Abstract:
Instability following total hip arthroplasty (THA) remains a significant clinical concern, often exacerbated by structural compromise of the hip capsule due to pre-existing pathology or the necessities of surgical approaches. Understanding the intricate biomechanical contribution of the hip capsule to overall joint stability is paramount for improving surgical outcomes and reducing dislocation rates. This study addresses this challenge by developing and validating an experimentally grounded, fiber-direction-based finite element model of the human hip capsule, which was then integrated into an established three-dimensional model of impingement and dislocation.
The biomechanical model's validity was rigorously established by demonstrating close similarity between its predictions and results obtained from cadaveric experiments conducted in a servohydraulic hip simulator, ensuring its accuracy in replicating real-world joint mechanics. Through extensive parametric computational runs, the study systematically explored the effects of various factors on the capsule's contribution to stability. These factors included graded levels of capsule thickness, the extent and location of regional detachment from the capsule's femoral or acetabular insertion sites, and the influence of different surgical repair configurations. The model quantified changes in total hip construct stability, including dislocation dissipation energy, and examined the tensile loads developed within individual sutures during simulated repair scenarios.
The results unequivocally demonstrate the critical biomechanical role of the hip capsule in maintaining total hip construct stability, even during impingement and subluxation events. Graded compromise of the capsule consistently led to reduced stability, highlighting its indispensable function. Furthermore, the study provided valuable biomechanical insights into the efficacy of various repair strategies, showing how different suture numbers and patterns can restore stability and the tensile forces they must withstand. These advanced computational biomechanics tools provide crucial insights for surgeons to optimize capsule-sparing or repair techniques during THA, ultimately contributing to a reduction in post-operative instability and improving long-term patient outcomes.
