The Vascularization Course of Labral Autograft and Its Effect on Tissue Healing: Acetabular Labral Augmentation Versus Labral Reconstruction in a Porcine Model

Abstract

Background: The preservation of the native labral vascularization is assumed to be the potential advantage of acetabular labral augmentation, the effect of which remains unknown. Purpose: To identify the vascular distribution within the labral autograft and its effect on the healing process between labral augmentation (AUG) and reconstruction (RECON) in a porcine model. Study Design: Controlled laboratory study. Methods: A total of 36 pigs randomly underwent unilateral labral augmentation or reconstruction (AUG group, n = 18; RECON group, n = 18). The pigs were randomly sacrificed at 6, 12, and 24 weeks postoperatively. The labral autografts were harvested for macroscopic evaluation and histologic assessment. The labral autograft was zoned into 2 halves to observe the vascular distribution: the capsular half (zone I) and the articular half (zone II). Each zone was divided into 2 parts: the peripheral part (IA and IIA) and the part attached to the acetabulum (IB and IIB). Results: At 6 weeks, there existed more vascular ingrowth in zone I, whereas zone IIB appeared nearly avascular in both groups. At 12 weeks, the area with the greatest vascularity was zone II in the RECON group and zone IA in the AUG group. The vascularity was concentrated at zones IA and IIA in both groups at 24 weeks. The labral autografts were hypertrophic with sufficient filling of the labral defect in both groups at 6 weeks. At 12 weeks, an insufficient volume of the articular half was observed in 3 of 6 labral autografts in the RECON group, while all autografts remained well integrated with the chondrolabral junction in the AUG group. At 24 weeks, unsatisfactory merging of the labral autograft with the cartilage at the articular side was found in 2 of 6 labral autografts in the RECON group, which was not observed in the AUG group despite the sufficient volume of autografts labrum in both groups. Conclusion: Slow vascular ingrowth within the articular half might account for the poor healing of the reconstructed labral autograft. Labral augmentation provides the possibility of better tissue healing because of the preservation of the original chondrolabral junction compared with labral reconstruction. Clinical Relevance: Labral augmentation might be a feasible alternative to labral reconstruction under the condition of viable labral remnants.

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

“…Second, we did not explore the effect of different graft materials on tissue healing. In a prior cadaveric study 19 , we found that the porcine tensor fasciae latae was too thin to be tubularized. In contrast, we found that the initial tubular shape and sufficient volume of the Achilles autograft made it a suitable option, and no related complications occurred in the present study.…”

“…Based on a previous study that included histological analysis 19 , the desired sample size for 2-sample t tests was calculated (PASS version 15; NCSS) with a error = 0.05 and power = 0.8. Continuous variables were expressed as the mean and 95% confidence interval (CI).…”

“…The procedures were performed as previously described 19 . Pigs were anesthetized in the lateral position on an operating table by inhalation of 2.5% to 3% isoflurane.…”

Tissue Regrowth and Its Vascularization Through Bone Marrow Stimulation: Microfracture at the Acetabular Rim for Irreparable Labral Tear in a Porcine Model

“…11,15,22,23,31 However, our previous results have shown that poor tissue healing occurred because of the slow and insufficient vascular ingrowth within the articular half of the reconstructed autograft. 25 Given that, this study aimed to explore the possibility of improving the vascularization of the inner half through bone marrow stimulation and to find out whether the volume of the regrown tissue is sufficient to fill the labral defect after microfracture at the bony rim of the acetabulum. Through penetrating the subchondral plate, a biological response for tissue repair is stimulated within the formed marrow clot, which provides an environment for mesenchymal stem cells to differentiate and finally mature into a fibrous repair matrix.…”

“…11,15,22,23,31 However, our previous results have shown that poor tissue healing occurred because of the slow and insufficient vascular ingrowth within the articular half of the reconstructed autograft. 25 Given that, this study aimed to explore the possibility of improving the vascularization of the inner half through bone marrow stimulation and to find out whether the volume of the regrown tissue is sufficient to fill the labral defect after microfracture at the bony rim of the acetabulum.…”