Equivalent to the human knee, the equine stifle is an intricate assembly of bone, joint, and soft tissues. Problems with the stifle commonly cause pain and lameness in equine athletes. Cathleen Mochal-King, DVM, MS, Dipl. ACVS-LA, associate clinical professor and service chief of equine surgery and medicine at Mississippi State University’s College of Veterinary Medicine, described how veterinarians diagnose and treat stifle-associated lameness at the 2025 Veterinary Meeting and Expo, held Jan. 25-29, in Orlando, Florida.

Diagnosing Stifle-Associated Lameness

Three joints make up the stifle, but no single joint compartment communicates with all articular (related to the joint) spaces; in other words, there is no continuous fluid connection among them. This means veterinarians need to perform multiple nerve blocks and joint injections, said Mochal-King. She added that veterinarians should be aware of the anatomy of the meniscus, the fibrocartilage found between the femur and the tibia. There are two menisci in each stifle: one medial (toward the horse’s center line) and one lateral. Both can tear, causing performance-limiting pain and lameness.

During soundness exams Mochal-King said she looks for a wider base stance in the hind limbs as an indicator of potential stifle issues in horses. She also observes how the height of the tuber coxae—a bony projection on the pelvis, located on the ilium and often called the point of the hip—varies between the left and right sides as the horse moves, which can help pinpoint the lame limb. After physical and gait examinations, Mochal-King performs flexion tests and nerve blocks to localize the lameness.

When she incorporates radiography into her diagnostic approach, Mochal-King said she likes to extrapolate as much information from the images as possible. “People aren’t reading X rays as well as they used to because we’ve got other diagnostics now, but there’s a lot that you can see on a radiograph,” she said, pointing to—for example—subtle changes such as flat condyles (the typically rounded articular surfaces of the femur or tibia become flattened) that can predispose a horse to medial meniscal tears.

Combining Ultrasound-Guided PRP Injections With Adjunct Therapies

Mochal-King said she treated 15 meniscal tears in 2024 and had success using ultrasound-guided platelet-rich plasma (PRP) injections in the standing patient. “In addition to its regenerative properties, PRP acts like tissue glue to help heal the tears,” she explained. She said she was particularly meticulous about injection site preparation and added amikacin (an antibiotic) to the injection to reduce the risk of septic arthritis.

She said she also used shock wave therapy for stifle lameness because it “really helps with the fiber pattern and in strengthening the collagen pattern throughout tendons and ligaments.” Out of the 15 meniscus tears she saw in the past year, all but one patient went back to work.

Surgically Managing Stifle Lameness

When a stifle injury warrants surgical intervention (i.e. it cannot be successfully managed with rest, rehabilitation, and/or medical treatment), Mochal-King said she prefers coupling arthroscopic debridement with PRP injection. She’s also had success with drilling and curetting (scraping to remove tissue) subchondral bone cysts from the outside rather than entering the joint. With this type of surgical procedure, she emphasized the importance of horses returning to controlled exercise following the procedure, typically 60 days post-surgery.

Successful Outcomes and Final Thoughts

Performing a thorough assessment can help veterinarians successfully diagnose stifle lameness in horses. Mochal-King said she prefers to treat common stifle-associated lameness problems, such as meniscal injuries, with PRP and shock wave, only turning to surgery as needed.