Second carpal bone slab fracture and subluxation of the middle carpal joint in a horse subsequent to arthrodesis of the carpometacarpal joint.

The research article is about complications observed in a horse after the arthrodesis surgical treatment for carpometacarpal osteoarthritis. Namely, a slab fracture of the second carpal bone and subluxation of the middle carpal joint resulted from the surgery and led to severe lameness in the horse.

Objective of the Study

• The study aimed to highlight the potential complications that can occur from arthrodesis of the carpometacarpal (CMC) joint using a specific drilling technique. This was achieved through a case report of a 12-year-old Quarter Horse mare diagnosed with CMC-OA, who underwent the procedure.

Methodology

• The surgery was carried out under general anesthesia with the horse in right lateral recumbency.
• To destroy the articular cartilage and expose the subchondral bone, the surgical procedure involved inserting a 4.5mm drill bit at three drilling sites 5-6 cm into the CMC joint.
• The drill bit was then “fanned” 30-45° in the plane of the joint and 5-10° in the long axis of the limb under fluoroscopic guidance.

Result

• The horse presented severe lameness from the operated limb two weeks after surgery.
• Upon examination, a slab fracture of the second carpal bone (C2) and subluxation, or partial dislocation, of the middle carpal (MC) joint was diagnosed.
• Due to the severe nature of the complications and poor prognosis, the horse was humanely euthanized.

Conclusion

• The study concluded that the fanning technique, a part of the arthrodesis surgery, may increase the risk of certain complications, including carpal bone fractures, joint instability, and MC joint subluxation.
• There needs to be a balance between articular surface destruction and maintenance of joint stability when using this technique. This highlights the importance of evaluating surgical approaches and techniques for such conditions to minimize potential side effects and complications.