NM Fitzpatrick, KL Perry.
Fitzpatrick Referrals, Farnham, United Kingdom

ACVS Abstract 2007 

The canine radial carpal bone has 3 centres of ossification. Radial carpal fracture has been documented through the fusion planes. Predilection in the Boxer breed and documentation of incomplete radial carpal fracture is consistent with aetiopathogenesis of incomplete ossification. This report documents diagnosis and treatment of bipartite radial carpal bone in 2 dogs.  (1) 5y11m Labrador cross with left thoracic limb lameness and pain on carpal manipulation.

A contralateral tripartite radial carpal fracture had previously been treated with pancarpal arthrodesis.  (2) 1y4m Boxer with right thoracic limb lameness and carpal swelling with pain on carpal manipulation. In both cases a sagittal radiolucent fissure was observed traversing the radial carpal bone proximo-distally on dorso-palmar radiography. Cranio-lateral arthrotomy allowed identification of the subchondral fissure plane. A cannulated headless titanium variable-pitched tapered compression screw (Acutrak, Acumed, Hillsboro, Oregon, USA) was inserted along a guide-wire and countersunk beneath the articular surface of the radial carpal bone to compress the fissure plane. Lameness and pain on manipulation resolved in both cases by six weeks.

Implant positioning was maintained and radiolucency was no longer evident across the fissure plane. Comfort on manipulation and resolution of lameness were maintained at 12 weeks. The subchondral fissure planes did not traverse the articular cartilage consistent with an aetiopathogenesis of incomplete ossification rather than trauma. Cannulation of the implant allows use of a k-wire to facilitate accurate positioning. Headless design reduces the risk of splitting small fragments and avoids interference with joint function. Short-term outcome measures are encouraging.