Femoral and Humeral Diaphyseal Fracture Repair in Cats

Long bone fractures in the cat
Femoral fractures accounting for 38% and humeral fractures for 5-13% of all fractures in one survey (1).

Investigations
Prior to fracture repair it is important to ascertain that the cat is stable for anesthesia and the nerve supply is intact. orthogonal radiographic views should be taken of the affected and contralateral bone. oblique views may be useful to exclude fissures.

Intramedullary pinning (iM)
A femoral iM pin should be placed in a normograde fashion from the intertrochanteric fossa to avoid risk of sciatic nerve damage (2). an oblique fracture, where the length of the oblique part is at least twice the diameter of the bone, may be suitable for cerclage wiring in combination with iM pinning. Cerclage wire of 0.8mm or 22G should be used and at least two wires should be placed. Short oblique or transverse fractures may remain rotationally unstable when a single iM pin is used for fixation. Methods to reduce rotation include the addition of an external skeletal fixator (ESf) (3), use of multi- ple pins (stack pins), a triangular nail, an interlocking nail or plate and screw fixation.
In cats it is generally not possible to pass the iM pin right into the medial humeral con- dyle / epicondyle (4), which is often the technique recommended in dogs. the iM pin should therefore be aimed towards the centre of the medullary canal. the pin can be passed in a retrograde or normograde fashion. the intramedullary canal narrows in the distal humerus and this area should be assessed when selecting pin size. Simple long oblique or spiral fractures in young cats can be successfully repaired with cerclage wire and iM pinning. if the fracture is rotationally unstable or fissured consider augmenting fixation with an ESf. [...]