An alternative arthroscopic approach to the caudal pouches of the equine lateral femorotibial joint

Background: Current arthroscopic approaches to the caudal pouches of the lateral femorotibial joint are challenging and risk iatrogenic nerve and cartilage injury.

Objective: Describe an alternative arthroscopic approach to the caudal pouches of the lateral femorotibial joint in the horse and report intra-articular abnormalities observed during diagnostic stifle arthroscopy of these pouches.

Study design: Descriptive cadaver anatomical and clinical study.

Methods: An approach to the caudal pouches of the lateral femorotibial joint was developed during clinical surgery using an arthroscopic portal in the popliteal tunnel of the femorotibial joint. Relevant anatomy of the lateral femorotibial joint was reviewed and the arthroscopic landmarks validated on 19 cadaver limbs. The procedure was then incorporated as part of routine inspection of 38 joints in 33 horses.

Results: Entry and examination of both pouches of the caudal lateral femorotibial joint was consistently achieved using an arthroscopic portal immediately cranial to the lateral collateral ligament in both cadaver and clinical limbs, with no adverse effects noted in the latter. Contrary to published descriptions, the division of the pouches was principally formed by a meniscopopliteal septum derived from the joint capsule in all cases, rather than the popliteus muscle and tendon as previously described. Abnormalities were detected in five cases. The finding of bilateral tearing within the popliteus muscle may represent a previously unrecognised arthroscopic condition.

Main limitation: Limited case numbers.

Conclusion: An arthroscopic portal immediately cranial to the lateral collateral ligament permitted consistent entry into the popliteal tunnel and both pouches of the caudal lateral femorotibial joint.