Anatomical variations of the equine popliteal tendon

The function of the popliteal muscle and tendon in horses remains undescribed. In humans, it is considered a stabilizer of the posterior-lateral region of the knee; its function is closely related to that of the lateral collateral ligament (LCL) and meniscus. The popliteal tendon (PopT) constitutes the main proximal attachment of the popliteus muscle to the femur, and in humans, insertional variations have been described. Knowledge of anatomical variations is needed for the correct interpretation of diagnostic images and arthroscopic findings. To elucidate further the anatomy of the equine PopT, both hind limbs of 30 horses were dissected. Similar to humans, the equine PopT has 3 variants (types I, II, and III) depending on the number of components forming the tendon. Additionally, the area of insertion varies; the location can be either cranial, underneath, or caudal to the proximal insertion of the LCL. Furthermore, the PopT has a constant attachment to the lateral meniscus. The results of the present study are useful for clinicians working with equine orthopedics, as the tendon and insertional variants could affect the interpretation of diagnostic images and arthroscopic examinations.