Risk factors for subchondral insufficiency fracture of the femoral head in renal transplant patients.

INTRODUCTION: Risk factors associated with subchondral insufficiency fracture (SIF) of the femoral head have not been established. The aim of the present study was to determine the incidence and risk factors for SIF of the femoral head following renal transplantation (RT). MATERIALS AND METHODS: We analyzed the cases of 681 RT patients (mean age at surgery: 49.5 ± 13.6 years, 249 women, 432 men) to determine the incidence of SIF. Hip magnetic resonance imaging (MRI) was performed 6 months post-RT. The following potential predictors of SIF were evaluated: (1) patient's condition at RT: bone mineral density (BMD), pre-RT laboratory values including calcium (Ca), phosphorus (P), calcium-phosphorus product (Ca × P), and intact parathyroid hormone; the patient and donor's blood relationship; and mismatching number of human leukocyte antigens (HLAs), and (2) post-RT dosage(s) of steroid(s), the immunosuppressive regimen, and the incidence of acute rejection. RESULTS: SIF was observed in 15 hips (13 patients, 1.9%). We successfully matched 39 patients without SIF. A multivariate logistic regression analysis adjusted for cumulative dosages of steroids, revealed the following were risk factors for SIF: osteoporosis (OR: 11.4, p = 0.046), lumbar BMD (OR: 0.003, p = 0.038), pre-RT serum P (OR 2.68, p = 0.004), and pre-RT serum Ca × P (OR: 1.11, p = 0.005). CONCLUSION: Since osteoporosis, the lumbar BMD, serum P, and serum Ca × P were identified as risk factors for a post-RT SIF, these factors should be evaluated before RT for the prediction of the SIF risk.

Effects of additional neck cut of the femur on the range of motion in total hip arthroplasty for hip dislocation: a computer simulation study.

BACKGROUND: Subtrochanteric shortening osteotomy (SSO) is commonly performed in total hip arthroplasty (THA) for high hip dislocation. However, this procedure is technically difficult and includes complications. Additional neck cut (ANC) of the femur is a procedure that involves femoral shortening by possibly eliminating the need for SSO in THA for high hip dislocation. Herein, we evaluated the effect and the depth limit of ANC of the femur on the range of motion (ROM) in THA for high hip dislocation. METHODS: ROM was measured in 26 patients with high hip dislocation using computer software. The stem was deeply positioned at 5-mm intervals from 0 mm to 30 mm (7 groups). The ROM before impingement was measured during flexion, internal rotation (IR) at 90° flexion, external rotation (ER) and abduction. Receiver operator coefficient (ROC) curves for abduction were generated. The cut-off value of ANC where the required ROM was achieved was also determined. RESULTS: Deeper ANCs increased the ROM values during flexion and IR, but they decreased the ROM values during ER and abduction. The ROM values during ER were also limited in 0-mm ANCs. According to the result of the ROC curve for abduction, 15 mm was considered as the permissible range of ANC. CONCLUSIONS: In THA for high hip dislocation additional neck cut should be taken into consideration for hips requiring less than 15-mm shortening. For more extended corrections a subtrochanteric shortening osteotomy should be performed.

Short-range UV-LED irradiation in postmenopausal osteoporosis using ovariectomized mice.

Postmenopausal osteoporosis is crucial condition that reduces the QOL of affected patients just like aged type osteoporosis. The aim of this study was to evaluate the effectiveness of short-range UV-LED irradiation in postmenopausal osteoporosis using ovariectomized mice. Preliminary experiments identified the time of onset of osteoporosis after ovariectomy (8 weeks) in our model. We have set up a total of 4 groups (n = 8/group); vitamin D-repletion with UV irradiation (Vit.D+UV+), vitamin D-repletion without UV irradiation (Vit.D+UV-), vitamin D-deficiency with UV irradiation (Vit.D-UV+), vitamin D-deficiency without UV irradiation (Vit.D-UV-), and. From 8 weeks after ovariectomy, UV was irradiated for 24 weeks. At the time of 16 and 24 weeks' irradiation, serum Vit.D levels, various markers of bone metabolism, bone mineral density, and bone strength were evaluated, and histological analyses were performed. In addition, muscle strength was analyzed. Serum 25-hydroxyvitamin D [25 (OH) D] levels at 40 and 48 weeks of age were increased in the Vit.D-UV+ group compared to the Vit.D-UV-group. Cortical thickness evaluated with micro-CT and strength of bone were significantly higher in Vit.D-UV+ group than those in Vit.D-UV- group. There was no difference in muscle strength between Vit.D-UV+ group and Vit.D-UV- group. No obvious adverse effects were observed in UV-irradiated mice including skin findings. Short-range UV irradiation may ameliorate postmenopausal osteoporosis associated with a state of vitamin D deficiency.

