Headless self-compressing cannulated screw fixation for treatment of radial carpal bone fracture or fissure in dogs.

Perry K, Fitzpatrick N, Johnson J, Yeadon R.

Objectives: To report the application and clinical outcome of the treatment of radial carpal bone fracture in five dogs using a variably-pitched, headless cannulated compression screw (Acutrak(R)). Methods: Arthroscopy was performed prior to surgical repair in three cases. In two cases, a fissure within the radial carpal bone was more clearly apparent when oblique indirect illumination was employed at arthrotomy. Following Acutrak(R) screw placement via arthrotomy, external coaptation was applied in all cases for a period of two weeks. Results: Five dogs were treated, of which four were Boxers, and one was a Labrador Retriever crossbreed. All dogs were lame prior to treatment. There was no history of trauma, and all dogs had soft tissue swelling on the dorsal aspect of the radiocarpal joint. In all cases the fissure or fracture line was oblique in orientation, extending disto-medially from the midpoint of the radiocarpal joint proximally to the level of the second carpal bone distally. All fractures treated demonstrated progressive radiographic healing, and all dogs were free of lameness at six weeks post- operatively, but two of the five fractures failed to reach complete radiographic union. All dogs remained lameness-free with mean follow-up of 12.5 months. Discussion: Acutrak(R) screws are headless devices which achieve compression, even in small bone fragments. Threads engage both the near and far fracture segments, leading to increased screw-bone contact which maximizes pull-out strength and may increase the fatigue strength of the screw. Clinical significance: Fixation of two-piece canine radial carpal-bone fractures with the Acutrak(R) screw proved a reliable alternative to conventional compression screw fixation, and may have benefits over alternatives attributable to screw design and application technique.