Autogenous Osteochondral Graft Associated with IGF-1 in Induced Articular Cartilage Lesion in Rabbits

Abstract

Background: Articular cartilage has a limited capacity for regeneration and of the various treatments proposed, none have reached appropriate therapeutic effectiveness. This study aimed to evaluate autogenous osteochondral grafts in intact or macerated format, in association with or without insulin-like growth factor type-1 (IGF-1) in the repair of osteochondral defects induced in the femoral trochlear groove of rabbits.

Materials, Methods & Results: Seventeen healthy White New Zealand rabbits were selected for this study. The rabbits were female, six months old, and had an average body weight of 4.5 kg. All 34 stifle joints were subjected to autogenous osteochondral grafting in the femoral trochlear groove. The joints were divided into four groups designated as intact osteochondral graft with IGF-1 (INT + IGF), intact osteochondral graft with physiological solution (INT + FIS), macerated osteochondral graft with IGF-1 (MAC + IGF), and macerated osteochondral graft with physiological solution (MAC + FIS). Serial evaluations were performed by orthopedic and radiographic examination. After 6 and 12 weeks postoperatively, the grafted area was subjected to macroscopic, histological, and immunohistochemical analyses. Although no statistically significant differences were found between the groups in relation to clinical, macroscopic, histological, and immunohistochemical aspects, a tendency of IGF-1 to promote tissue repair was evident. In the radiographic evaluation, the articular surface and the recipient site in both groups with IGF-1 showed significantly more effective filling (P ≤ 0.05). Regardless of the group, collagen type 2 production, as assessed by immunohistochemistry, was found to be appropriate on the grafted articular surface.

Discussion: In extensive cartilage lesions, the use of intact osteochondral grafts may be infeasible due to donor site morbidity. An alternative is the use of macerated osteochondral grafts, which cover a larger area and act as a support and cellular source in the repair process. Growth factors have been evaluated in association with grafted tissues to aid tissue repair, and IGF-1 is currently prominent. In the radiographic analysis of the present study, when comparing sites subjected to osteochondral grafting, presence of the whole graft evidenced adequate local filling in all groups. However, graft integration was apparently rapid and effective in the INT + IGF and MAC + IGF groups from the sixth and ninth weeks of the procedure, respectively. In the macroscopic evaluation at the twelfth week, graft integration with the original cartilaginous tissue was more evident, especially in both groups treated with IGF-1. It is likely that the property of IGF-1 to increase chondrogenesis in the cartilage repair of articular lesions in vivo may have contributed to these results in radiographic and macroscopic examinations. Histological examination showed no significant difference between groups in the same period of time; however, it was observed that addition of IGF-1 promoted a more evident tissue reaction and cellular activation, potentiating the process of reabsorption and repair in the grafted tissue. Immunohistochemical analysis showed similar immunoreactivity for collagen type 2 in all groups as early as the sixth week. However, a small portion of these tissues cannot be considered true hyaline cartilage due to the absence of some typical features. In summary, addition of IGF-1 to the autogenous osteochondral graft seemed to stimulate reabsorption and replacement processes in the grafted tissue. The grafts showed adequate ability to repair articular cartilage, displaying formation of collagen type 2 similar to that in the original tissue.