Low energy irradiation of narrow-range UV-LED prevents osteosarcopenia associated with vitamin D deficiency in senescence-accelerated mouse prone 6.

Deficiency of vitamin D is an important cause of osteosarcopenia. The purpose of this study is to examine the effects of low energy narrow-range UV-LED on osteosarcopenia in animal models of senescence-accelerated mouse prone 6 (SAMP6). Preliminary experiments specified the minimum irradiance intensity and dose efficacy for vitamin D production (316 nm, 0.16 mW/cm2, 1,000 J/m2). we set a total of 4 groups (n = 8 per group); vitamin D-repletion without UV irradiation (Vit.D+UV-), vitamin D-repletion with UV irradiation (Vit.D+UV +), vitamin D-deficiency without UV irradiation, (Vit.D-UV-), and vitamin D-deficiency with UV irradiation (Vit.D-UV +). Serum levels of 25(OH)D at 28 and 36 weeks of age were increased in Vit.D-UV+ group as compared with Vit.D-UV- group. Trabecular bone mineral density on micro-CT was higher in Vit.D-UV+ group than in Vit.D-UV- group at 36 weeks of age. In the histological assay, fewer osteoclasts were observed in Vit.D-UV+ group than in Vit.D-UV- group. Grip strength and muscle mass were higher in Vit.D-UV+ group than in Vit.D-UV- group at 36 weeks of age. Signs of severe damage induced by UV irradiation was not found in skin histology. Low energy narrow-range UV irradiation may improve osteosarcopenia associated with vitamin D deficiency in SAMP6.

Incidence and risk factors for osteonecrosis of the hip in renal transplant patients: a prospective single-centre study.

BACKGROUND: There is a lack of evidence about the risk factors associated with osteonecrosis of the femoral head (ONFH). PURPOSES: To determine the incidence and risk factors for ONFH following renal transplantation (RT). METHODS: In total, data of 681 RT patients (mean age at surgery, 49.5 ± 13.6 years; 249 women and 432 men) were evaluated to determine the incidence of ONFH. Hip magnetic resonance imaging (MRI) was performed six months after RT. The following potential predictors of ONFH were evaluated: (1) patient's condition at RT; laboratory test results including calcium (Ca), phosphorus (P), calcium-phosphorus product (Ca × P), and intact parathyroid hormone before RT; blood relationship between the patient and donor; and mismatching number of human leukocyte antigens (HLAs), especially HLA class I and class II and (2) dosages of steroids after RT, immunosuppressive regimen, and incidence of acute rejection. RESULTS: ONFH was observed in 30 hips (21 cases, 3.1%). We successfully matched 63 patients without ONFH. Multivariate logistic regression analysis, adjusted for cumulative dosages of steroids, revealed that mismatching number of HLA (hazard ratio [HR], 1.61; 95% confidence interval [CI], 1.10-2.36; p = 0.014), HLA class II (HR, 3.73; 95% CI, 1.46-9.56; p = 0.001), P before RT (HR, 1.62; 95% CI, 1.02-2.58; p = 0.041), and Ca × P  before RT (HR, 1.06; 95% CI, 1.01-1.11; p = 0.024) were risk factors for ONFH. CONCLUSION: A greater number of HLA mismatches, HLA class II, serum P, and serum Ca × P were risk factors for ONFH after RT. Therefore, these factors should be evaluated in order to predict ONFH after RT.

Effects of ultraviolet irradiation with a LED device on bone metabolism associated with vitamin D deficiency in senescence-accelerated mouse P6.

AIMS: This study investigated effects of narrow-range ultraviolet irradiation (UVR) by a new UV-LED device on vitamin D supply and changes of bone in senescence-accelerated mouse P6 (SAMP6) with vitamin D deficiency. MAIN METHODS: We used female SAMP6 mice as a senile osteoporotic model. We set a total of 3 groups (n = 4 per group); D-UVR+ group (vitamin D deficient-dietary and UVR), D- (vitamin D deficient-dietary), and D+ groups (vitamin D contained-dietary). Mice in the D-UVR + group were UV-irradiated (305nm) with 1 kJ/m2 twice a week for 12 weeks from 20 to 32 weeks of age. Serum 25(OH)D, 1,25(OH)2D, and micro-computed tomography (CT) were assessed over time. Mechanical test, and histological assay were performed for femurs removed at 32 weeks of age. KEY FINDINGS: UVR increased both serum 25(OH)D and 1,25(OH)2D levels at 4 and 8 weeks-UVR in the D-UVR+ group compared with that in the D- group (P < 0.05, respectively). Relative levels of trabecular bone mineral density in micro-CT were higher in the D-UVR+ group than in the D- group at 8 weeks-UVR (P = 0.048). The ultimate load was significantly higher in the D-UVR+ group than in the D- group (P = 0.036). In histological assay, fewer osteoclasts and less immature bone (/mature bone) could be observed in the D-UVR+ group than in the D- group, significantly. SIGNIFICANCE: UVR may have possibility to improve bone metabolism associated with vitamin D deficiency in SAMP6 mice.

