Study: Surgery to Fix Patella Problem Often Successful

During an MPLS procedure, the surgeon inserts a blade or needle through the skin to split the medial patellar ligament—often with the horse standing sedated.

Photo: Aziz Tnibar, DVM, PhD, DECVS

When a horse’s patella locks up, owners can hope for a resolution through conservative treatments such as increased exercise, corrective farriery, intraligamentary injections, and even acupuncture. But when those treatments fail, you might want to turn to surgery, suggest scientists in Denmark.

The standard surgical treatment for upward fixation of the patella (UFP) used to be a procedure known as medial patellar ligament desmotomy (in which the surgeon cuts the ligament to release the locked patella). But it comes with its own set of post-surgical complications, and not all owners are satisfied with the results.

Fortunately, a less invasive procedure called medial patellar ligament splitting (MPLS) has been showing good outcomes, and Aziz Tnibar, DVM, PhD, Dipl. ECVS, and colleagues recently completed a long-term follow-up evaluating treated horses. The long-term results, according to the research team, are very positive, with a 97.6% success rate.

“This procedure is currently the best surgical treatment for this condition,” said Tnibar, a specialist in equine surgery at the Faculty of Health and Medical Sciences of the University of Copenhagen, in Taastrup.

During an MPLS procedure, the surgeon inserts a blade or needle (sometimes guided by ultrasound) through the skin to split the proximal (inner) third part of the medial patellar ligament—often with the horse standing sedated.

In their review of 85 horses undergoing MPLS between 1999 and 2013, Tnibar and his fellow researchers were able to follow horses up to 14 years after surgery, he said. Most of the horses were Warmbloods used for pleasure riding. The severity of the condition varied considerably, but in all cases the horses had not responded to conservative treatments. Since 2004, the vast majority of the horses had undergone standing surgery, he said.

Upward fixation of the patella resolved completely in 83 of the 85 horses within two weeks of surgery—and 23 of them had full resolution within 24 hours of surgery, Tnibar said. All of these horses returned to their regular exercise program after surgery without further patellar issues. In the two remaining cases, the surgery proved unsuccessful. Ultrasound showed thickening of the ligament in those two cases without any other explanation for the poor response.

Many of the horses had brief postoperative pain, which resolved after a few days with non-steroidal anti-inflammatories. The surgical sites all healed without complications, and there were no post-surgical complications of any kind, either short- or long-term.

“I recommend this procedure every time the conservative treatment is not working,” Tnibar told The Horse. “MPLS completely superseded all previous surgical management techniques for this condition because it’s highly successful and noninvasive, and the horse can return to athletic activity very quickly.”

Veterinarians should treat horses with UFP conservatively first and then surgically if necessary, he said. But owners should not delay treatment because untreated UFP can, in rare cases, lead to more severe problems. “If the horse has a fixed patella and slips and falls, there is a risk of hip luxation, which is a very serious condition,” he said.

The study, "Medial patellar ligament splitting in horses with upward fixation of the patella: A long-term follow-up," will be published in an upcoming issue of the Equine Veterinary Journal.

About the Author

Christa Lesté-Lasserre, MA

Christa Lesté-Lasserre is a freelance writer based in France. A native of Dallas, Texas, Lesté-Lasserre grew up riding Quarter Horses, Appaloosas, and Shetland Ponies. She holds a master’s degree in English, specializing in creative writing, from the University of Mississippi in Oxford and earned a bachelor's in journalism and creative writing with a minor in sciences from Baylor University in Waco, Texas. She currently keeps her two Trakehners at home near Paris. Follow Lesté-Lasserre on Twitter @christalestelas.

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