33rd Annual Scientific Meeting proceedings

Introduction

During mosaic arthroplasty cylindrical osteochondral grafts are harvested from less-weightbearing articular surface. The purpose of this experimental study is to investigate filling characteristics of donor channels, which were either left empty of filled with a biodegradable polymer to prevent bleeding and promote postoperative healing.

Materials and Methods

Fifteen femoropatellar joints of 10 mature warmblood horses were operated. Osteochondral grafts of 8.5mm and 6.5mm diameter and 30mm in length were harvested from the medial femoral trochlea. 50% of the donor channels were filled with a biodegradable polymer (PolyActive). The animals were euthanized 18 months later and macroscopic and histologic assessment of the donor sites was performed.

Results

All channels filled up with cancellous bone with a coverage of hyalin-like cartilage (11/40), fibrocartilage (10/40) or fibrous connective tissue (11/40). In 8 cases coverage of the subchondral bone was absent or was of very poor quality. The size of the channel did not significantly affect healing characteristics. Excellent quality repair tissue was more frequently present in case of PolyActive-filled channels (p=0.0002). Plug insertion depth affected fibrocartilage quality significantly (p=0.0309).

Discussion/Conclusions

Donor channels fill with cancellous bone and develop fibrocartilage covers 18 months following surgery. Hyaline-like cartilage developed in 27.5% of the cases. PolyActive can be effectively used to fill the donor channels, however the depth of insertion critically affects the quality of cartilage cover. Soft porous tissue was filling up the channels 24 months following harvesting, which was highly inferior to normal cancellous bone.