Measurement of equivalence between the web and paper versions of the Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire.

Objectives: Digitised patient-reported outcome may be beneficial for physicians and patients. The Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ) can only be completed with paper and pencil (pJHEQ). We newly developed a web version of the JHEQ (wJHEQ). This study aimed to determine whether the scores obtained with the wJHEQ are equivalent to those from the pJHEQ, how much the wJHEQ would decrease missing answers, and which JHEQ the participants preferred to use.Methods: To measure equivalence between the pJHEQ and wJHEQ, we evaluated the mean score difference for each subscale (pain, movement, mental) and Visual Analogue Scale (VAS; satisfaction, right hip pain, left hip pain) and then assessed the intraclass correlation coefficients (ICC) between the two scores. ICC values ≥0.75 were defined as excellent agreement. We used Bland-Altman analysis to assess level of agreement between the values of the two questionnaires. We compared the number of incomplete forms and amount of missing data between the two questionnaires. We investigated ease of use by asking the participants which format was easier to use.Results: This study comprised 113 patients (mean age 58.1 years, 81% female) with hip disease. Mean score differences for each subscale between the wJHEQ and pJHEQ were not significantly different. The values of ICC for each subscale and each VAS were all >0.75. All 113 participants completed the wJHEQ questionnaire, whereas nine patients did not complete the pJHEQ form. There was a significant statistical difference between the completion rate of the wJHEQ and that of the pJHEQ (p = .0017). Fifty-seven participants (55%) preferred the wJHEQ, whereas 33 participants (32%) preferred the pJHEQ.Conclusion: The wJHEQ was found to be equivalent to the original pJHEQ. The wJHEQ significantly decreased the numbers of missing answers and incomplete forms. The participants felt ease of use was nearly equivalent. The wJHEQ might help facilitate more complete assessments in clinical trials and research.

Comparison of Wear Rate between Ceramic-on-Ceramic, Metal on Highly Cross-linked Polyethylene, and Metal-on-Metal Bearings.

Objective Currently, there is a lack of evidence on the medium-term follow-up of cementless total hip arthroplasty (THA) using metal on highly cross-linked polyethylene (MoP), ceramic-on-ceramic (CoC), and metal-on-metal (MoM) bearings. Our aim was to calculate the 5- to 10-year wear rate and the incidence rate of osteolysis for 3 types of bearings. Methods A total of 77 patients underwent MoP, 105 underwent ceramic CoC, and 55 underwent MoM THAs. The average patient age at the time of surgery was 64.7, 55.9, and 59.9 years old in the MoP, CoC, and MoM bearings, respectively. Clinical and radiologic measurements at a mean follow-up of 7.6 years were analyzed. Results The mean postoperative Harris hip scores showed no difference among the groups. The mean annual liner wear rates were 0.0160, 0.0040 and 0.0054 mm/year in MoP, CoC bearings, and MoM bearings, with that of CoC bearings being significantly lower than the others. Osteolysis (14.5%) among MoM bearings was significantly more frequently observed compared with the others. Kaplan-Meier survival at 10 years with implant loosening, or revision THA as the endpoint, was 96.1% (95% confidence interval [CI]: 88.4-98.7) for MoP, 98.6% (95% CI: 90.3-98.6) for CoC bearing, and 98.2% (95% CI: 88.0-99.7) for MoM bearings ( p = 0.360). Conclusion Excellent clinical and radiological outcomes were obtained for MoP and CoC bearings.

Comparison of Wear Rate between Ceramic-on- Ceramic, Metal on Highly Cross-linked Polyethylene, and Metal-on-Metal Bearings / Comparação da taxa de desgaste entre componentes de cerâmica sobre cerâmica, de metal sobre polietileno de alta ligação cruzada e de metal sobre metal

Abstract Objective Currently, there is a lack of evidence on the medium-term follow-up of cementless total hip arthroplasty (THA) using metal on highly cross-linked polyethylene (MoP), ceramic-on-ceramic (CoC), and metal-on-metal (MoM) bearings. Our aim was to calculate the 5- to 10-year wear rate and the incidence rate of osteolysis for 3 types of bearings. Methods A total of 77 patients underwent MoP, 105 underwent ceramic CoC, and 55 underwent MoM THAs. The average patient age at the time of surgery was 64.7, 55.9, and 59.9 years old in the MoP, CoC, and MoM bearings, respectively. Clinical and radiologic measurements at a mean follow-up of 7.6 years were analyzed. Results The mean postoperative Harris hip scores showed no difference among the groups. The mean annual liner wear rates were 0.0160, 0.0040 and 0.0054 mm/year in MoP, CoC bearings, and MoM bearings, with that of CoC bearings being significantly lower than the others. Osteolysis (14.5%) among MoM bearings was significantly more frequently observed compared with the others. Kaplan-Meier survival at 10 years with implant loosening, or revisionTHA as the endpoint, was 96.1% (95% confidence interval [CI]: 88.4-98.7) forMoP, 98.6% (95% CI: 90.3-98.6) for CoC bearing, and 98.2% (95% CI: 88.0-99.7) for MoM bearings (p = 0.360). Conclusion Excellent clinical and radiological outcomes were obtained for MoP and CoC bearings.

