The acetabular labrum plays a major role in hip joint mechanics and restoration of labral function and is considered key for success in hip preservation surgery. The purpose of this study was to evaluate the effects of segmental labrectomy and defect reconstruction with a synthetic polyurethane scaffold (PS).
A cadaveric biomechanical study was performed using 10 hips from 5 fresh-frozen pelvises with an intact acetabular labrum without osteoarthritis. Using an intra-articular pressure measurement system (Tekscan), contact area (CA), contact pressure (CP) and peak force (PF) were assessed for the following conditions: 1) Intact labrum; b) Anterosuperior partial labrectomy; c) Reconstruction with PS. All specimens were analyzed for each condition in 4 positions: 90º flexion, 90º flexion plus internal rotation, 90º flexion plus external rotation, and 20º extension and with a labral seal test. The relative change from the intact condition (value = 1) was determined for all conditions and positions.
When compared to the intact labrum, segmental labrectomy resulted in a significant decrease in CA (p<0.001) and a significant increase in PF (p<0.001) in all positions. CP (p<0.001) increased significantly in all positions except in extension (p=0.48). Following labrectomy, scaffold reconstruction of the segmental defect resulted in a significant increase in contact area as well as a significant decrease in contact pressure and peak force across all positions (p<0.05). In comparison to the intact labrum, scaffold reconstruction restored CA and PF to normal in all positions (p>0.05) whereas contact pressure was significantly decreased compared to labrectomy (p<0.05) but did not return to normal values (p>0.05). The labral seal was lost in all specimens following partial labrectomy and was restored in 80% of the specimens after scaffold labrum reconstruction.
Femoro-acetabular contact mechanics significantly worsened after segmental labrectomy. Reconstruction with a synthetic polyurethane scaffold reversed the loss in contact area and reduced both contact pressure and peak force caused by partial labrectomy. Contact area and peak force were normalized and the labral seal was re-established in the majority of cases.