Human Acellular Dermis as Spacer for Small Joint Arthroplasty: Analysis of Revascularization in a Rabbit Trapeziectomy Model

BACKGROUND: Carpometacarpal (CMC) osteoarthritis affects 8-12% of the general population. Surgical management provides symptomatic relief for 78% of patients who fail conservative therapy, but little consensus exists regarding which surgical procedure provides superior patient outcomes. Recent human trials substituted exogenous acellular dermal matrices (ADMs) in the bone space, but there is no quantitative histological data on the outcome of ADMs in this environment. We aimed to quantify the revascularization and recellularization of ADMs in the joint space using a rabbit model. METHODS: Bilateral lunate carpal bones were surgically removed in New Zealand rabbits. ADM and autologous tissue were implanted in place of the lunate of the right and left wrists, respectively. ADM was also implanted subcutaneously as a non-joint control. Histological and immunofluorescence analysis was performed after collection at zero, six, and twelve weeks. RESULTS: Quantitative analysis of anti- α- smooth muscle actin (SMA) and CD31 immunofluorescence revealed a sequential and comparable increase of vascular lumens in joint space and subcutaneous ADMs. In contrast, autologous tissue implanted in the joint space did not have a similar increase in SMA- or CD31-positive lumens. Semi-quantitative analysis revealed increased cellularity in both autologous and ADM wrist implants at each time point, while average cellularity of subcutaneous ADM peaked at six weeks and regressed by twelve. Trichrome and Sirius Red staining revealed abundant collagen at all time points. CONCLUSIONS: The trapeziectomy joint space supports both cellular and vascular ingrowth into human ADM. * Authors contributed equally Disclosures: This work was funded in part by a grant from the Musculoskeletal Transplant Foundation/Plastic Surgery Foundation. AKW is supported by NIH 1K08HL132110-01. All procedures were approved by the Keck School of Medicine of USC Institutional Animal Care and Use Committee (IACUC #20099) and animals were housed according to recommendations from the USC Department of Animal Resources (DAR) Corresponding Author: Alex K. Wong, Division of Plastic and Reconstructive Surgery, Department of Surgery, Keck School of Medicine of USC, 1510 San Pablo St. Suite 415, Los Angeles, CA 90033 USA. Alex.Wong@med.usc.edu ©2018American Society of Plastic Surgeons

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