Department of Orthopaedic Surgery, University of Regensburg, Asklepios Klinikum, Kaiser-Karl-V.-Allee 3, 93077, Bad Abbach, Germany.
Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA.
J Orthop Traumatol. 2024 Aug 14;25(1):38. doi: 10.1186/s10195-024-00785-z.
Modular acetabular components for total hip arthroplasty (THA) provide intraoperative flexibility; however, polyethylene liner dissociation may occur. This study aimed to examine the incidence and causes of liner dissociation associated with a specific acetabular component design at a single centre.
A retrospective analysis of 7027 patients who underwent primary THA was performed to identify isolated liner dislocations. Patient demographics, clinical presentations, surgical and implant details, and both radiographic and computed tomography (CT) findings were analysed. Patients with liner dislocation were matched to a control group via 2:1 propensity score matching, and a logistic regression analysis was employed to identify associated risk factors.
A total of 32 patients (0.45%) experienced liner dislocation at a mean 71.47 ± 60.10 months post surgery. Significant factors contributing to dislocations included the use of a conventional compared with a highly crosslinked polyethylene component (p = 0.049) and screw fixation (p = 0.028). Radiographic and CT analysis highlighted the importance of proper component orientation, revealing that patients experiencing dislocations demonstrated significantly lower acetabular cup anteversion angles (p = 0.001) compared with the control group. Impingement and malposition, identified in 41% and 47% of the cases, respectively, further underscored the multifactorial nature of dislocation risks.
While the overall rate of polyethylene liner dislocation was low, the findings of this study highlight the importance of appropriate cup placement to decrease the risk of dissociation. It further substantiates the influence of impingement and malposition in liner displacement, with increased mechanical stress exerted on the locking mechanism under adverse conditions and the potential risk increase due to screw placement.
全髋关节置换术（THA）中的模块化髋臼组件提供了术中的灵活性，但聚乙烯衬垫可能会发生分离。本研究旨在检查单一中心特定髋臼组件设计相关的衬垫分离的发生率和原因。
对 7027 例接受初次 THA 的患者进行回顾性分析，以确定孤立的衬垫脱位。分析患者的人口统计学、临床表现、手术和植入物细节以及影像学和计算机断层扫描（CT）结果。通过 2:1 倾向评分匹配将有衬垫脱位的患者与对照组匹配，并采用逻辑回归分析确定相关的危险因素。
共有 32 例患者（0.45%）在术后平均 71.47±60.10 个月时发生衬垫脱位。导致脱位的显著因素包括使用传统聚乙烯与高交联聚乙烯组件（p=0.049）和螺钉固定（p=0.028）。影像学和 CT 分析强调了正确组件方向的重要性，结果显示脱位患者的髋臼杯前倾角明显较低（p=0.001）与对照组相比。分别在 41%和 47%的病例中发现撞击和错位，进一步强调了脱位风险的多因素性质。
尽管聚乙烯衬垫脱位的总体发生率较低，但本研究结果强调了适当杯放置以降低分离风险的重要性。它进一步证实了撞击和错位对衬垫位移的影响，在不利条件下对锁定机制施加更大的机械应力，以及由于螺钉放置而潜在的风险增加。
