Biomechanical Response to Distraction of Hip Capsular Reconstruction With Human Acellular Dermal Patch Graft.

Abstract

To quantify the biomechanical properties of the hip capsule with human dermal allograft reconstruction to determine whether a dermal patch restored capsular resistance to distraction. Nine cadaveric hip specimens were dissected until capsule and bony structures remained and were then mounted in a testing fixture in neutral flexion and abduction. Four states of the hip capsule were sequentially tested under axial distraction of 5 mm measured with video analysis and with resultant force measurement: (1) intact hip capsule, (2) interportal capsulotomy, (3) capsulectomy to the zona orbicularis, and (4) capsular reconstruction with human dermal allograft using acetabular anchors and capsule-to-patch sutures. Capsulectomy was different from intact (P = .036), capsulotomy differed from capsulectomy (P = .012), and the repair was statistically significantly different from capsulectomy (P = .042); intact and reconstructed cases were not statistically significantly different. The force required for 5 mm of distraction decreased after interportal capsulotomy by an average of 9% compared with the intact state and further decreased after capsulectomy by 30% compared with the intact state. After capsular reconstruction using dermal allograft, force requirements increased by an average of 36% from the capsulectomy state, only 5% below the intact state. Human dermal allograft tissue graft provides restoration of distractive strength for use during hip capsule reconstruction with acetabular anchor fixation and distal soft-tissue fixation after capsulectomy in a cadaveric model. Capsular repair or reconstruction with a dermal patch offers time-zero restoration of function; intact and reconstructed cases showed no difference, and reconstruction restored a capsulectomy to a biomechanical equivalent of the intact case when distraction was applied.