Subluxation/luxation of the second carpal bone in two racing greyhounds and a Staffordshire bull terrier

Abstract

Subluxation of the second carpal bone (C2) in two racing greyhounds, and luxation associated with other carpal injuries in a Staffordshire bull terrier, were diagnosed as causes of thoracic limb lameness. The clinical signs of subluxation were subtle, with local soft tissue swelling and a pain reaction on digital pressure over the dorsal aspect of C2. In contrast, the dog with a complete luxation was very lame, having marked soft tissue swelling with carpal hyperextension and valgus. Diagnosis was made by radiography. Subluxation of C2 was seen as a small, dorsally displaced opacity between the proximal and distal rows of carpal bones on the mediolateral view and, on the oblique view taken in only one case, as a marked dorsal displacement of one-third of the proximal joint surface of C2. In the case of luxation, C2 appeared on the mediolateral view lying dorsal to the radial carpal bone. There was also fracture of C4. Both greyhounds were treated by internal fixation and returned to racing. The Staffordshire bull terrier was treated by pancarpal arthrodesis with a successful outcome.

Bilateral radial carpal bone luxation and its treatment in a dog

“…These cause the os carpi radiale to create a 90° angle around the dorsopalmar and mediolateral axes and settle palmaromedially. In this position, the luxated os carpi radiale restricts the flexion motion of the carpus and produces carpal varus deviation (2,5,10,11). Loss of stability of the carpal joint to the medial was clearly observed in our case.…”

“…Luxation of the radial carpal bone generally occurs with the overextension of the carpus during extreme limb loading, as a result of a road accident, or when jumping/ falling from a height (2). Carpal hyperextension due to axial loading of the joint commonly results in damage to the ligaments and the palmar fibrocartilaginous pad (10). The radial carpal bone rotates 90° around its dorsopalmar and mediolateral axes, which results in the bone orientating so that the medial aspect is farthest proximal, with the convex proximal articular surface facing dorsally accompanied by a rupture of the short radial collateral ligament and dorsal joint capsule.…”

Use of circular external skeletal fixator constructs to stabilize tarsometatarsal arthrodeses in three dogs

“…Although both greyhounds in this report were electively retired from racing following their injury, previous reports of racing greyhounds receiving tarsometatarsal or pancarpal arthrodesis (13,14) indicate that small-joint arthrodesis may not necessarily limit an athletic performance in dogs. Indeed, while their racing career was not resumed, both greyhounds in this report were able to perform heavy exercise without any evidence of lameness and all three of the dogs had an acceptable long-term (44 to 55 months) functional outcome of their operations.…”

Dorsal tarsal instability in three racing greyhounds

“…A further reason for elective removal is that the screw may accidentally cross a joint space, as accurate placement can be difficult in the smaller tarsal bones. Screw placement across low motion joints has been shown to cause lameness (Guilliard 2001). Removal of implants could be considered only if the dog showed lameness on the resumption of racing.…”