OP5.2 Restoration of Hip Distractive Stability is Achieved with Circumferential Labral Reconstruction and Correlates with Acetabular Rim Angle: A Cadaveric Biomechanical Analysis

Background: The essential component of managing femoroacetabular impingement involves the reinstatement of the original labrum function. Circumferential labral reconstruction (CLR) has shown lasting results, proving to be as effective as labral repair. However, biomechanical studies of CLR are limited and have not established the efficacy of the modern knotless all-suture anchor (ASA) pull-through technique.

Hypothesis/Purpose: 1) CLR with knotless ASA fixation will restore native labral suction seal biomechanics; 2) Tensioning the ASA to a high-tension state will increase the peak distractive force; 3) Acetabular rim preparation angle correlates with the degree of labral seal restoration.

Study Design: Controlled laboratory study

Methods: Eight fresh-frozen human cadaveric hips were dissected free of all soft tissue except the native labrum and transverse acetabular ligament. On an electromechanical testing system, the hips were compressively loaded to 250 N to initiate a suction seal and distracted at a rate of 10 mm/s until rupture of the suction seal occurred. Hips were tested in four states: 1) Intact labrum, 2) full labral removal, 3) knotless CLR with moderate anchor tension, and 4) CLR with high anchor tension. Peak distractive force (N) was compared using repeated-measures analysis of variance (p<0.05). Rim angles (θ) were measured at labral clockface positions using a 3-D digitizer stylus following rim preparation. Linear regression plots compared θ and peak distractive force in the CLR state.

Results: Peak force values were (mean±SE) 138±13.6 N for the intact labrum, 18.4±2.79 N for labral excision, 95.4±23.3 N for moderate-tension CLR, and 126±27.3 N for high-tension CLR. Significant differences were only observed when comparing full labral removal to intact (P<0.001), moderate-tension CLR (P=0.016), and high-tension CLR (P=0.002) conditions. Steeper acetabular rim angles (smaller θ) were correlated with greater suction seal restoration (P<0.05).

Conclusion: Circumferential labral reconstruction restored distractive stability on average to 82.0% of the intact value following labral deficiency. Re-tensioning marginally increased peak distractive forces, though not significantly. Steeper acetabular rim bevels correlated with greater peak suction seal restoration than those with shallower rim bevels.