Reduced degenerative articular cartilage changes after meniscal allograft transplantation in sheep

The objective of this study was to examine the gross changes after meniscal allograft transplantation with reference to the development of degenerativ e articular cartilage changes (DACC) and to examine the transplant behavior . The medial menisci of both knees in 32 Iceland sheep were operated on wit h either sham operation (C6), medial meniscectomy (M6). primary transplanta tion (P6). or secondary transplantation 3 months after meniscectomy (S6). T hese sheep were observed for 6 months, Another six sheep were observed for 3 months after meniscectomy (M3) and contralateral sham operation (C3). The DACC of the knee were visualized with an intra-articular toluidine blue in jection. The dissemination area Of DACC on the medial tibial plateau (MTP), the meniscal area, and the meniscus-free, exposed central area on the MTP were measured by computer image analysis based on digitized photos of the t ibial plateau. These area measurements were calculated relative to the area of the MTP. The DACC in P6 knees had a mean of 4.3%, which was less than t he 12.6% in M6 (P < 0.001) and the 16.1% in S6 (P < 0.001), but more pronou nced than the 0.5% in C6 (P < 0.005). There were no detectable differences in DACC between M6, S6 and M3 (16.9%). The measurements of DACC were reprod ucible with correlation coefficient, r = 0.97 on intra-tester test-retest m easurements. The area. of the free exposed MTP was larger in P6 and in S6 t han in C6 (P < 0.001), demonstrating a displacement of the graft. S6 transp lants showed shrinkage and were smaller than C6 menisci (P < 0.01). In conc lusion, primary meniscal allograft transplantation reduced DACC within 6 mo nths in sheep knees, but DACC were still present in transplanted knees. The meniscal transplants demonstrated peripheral displacement.