A study shows that ligament-splitting surgery can be effective in fixing “sticky” stifles.

Upward fixation of the patella—also called sticking or locking stifles—occurs when the medial patellar ligament of the stifle becomes hooked on the end of the femur. When this occurs, the horse cannot flex the joint or advance the limb. The leg usually becomes “unlocked” when the leg is flexed again, often with a jerky motion. Mildly affected horses may still be ridden, but in more severe cases they may not be able to perform.

Conditioning and corrective shoeing resolve some cases of sticking stifles, but surgical options are often considered for stubborn cases. In one surgical technique, called “splitting,” several small incisions are made in the medial patellar ligament. As these incisions heal, the ligament thickens with scar tissue, which makes it less likely to become stuck on the femur.

To determine the success rate of the procedure, researchers at Peterson and Smith Equine Hospital in Ocala, Florida, reviewed the records of 24 horses who had it done at the clinic from 2005 to 2012. Follow-up interviews with the owners, trainers and referring veterinarians were also conducted.

The data showed that 71 percent of the horses were able to return to their intended use, and 18 percent eventually performed at a higher level. Thirty-three percent of horses had a recurrence of upward fixation of the patella after surgery. Despite these statistics, only 50 percent of owners reported they were satisfied with the results of the procedure.

The researchers call for further study into both medical and surgical procedures to address locking stifles.

Reference: “Outcome of medial patellar ligament desmoplasty for treatment of intermittent upward fixation of the patella in 24 horses (2005-2012),” Canadian Veterinary Journal, February 2015

This article first appeared in EQUUS issue #453, June 2015.

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