Biomechanical Evaluation of 4 Suture Techniques for Hip Capsular Closure

Background: The most reliable suture technique for capsular closure after a capsulotomy remains unknown. Purpose: To determine which suture technique best restores native stability after a 5-cm interportal capsulotomy. Study Design: Controlled laboratory study. Methods: Ten human cadaveric hip specimens were tested using a 6-degrees-of-freedom robotic arm in 7 states: intact, capsular laxity, 5-cm capsulotomy, standard suture, shoelace, double shoelace, and Quebec City slider (QCS). Rotational range of motion (ROM) was measured across 9 tests: flexion, extension, abduction, abduction at 45 degrees of flexion, adduction, external rotation, internal rotation, anterior impingement, and log roll. Distraction (ie, femoral head translation [FHT]) was measured across a range of flexion and abduction angles. Results: When compared with the native state, the 5-cm capsulotomy state showed the largest laxity increases on all tests, specifically in external rotation ROM (+13.4 degrees), extension ROM (+11.5 degrees), and distraction FHT (+4.5 mm) (P < .001 for all). The standard suture technique was not significantly different from the 5-cm capsulotomy on any test and demonstrated significantly more flexion ROM than the double shoelace suture (+1.41 degrees; P = .049) and more extension ROM (+5.51 degrees; P = .014) and external rotation ROM (+6.03 degrees; P = .021) than the QCS. The standard suture also resulted in significantly higher distraction FHT as compared with the shoelace suture (+1.0 mm; P = .005), double shoelace suture (+1.4 mm; P < .001), and QCS (+1.1 mm; P = .003). The shoelace, double shoelace, and QCS techniques significantly reduced hip laxity when compared with the 5-cm capsulotomy state, specifically in external rotation ROM (respectively, -8.1 degrees, -7.8 degrees, and -10.2 degrees), extension ROM (-6.3 degrees, -7.3 degrees, and -8.1 degrees), and distraction FHT (-1.8, -2.2, and -1.9 mm) (P <= .003 for all). These 3 techniques restored native stability (no significant difference from intact) on some but not all tests, and no significant differences were observed among them on any test. Conclusion: Hip capsule closure with the standard suture technique did not prevent postoperative hip instability after a 5-cm capsulotomy, and 3 suture techniques were found to be preferable; however, none perfectly restored native stability at time zero.