Experimental Studies in Tendinopathy and Use of a Novel Tendon Autograft for Cartilage Resurfacing: An Ovine Model

Abstract

Cartilage damage and osteoarthritis are enormous medical problems in humans and animals. The inherent poor regenerative capacity of articular cartilage after injury results in loss of an appropriate weight-bearing surface, so a need exists for a joint ‘resurfacing’ material which can integrate into the joint. Recent studies have shown that injured tendon develops some chondroid features, suggesting potential as a cartilage resurfacing material. Our initial study utilized a surgical model of tendinopathy in sheep to investigate the features of tendon healing over time, and to identify the time point at which the injured tendon has the most chondroid features. The second study used pathological chondroid tendon harvested at 8 weeks, and implanted this material into acute lesions of the ovine trochlear groove. Pathological tendon implants were compared to normal tendon implants, untreated lesions and non-operated subjects. Joints were evaluated using radiographic and gross evaluation, gene expression analysis, and histology 6 months after graft implantation. Gross, radiographic, gene expression and histological analyses demonstrating a degenerative response to grafting of pathological tendon. In contrast, on gross evaluation, normal tendon appeared to provide a suitable cartilaginous surface in some subjects, although gene expression and histological data did not indicate any improvement in contrast to ungrafted sheep with untreated lesions. This pilot study suggests that normal tendon may be a valuable source of graft material for acute cartilage lesions, and may be a useful ‘scaffold’ for resurfacing. Overall this pilot study indicates that normal tendon, as a freely available autogenous tissue with multiple dispensable sources within the body, presents an intriguing option as a scaffold for future cartilage repair and warrants further attention.