Postoperative assessment of vascularity of the femoral head after surgical hip dislocation

Treatment for femoroacetabular impingement includes surgical hip dislocation and recontouring the femoral head-neck junction. However, a potential complication of this procedure is avascular necrosis. The purpose of this study was to assess radiographically the vascularity of the femoral head after surgical hip dislocation. Ten patients underwent surgical hip dislocation and recontouring of the femoral head-neck junction for femoroacetabular impingement. Postoperatively, all 10 patients underwent magnetic resonance imaging of the hip. Magnetic resonance imaging revealed no evidence of osteonecrosis in all patients. This study provides clear radiographic evidence that surgical hip dislocation may be performed without causing avascular necrosis of the femoral head.     

关节镜下踝关节清理术治疗8例踝关节前部撞击综合征

[背景]探讨关节镜在治疗踝关节前部撞击综合征中的应用价值.[病例报告]回顾性分析关节镜下手术治疗8例踝关节前部撞击综合征的临床资料,见术后全部患者功能恢复良好,均未发生并发症.[讨论]关节镜下治疗踝关节前部撞击综合征具有创伤小及可早期恢复功能等优点.     

Metal-on-metal hip resurfacing: the effect of cup position and component size on range of motion to impingement

The aim of this dry bone study was to determine the range of hip motion to impingement for different hip resurfacing cup positions and component sizes. The maximum angles of hip flexion, extension, abduction, and adduction were calculated from 3-dimensional coordinates for: 1. Cup inclination of 30 degrees , 40 degrees , 50 degrees , 60 degrees , and 70 degrees with fixed anteversion; 2. Cup anteversion of 0 degrees , 10 degrees , 25 degrees , 35 degrees , and 45 degrees with fixed inclination; and 3. 3 different component sizes on the same size dry bones. An acetabular component inclination of 50 degrees and an anteversion of 25 degrees allowed the most physiologic range of hip motion. A larger-diameter femoral component relative to the native femoral neck diameter resulted in a greater range of hip motion to impingement.     

Femoroacetabular impingement

Femoroacetabular impingement is a relatively recently appreciated "idiopathic" cause of hip pain and degenerative change. Two types of impingement have been described. The first, cam impingement, is the result of an abnormal morphology of the proximal femur, typically at the femoral head-neck junction. Cam impingement is most common in young athletic males. The second, pincer impingement, is the result of an abnormal morphology or orientation of the acetabulum. Pincer impingement is most common in middle-aged women. This article reviews the imaging findings of cam and pincer type femoroacetabular impingement. Recognition of these entities will help in the selection of the appropriate treatment with the goal of decreasing the likelihood of early degenerative change of the hip.     

Impingement syndromes of the ankle

Ankle impingement syndromes are categorised according to their anatomical site around the tibiotalar joint. Anterolateral, anterior and posterior ankle impingement has been extensively described in the orthopaedic and radiology literature with more recent studies describing posteromedial and anteromedial impingement. This article aims to demonstrate the potential spectrum of imaging findings for each ankle impingement syndrome as well as the relative contributions of ultrasound and MR imaging for diagnosis and image-guided treatment.     

A novel cell compatible impingement system to study in vitro drug absorption from dry powder aerosol formulations

A modified Astra type multistage liquid impinger (MSLI) with integrated bronchial cell monolayers was used to study deposition and subsequent drug absorption on in vitro models of the human airway epithelial barrier. Inverted cell culture of Calu-3 cells on the bottom side of cell culture filter inserts was integrated into a compendial MSLI. Upside down cultivation did not impair the barrier function, morphology and viability of Calu-3 cells. Size selective deposition with subsequent absorption was studied for three different commercially available dry powder formulations of salbutamol sulphate and budesonide. After deposition without size separation the absorption rates from the aerosol formulations differed but correlated with the size of the carrier lactose particles. However, after deposition in the MSLI, simulating relevant impaction and causing the separation of small drug crystals from the carrier lactose, the absorption rates of the three formulations were identical, confirming the bioequivalence of the three formulations.     

