Department of Biomechanics, Hospital for Special Surgery, New York, NY.
Adult Reconstruction and Joint Replacement Division, Department of Orthopaedic Surgery, Hospital for Special Surgery, New York, NY.
J Arthroplasty. 2018 May;33(5):1449-1454. doi: 10.1016/j.arth.2017.12.005. Epub 2017 Dec 13.
Sitting radiographs have been used as a pre-operative tool to plan patient-specific total hip arthroplasty (THA) component position that would improve hip stability. Previous work has demonstrated that spinal mobility may impact functional acetabular position when seated. We sought to determine whether patients who dislocate following THA have different sitting spinopelvic alignment or acetabular component orientation compared to patients who did not dislocate.
A consecutive series of 1000 patients underwent post-operative low-dose biplanar spine-to-ankle lateral radiographs in standing and sitting positions 1 year following THA. Twelve patients (1% of all patients) experienced hip dislocation. Patients were categorized as having normal lumbar spines (without radiographic arthrosis) or as having lumbar multi-level degenerative disc disease. Measurements of spinopelvic alignment parameters (including sacral slope, lumbar lordosis, and proximal femur angles) and acetabular component orientation in sitting position (functional inclination and functional anteversion) were performed.
Patients who dislocated had significantly less spine flexion, less change in pelvic tilt, and more hip flexion from standing to sitting positions compared to patients with normal spines. In sitting position, dislocators had acetabular components with less functional inclination and less functional anteversion.
This study demonstrates that patients with fixed spinopelvic alignment from standing to sitting position are at higher risk of hip dislocation. Imaging patients from standing to sitting position using this technique can provide valuable information on whether a patient has fixed spinopelvic alignment with postural changes and is therefore at higher risk of dislocation.
坐立位 X 线片已被用作术前工具，用于规划特定患者的全髋关节置换术（THA）组件位置，以改善髋关节稳定性。先前的研究表明，脊柱活动度可能会影响坐立时的功能性髋臼位置。我们旨在确定在接受 THA 后发生脱位的患者与未脱位的患者相比，其坐立位脊柱骨盆排列或髋臼组件方向是否存在差异。
连续系列的 1000 例患者在接受 THA 后 1 年接受术后低剂量双平面脊柱-踝关节侧位 X 线片，包括站立位和坐位。12 例患者（占所有患者的 1%）发生髋关节脱位。患者分为腰椎正常（无影像学关节炎）或腰椎多节段退行性椎间盘疾病。测量坐位时脊柱骨盆排列参数（包括骶骨倾斜度、腰椎前凸和股骨近端角度）和髋臼组件方向（功能倾斜度和功能前倾角）。
与腰椎正常的患者相比，脱位患者从站立位到坐位时脊柱前屈明显减少，骨盆倾斜度变化较小，髋关节屈曲度增加。在坐位时，脱位患者的髋臼组件具有较小的功能倾斜度和较小的功能前倾角。
本研究表明，从站立位到坐位时脊柱骨盆固定排列的患者髋关节脱位风险更高。使用该技术从站立位到坐位对患者进行成像可以提供有关患者是否存在固定的脊柱骨盆排列以及是否存在更高脱位风险的有价值信息。