Resumo Objetivo Hoje, não há evidências sobre o acompanhamento em médio prazo da artroplastia total do quadril (ATQ) não cimentada com componentes de polietileno de alta ligação cruzada (highly cross-linked) sobre metal (MoP, na sigla em inglês), de cerâmica sobre cerâmica (CoC, na sigla em inglês), e de metal sobre metal (MoM, na sigla eminglês). Nosso objetivo foi calcular a taxa de desgaste entre 5 a 10 anos e a taxa de incidência de osteólise nos 3 tipos de componentes. Métodos Um total de 77 pacientes foram submetidos a ATQ com componentes de MoP; 105 foram submetidos ao mesmo procedimento com componentes de CoC, e 55 foram submetidos à ATQ com componentes de MoM. A média de idade dos pacientes no momento da cirurgia foi de 64,7, 55,9 e 59,9 anos nos grupos de componentes MoP, de CoC, e de MoM, respectivamente. Asmedidas clínicas e radiológicas emumperíodo médio de acompanhamento de 7,6 anos foram analisadas. Resultados As pontuações médias de Harris no período pós-operatório não mostraram diferença entre os grupos. As taxas médias anuais de desgaste do revestimento foram de 0,0160, 0,0040 e 0,0054 mm/ano em componentes de MoP, de CoC, e de MoP, respectivamente; a taxa de desgaste dos componentes de CoC foi significativamente menor do que as dos demais. A osteólise (14,5%) nos componentes de MoM foi significativamente mais frequente em comparação aos demais. A sobrevida de Kaplan- Meier aos 10 anos comafrouxamento do implante ou revisão da ATQ como desfecho foi de 96,1% (intervalo de confiança [IC] de 95%: 88,4-98,7) nos componentes de MoP, de 98,6% (IC95%: 90,3-98,6) nos componentes de CoC, e de 98,2% (IC95%: 88,0-99,7) nos componentes de MoM (p = 0,360). Conclusão Os resultados clínicos e radiológicos de componentes de MoP e de CoC foram excelentes.

Acetabular fracture non-union with pelvic discontinuity treated with two-stage total hip arthroplasty after intra- and extra-articular plate fixation.

Surgical intervention for the treatment of acetabular fracture non-union is often challenging. Here, we present a case of acetabular fracture non-union with pelvic discontinuity in a patient who underwent cemented total hip arthroplasty (THA) after intra- and extra-articular plate fixation. The case was a 70-year-old male with left T-shaped acetabular fracture non-union neglected for 5 months after the injury. The anterior and posterior columns were not healed, and the articular surface was displaced toward the medial side with a protrusion of the collapsed femoral head. As the first surgical intervention, we performed intra- and extra-articular plate fixation after femoral head decapitation. We fixed non-union regions from the inferior acetabular margin to the anterior column using a pelvic reconstruction plate bent three-dimensionally at the acetabular curvature on the intra-articular side. Furthermore, we fixed that of the posterior column on the outside of the acetabulum using a bent pelvic reconstruction plate. Union of the anterior and posterior columns was observed at 4 and 6 months after the first surgical intervention. At 7 months, we performed a cemented THA without additional bone grafting. At 1-year follow-up, the patient did not have left coxalgia and could walk without any gait supports. Based on our experience, we propose this surgical protocol as a useful treatment option for cases of acetabular fracture non-union.

What factors predict ceramic liner malseating after ceramic-on-ceramic total hip arthroplasty?

