Fresh Allograft Replacement for Osteochondral Lesions of the Talus

Abstract

Category: Basic Sciences/Biologics Introduction/Purpose: Large osteochondral lesion of the talus (OLT) can be difficult to treat. Although many treatment options exist, fresh osteochondral allograft transplantation has demonstrated promise as the primary treatment for OLTs with substantial cartilage and bone involvement as well as a secondary treatment option after failure of other cartilage repair techniques. Fresh osteochondral allografts are size-matched from organ donors and, in theory, have healthy articular cartilage and bone. However, the quality of allograft cartilage and bone has never been examined with respect to the OLT cartilage and bone being replaced. The purpose of this study was to perform a matched comparison of the cartilage and bone from patients OLTs to the fresh osteochondral allograft replacement. Methods: Discarded intact osteochondral specimens were collected from 8 patients undergoing surgery for an OLT. The specimens included the excised OLT and a portion of the fresh allograft replacement that the same patient received at the time of surgery. Histologic analysis was performed. The safranin-o histology was then scored using the International Cartilage Repair Society (ICRS) histopathology grading and staging system. In this system the grade determines cartilage and bone destruction on a scale of 0 to 6.5, the stage determines the percentage of involvement in the specimen on a scale of 0 to 4, and the total score is the grade multiplied by the stage. The surface roughness was also compared between the OLT and allograft cartilage using ImageJ software (NIH). Paired t-tests were performed on the ICRS grade, stage, and total score, and surface roughness comparing the OLTs and allografts. Significance was set at p<0.05. Results: Gross histological inspection of the samples demonstrated cartilage erosion and subchondral bone destruction in the OLTs. In constrast, the osteochondral allografts demonstrated intact cartilage surface and normal subchondral bone in the allografts (Figure 1). The ICRS grade, stage, and total score were significantly higher in the implanted allografts compared to the resected OLTs (Figure 2); indicating better cartilage and bone morphology for the allografts compared to the OLTs. In fact, the mean grade and stage for the allograft samples were both less than a score of 1 which corresponds to healthy cartilage and bone with less than 10% surface fibrillations. Moreover, the surface roughness of the allograft cartilage was significantly smoother than the OLT cartilage. Conclusion: This is the first study to demonstrate that the use of fresh allograft transplantation for the treatment of OLTs replaces the damaged cartilage and bone with normal or near normal cartilage and bone. The replacement of damaged cartilage and subchondral bone with normal or near normal cartilage and bone may be the reason for improved pain relief and functional outcomes after fresh allograft transplantation for OLTs.