[Comparative study on repair of medium and large-sized osteochondral compound defects with mosaicplasty]

To investigate the effectiveness of mosaicplasty in repair of large-sized osteochondral compound defects and the integrity of transplanted tissue with recipient sites so as to lay a foundation for clinical application.

Twenty-four adult goats were divided into 3 groups randomly. The diameters of defect were 6 mm for the medium-sized defects and 9 mm for the large-sized defects, which were created by a trepan. All of the defects were repaired with osteochondral plugs in diameters of 2 mm (the medium-sized defects) or 3 mm (the large-sized defects). The osteochondral plugs were harvested around the intercondylar fossa or intertrochlea groove, and pressed into the recipient sites by specialized instruments in a mosaic mode. No internal fixation was needed and the animal were allowed to move freely after operation. From 4 to 24 weeks postoperatively, the specimens were observed in gross and under electromicroscopy. X-ray detection and glycosaminoglycan (GAG) analysis were also performed to testify the healing process and the integrity of the cartilage and subchondral bone.

The transplanted subchondral bone was integrated firmly with each other or with recipient sites in both mosaicplasty groups. But 24 weeks postoperatively, transplanted cartilage was not integrate with each other apparently. Obvious cleavage between cartilage plugs could be seen. But in the large-sized defect groups, some of the osteochondral plugs were relapsed into the defects leaving the recipient sites some steps, leading to some degree of abrasion in the opposing articular cartilage. There was no significant difference in the GAG content between the transplanted cartilage and normal cartilage. X-ray analysis also demonstrated the healing process between the subchondral bone.

Mosaicplasty can repair the medium or small-sized osteochondral defects efficiently.