Arthroscopic removal of axial osteochondral fragments of the plantar/palmar proximal aspect of the proximal phalanx in horses: 119 cases (1988-1992).

The study reviews medical cases of 119 horses that underwent a specific type of arthroscopic surgery to remove bone fragments from a certain area of their foot structure, looking at factors like age, breed, and performance outcomes post-surgery.

Summary of the Study

• The research took place from 1988 to 1992 and involved the review of medical records of 119 horses that underwent arthroscopic (minimally invasive keyhole surgery using a small camera and surgical instruments) removal of axial osteochondral (bone and cartilage) fragments from the plantar (sole or bottom surface of foot) or palmar (palms of hands) proximal aspect (closer to the main mass of the body) of the proximal phalanx, which is the bone in the foot or hand immediately below the digits.
• Of these 119 horses, the majority (92%) were Standardbred racehorses, a breed that is often used for racing. Most (78%) of the horses were younger than 3 years old. The gender distribution was consistent with the general equine population at the medical facility.
• These bone fragments were most frequently seen in the hind limbs of the horses, specifically on the medial aspect (closer to the middle of the body) of the left hind limb. Bilateral fragmentation (on both sides) occurred in 18% of the horses, while 13% had fragments in both the medial and lateral (farther from the middle of the body) aspect within the same joint.

Concurrent Conditions and Outcomes

• Some of the horses (13%) had a concurrent condition known as osteochondritis dissecans, which is a joint condition where a piece of cartilage, along with a thin layer of the bone beneath, comes loose from the end of the bone. This was seen on the distal intermediate ridge of the tibia (lower leg bone), and 25% showed signs of osteoarthritis in the distal intertarsal and tarsometatarsal articulations/joints.
• 63% of the racehorses and all of the nonracehorses were able to return to their preoperative performance levels following the surgery. The study found no significant correlation between outcome and the number/distribution of fragments, concurrent osteochondritis dissecans lesions of the distal intermediate ridge of the tibia, or tarsal osteoarthritis.

Significant Findings and Conclusion

• The study detected certain abnormal surgical findings, such as articular cartilage fibrillation (fraying or roughening of the surface of cartilage) or synovial proliferation (increase in the lining of the joint), were significantly associated with a poor outcome. These observations were made in 31% of the 32 horses with unsuccessful outcomes, and only in 2% of the 55 horses with successful outcomes.
• Therefore, the study suggests that while these types of surgery can potentially bring horses back to preoperative performance levels, the presence of certain abnormal surgical findings linked to joint health may significantly affect their prospects for a positive outcome.