Suspensory apparatus prosthesis in the horse. Part 2: In vivo evaluation in a suspensory apparatus disruption model.

This study examines the in vivo effects of a synthetic ligament implanted in horses with a surgically disrupted suspensory apparatus. While initial results showed some drawbacks like synovitis and prosthesis fragmentation, improvements in lameness and weight bearing were noted over time.

Research Context and Approach

• The subject of this paper is a study where six adult horses had the suspensory apparatus of one forelimb surgically disrupted. This was done through the transection of the distal sesamoidean ligaments.
• A double-braided prosthetic ligament, constructed from aramid yarn, was then installed to provide support for the metacarpophalangeal joint’s flexor surface.
• This prosthesis was placed by routing it through tunnels in the third metacarpal bone and the proximal phalanx. It was thereafter secured to the bone using screws.
• The researchers conducted evaluations through various means before surgery as well as at weeks 16 and 30 post-surgery. These involved radiography, synovial fluid analysis, cinematography, and dynamography.

Observations and Results

• Postoperative radiographs revealed supracondylar cortical lysis and periosteal proliferation.
• Analysis of synovial fluid indicated the development of synovitis and some fragmentation of the prosthesis.
• There was a decrease in weight bearing and metacarpophalangeal joint motion, with some loading being transferred to the forelimb opposite the one that was operated on.
• However, clinical lameness was seen to improve during the second half of the 30-week period. There was also an increase in weight bearing during the same period.
• Necropsy performed at the end of the research period revealed prosthesis abrasion and articular surfaces in contact with the prosthesis.
• Lastly, the researchers noted that diffuse granulomatous synovitis had developed as a response to fragments of the aramid fiber present within the synovium.

Conclusion

• Overall, the study offered valuable insights into the in vivo effects of a prosthetic approach to treating suspensory apparatus disruption in horses. While it was noted that there were several complications following surgery including prosthesis fragmentation and synovitis, there were also positive signs with improvement in clinical lameness and increased weight bearing over time.