BACKGROUND: There is a lack of evidence about the risk factors associated with the malseating of the acetabular liner after ceramic-on-ceramic (CoC) total hip arthroplasty (THA). Therefore, we performed a complementary retrospective case-control study to determine the factors predicting the malseating of the acetabular liner after CoC THA and to evaluate the relationship between malseating and (1) osteoarthritis, (2) particularly in terms of the new radiographic parameter "bone sclerotic length" of the acetabular bone. HYPOTHESIS: Osteoarthritis, particularly bone sclerotic length, was an independent risk factor for malseating of ceramic liners. PATIENTS AND METHODS: In total, 219 CoC THAs (174 women and 45 men) were evaluated to determine the risk factors influencing the malseating of the acetabular ceramic liner. An average patient age at the time of surgery was 55.9±9.5 years (range, 23 to 75 years). Data on patient background and preoperative radiographs, such as Tönnis grades; Crowe classification; and indices of acetabular osteoarthritis change; including bone cyst, osteophyte and bone sclerosis, were assessed. The bone sclerotic length in patients with osteoarthritis was measured as the slant distance between the bilateral edges of the sclerosis lesion of the acetabulum on the anteroposterior view. RESULTS: Preoperative less hip flexion (hazard ratio [HR]: 0.98; 95% CI: 0.97-0.99), osteoarthritis (HR: 3.15; 95% CI: 1.02-9.70) and the bone sclerotic length (HR: 1.83; 95% CI: 1.35-2.48) were independent risk factors determining the malseating of ceramic liners. Receiver operating characteristic curve analysis showed that a bone sclerotic length of 24.6mm was defined as the cut-off point for the malseating of the ceramic liner. DISCUSSION: Age, preoperative less flextion, osteoarthritis, and the bone sclerotic were independent risk factors determining malseating of ceramic liners. The acetabular shell can also deform upon insertion of the cup with sclerotic bone of the acetabulum and prevent correct seating of liners. Therefore, these factors must be taken into consideration when seating the ceramic liner. LEVEL OF EVIDENCE: Case control study III, case control retrospective design.

32-mm ceramic-on-ceramic total hip arthroplasty versus 28-mm ceramic bearings: 5- to 15-year follow-up study.

INTRODUCTION:: This study aimed to compare the clinical and radiographic results of 28-mm ceramic-on-ceramic (CoC) total hip arthroplasty (THA) to those of 32-mm CoC during a 5- to 15-year follow-up period. METHODS:: 107 joints (95 women and 6 men) underwent 28-mm CoC, and 60 (49 women and 7 men) underwent 32-mm CoC. The average patient age at the time of surgery was 56.1 and 55.7 years in the 28-mm and 32-mm CoC groups, respectively. Clinical and radiologic measurements of all patients were analysed. RESULTS:: The mean preoperative Harris hip score (HHS) was similar in the 2 groups (28-mm, 58.9; and 32-mm, 58.5). However, at final follow-up, the mean HHS of the 32-mm CoC (91.8) was significantly better than that of the 28-mm CoC (88.2) ( p = 0.003), as were the ranges of motion (ROM) for flexion (98.3 ± 13.5° vs. 87.3 ± 19.3°, p < 0.001) and abduction (27.8 ± 14.9° vs. 22.1 ± 19.3°, p = 0.007). The mean wear rate was 0.0044 mm/year for the 28-mm CoC and 0.0044 mm/year for the 32-mm CoC. No ceramic fractures were found in the 2 groups. One joint in the 28-mm CoC (0.9%) required revision owing to progressive osteolysis. Kaplan-Meier survival at 10 years, with implant loosening or revision THA as the endpoint, was 98.3% for 28-mm CoC and 100% for 32-mm CoC ( p = 0.465). CONCLUSION:: There was no significant difference in ceramic-related complications between the 2 groups. Our study demonstrated that the 32-mm and 28-mm CoC are safe and are associated with good clinical outcomes.

Same survival but higher rate of osteolysis for metal-on-metal Ultamet versus ceramic-on-ceramic in patients undergoing primary total hip arthroplasty after 8 years of follow-up.

BACKGROUND: To avoid wear-induced osteolysis, ceramic-on-ceramic (CoC) and metal-on-metal (MoM) bearings have been developed. At present, there are no direct material related clinical comparisons between cementless total hip arthroplasty with CoC and MoM at more than 5-year follow-up. The bearing that is more likely to prevent osteolysis is still controversial. Therefore, we performed a retrospective case control study evaluating CoC and MoM cementless THAs in order to: - compare the longevity and complications for CoC and MoM THAs at 5-10 years postoperatively; - compare the incidence of osteolysis between both type THAs; - evaluate pseudotumors in MoM THAs. HYPOTHESIS: CoC THAs will have a lower rate of osteolysis, better longevity, and better clinical outcomes than MoM THAs. PATIENTS AND METHODS: Ninety-six hips underwent CoC THAs, and 56 hips underwent MoM THA (Ultamet, Pinnacle, Depuy). Average patient age at the time of surgery was 57.1 years (range, 28 to 77 years). RESULTS: There were no differences with regard to the Harris hip score (89.5 and 90.3 for the CoC and MoM groups, respectively). Osteolysis (9 hips, 14.3%) among MoM THAs were significantly more frequently observed compared to CoC THAs (2 hips, 2.1%). Kaplan-Meier survival at 8 years with implant loosening or revision THA as the endpoint was 98.2% (95% CI: 87.8-99.8) for CoC, and 98.6% (95% CI: 90.2-99.8) for MoM (p=0.684). There was one audible squeaking (1.0%) and no ceramic fracture among CoC THAs. Five (8.9%) hips showed pseudotumors among MoM THAs. DISCUSSION: CoC THAs had a low incidence of osteolysis. No significant difference was seen in the 8-year survival rate between implants, when using implant loosening and revision THA as endpoints. These data indicate that CoC THAs have excellent clinical and radiological outcomes, compared with MoM THAs. Ultamet MoM had a higher rate of osteolysis compared to other MoM bearings; the cup modularity (without polyethylene) and the use of 36mm heads as well as the process of production (after 2006) may play a significant role in the higher rate of osteolysis. LEVEL OF EVIDENCE: III, Case control study, case control retrospective design.

