Accessory carpal bone fracture repair by means of computer‐assisted orthopaedic surgery in a Warmblood stallion

Abstract

Summary A 10‐year‐old, 595 kg Irish Warmblood stallion used for showjumping was presented with a marked right forelimb lameness at walk. The horse sustained a dorsal plane fracture of the accessory carpal bone (ACB) when falling with both carpi in flexion. The fracture was repaired by means of computer‐assisted orthopaedic surgery (CAOS) using two cortex screws placed in lag fashion. In a second CAOS procedure, a dorsoproximal fragment of the ACB was removed after further proximal displacement had become apparent. Both surgical procedures were facilitated by the application of a fibreglass cast to immobilise the carpus in extension and to allow for the placement of the patient tracker distant from the surgical site. One year after surgery, the horse had returned to full athletic activity. Neither the antebrachiocarpal joint nor the carpal sheath were distended. Control radiographs and standing cone beam computed tomography showed complete osseous union of the fracture and osteophyte formation on the caudal aspect of the radius and the proximal border of the ACB.

Fracture of the accessory carpal bone—conservative or surgical therapy?

“…For unknown reasons, the ACB is not displaced medially during flexion, which predisposes it to fracture. These events usually lead to a fracture configuration similar to that described by de Preux et al (2022); the fracture is characterised by a vertical course with an additional fragment in the dorsoproximal region of the ACB (Figs 1 and 2). However, other configurations have also been described.…”

“…De Preux et al. (2022) describe the successful treatment of a multiple fracture of the accessory carpal bone (ACB) in a horse. This is a remarkable report because surgical repair of ACB fractures is difficult, and thus, successful treatment has seldom been reported.…”

“…De Preux et al. (2022) used CAOS to insert two lag screws, a 4.5‐mm and a 3.5‐mm cortical screw, into the ACB of their patient. The 4.5‐mm cortical screws likely provided better stability than 3.5‐mm cortical screws because the latter are much less stable for fracture treatment in horses.…”

“…Koch and colleagues developed an alternative to using pins in the bones by fixing the limb in a hard shell, which prevented movement and acted as a reference for the infrared camera. This improved technique allows increased surgical precision and has been used to successfully treat various orthopaedic problems in horses (De Preux et al, 2020a;De Preux et al, 2020b). De Preux et al (2022 used CAOS to insert two lag screws, a 4.5-mm and a 3.5-mm cortical screw, into the ACB of their patient.…”

“…We believe that surgical fixation will be the preferred option for the treatment of ACB fractures in the future. Fixation can be done using lag screws, as described by de Preux et al (2022), or with plates. The application of plates is somewhat easier because they can be applied laterally, which provides ample space for the screws.…”