Meniscus and Meniscal Ligament Injuries in Horses

Injuries to the menisci and the meniscal ligaments can cause stifle lameness in adult horses. Lesions range from mild fibrillation of the meniscal ligaments and surface of the menisci, causing low-grade, chronic lameness, to severe tears of the meniscal ligament and menisci, causing acute and severe lameness. The medial meniscus is more commonly affected.

Effusion of the femorotibial joints is a common clinical sign associated with meniscal or meniscal ligament injuries. In most horses, lameness is improved by intra-articular anesthesia of the femorotibial joints. Subtle radiographic changes might be evident with enthesiophytes or lytic areas at the site of attachment of the meniscal ligament or dystrophic mineralization within the meniscus. Osteoarthritic changes might be evident in horses with chronic or severe injuries. Ultrasonographic examination can be useful to demonstrate meniscal injury.

Arthroscopic examination is indicated in horses that do not respond to conservative treatment for meniscal or meniscal ligament injuries (ie, rest and anti-inflammatory medication followed by controlled rehabilitation). Arthroscopy enables some assessment of the extent and severity of injury; however, only the cranial and caudal poles of the menisci are visible arthroscopically. Arthroscopy also enables torn or fibrillated fibers of the meniscal ligaments to be debrided and flaps of meniscus or fibrillated meniscal tissue to be removed.

The prognosis for a horse's return to athletic function after injury to the menisci or the meniscal ligaments depends on the severity of injury; overall, it is guarded to fair. Horses with severe tears that extend beneath the femoral condyle and horses with concurrent osteoarthritis have a considerably poorer prognosis.