A Possible New Radiographic Predictor of Progression of Osteoarthritis in Developmental Dysplasia of the Hip: The Center Gap.

BACKGROUND: Patients with comparable severities of developmental dysplasia of the hip (DDH) may variably progress to osteoarthritis (OA) over time. Although joint congruency may be associated with OA progression in patients with DDH, it has only been assessed subjectively. We assessed the gap between the rotational centers of the acetabulum and femoral head (center gap) as a possible predictive measure of OA progression in patients with DDH. QUESTIONS/PURPOSES: In patients with bilateral DDH, we asked: (1) What is the probability of OA progression (Tönnis grade) or symptom development (pain) in the asymptomatic contralateral hip of patients with DDH undergoing unilateral joint-preserving surgery? (2) Is the center gap measurement associated with OA progression or symptom development in these hips? (3) Is the center gap measurement correlated with previous radiographic parameters? METHODS: A total of 297 patients (319 hips) underwent unilateral eccentric rotational acetabular osteotomy at our institution between July 1989 and December 1999. We performed no other joint-preserving surgery to treat patients with DDH during this timeframe. The inclusion criteria for the study were patients younger than 55 years of age, the contralateral hip classified as Tönnis Grade 0, no previous surgical interventions, and asymptomatic at the time of eccentric rotational acetabular osteotomy (155 patients, 155 hips). The exclusion criteria were a contralateral hip without dysplasia (four patients, four hips), loss to followup before 10 years (42 patients, 42 hips [27%]), or missing medical records or radiographs (21 patients, 21 hips [14%]). The remaining 88 patients (88 hips; 11 males and 77 females) with a mean age of 39 years (range, 17-53 years) and mean followup of 20 years (range, 10-27 years) were analyzed. From the institutional database, radiographic parameters including the center gap in the AP view were assessed using radiographs at the time of eccentric rotational acetabular osteotomy, and the Tönnis grade was recorded 1 year postoperatively and annually thereafter retrospectively. We defined migration of the rotational center of the femoral head based on the rotational center of the acetabulum in the horizontal plane as center gap X (mm) and in the vertical plane as center gap Y (mm) and defined the absolute value between the centers as center gap distance (mm). Using κ statistics, intra- and interobserver reliabilities were determined to be 0.896 and 0.857 for center gap X, 0.912 and 0.874 for center gap Y, and 0.912 and 0.901 for the center gap distance, respectively. When patients reported any contralateral ipsilateral hip pain during clinic visits, the hip was considered symptomatic. Kaplan-Meier survivorship analyses were performed with OA progression or symptom development in the nonoperative hip as the endpoint. Multivariate analyses were performed to assess risk factors for each outcome using the Cox proportional hazards model. Correlation analyses between the center gap and other parameters including lateral center-edge angle, femoral head extrusion index, acetabular depth-to-width index, femoral head lateralization, minimum width of the joint space, head sphericity, and joint congruency were performed using Pearson's correlation coefficient. RESULTS: At 20 years postoperatively, the probability of OA progression in the nonoperative hip was 13% (95% confidence interval [CI], 7.1-22.1) and the probability of symptom development was 34% (95% CI, 24.7-46.1). The center gap X measurements in the groups with OA progression (lateral 2.0 ± 2.1 [SD] mm) or symptom development (lateral 0.9 ± 2.4 mm) took a more lateral direction than those in the group without OA progression (medial 0.4 ± 2.1 mm) or symptom development (medial 0.5 ± 2.0 mm) (OA progression, p < 0.001; symptom development, p = 0.005). The center gap Y measurements in the groups with OA progression (distal 2.7 ± 7.1 mm) or symptom development (distal 2.1 ± 6.0 mm) took a more distal direction than those in the group without OA progression (proximal 1.6 ± 6.2 mm) or symptom development (proximal 2.5 ± 6.1 mm) (OA progression, p = 0.027; symptom development, p = 0.001). Independent risk factors for OA progression were the femoral head extrusion index (hazard ratio [HR], 1.11; 95% CI, 1.01-1.22; p = 0.028) and the center gap X (HR, 1.52; 95% CI, 1.07-2.16; p = 0.019), whereas no independent risk factors for symptom development were found. The center gap in the horizontal plane had no correlations with any other radiographic parameter studied. CONCLUSIONS: The center gap in the horizontal plane had a modest association with OA progression in this group of patients with DDH. Future studies are needed to determine the normal value of the center gap for patients without DDH and to assess the center gap in lateral radiographic views. LEVEL OF EVIDENCE: Level IV, prognostic study.

