Department of Trauma and Orthopaedic Surgery, Hôpital Universitaire Carémeau, Place du Pr. Robert Debré 30029, Nîmes Cédex 9, France.
Mechanical and Civil Engineering Laboratory, UMR 5508, University of Montpellier, Montpellier, France.
Arch Orthop Trauma Surg. 2023 Aug;143(8):4773-4783. doi: 10.1007/s00402-022-04722-9. Epub 2023 Jan 31.
In total hip arthroplasty (THA), misplacement of the implant can provide instability. Adequate orientation of the acetabular cup is a challenge due to variations in inter-individual anatomy and kinematics of the pelvis in everyday life. The aim of this study was to characterize the kinematic factors influencing the risk of dislocation in order to give recommendations for optimal placement of the cup. We hypothesized that the lack of pelvic adaptation would influence the risk of prosthetic instability and motivate adapted.
Eighty patients with primary unilateral THA were included in a matched case-control study. Seventy-four patients were divided into two groups: group 1 (G1) consisting of patients with postoperative THA dislocation (37 patients) and group 2 (G2), without episodes of dislocation within two years postoperatively (37 patients). In both groups, spino-pelvic parameters and cup orientation were measured in standing and sitting positions with EOS X-ray imaging and compared to each other between 12 and 24 months post-operatively.
No significant difference between the two groups was found for static parameters. In a sitting position, a lack of pelvic retroversion with a significant lower variation in sacral slope was observed in group 1 (8.0° ± 9.3 for G1 versus 14.7° ± 6.2 for G2, p < 0.01). Twenty-two (59%) patients with THA instability had sacral slope variations of less than 10° versus eight (21% of patients) with stable THA (p < 0.01). Cup orientation in the Lewinnek safe zone was not significantly different (59% vs 67%, p = 0.62), and the spino-pelvic parameters and cup orientation measured did not change between the standing and sitting positions. However, only 14 (37%) cups in G1 were in the functional safe zone versus 24 (67%) in G2 (p = 0.03).
Static parameters of the sagittal spinopelvic balance have a low predictive value for prosthetic instability. Dynamic analysis is essential. Kinematic parameters must be taken into account in determining the ideal position of the cup or stem. Stiffness with locked standing or sitting pelvis must be integrated in order to determine a personalized safe zone.
Level III (matched case-control study).
在全髋关节置换术（THA）中，植入物的位置不当会导致不稳定。由于个体间解剖结构和日常生活中骨盆运动学的差异，髋臼杯的适当定位是一个挑战。本研究旨在分析影响脱位风险的运动学因素，为杯的最佳放置提供建议。我们假设骨盆适应不良会影响假体不稳定的风险，并促使适应不良。
80 例初次单侧 THA 患者纳入本匹配病例对照研究。74 例患者分为两组：第 1 组（G1）包括术后发生 THA 脱位的患者（37 例）和第 2 组（G2），术后 2 年内无脱位发作的患者（37 例）。在两组中，均采用 EOS X 射线成像在站立和坐位时测量脊柱骨盆参数和杯的方向，并在术后 12-24 个月时进行比较。
两组之间静态参数无显著差异。在坐位时，G1 组骨盆后倾不足，骶骨倾斜度变化明显较小（8.0°±9.3 对 14.7°±6.2，p<0.01）。22 例（59%）THA 不稳定患者的骶骨倾斜度变化小于 10°，8 例（21%）THA 稳定患者的骶骨倾斜度变化小于 10°（p<0.01）。Lewinnek 安全区的杯方向无显著差异（59%对 67%，p=0.62），站立位和坐位测量的脊柱骨盆参数和杯方向无变化。然而，G1 组仅有 14 个（37%）杯位于功能安全区，而 G2 组有 24 个（67%）（p=0.03）。
矢状位脊柱骨盆平衡的静态参数对假体不稳定的预测价值较低。动态分析是必要的。在确定杯或柄的理想位置时，必须考虑运动学参数。为了确定个性化的安全区，必须整合僵硬的站立或坐姿骨盆。
III 级（匹配病例对照研究）。
