Tissue Integration and Chondroprotective Potential of Acetabular Labral Augmentation with Autograft Tendon

Abstract

Background: The aim of this study was to explore the tissue healing process and changes in articular cartilage following acetabular labral augmentation in a porcine model. Methods: The labrum was resected unilaterally from 10 o’clock to 1 o’clock on the capsular side in 36 pigs. Eighteen pigs underwent labral augmentation (AUG group) using autologous Achilles tendon. No additional procedures were performed in the remaining pigs (control group). The pigs were killed at 6, 12, or 24 weeks postoperatively for histological assessment and measurement of the inflammatory cytokines interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF)-α in synovial fluid. Results: All autografts were well placed in the labral defect in the AUG group, and good integration of the autograft with the remnant chondrolabral junction was observed at 24 weeks; only scar tissue was observed in the control group at 6, 12, and 24 weeks. Fibrochondrocytes were concentrated at the transition between the autograft and native labrum at early time points, and the cells within the autograft labrum were predominantly fibrochondrocytes at 24 weeks. Rough and irregular articular cartilage surfaces were observed in 3 of the 6 samples in the AUG group at 24 weeks; the others appeared smooth. Focal cartilage erosion (predominantly in the acetabulum) occurred in all samples in the control group at 12 and 24 weeks. The Mankin score at 24 weeks was significantly lower in the AUG group than in the control group (mean [95% confidence interval]: 2.33 [1.06 to 3.6] versus 9 [8.06 to 9.94], p < 0.001). Likewise, the concentrations of all cytokines (in pg/mL) were significantly lower in the AUG group than in the control group at 24 weeks (IL-6: 166.6 [155.22 to 177.94] versus 245.9 [242.66 to 249.14], p < 0.001; IL-1β: 122.1 [116.4 to 127.83] versus 282.9 [280.29 to 285.51], p < 0.001; and TNF-α: 56.22 [53.15 to 59.29] versus 135 [131.66 to 138.24], p < 0.001). Conclusions: Autograft tendon used for labral augmentation was able to integrate well with the native labrum, which may help to preserve the articular cartilage. Clinical Relevance: Labral augmentation with autograft tendon may be a feasible option in cases of viable labral remnants.