Comparison of cementless total hip arthroplasty survivorship between metal-on-highly cross-linked polyethylene and ceramic on ceramic bearings: A case control study with a 5-9-year follow-up.

BACKGROUND: Currently, there is a lack of evidence on the medium-term follow-up of cementless total hip arthroplasty (THA) using metal-on-highly cross-linked polyethylene bearing (MoXPE), ceramic on ceramic bearing (CoC) at more than 5 years follow-up. Therefore, we performed a case control study to: compare the incidence rate of osteolysis; compare the longevity for both types of THAs, and to evaluate the wear rate of MoXPE THAs. HYPOTHESIS: CoC THAs will have a lower rate of osteolysis and better longevity than MoXPE THAs. PATIENTS AND METHODS: We performed a retrospective analysis of 77 MoXPE (68 women, 9 men) and 105 CoC (85 women, 20 men) THAs, with an average patient age at the time of surgery of 64.7 years (range, 27 to 76 years). The cohorts were matched according to sex, body mass index, or diagnosis of hip joint disease. Clinical and radiologic measurements were analyzed at a mean follow-up of 6.7 years (range, 5-9 years). RESULTS: There were no between-group differences with regard to the Harris hip score (87.0 [64.0-98.0] and 89.9 [70.0-100.0] for the MoXPE and CoC group, respectively) and the incidence rate of osteolysis (2.6% and 1.9%, respectively). Revision was required for 1 case for each THA type. The Kaplan-Meier survival at 8 years, using implant loosening or revision as the end-point of analysis, was 96.1% (95% confidence interval [CI], 90.0-99.3) for the MoXPE group and 98.9% (95% CI, 92.2-99.8) for the CoC group (p=0.189). The mean annual liner wear rate was 0.0160mm/year (range, 0.0050 to 0.0390mm/year) for the MoXPE THAs. DISCUSSION: There was no difference between CoC and MoXPE THAs in the incidence of osteolysis or in survival rate at 8 years post-surgery. Excellent clinical and radiological outcomes were obtained for both types of bearings. LEVEL OF EVIDENCE: III, Case control study, case control retrospective design.

The influence of early radiolucent lines appearing on femoral head penetration into HXLPE cemented sockets.

INTRODUCTION: This study investigates differences in femoral head penetration between highly cross-linked polyethylene (HXLPE) cemented sockets both with and without radiolucent lines (RLLs) in the early postoperative phase and at 5 years follow-up. METHODS: There were 35 patients (37 hips), mean age of 66.8 years, who underwent total hip arthroplasty (THA) using highly HXLPE cemented sockets. They were divided into 2 groups based on postoperative the early appearance of RLLs. Femoral head penetrations on both anteroposterior- and Lauenstein-view radiographs were evaluated, and the mean polyethylene (PE) wear rate was calculated based on femoral head penetrations between 2 and 5 years. RESULTS: Femoral head penetrations in the proximal direction were 0.075 mm and 0.150 mm in the RLL and non-RLL groups at 1 year postoperatively ( p = 0.019). At 5 years measured penetration was 0.107 mm and 0.125 mm in the RLL and non-RLL groups, respectively ( p = 0.320). The mean PE wear rates in anteroposterior-view were 0.008 mm/year and 0.003 mm/year in the RLL and non-RLL groups ( p = 0.390) and those in Lauenstein-view were 0.010 mm/year and 0.005 mm/year, respectively ( p = 0.239). CONCLUSIONS: In the RLL group, the PE bedding-in was less compared with those in the non-RLL group. Additionally, the mean PE wear rate in the RLL group tended to be higher than that in the non-RLL group. The distribution of stress loading through the cement may differ according to whether early RLLs appear.

Do femoral head collapse and the contralateral condition affect patient-reported quality of life and referral pain in patients with osteonecrosis of the femoral head?

PURPOSES: The objectives of this study were to investigate patient-reported outcomes and referral pain at the first visit in patients with osteonecrosis of the femoral head (ONFH) and to clarify the influence of collapse of the femoral head and the contralateral condition. METHODS: The study included 105 patients (130 hips) with ONFH at the first visit, who were divided into two groups based on the presence of bilateral walking hip pain (bilateral group 25 patients, 50 hips) and unilateral hip pain (unilateral group 80 patients, 80 hips). We compared the Short Form-36 (SF-36), Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ), and visual analog scale (VAS) responses for hip, knee, and low back pain between the groups to investigate the influence of the contralateral condition. Regarding the influence of femoral head collapse, we investigated these subjects based on the stage classification in the unilateral group. RESULTS: The physical component summary (PCS) of the SF-36 and all domains of the JHEQ were poorer in the bilateral group than in the unilateral group. In addition, the VAS score for low back pain was significantly poorer in the bilateral group than in the unilateral group. Regarding the collapse of the femoral head, the SF-36 for the PCS and JHEQ for pain had a significant relationship in the ONFH stage. The VAS scores for hip and knee pain had a significant relationship in the ONFH stage. CONCLUSION: Collapse of the femoral head and the contralateral condition of ONFH strongly affect patients' activities of daily life.

