Pullen W Michael, Henebry Andrew, Gaskill Trevor
Department of Orthopaedic Surgery, Naval Medical Center Portsmouth, Portsmouth, Virginia, USA.
Department of Orthopaedic Surgery, Naval Medical Center Portsmouth, Portsmouth, Virginia, USA
Am J Sports Med. 2014 Nov;42(11):2643-8. doi: 10.1177/0363546514548854. Epub 2014 Sep 11.
Radiographic measures of acetabular coverage are essential screening tools used to characterize bony structure contributing to femoroacetabular impingement (FAI). Small changes in pelvic tilt result in altered radiographic measures of acetabular coverage. Positional changes in pelvic tilt are known to occur between the supine and weightbearing positions. It is unclear whether alteration of pelvic tilt between these positions is clinically sufficient to influence measures of acetabular coverage.
PURPOSE/HYPOTHESIS: To determine whether, and to what degree, imaging position (supine vs weightbearing) is capable of altering several measures of acetabular orientation: pubic symphysis to sacrococcygeal distance (PSSC), angle of Sharp (SA), Tönnis angle (TA), percentage of acetabular crossover (CO), and lateral center-edge angle of Wiberg (LCEA). The hypothesis was that imaging position would significantly alter all measures of acetabular orientation.
Cohort study (diagnosis); Level of evidence, 2.
A total of 50 consecutive symptomatic hips referred to a single provider for FAI were evaluated with standardized supine and weightbearing anteroposterior pelvic radiographs. Two independent reviewers blinded to patient positioning reviewed each radiograph at 2 separate time points. Mean measurements in each position were compared by use of paired Student t tests, and a Bonferroni-adjusted significance level of P = .01 was used to represent significance.
Statistically significant differences between the supine and weightbearing radiographs were identified for PSSC and all measures of acetabular coverage (P < .003). The mean PSSC decreased between the supine and weightbearing positions by an average of 13.4 mm (P < .001), thereby resulting in decreased mean LCEA, TA, SA, and CO of 1.2°, 1.3°, 0.8°, and 6.3%, respectively (P < .002). The change in positional pelvic tilt was not uniformly predictable and accounted for large measurement changes in some individuals. PSSC also demonstrated considerable inter- and intrasubject variability but averaged 55.8 mm supine and 44.9 mm weightbearing for females and 37.0 mm supine and 20.6 mm weightbearing for males.
In this study of nonarthritic adult patients with hip pain, the data indicate that positional changes are capable of significantly altering pelvic tilt and radiographic measures of acetabular coverage. It appears that the weightbearing position typically, but not universally, correlates with additional posterior pelvic tilt and decreased measures of acetabular coverage. Individual positional variability can contribute to large-magnitude changes in radiographic acetabular measures.
髋臼覆盖度的影像学测量是用于描述导致股骨髋臼撞击症（FAI）的骨结构的重要筛查工具。骨盆倾斜的微小变化会导致髋臼覆盖度的影像学测量结果改变。已知骨盆倾斜的位置变化会发生在仰卧位和负重位之间。尚不清楚这些位置之间骨盆倾斜的改变在临床上是否足以影响髋臼覆盖度的测量。
目的/假设：确定成像位置（仰卧位与负重位）是否以及在何种程度上能够改变髋臼方向的几种测量指标：耻骨联合至骶尾骨距离（PSSC）、夏普角（SA）、托尼斯角（TA）、髋臼交叉百分比（CO）以及维伯格外侧中心边缘角（LCEA）。假设是成像位置会显著改变髋臼方向的所有测量指标。
队列研究（诊断）；证据等级，2级。
对连续50例因FAI转诊至单一医疗服务提供者处的有症状髋关节进行标准化仰卧位和负重位前后位骨盆X线片评估。两名对患者体位不知情的独立审阅者在2个不同时间点分别查看每张X线片。使用配对t检验比较每个位置的平均测量值，并采用经邦费罗尼校正的显著性水平P = 0.01来表示显著性。
仰卧位和负重位X线片之间在PSSC以及所有髋臼覆盖度测量指标上均存在统计学显著差异（P < 0.003）。仰卧位和负重位之间PSSC的平均值平均下降了13.4毫米（P < 0.001），从而导致平均LCEA、TA、SA和CO分别下降1.2°、1.3°、0.8°和6.3%（P < 0.002）。骨盆倾斜位置的变化并非一致可预测，且在一些个体中导致了较大的测量变化。PSSC在个体间和个体内也表现出相当大的变异性，但女性仰卧位平均为55.8毫米，负重位平均为44.9毫米；男性仰卧位平均为37.0毫米，负重位平均为20.6毫米。
在这项针对非关节炎性成年髋关节疼痛患者的研究中，数据表明位置变化能够显著改变骨盆倾斜和髋臼覆盖度的影像学测量结果。似乎负重位通常（但并非普遍）与骨盆进一步后倾以及髋臼覆盖度测量值降低相关。个体位置变异性可导致髋臼影像学测量值出现大幅度变化。
