Transarticular Fixation of a Failed Anatomic Repair using an IMEX ROM Hinge to Allow Early Return to Function

Case Description: A 5-year-old domestic short hair feline was presented after a failed anatomical repair of a total stifle subluxation with multiple ligament injuries. There was a severe medial patella luxation with medial and collateral instability. A cranial and caudal drawer was present in the stifle. On radiographs, a stifle subluxation was seen.

A lateral transarticular type I external fixator was placed across the stifle joint with three 2.4-mm Imex interface half pins in the femur and three 2.4-mm Imex interface half pins in the tibia. An Imex ROM hinge was placed with the hinge entered over the stifle. The hinge was set at a normal weight bearing angle judged on the contralateral leg. The hinge was tightened to allow no motion in the stifle for the first 2 weeks postsurgery. The patient was weight being on the leg 3days postsurgery. At 2 weeks, the hinge was loosened to allow 20% of the normal range of motion. Weight bearing decreased for the first 2days after allowing increased ROM but then returned to normal. At 4 weeks postsurgery, the hinge was loosened to allow 60% range of motion. The patient continued to use the leg at all times.

At 6weeks postsurgery, the hinge was removed and stability of the stifle assessed under sedation. There was a mild cranial and caudal drawer but no medial or lateral instability. The patient returned to full weight bearing after removal of the external fixator.

Acknowledgement: None.