Impact of the Conjoined Tendon on Preventing Dislocation Following Direct Anterior Total Hip Arthroplasty: A Cadaver Study

Background: Investigating the stabilizing impact of the piriformis and conjoined tendons post-direct anterior total hip arthroplasty (DATHA) forms the crux of this study, given the pertinence of hip stability in postoperative outcomes and long-term patient mobility. Methods: Utilizing 16 hips from 8 fresh frozen cadavers, the study establishes two cohorts: the piriformis tendon group and the conjoined tendon group. A rigorous assessment involving simulated anterior and posterior dislocations post-DATHA was implemented, quantifying the torque requisite for dislocation under three scenarios: pre-severance, post-severance, and post-reconstruction. Results: Piriformis tendon group analysis demonstrated inconsequential variations in torque for anterior and posterior dislocations post-tendon severance (p = 0.9801, p = 0.9854) and post-reconstruction (p = 0.2952, p = 0.0801) relative to the intact state. Conversely, the conjoined tendon group witnessed a significant diminution in dislocation torque subsequent to tendon severance (p < 0.0001), with a notable escalation post-reconstruction (p < 0.0001). Conclusion: This study underscores the preeminent role of the conjoined tendon in ensuring hip stability following DATHA, highlighting the cruciality of its preservation and reconstruction during surgical interventions. Such insights bear significant implications for surgical methodologies in orthopedic practice, particularly concerning minimizing postoperative dislocation risks in DATHA.