X线“阴性”髋痛患者髋股撞击征的临床影像学研究

目的 髋股撞击征(femoroacetabular impingement,FAI)作为髋关节骨性关节炎的可能病因近年愈受重视,但尚缺乏国人流行病学相关研究,本研究回顾性分析既往X线"阴性(未见异常)"髋痛患者中FAI的临床流行病学特点及其临床意义.方法 整理2007年12月至2008年8月期间西南医院影像中心保存的所有患者门诊骨盆前后位X线资料1 128例,按设定的纳入和排除标准筛选出研究对象.FAI诊断标准:(1)Cam型FAI:ɑ角大于55°;(2)Pincer型FAI:"8"字征阳性.分别统计FAI患者性别、年龄段及发生部位.测量髋痛一侧的髋关节前后位X线的ɑ角测量、半径高与半径比值(1/1Ra)和1/2半径高与半径比值(1/2Ra)并观察是否存在"8"字征,对以上统计及测量进行流行病学分析.结果 1 128例患者骨盆前后位X线符合纳入标准269例,均表现单髋痛,其中男121例,女148例.影像学诊断符合FAI 42例(15.6%),男、女性分别为27例(22.3%)和15例(10.1%),两者差异有统计学意义(P<0.05).Cam型与Pincer型和混合型比较差异有统计学意义(P<0.05).ɑ角测量:Cam型FAI组为 86.3°±16.7°;非FAI组为46.3°±4.1°,两组间差异有统计学意义(P<0.05).1/1Ra和1/2Ra: Cam型FAI组分别为1.02±0.04 和0.74±0.06;非FAI组分别为0.86±0.03 和0.69±0.05.1/2Ra在Cam型FAI组和非FAI组间差异有统计学意义(P<0.05),而 1/1Ra在两组间差异无统计学意义(P>0.05).结论 FAI在X线"阴性"的髋痛患者的高发病率,提示其可能作为患者髋痛原因,具有不可忽略的临床意义.1/2半径高与半径比值可以作为Cam型FAI诊断的特异参数以进一步筛选出.     

Construct validity of a 12-item WOMAC for assessment of femoro-acetabular impingement and osteoarthritis of the hip

OBJECTIVE: Evaluation of the internal construct validity of the Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index adapted for use in patients with femoro-acetabular impingement (FAI) and osteoarthritis (OA) of the hip. METHODS: Distribution of a German version of WOMAC to patients upon first consultation. Patients with FAI [n=100, mean age 31.7 years, standard deviation (SD) 9.7] and OA (n=57, mean age 60.3 years, SD 11.7) and without comorbidities or prior hip surgery were included and compared to age- and gender-matched control population to FAI (n=200, mean age 32.6 years, SD 5.6). WOMAC data of 157 questionnaires were evaluated by Rasch analysis using RUMM2020 software. RESULTS: Summation of total WOMAC shows misfit to the Rasch model as well as multidimensionality. While the pain subset shows adequate fit and is unidimensional, item reduction is required to fit a unidimensional subset of functional items to the Rasch model. Summating the two fitting subsets yields again slight model misfit and multidimensionality requiring further item reduction. Finally, a 12-item version of the total WOMAC shows good model fit and unidimensionality, i.e., internal construct validity, for assessment of patients with FAI and OA without differential item functioning (DIF). A person separation index (PSI)=0.93 indicates a high internal consistency reliability for the 12-item subscale. Scores for FAI are significantly higher than control (P<0.001, effect size 0.71) and lower than OA group (P<0.001, effect size 0.45). Adequate statistical power is shown discriminating the three groups, therefore indicating some evidence also for external construct validity. CONCLUSIONS: The WOMAC as a total construct is multidimensional and summating the subsets into a total score is not valid. The reduced 12-item WOMAC is demonstrated to have internal construct validity for assessing patients with FAI and OA on the same scale and high internal consistency reliability. Discrimination of the groups with adequate statistical power also indicates external construct validity.     

A unique failure mechanism of a constrained total hip arthroplasty: a brief review of the literature

Constrained acetabular systems are successful in achieving stability in patients with recurrent dislocations, abductor deficiency, or where a source of instability cannot be determined. We report on one patient with 2 dissociations of a tripolar constrained acetabular liner caused by impingement when the patient exceeded the allowed range of motion. The inner liner dissociated from the outer liner, whereas the reinforcing ring remained intact and in place. Despite an extensive literature search, we were unable to find any other published reports concerning this specific mode of failure for this constrained liner. Surgeons should be aware that constrained liners are not infallible and have limitations to range of motion. Maximizing the size of the femoral head may reduce the risk of this mode of failure.