona orbicularis, appears grossly and biomechanically to act as a locking ring wrapping around the neck of the femur and is a key structure for hip stability in distraction. (C) 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:989-995, 2009

DOI： 10.1002/jor.20852

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Little data exists on the original morphology of acetabular dysplasia obtained from patients without radiographic advanced osteoarthritic changes. The aim of this study was to investigate the distribution and degree of acetabular dysplasia in a large number of patients showing no advanced degenerative changes using three-dimensional computed tomography (3DCT).
Eighty-four dysplastic hips in 55 consecutive patients were studied. All 84 hips were in pre- or early osteoarthritis without radiographic evidence of joint space narrowing, formation of osteophytes or cysts, or deformity of femoral heads. The mean age at the time of CT scan was 35 years (range 15-64 years). 3D images were reconstructed and analyzed using recent computer imaging software (INTAGE Realia and Volume Player). Deficiency types and degrees of acetabular dysplasia were precisely evaluated using these computer software.
The average Harris hip score at CT scans was 82 points. Twenty-two hips (26%) were classified as anterior deficiency, 17 hips (20%) as posterior deficiency, and 45 hips (54%) as lateral deficiency. No significant difference was found in the Harris hip score among these groups. The analysis of various measurements indicated wide variations. There was a significant correlation between the Harris hip score and the acetabular coverage (p < 0.001).
Our results indicated wide variety of deficiency type and degree of acetabular dysplasia. Hips with greater acetabular coverage tended to have a higher Harris hip score.

DOI： 10.1007/s00256-008-0601-x

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHURCHILL LIVINGSTONE INC MEDICAL PUBLISHERS  

We have developed an intraoperative model to quantify total hip arthroplasty impingement and dislocation mechanics using fluoroscopy and shape-matching techniques. Two patient groups were investigated: group I consisted of 12 hips using 28- or 32-mm femoral heads and an anterolateral Surgical approach, and group 2 consisted of 17 hips using 22- or 26-mm femoral heads and a posterolateral Surgical approach. During intraoperative hip stability testing consisting of extension and external rotation motions, group 1 was more unstable, and prosthetic impingement was the major reason for dislocation. With flexion and internal rotation motions, group 2 was more unstable, and superior-lateral impingement or soft tissue traction was the major reason for dislocation. Intraoperative quantitative assessment of hip mechanics provides a safe and clinically relevant method to characterize potential complications and evolve techniques to prevent them.

DOI： 10.1016/j.arth.2007.07.004

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Various methods of periacetabular osteotomy have been described. Since 1990, we have performed rotational acetabular osteotomy through an Ollier lateral U transtrochanteric approach without massive bone graft. This study investigated whether our technique could provide relief from symptoms, whether postoperative hip abductor weakness would be a critical complication, and whether appropriate acetabular coverage could be achieved. We followed in 101 patients (110 consecutive hips) with a mean age at surgery of 32.5 years and a minimum followup of 5 years (mean, 8.3 years; range, 5-16.2 years). Satisfactory results were found in 94 (85%) hips. A positive Trendelenburg sign was observed in eight (7%) hips at last followup. Appropriate postoperative coverage was provided with an average centeredge angle of 35 degrees. We found radiographic evidence of deterioration of osteoarthritic changes in 14 (13%) hips. Complications included deep infection (one patient); pulmonary embolism (one patient); osteonecrosis of the rotated acetabular fragment (two patients); and proximal displacement of the greater trochanter because of breakage of the polylevolactic acid screws (four patients). This procedure allows osseous cuts with good operative exposure and provides relief from symptoms in most painful dysplastic hips.

DOI： 10.1097/BLO.0b013e31803b942a

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHURCHILL LIVINGSTONE INC MEDICAL PUBLISHERS  

This article presents the midterm results of hybrid total hip arthroplasty for patients with hip dysplasia by use of a tight fit technique for the femoral component. We followed up 113 hips in 99 patients for a mean of 11 years. All final femoral rasps used in this study overrasped by 0.5 to 1.0 mm for stem insertion, resulting in relatively thin cement mantles. Both components of one hip were removed because of infection. The other 5 acetabular components were revised for osteolysis, recurrent dislocation, or dislodgement of the polyethylene liner. No femoral component was revised for aseptic loosening. We conclude that the tight fit technique using a canal-filling stein may produce good long-term results for patients with hip dysplasia.