Preoperative Canal Bone Ratio is Related to High-Degree Stress Shielding: A Minimum 5-Year Follow-Up Study of a Proximally Hydroxyapatite-Coated Straight Tapered Titanium Femoral Component.

BACKGROUND: Few studies have reported risk factors for stress shielding. We sought to evaluate clinical and radiographic outcomes of a proximally hydroxyapatite-coated straight tapered titanium femoral component stem during a minimum 5-year follow-up and identify factors associated with high-degree stress shielding. METHODS: A total of 156 total hip arthroplasties (n = 124; 98 women and 26 men; mean age, 56.5 years) with a minimum follow-up period of 5 years were included in the study. Clinical and radiologic measurements at follow-up (range, 5-16.3 years; mean, 10.2 years) were analyzed. RESULTS: The mean preoperative Harris Hip Score (HHS) was 56.6, and the mean HHS at the latest follow-up was considerably improved at 86.8. Stress shielding at the latest follow-up was low degree in 136 (87%) hips and high degree in 20 (13%) hips. On average, high-degree stress shielding occurred 9.9 years (5-14 years) after surgery. The results of Cox proportional hazard analysis showed that a canal bone ratio ≥ 0.49 was an independent risk factor for high-degree stress shielding (P = .0075; hazard ratio, 3.981). HHS at the latest follow-up was significantly lower in high-degree stress shielding than in low-degree stress shielding (80.7 and 87.7, respectively; P = .0030). CONCLUSION: Preoperative canal bone ratio ≥ 0.49 is independently associated with high-degree stress shielding. In addition, the number of cases with high-degree stress shielding significantly increased over time during a mean 10-year follow-up.

Independent association of joint space narrowing, cyst formation and health-related quality of life of patients with hip osteoarthritis in Japan.

INTRODUCTION: This study clarified individual associations of joint space narrowing (JSN) and radiographic features (RF) of hip osteoarthritis (HOA), i.e., cyst and osteophyte formation and subchondral sclerosis, with quality of life (QOL) in Japanese HOA patients. METHODS: This cross-sectional study comprised 117 Japanese HOA patients (98 women, 17 men; mean age, 61.2 years). We recorded locations and the size of each RF and measured JSN on the acetabular side (Ace) or femoral head (FH). We evaluated pain with the Visual Analog Scale (VAS) and assessed QOL with the physical component summary (PCS) and mental component summary (MCS) of the Medical Outcomes Study Short Form-36. We compared QOL with/without the RF on the Ace, FH or both and analyzed relationships between each RF and VAS, PCS and MCS with linear regression analysis. We assessed independent associations of each RF with PCS and MCS with multiple regression analysis using various independent variables. RESULTS: VAS values with the cyst on the Ace only were significantly lower than those with the cyst at both locations. PCS values with the cyst on the Ace only were significantly higher than those for both locations. Independent associations existed for maximum cyst length on the Ace and FH with VAS and for JSN with PCS, but none existed for MCS. CONCLUSIONS: Our study suggested that the location and the size of the cyst formation were associated with both VAS and QOL in Japanese HOA patients. The JSN was independently associated with the PCS.

The poor quality and reliability of information on periacetabular osteotomy on the internet in Japan.

Although many patients use the internet to access health-related information, the quality and the reliability of the information is highly inconsistent. Periacetabular osteotomy (PAO) is one of the surgical procedures for hip dysplasia. However, medical information on PAO is limited on the internet. This study aims to evaluate the quality and reliability of information available on PAO on the internet in Japan. A web search was conducted on two search engines for the following terms: "hip osteotomy," "pelvic osteotomy," and "osteotomy for hip preservation" in Japanese. In total, we found 120 websites. To determine the quality and reliability of information on each website, we used the Health on the Net Foundation (HON) score, the Brief DISCERN score, and an osteotomy-specific content (OSC) score. After eliminating duplicate websites, we reviewed 49 unique websites. Only three websites (6.1%) had good reliability, as indicated by their HON scores. Twelve websites (24.4%) had good-quality information, as measured by their Brief DISCERN scores. As evaluated by their OSC scores, physician websites were found to be biased toward etiology and surgical indication and did not provide information on the complications of procedures. Non-physician websites were generally insufficient. The information about PAO on the internet is, therefore, unreliable and of poor-quality for Japanese patients.