Biomechanical and Histological Evaluation of Osteochondral Transplantation in a Rabbit Model

Abstract

Background Biomechanical and histological properties of osteochondral transplantation have not been extensively examined. Hypothesis Osteochondral grafts have properties similar to native articular cartilage. Study Design Controlled laboratory study. Methods A 2.7 mm (diameter) × 4.0 mm (depth) osteochondral defect was created in 17 New Zealand white rabbit knees. An osteochondral graft, harvested from the contralateral knee, was transplanted into the defect. Eight rabbits were sacrificed each at 6 and 8 weeks. Results The 12-week grafts (1213.6 ± 309.0 N/mm) had significantly higher stiffness than the 6-week grafts (483.1 ± 229.1 N/mm; P< .001) and of normal cartilage (774.8 ± 117.1 N/mm; P< .003). Stiffness of the 6-week grafts was significantly lower than normal cartilage (P< .036). At all time points, full-thickness defects had significantly lower stiffness than normal cartilage (P< .001). Histologically, transplanted grafts scored significantly higher than the full-thickness defects (P< .001). The defects showed inconsistent, fibrocartilage healing. The grafts demonstrated cartilage viability, yet with a persistent cleft between the graft and host. Conclusions Osteochondral transplants undergo increased stiffness in the short term, with evidence of structurally intact grafts. Clinical Relevance Osteochondral transplantation may be a viable treatment option; however, long-term investigation on graft function is necessary.