DOI： 10.1016/j.arth.2006.01.016

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPRINGER-VERLAG TOKYO  

The purpose of this study was to evaluate the long-term results of simple varus intertrochanteric osteotomy for osteonecrosis of the femoral head. Forty hips in 31 patients were included, with an average age at the time of surgery of 34 years (range, 21-51 years). The mean duration of follow-up was 12.1 years (range, 5-23 years). Osteonecrosis was high-dose-steroid-induced in 20 patients, alcohol-induced in 7 patients, and idiopathic in 4 patients. The amount of varus correction ranged from 15 degrees to 40 degrees (mean, 23 degrees). The JOA hip score increased from a preoperative average of 71 points to 85 points at the most recent follow-up. Thirty (75%) of the 40 hips showed good or excellent results, 10 (25%) hips had fair or poor results, and 4 hips needed prosthetic arthroplasty. In 28 hips with equal to or greater than 25% postoperative lateral head index, 24 (86%) hips showed good or excellent results. Average shortening of leg length was 1.8 cm. Our findings indicate that if necrotic lesions are limited medially and the lateral part of the femoral head remains intact, good long-term results can be obtained by simple varus osteotomy.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SAGE PUBLICATIONS LTD  

Health-related quality of life (HRQOL) of systemic lupus erythematosus (SLE) patients with hip arthroplasty after medium to long-term follow-up has not been reported. We conducted a retrospective study for SLE patients with osteonecrosis of the femoral head (ONF). Forty-seven consecutive arthroplasties were performed in 36 patients. Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Medical Outcome Survey Short Form 36 (SF-36) and Harris hip score were evaluated. Two patients died before the four-year follow-up and two patients were lost to follow-up. The remaining 43 hips in 32 patients with an average age at surgery of 35 years and an average follow-up of 12.0 years (range 4.0-25.0) were assessed. Bipolar hemiarthroplasty was performed for 18 hips in 12 patients, and total hip arthroplasty (THA) was performed for 25 hips in 20 patients. The mean WOMAC scores for pain and function at the recent followup were 90.8 +/- 8.5points and 79.0 +/- 18.3 points. Patients with THA had significantly high scores in SF-36 physical functioning (P < 0.05) and bodily pain (P < 0.03) compared to those with bipolar hemiarthroplasty. Although improvement could not reach the level of general population, the hip arthroplasty contributed to support HRQOL of SLE patients.

DOI： 10.1177/0961203307077989

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHURCHILL LIVINGSTONE INC MEDICAL PUBLISHERS  

We present the results of total hip arthroplasty using S-ROM (Depuy, Warsaw, Ind) prosthesis combined with corrective femoral transverse osteotomy for hips with proximal femoral deformity. Fourteen hips were followed up for a mean of 61 months (range, 36-95 months), with a mean age at surgery of 55 years (range, 44-69 years). The average intraoperative blood loss was 638 mL, and the average operative time was 136 minutes. The average Harris Hip Score increased from 38.0 (range, 15.0-55.7) preoperatively to 82.0 (range, 34.6-92.7) at the latest follow-up. All the hips except for 1 acquired union of osteotomy and bone ingrowth. S-ROM modular stem, which gives sufficient rotational stability at both proximal and distal parts of the osteotomy, is useful for total hip arthroplasty combined with corrective femoral transverse osteotomy.

DOI： 10.1016/j.arth.2005.08.016

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER ROENTGEN RAY SOC  

OBJECTIVE. The purpose of this study was to determine the significance of risk factors on MR images for predicting the outcome of patients with osteonecrosis of the femoral head.
SUBJECTS AND METHODS. Eighty-three asymptomatic or minimally symptomatic hips in 61 consecutive patients were followed up prospectively. Inclusion criteria included osteonecrosis of the femoral head identified by typical MRI findings, with no radiographic evidence of progression of collapse, and Harris hip score of 85 points or more. Every 3 months. the patients underwent clinical and radiographic examination, and MR images were obtained at 6- to 12-month intervals. Follow-up continued until worsening of hip pain with Harris hip score of less than 70 points or surgery. Asymptomatic hips were followed up for at least 24 months. The mean clinical and radiographic follow-up period after the initial diagnosis was 60 months (range, 3-168 months).
RESULTS. Thirty-six (43%) of the 83 hips were symptomatic at the last follow-up. Bone marrow edema was present in 28 hips (34%) during the follow-up period. Twenty-seven (96%) of the 28 hips were symptomatic, and bone marrow edema significantly correlated with worsening of hip pain (p < 0.0001). The necrotic volume of hips with bone marrow edema was significantly larger than those without bone marrow edema (p < 0.0001). Bone marrow edema was found to be the most significant risk factor for worsening of pain (p < 0.0001).
CONCLUSION. Bone marrow edema strongly con-elated with necrotic volume and was the most significant risk factor for worsening of hip pain. A large necrotic volume of 30% or more may be the second useful indicator for predicting future worsening of hip pain.

