Good News, Bad News for Sport Horses Suffering Meniscal Injuries

While the majority of horses with meniscal injuries in the stifle return to some degree of athleticism following treatment, less than half return to their previous or intended level of performance. Meniscal injuries, which are the most frequent soft-tissue lesion in the stifle, are therefore career-limiting in many cases.

The meniscus is a disc of connective tissue lying between the femur and tibia in the stifle joint. Because there are two “sides” of the stifle—an inner or medial aspect and an outer or lateral aspect—there are two menisci in each stifle joint, one on each side.

“Menisci help lubricate, stabilize, and cushion the stifle, a major weight-bearing joint. Due to the substantial forces on the stifle joint, the menisci can be damaged by compression during weight bearing or extension of the stifle, shearing forces, and tension from adjacent ligaments, among other causes,” explained Kathleen Crandell, Ph.D., a nutritionist for Kentucky Equine Research.

Medial meniscal injuries occur far more frequently than lateral ones, accounting for 83% of meniscal issues, according to published reports.

Fully evaluating and grading meniscal injuries, usually on a scale from 1 to 3, requires arthroscopy—viewing stifle joint structures with a tiny camera inserted through an incision. In addition to surgical exploration, certain lesions can be treated arthroscopically.

Considering how commonly meniscal injuries occur in sport horses, long-term data regarding return to athleticism are scant. Two veterinarians from Tufts University, including a board-certified equine surgeon, retrospectively reviewed data from 76 horses with meniscal injuries. All horses underwent arthroscopic evaluation and treatment—though specific treatments were not described—and follow-up data obtained at least 1.5 years after arthroscopy were collected.

The published data showed that the long-term prognosis for return to function was considered fair.^*

“Only 40% of the sport horses in the study returned to their previous level of work, and 15% of horses did not perform at all following surgery. Just over one-third of the horses suffered persistent lameness following treatment,” Crandell said.

She added, “However, if we were to take a more positive view, 85% did return to some level of performance.”

About 40% of the horses that continued to compete required annual intra-articular corticosteroid injections of the affected stifle to control inflammation and lameness.

Horses in the study were involved in a wide range of sports: dressage, show jumping, show hunter, eventing, and equitation, and researchers observed no differences between disciplines at outcome.

Severity of meniscal injury also did not affect outcome. Further, applying orthobiologics, such as stem cells, autologous conditioned serum, and platelet-rich plasma, did not improve the chances of returning to work in this study. Nonetheless, the research team stated, “The use of orthobiologics may influence the prognosis, and further studies are warranted to evaluate their use in horses with meniscal injuries.”

Other products that will support joint health following trauma include nutritional supplements containing glucosamine, chondroitin sulfate, and hyaluronic acid.

“Glucosamine HCl, chondroitin sulfate, and hyaluronic acid provide broad-spectrum support by helping maintain joint fluid viscosity, reducing cartilage damage, and stimulating cartilage repair,” Crandell said.

*Davis, J.G., and J.M. García-López. Arthroscopic findings and long-term outcomes in 76 sport horses with meniscal injuries (2008-2018). Veterinary Surgery 51(3):409-417.