The Effect of Capsulectomy on Hip Joint Biomechanics

BACKGROUND: Capsulectomy is performed during hip arthroscopic surgery in young adult patients with hip pain to improve intraoperative visualization. The stability of the hip joint after anterior capsulectomy is relatively unknown. PURPOSE: To evaluate anterior hip stability in capsular sectioned states with a labral injury to test whether the load required for anterior translation would decrease with greater capsular injuries. STUDY DESIGN: Controlled laboratory study. METHODS: Sixteen hips from 8 of 10 human cadaveric pelvises (mean age, 54.25 years) were prepared/mounted onto a custom-built fixture and tested in 5 states: intact capsule, intact labrum (all intact); sutured capsule, intact labrum (sutured intact); sutured capsule, 1-cm partial labrectomy (sutured labrectomy); partial capsulectomy, 1-cm partial labrectomy (partial capsulectomy); and total capsulectomy, 1-cm partial labrectomy (total capsulectomy). Each hip was tested in a neutral position with a 20-N compressive force. The load at 12 mm of anterior translation was recorded for each state after 2 preconditioning trials. RESULTS: A repeated-measures analysis of variance with Bonferroni adjustment showed no difference between the all-intact versus sutured-intact states and demonstrated no significant difference between the sutured-intact and sutured-labrectomy states. There were significant differences between the sutured-labrectomy and partial capsulectomy (P = .01), sutured-labrectomy and total capsulectomy (P < .001), and partial capsulectomy and total capsulectomy (P = .04) states. CONCLUSION: The findings demonstrate that the capsule/labrum plays an important role in anterior hip stability and that the iliofemoral ligament is crucial for preventing anterior translation in labral-injured states. In addition, the ischiofemoral and pubofemoral ligaments provide resistance to anterior translation in iliofemoral- and labral-deficient states. Intraoperative capsulectomy should be avoided in patients with large, irreparable labral tears to prevent postoperative anterior hip instability. CLINICAL RELEVANCE: This study quantifies the roles of the capsulolabral structures in anterior hip stability and demonstrates the importance of maintaining/repairing them during hip arthroscopic surgery.