DOI： 10.2214/AJR.05.0086

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

The purpose of our study was to investigate the bone union rates and complication rates, including breakage of screws, infection, and osteolysis, in hip osteotomies using poly-L-lactic screws. We prospectively followed up Ill hips in 100 patients using conventional radiography, in which 81 rotational acetabular osteotomies, 26 Chiari pelvic osteotomies, and four Sugioka's transtrochanteric osteotomies were performed. The mean age of the patients at the time of surgery was 34 years, and the mean followup was 5.4 years. Eighty-one osteotomized acetabula and 98 osteotomized greater trochanters were fixed using poly-L-lactic screws. These hips were compared with 64 hips in 58 patients using metallic screws. Bone union was achieved in 80 of the 81 acetabular osteotomies, except in one hip with postoperative deep infection. Proximal displacement of the greater trochanter because of poly-L-lactic screw breakage occurred in six (6%) hips. None of the metallic screws broke. Osteolysis occurred in one hip with a trochanteric osteotomy using poly-L-lactic screws. Poly-L-lactic screws are suitable to transfix the osteotomized acetabulum, but there is some risk of fracture when used to reattach an osteotomized greater trochanter. Complete bone ingrowth in the screw channels cannot be expected for several years after insertion. Osteolysis is a possible complication.

DOI： 10.1097/01.blo.0000195411.14364.f7

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

The number of stem designs for total hip arthroplasty is increasing, and occasionally design changes have yielded unexpected clinical results. At present, we are not able to clearly identify which parameter of the stem is most important, and the optimum value of many parameters. The goals of this study were to identify which parameter is most important, to understand the effect of design change, and to find the optimum stem shape. For this purpose, we used adaptive p-method together with three-dimensional computer-aided design software program for the design sensitivity analysis (DSA) and shape optimization of the stem. The results suggested that increasing the lateral and medial width of the distal cross-section together with decreasing the medial-lateral width and the medial radius of the distal cross-section from the default value would lead to a decrease in the largest maximum principal stress of the distal cement. The medial width of middle cross-section, however, was not so simple. The result of DSA suggested that decreasing this parameter from the default value decreased the stress in the distal cement, but the optimum shape was obtained by increasing this parameter. The method used in this study will assist our engineers and surgeons in the process of modifying and optimizing the stem design. (c) 2005 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jbiomech.2005.05.024

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

There have been few reports regarding midterm to long-term results of intertrochanteric varus osteotomy for treatment of hip dysplasia. We investigated 55 hips in 46 patients, with an average age at surgery of 32 years (range, 12-55 years), for an average followup of 17 years (range, 6-28 years). Preoperative osteoarthritis was Tonnis Grade 0 in seven hips, Grade I in 23 hips, Grade 2 in 21 hips, and Grade 3 in four hips. Preoperative anteroposterior radiographs of the 55 hips showed almost perfect congruency between the acetabulum and the femoral head with the hip in an abducted position. Excellent or good clinical results were obtained in 23 hips (42%). Using a Harris hip score less than 70 points or the time until additional surgery as the end point, the cumulative rates of survival were 81% at 10 years, 60% at 20 years, and 50% at 25 years. The clinical results of patients with Grade 0, 1, or 2 osteoarthritis, with good spherical femoral head and mild dysplasia, were acceptable; however, this osteotomy might not be indicated for patients with Grade 3 osteoarthritis or for those with severe acetabular dysplasia.

DOI： 10.1097/01.blo.0000152881.59724.39

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DOI： 10.1007/s00776-005-0906-8

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BRITISH EDITORIAL SOC BONE JOINT SURGERY  

We present the medium-term results of hybrid total hip arthroplasties using pre-coated stems with a second-generation cementing technique. The 128 hips in 111 patients (18 and 93 women) were followed up at a mean of 11 years after surgery. The mean age at time of surgery was 61 years. Both components of one hip were removed at ten months after surgery for infection. None of the other 127 femoral components showed possible, probable, or definite loosening at the most recent follow-up. Five acetabular components were revised for aseptic loosening, recurrent dislocation, or displacement of the polyethylene liner from the metal shell. The mean Harris hip score at follow-up was 84 points. A pre-coated femoral component with a second-generation cementing technique provides good clinical function and survival in the medium term.

DOI： 10.1302/0301-620X.87B3.15281

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Bone and Joint Surgery Inc.  

BACKGROUND: It is not clear whether a Chiari pelvic osteotomy performed for the treatment of advanced osteoarthritis can delay the need for total hip arthroplasty. We present the mid-term results of the Chiari pelvic osteotomy performed for the treatment of Tönnis grade-3 osteoarthritis (large cysts, severe narrowing of the joint space, or severe deformity or necrosis of the head with extensive osteophyte formation), with a particular focus on whether this procedure can delay the need for total hip arthroplasty. METHODS: We followed thirty-two hips in thirty-one patients with Tönnis grade-3 osteoarthritis who had refused total hip arthroplasty and had been treated with a Chiari pelvic osteotomy. The mean age at the time of surgery was 35.2 years. The mean duration of follow-up was 11.2 years, at which time clinical evaluation with the Harris hip score and radiographic evaluation were performed. RESULTS: The average Harris hip score improved from 52 points preoperatively to 77 points at the time of follow-up
the average pain score improved from 20 to 31 points. Three hips with a hip score of &lt
70 points required total hip arthroplasty. With a hip score of &lt
70 points as the end point, the cumulative rate of survival at ten years was 72%. The clinical outcome was significantly influenced by the preoperative center-edge angle (p = 0.004), the preoperative acetabular head index (p = 0.039), achievement of the appropriate osteotomy level (p = 0.011), and superior migration (p = 0.009) and lateral migration (p = 0.026) of the femoral head. CONCLUSIONS: Although the clinical results were inferior to those of total hip arthroplasty, Chiari pelvic osteotomy may be an option for young patients with advanced osteoarthritis who prefer a joint-conserving procedure to total hip arthroplasty and accept a clinical outcome that is predicted to be less optimal than that of total hip arthroplasty. Moderate dysplasia and moderate subluxation without complete obliteration of the joint space and a preoperative centeredge angle of at least 10° are desirable selection criteria. Copyright © 2005 by The Journal of Bone and Joint Surgery, Incorporated.

