Cylindrical press-fit osteochondral allografts for resurfacing the equine metatarsophalangeal joint.

The research study focuses on the potential of using cylindrical, orthotopic, press-fit, osteochondral allografts to resurface equine fetlock joints and the subsequent evaluation of their performance.

Methods

• The research involved an experimental study on ten mature, mixed-breed horses. The horses were divided into two groups; six horses received the grafts and four were sham operated i.e., underwent a procedure mimicking the transplantation but didn’t receive any graft.
• 6.5-mm diameter cylindrical, osteochondral grafts were harvested aseptically from the metatarsophalangeal joints of horse cadavers.
• The surgical approach involved creating a bone block at the origin of the medial collateral ligament along with luxation of the metatarsophalangeal joint. The grafts were then placed into the medial and lateral metatarsal condyles in the recipient horses.

Monitoring and Evaluation

• Horses were monitored over a period of 25 weeks. Radiographs were taken at 8 and 25 weeks, and lameness was evaluated at 25 weeks.
• Analyses included gross evaluation, microradiography, paravital staining, light microscopy, and cartilage biochemistry.

Results

• No surgical complications related to the procedures were observed. The interface between the grafts and the surrounding articular cartilage was found to be congruous, ranging from satisfactory to excellent.
• Two out of the six horses that received the transplantation were sound at 25 weeks. Most grafts showed more than 90% articular cartilage coverage.
• The histologic and microradiographic analysis showed good graft incorporation and articular cartilage survival in the horses.
• The sulphated glycosaminoglycan concentration, a major component of the cartilage’s extracellular matrix that provides resistance to compression, was found to be decreased in the grafted tissue. This could be an area of future exploration about its implications.

Conclusions

• The study concluded that the viability of osteochondral allografts in the equine fetlock can be attributed to adequate congruency, stable graft fixation, and the use of orthotopic tissue. The host horses’ reaction to the allograft bone tissue did not affect the cartilage viability, which is a positive outcome.
• However, before the procedure is employed on a larger scale, some improvements are required to minimize damage to grafts and technique-associated incongruities of the articular surface at the time of grafting. It is also suggested that larger grafts might be required in order to resurface a more extensive surface area on the joint.