Wyatt Michael, Weidner Jan, Pfluger Dominik, Beck Martin
Clinic for Orthopaedic and Trauma Surgery, Luzerner Kantonsspital, Spitalstrasse 4, 6004, Lucerne, Switzerland.
Clin Orthop Relat Res. 2017 Mar;475(3):861-869. doi: 10.1007/s11999-016-5137-0. Epub 2016 Oct 28.
The definition of osseous instability in radiographic borderline dysplastic hips is difficult. A reliable radiographic tool that aids decision-making-specifically, a tool that might be associated with instability-therefore would be very helpful for this group of patients.
QUESTIONS/PURPOSES: (1) To compare a new radiographic measurement, which we call the Femoro-Epiphyseal Acetabular Roof (FEAR) index, with the lateral center-edge angle (LCEA) and acetabular index (AI), with respect to intra- and interobserver reliability; (2) to correlate AI, neck-shaft angle, LCEA, iliocapsularis volume, femoral antetorsion, and FEAR index with the surgical treatment received in stable and unstable borderline dysplastic hips; and (3) to assess whether the FEAR index is associated clinical instability in borderline dysplastic hips.
We defined and validated the FEAR index in 10 standardized radiographs of asymptomatic controls using two blinded independent observers. Interrater and intrarater coefficients were calculated, supplemented by Bland-Altman plots. We compared its reliability with LCEA and AI. We performed a case-control study using standardized radiographs of 39 surgically treated symptomatic borderline radiographically dysplastic hips and 20 age-matched controls with asymptomatic hips (a 2:1 ratio), the latter were patients attending our institution for trauma unrelated to their hips but who had standardized pelvic radiographs between January 1, 2016 and March 1, 2016. Patient demographics were assessed using univariate Wilcoxon two-sample tests. There was no difference in mean age (overall: 31.5 ± 11.8 years [95% CI, 27.7-35.4 years]; stable borderline group: mean, 32.1± 13.3 years [95% CI, 25.5-38.7 years]; unstable borderline group: mean, 31.1 ± 10.7 years [95% CI, 26.2-35.9 years]; p = 0.96) among study groups. Treatment received was either a periacetabular osteotomy (if the hip was unstable) or, for patients with femoroacetabular impingement, either an open or arthroscopic femoroacetabular impingement procedure. The association of received treatment categories with the variables AI, neck-shaft angle, LCEA, iliocapsularis volume, femoral antetorsion, and FEAR index were evaluated first using Wilcoxon two-sample tests (two-sided) followed by stepwise multiple logistic regression analysis to identify the potential associated variables in a combined setting. Sensitivity, specificity, and receiver operator curves were calculated. The primary endpoint was the association between the FEAR index and instability, which we defined as migration of the femoral head either already visible on conventional radiographs or recentering of the head on AP abduction views, a break of Shenton's line, or the appearance of a crescent-shaped accumulation of gadolinium in the posteroinferior joint space at MR arthrography.
The FEAR index showed excellent intra- and interobserver reliability, superior to the AI and LCEA. The FEAR index was lower in the stable borderline group (mean, -2.1 ± 8.4; 95% CI, -6.3 to 2.0) compared with the unstable borderline group (mean, 13.3 ± 15.2; 95% CI, 6.2-20.4) (p < 0.001) and had the highest association with treatment received. A FEAR index less than 5° had a 79% probability of correctly assigning hips as stable and unstable, respectively (sensitivity 78%; specificity 80%).
A painful hip with a LCEA of 25° or less and FEAR index less than 5° is likely to be stable, and in such a situation, the diagnostic focus might more productively be directed toward femoroacetabular impingement as a potential cause of a patient's pain, rather than instability.
Level III, diagnostic study.
在影像学表现为边缘发育不良的髋关节中，骨不稳定的定义较为困难。因此，一种有助于决策制定的可靠影像学工具，尤其是一种可能与不稳定相关的工具，对于这类患者将非常有帮助。
问题/目的：（1）比较一种新的影像学测量方法，即我们所称的股骨-骨骺髋臼顶（FEAR）指数，与外侧中心边缘角（LCEA）和髋臼指数（AI）在观察者内和观察者间的可靠性；（2）将AI、颈干角、LCEA、髂腰肌体积、股骨前倾角和FEAR指数与稳定和不稳定的边缘发育不良髋关节所接受的手术治疗进行关联分析；（3）评估FEAR指数是否与边缘发育不良髋关节的临床不稳定相关。
我们使用两名独立的盲法观察者，在10张无症状对照的标准化X线片上定义并验证了FEAR指数。计算了组内和组间相关系数，并辅以Bland-Altman图。我们将其与LCEA和AI的可靠性进行了比较。我们进行了一项病例对照研究，使用了39例接受手术治疗的有症状的边缘性影像学发育不良髋关节的标准化X线片和20例年龄匹配的无症状髋关节对照（2:1比例），后者是2016年1月1日至2016年3月1日期间因与髋关节无关的创伤到我院就诊且有标准化骨盆X线片的患者。使用单变量Wilcoxon双样本检验评估患者人口统计学特征。各研究组间平均年龄无差异（总体：31.5±11.8岁[95%CI，27.7 - 35.4岁]；稳定边缘组：平均32.1±13.3岁[95%CI，25.5 - 38.7岁]；不稳定边缘组：平均31.1±10.7岁[95%CI，26.2 - 35.9岁]；p = 0.96）。所接受的治疗要么是髋臼周围截骨术（如果髋关节不稳定），要么对于股骨髋臼撞击症患者，进行开放或关节镜下股骨髋臼撞击症手术。首先使用Wilcoxon双样本检验（双侧）评估所接受治疗类别与变量AI、颈干角、LCEA、髂腰肌体积、股骨前倾角和FEAR指数之间的关联，然后进行逐步多元逻辑回归分析，以确定联合情况下的潜在相关变量。计算敏感性、特异性和受试者工作特征曲线。主要终点是FEAR指数与不稳定之间的关联，我们将不稳定定义为在传统X线片上已可见的股骨头移位、在前后位外展片上股骨头复位、Shenton线中断或在磁共振关节造影时后下关节间隙出现钆的新月形积聚。
FEAR指数在观察者内和观察者间均显示出极好的可靠性，优于AI和LCEA。与不稳定边缘组（平均13.3±15.2；95%CI = 6.2 - 20.4）相比，稳定边缘组的FEAR指数更低（平均 - 2.1±8.4；95%CI = - 6.3至2.0）（p < 0.001），且与所接受的治疗关联度最高。FEAR指数小于5°时，正确区分稳定和不稳定髋关节的概率分别为79%（敏感性78%；特异性80%）。
LCEA为25°或更小且FEAR指数小于5°的疼痛性髋关节可能是稳定的，在这种情况下，诊断重点可能更有效地指向股骨髋臼撞击症作为患者疼痛的潜在原因，而非不稳定。
III级，诊断性研究。