DOI： 10.2106/00004623-200509001-00005

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOURNAL BONE JOINT SURGERY INC  

Background: It is not clear whether a Chiari pelvic osteotomy performed for the treatment of advanced osteoarthritis can delay the need for total hip arthroplasty. We present the mid-term results of the Chiari pelvic osteotomy performed for the treatment of Tonnis grade-3 osteoarthritis (large cysts, severe narrowing of the joint space, or severe deformity or necrosis of the head with extensive osteophyte formation), with a particular focus on whether this procedure can delay the need for total hip arthroplasty.
Methods: We followed thirty-two hips in thirty-one patients with Tonnis grade-3 osteoarthritis who had refused total hip arthroplasty and had been treated with a Chiari pelvic osteotomy. The mean age at the time of surgery was 35.2 years. The mean duration of follow-up was 11.2 years, at which time clinical evaluation with the Harris hip score and radiographic evaluation were performed.
Results: The average Harris hip score improved from 52 points preoperatively to 77 points at the time of follow-up; the average pain score improved from 20 to 31 points. Three hips with a hip score of <70 points required total hip arthroplasty. With a hip score of <70 points as the end point, the cumulative rate of survival at ten years was 72%. The clinical outcome was significantly influenced by the preoperative center-edge angle (p = 0.004), the preoperative acetabular head index (p = 0.039), achievement of the appropriate osteotomy level (p = 0.011), and superior migration (p = 0.009) and lateral migration (p = 0.026) of the femoral head.
Conclusions: Although the clinical results were inferior to those of total hip arthroplasty, Chiari pelvic osteotomy may be an option for young patients with advanced osteoarthritis who prefer a joint-conserving procedure to total hip arthroplasty and accept a clinical outcome that is predicted to be less optimal than that of total hip arthroplasty. Moderate dysplasia and moderate subluxation without complete obliteration of the joint space and a preoperative center-edge angle of at least -10degrees are desirable selection criteria.
Level of Evidence: Therapeutic study, Level IV (case series [no, or historical, control group]). See Instructions to Authors for a complete description of levels of evidence.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

The purpose of the current study was to determine whether stress fractures and shin splints could be discriminated with MRI in the early phase. Twenty-two athletes, who had pain in the middle or distal part of their leg during or after sports activity, were evaluated with radiographs and MRI scans. Stress fractures were diagnosed when consecutive radiographs showed local periosteal reaction or a fracture line, and shin splints were diagnosed in all the other cases. In all eight patients with stress fractures, an abnormally wide high signal in the localized bone marrow was the most detectable in the coronal fat-suppressed MRI scan. In 11. patients with shin splints, the coronal fat-suppressed MRI scans showed a linear abnormally high signal along the medial posterior surface of the tibia, and in seven patients with shin splints, the MRI scans showed a linear abnormally high signal along the medial bone marrow. No MRI scans of shin splints showed an abnormally wide high signal in the bone marrow as observed on MRI scans of stress fractures. This study showed that fat-suppressed MRI is useful for discrimination between stress fracture and shin splints before radiographs show a detectable periosteal reaction in the tibia.

DOI： 10.1097/01.blo.0000126333.13806.87

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We describe two patients with a constrained acetabular component who required treatment for recurrent dislocation showing postoperative periprosthetic acetabular bone loss. These hips required revision surgery and demonstrated considerable bone loss caused by the migrated acetabular component. Impingement may have occurred with increased stress at the bone-prosthesis interface, and the sharp ends of screws with a metal shell may have gradually plowed up the acetabular bone. These failures illustrate the potential risk of using a constrained acetabular component.

