Unicondylar fractures of the distal humerus are fairly common in small animal orthopedics. Fractures of the lateral aspect of the condyle are more commonly seen than medial fractures. The radius is the main weight bearing bone of the antebrachium and the radial head articulates with the lateral aspect of the condyle. Excessive force can then cause a shear injury of the lateral aspect of the distal humeral condyle. Some type of internal fixation is typically required. Lag screw fixation is recommended in mature animals. It is not recommended to compress the condyle in young growing animals. K-wires have been used, but with motion, K-wires tend to migrate or lose reduction of the condyle. Miniature stick-pins are useful for stabilizing condylar fractures of the distal humerus in small (<5 kg), young animals. They have more holding power in the soft bone than smooth K-wires and they don’t require the use of power equipment as when using screws. All that is needed is a hand chuck. I prefer to use the Mini Hand Chuck. It is not as bulky as the standard sized hand chuck.
Once the elbow is exposed and the joint explored, chose an appropriate sized mini stick-pin (IMEX® PN #06035, 06045, 06062, & 06078). Using the mini hand chuck (IMEX® PN #30008), the pin is driven (screwed) from the epicondyle into to the condyle to exit in the middle of the fractured condyle. In young animals the bone is soft enough this can be done by hand. The condyle is reduced (the chuck aids in helping with the reduction). Once the condyle is adequately reduced, the pin is screwed into the opposite side of the condyle. The threaded pin acts like a positional screw (vs. lag) which is preferred in the soft bone. The pin is then cut and the opposite smooth end is placed up the epicondyle into the distal humerus to provide rotational stability. Once the fracture is healed, the pins can be easily removed.
Tip submitted by Bert Shelley, DVM – Bradford Park Animal Hospital