DOI： 10.1007/s00402-003-0611-z

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

We evaluated intermediate-term results of primary cementless Omniflex prostheses. Forty-nine patients (57 hips) with a mean age of 44 years were observed for an average of 8.6 years. The average Harris hip score was 46 points before surgery and 87 points at final followup. Revision was done in five hips (9%) in five patients. Two acetabular components (4%) were revised because of breakage of the polyethylene insert. Three femoral components (5%) were revised because of aseptic loosening. Six femoral components (10%) were radiographically loose. Overall, 11 hips (19%) were considered mechanical failures. Osteolysis was identified around three acetabular components (5%) and around 20 femoral components (35%). Nine hips (16%) had femoral osteolysis around the distal stem tip. The average annual polyethylene liner wear was 0.18 mm. These results were inferior to those using other recent cementless total hip systems.

DOI： 10.1097/01.blo.0000093011.90435.38

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOURNAL BONE JOINT SURGERY INC  

Background: In recent studies, good intermediate-term results have been reported after primary hybrid total hip arthroplasty (a cementless acetabular component with a cemented femoral stem) for the treatment of primary osteoarthritis. However, few studies have described the results of this technique in patients with developmental dysplasia of the hip.
Methods: One hundred primary hybrid total hip replacements were performed in ninety patients to treat degenerative arthritis of the hip secondary to developmental dysplasia. Seventy-one patients (eighty-one hips) were available for clinical and radiographic evaluation. The average duration of follow-up was 10.6 years. There were ten men and sixty-one women. Seventy hips were classified as type 1 (dysplasia); seven, as type 2 (low dislocation); and four, as type 3 (high dislocation), according to the classification system of Hartofilakidis et al.
Results: At the time of the final follow-up, the average Harris hip score was 86 points. Structural autograft was used in fifteen hips to supplement acetabular coverage. Within five years postoperatively, the acetabular component in six of the fifteen hips had an average of 4.5 mm of vertical migration and an average increase in vertical rotation of 30, but the position appeared to stabilize thereafter. Revisions were performed in two hips because of recurrent dislocation. No acetabular or femoral component was revised because of aseptic loosening. Osteolysis was identified around two acetabular components and two femoral components. The average rate of polyethylene wear was 0.09 mm per year.
Conclusions: Hybrid total hip arthroplasty for the treatment of symptomatic degenerative arthritis secondary to developmental dysplasia provides favorable results at intermediate-term follow-up. With lower grades of dysplasia, the majority of patients can be treated effectively without a structural bone graft by placement of the cementless acetabular component at a medial or high position.
Level of Evidence: Therapeutic study, Level IV (case series [no, or historical, control group]). See Instructions to Authors for a complete description of levels of evidence.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BRITISH EDITORIAL SOC BONE JOINT SURGERY  

W e followed, prospectively, 77 patients (90 hips) with early-stage, non-traumatic osteonecrosis of the femoral head for a mean period of nine years. At the time of final review, 56 (62%) were symptomatic. Using the Cox model, the initial radiological stage, the progression of staging, the reduction in size of the lesions and the percentage of necrotic volume on MRI were identified as risk factors.
Using the Harris score of < 70 or surgery as the endpoint, the cumulative rates of survival were 60.0% at one year, 43.3 % at two years, 38.9 % at five years and 37.2% at ten years. Survival curves demonstrated that clinical deterioration could occur 90 months after the initial diagnosis, suggesting that asymptomatic patients should be followed carefully for several years. Radiological time-dependent reduction in size without progressive collapse may represent repair even when the collapse is minimal.

DOI： 10.1302/0301-620X.85B6.13794

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BRITISH EDITORIAL SOC BONE JOINT SURGERY  

W e present the mid- to long-term results of the Chiari pelvic osteotomy for dysplastic hips. We followed 135 hips in 129 patients, with a mean age at the time of surgery of 24 years, for a mean of 16.2 years. We used the anterior iliofemoral approach without trochanteric osteotomy in the initial 31 hips. Thereafter, we used transtrochanteric approaches in an attempt to ensure that the osteotomy was at the most appropriate level, and to advance the high-riding greater trochanter distally. The next 79 hips therefore underwent a posterolateral approach and the most recent 25 hips an Ollier lateral U approach. The clinical result was excellent or good in 103 hips (77 %). The outcome in 104 hips in which we used a transtrochanteric approach was superior, the osteotomy level was more appropriate and a Trendelenburg gait less common than in 31 hips in which we used an anterior approach. We therefore recommend the use of a transtrochanteric approach in order to ensure that the osteotomy is at an appropriate level and in order to achieve effective distal advancement of the high-riding greater trochanter.

DOI： 10.1302/0301-620X.85B2.13325

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHURCHILL LIVINGSTONE INC MEDICAL PUBLISHERS  

Eighty-three consecutive revisions in 74 patients using a porous-coated acetabular component without bulk bone graft were followed up for an average of 9.3 years (range, 5-13 years). A large-diameter cup was implanted in hips with adequate osseous support, and a high hip center technique using a standard- or smaller-diameter cup was selected in hips without sufficient bone stock. Acetabular bone deficiency was segmental in 18 hips, cavitary in 30, and combined segmental and cavitary in 35. Four (5%) cups were revised again; I for infection, I for dislodgement of the polyethylene liner from the metal shell, and 2 for recurrent dislocation. No acetabular components were categorized as definitely loose at final follow-up. The current satisfactory results encourage the use of this simple technique.

DOI： 10.1054/arth.2003.50029

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：American Society of Mechanical Engineers (ASME)  

A multiobjective optimization was used to solve several failure problems of cemented total hip arthroplasty. The objective functions were three
the principal stress in the bone cement, the shear stress of stem/cement interface and cement/bone interface. In the results, the cement stress was reduced by 49%, the stem-cement stress was reduced by 68%, and the cement-bone stress was reduced by 43%, compared with the basic model.

DOI： 10.1115/IMECE2003-41615

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS AS  

This study evaluated 68 consecutive hip osteotomies in 61 patients using absorbable poly-L-lactic acid screws for fixation. 47 hips underwent a rotational acetabular osteotomy, 17 hips Chiari's pelvic osteotomy, and 4 hips transtrochanteric rotational osteotomy. Cortical screws were used to transfix the osteotomized acetabulum, and cancellous screws to reattach the intraoperatively osteotomized greater trochanter. The average age at surgery was 35 (12-49) years. The mean duration of follow-up was 32 (18-46) months. All the osteotomized acetabulums united well, but 4 of 54 trochanteric osteotomies failed to unite.

DOI： 10.1080/000164702317281422

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHURCHILL LIVINGSTONE INC MEDICAL PUBLISHERS  

This study evaluated the sphericity of bearing surfaces ill total hip arthroplasty. The out-of-roundness of metal femoral heads, the inner surface of polyethylene liners, and commercially available ball hearings was measured. The hip prostheses were obtained directly from the manufacturers. The sphericity of the bearing surfaces was significantly inferior to that of the ball bearings. The sphericity of the femoral head on the sagittal plane was inferior to that oil the transverse plane. Several significant differences were found among different manufacturers. The sphericity of the femoral head on the sagittal plane and that of polyethylene significantly improved in 1999 and 2000 compared with those in 1995. Further improvement is desirable, however, because good sphericity is expected to prolong the functional performance of the prosthesis after total hip arthroplasty.

DOI： 10.1054/arth.2001.27673

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHURCHILL LIVINGSTONE INC MEDICAL PUBLISHERS  

Use of a constrained acetabular component is I option for the treatment of dislocation after total hip arthroplasty. We report a case of a constrained acetabular component that resulted in postoperative early fixation loss and required revision 12 days after primary surgery. The superoposterior wall of the acetabulum was destroyed by the migrated acetabular component. Sharp ends of screws with a metal shell may have plowed up acetabular bone gradually after fixation loss of the component. This failure illustrates the potential risk of using a constrained acetabular component for total hip arthroplasty.

DOI： 10.1054/arth.2001.26595

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

The authors introduce a technique of proximal femoral osteotomy using three-dimensionally corrective external fixator systems for treatment of Legg-Calve-Perthes disease and slipped capital femoral epiphysis, and describe the results of 47 hips in 44 children. Postoperative casting immobilization was not performed. All osteotomies gained the correction angle as planned. All osteotomies healed with no nonunions, malunions, device failures, or avascular necrosis. Complications occurred iri 7 (15%) of 47 hips. Pin tract infection occurred in six (13%) hips; one of these (2%) needed debridement. The bulky external fixator caused slight inconvenience, but the current results indicate that the proximal femoral osteotomy using the external fixator system provided an easily repeatable intraoperative varus/valgus and flexion/extension correction compared with other internal fixation devices, and sufficient fixation for children without significant complications.

DOI： 10.1097/00004694-200109000-00019

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

This study evaluated middle-term clinical and radiographic results of Salter innominate osteotomy for treatment of dysplastic, subluxated, or congenitally dislocated hips. Thirty-five hips in 33 patients with a mean age at index surgery of 4 years 7 months were followed up for an average of 16.5 years. Radiographic center-edge angle of Wiberg, acetabular index, and regularity of the femoral head were evaluated. Fifteen (43%) hips were in Group I, 11 (31%) hips were in Group II, six (17%) hips were in Group III, and three (9%) hips were in Group IV according to the Severin classification. Significant differences were found in the preoperative and recent center-edge angle (average, 1.1 degrees and 28.8 degrees in the excellent and good groups versus -5.3 degrees and 15.0 degrees in the fair and poor groups) and regularity of the femoral head (very irregular versus others). The current results indicate that after middle-term followup, Salter innominate osteotomy is an effective treatment, The authors conclude this procedure is indicated in patients who meet the criteria proposed by Salter.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

This study evaluated clinical and radiographic results of bipolar hemiarthroplasties for the treatment of osteonecrosis of the femoral head. Forty-eight hips in 35 patients with a mean age of 37 years who underwent primary bipolar hemiarthroplasties were observed for an average of 11.4 years. Osteonecrosis was associated with corticosteroid use (21 patients), alcohol (six patients), idiopathic (four patients), and other conditions (four patients), The average Harris hip score was 46 before surgery and 86 at the time of the final followup, Twenty (42%) hips were radiographic failures, and 12 (25%) hips were revised. Groin symptoms were present in 20 (42%) hips. Radiographic proximal migration greater than 4 mm and osteoarthritic signs of the acetabulum indicated a high risk of groin symptoms. The results were inferior to those previously reported for total hip arthroplasty. Thus, for the treatment of osteonecrosis of the femoral head in which necrotic lesions are wide, the authors no longer use this system and currently use total hip arthroplasty.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHURCHILL LIVINGSTONE INC MEDICAL PUBLISHERS  

For the purpose of reduction of polyethylene wear generated in artificial hip joints, concave dimples were formed on the surface of the metal femoral head by electrical discharge etching with the constant diameter of 0.5 mm. pitch of 1.2 inm, and depth of 0.1 mm. Using a hip joint simulator the total amount of polyetylene wear was 7.2 mg in the concave-patterned condition and 23.1 mg in the nonpatterned condition. The reasons for the reduction of polyethylene wear by the concave pattern may be i) a reduction of abrasive wear by providing escape dimples for wear particles and ii) an improvement in the lubricity on the frictional surface by Lire supply of lubricant that is stored in dimples.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BRITISH EDITORIAL SOC BONE JOINT SURGERY  

We present the long-term results of simple varus intertrochanteric osteotomy for osteonecrosis of the femoral head. We followed 26 hips in 20 patients, with a mean age at the time of surgery of 36 years, for a mean of 12.5 years. The mean varus angulation was 23 degrees.
The outcome in 19 of the hips (73%) was good or excellent; seven (27%) had a fair or poor result, with four needing some form of prosthetic arthroplasty.
Simple varus intertrochanteric osteotomy is indicated, even if the extent of the capital infarct comprises more than 50% of the diameter of maximum radial distance from the circumference, provided that after operation the medial necrotic lesion measures less than two-thirds of the weightbearing area, and the superolateral bone is normal.

DOI： 10.1302/0301-620X.81B6.10037

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Seventy-two femoral heads in 63 patients in Seventy-two femoral heads in 63 patients in whom avascular necrosis of the femoral head was in the early stage were followed up prospectively for a mean period of 6 years 1 month. All of the necrotic lesions were confirmed by magnetic resonance imaging. At the time of final outcome, 46 (64%) of the 72 hips were symptomatic. Necrotic lesions greater than 2/3 of the weightbearing portion on T1 weighted central coronal images indicated a high risk of clinical deterioration. Fifty-nine of the 72 hips initially had necrotic lesions greater than 2/3 of the weightbearing portion, and 44 (75%) of these 59 hips were symptomatic at the final outcome. However, in the radiographic assessment of 15 (25%) asymptomatic hips, even when the necrotic lesions were greater than 2/3 of the weightbearing portion as shown by magnetic resonance imaging, the continuous absence of any radiographic abnormality indicated the possibility of a continuous asymptomatic stage for at least several years.

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Language：Japanese   Publisher：東日本整形災害外科学会  

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Authorship：Lead author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)   Publisher：アークメディア  

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Language：English   Publisher：JOURNAL BONE JOINT SURGERY INC  

Background: It is not clear whether a Chiari pelvic osteotomy performed for the treatment of advanced osteoarthritis can delay the need for total hip arthroplasty. We present the mid-term results of the Chiari pelvic osteotomy performed for the treatment of Tonnis grade-3 osteoarthritis (large cysts, severe narrowing of the joint space, or severe deformity or necrosis of the head with extensive osteophyte formation), with a particular focus on whether this procedure can delay the need for total hip arthroplasty.
Methods: We followed thirty-two hips in thirty-one patients with Tonnis grade-3 osteoarthritis who had refused total hip arthroplasty and had been treated with a Chiari pelvic osteotomy. The mean age at the time of surgery was 35.2 years. The mean duration of follow-up was 11.2 years, at which time clinical evaluation with the Harris hip score and radiographic evaluation were performed.
Results: The average Harris hip score improved from 52 points preoperatively to 77 points at the time of follow-up; the average pain score improved from 20 to 31 points. Three hips with a hip score of <70 points required total hip arthroplasty. With a hip score of <70 points as the end point, the cumulative rate of survival at ten years was 72%. The clinical outcome was significantly influenced by the preoperative center-edge angle (p = 0.004), the preoperative acetabular head index (p = 0.039), achievement of the appropriate osteotomy level (p = 0.011), and superior migration (p = 0.009) and lateral migration (p = 0.026) of the femoral head.
Conclusions: Although the clinical results were inferior to those of total hip arthroplasty, Chiari pelvic osteotomy may be an option for young patients with advanced osteoarthritis who prefer a joint-conserving procedure to total hip arthroplasty and accept a clinical outcome that is predicted to be less optimal than that of total hip arthroplasty. Moderate dysplasia and moderate subluxation without complete obliteration of the joint space and a preoperative center-edge angle of at least -10degrees are desirable selection criteria.
Level of Evidence: Therapeutic study, Level IV (case series [no, or historical, control group]). See Instructions to Authors for a complete description of levels of evidence.

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Authorship：Lead author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)   Publisher：メジカルビュー社  

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Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)   Publisher：メジカルビュー社  

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Language：English   Publisher：SPRINGER-VERLAG  

We describe two patients with a constrained acetabular component who required treatment for recurrent dislocation showing postoperative periprosthetic acetabular bone loss. These hips required revision surgery and demonstrated considerable bone loss caused by the migrated acetabular component. Impingement may have occurred with increased stress at the bone-prosthesis interface, and the sharp ends of screws with a metal shell may have gradually plowed up the acetabular bone. These failures illustrate the potential risk of using a constrained acetabular component.

DOI： 10.1007/s00402-003-0611-z

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Language：English   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

We evaluated intermediate-term results of primary cementless Omniflex prostheses. Forty-nine patients (57 hips) with a mean age of 44 years were observed for an average of 8.6 years. The average Harris hip score was 46 points before surgery and 87 points at final followup. Revision was done in five hips (9%) in five patients. Two acetabular components (4%) were revised because of breakage of the polyethylene insert. Three femoral components (5%) were revised because of aseptic loosening. Six femoral components (10%) were radiographically loose. Overall, 11 hips (19%) were considered mechanical failures. Osteolysis was identified around three acetabular components (5%) and around 20 femoral components (35%). Nine hips (16%) had femoral osteolysis around the distal stem tip. The average annual polyethylene liner wear was 0.18 mm. These results were inferior to those using other recent cementless total hip systems.

DOI： 10.1097/01.blo.0000093011.90435.38

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Authorship：Lead author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)   Publisher：先端医学社  

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Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)   Publisher：日本股関節学会  

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Language：English   Publisher：JOURNAL BONE JOINT SURGERY INC  

Background: In recent studies, good intermediate-term results have been reported after primary hybrid total hip arthroplasty (a cementless acetabular component with a cemented femoral stem) for the treatment of primary osteoarthritis. However, few studies have described the results of this technique in patients with developmental dysplasia of the hip.
Methods: One hundred primary hybrid total hip replacements were performed in ninety patients to treat degenerative arthritis of the hip secondary to developmental dysplasia. Seventy-one patients (eighty-one hips) were available for clinical and radiographic evaluation. The average duration of follow-up was 10.6 years. There were ten men and sixty-one women. Seventy hips were classified as type 1 (dysplasia); seven, as type 2 (low dislocation); and four, as type 3 (high dislocation), according to the classification system of Hartofilakidis et al.
Results: At the time of the final follow-up, the average Harris hip score was 86 points. Structural autograft was used in fifteen hips to supplement acetabular coverage. Within five years postoperatively, the acetabular component in six of the fifteen hips had an average of 4.5 mm of vertical migration and an average increase in vertical rotation of 30, but the position appeared to stabilize thereafter. Revisions were performed in two hips because of recurrent dislocation. No acetabular or femoral component was revised because of aseptic loosening. Osteolysis was identified around two acetabular components and two femoral components. The average rate of polyethylene wear was 0.09 mm per year.
Conclusions: Hybrid total hip arthroplasty for the treatment of symptomatic degenerative arthritis secondary to developmental dysplasia provides favorable results at intermediate-term follow-up. With lower grades of dysplasia, the majority of patients can be treated effectively without a structural bone graft by placement of the cementless acetabular component at a medial or high position.
Level of Evidence: Therapeutic study, Level IV (case series [no, or historical, control group]). See Instructions to Authors for a complete description of levels of evidence.

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Language：English   Publisher：BRITISH EDITORIAL SOC BONE JOINT SURGERY  

W e followed, prospectively, 77 patients (90 hips) with early-stage, non-traumatic osteonecrosis of the femoral head for a mean period of nine years. At the time of final review, 56 (62%) were symptomatic. Using the Cox model, the initial radiological stage, the progression of staging, the reduction in size of the lesions and the percentage of necrotic volume on MRI were identified as risk factors.
Using the Harris score of < 70 or surgery as the endpoint, the cumulative rates of survival were 60.0% at one year, 43.3 % at two years, 38.9 % at five years and 37.2% at ten years. Survival curves demonstrated that clinical deterioration could occur 90 months after the initial diagnosis, suggesting that asymptomatic patients should be followed carefully for several years. Radiological time-dependent reduction in size without progressive collapse may represent repair even when the collapse is minimal.

DOI： 10.1302/0301-620X.85B6.13794

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Authorship：Lead author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)   Publisher：メジカルビュー社  

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