Arthroscopic approach and intra-articular anatomy of the equine discomandibular joint compartment of the temporomandibular joint.

Objective: To develop an arthroscopic approach to the discomandibular joint (DMJ), the ventral compartment of the temporomandibular joint (TMJ) of the horse.

Study Design: Experimental study.

Sample Population: Nine cadaveric equine heads and two live horses.

Methods: A 2.5-mm 30° arthroscope was used to explore the DMJ after joint distension. The first portal was created caudally, allowing placement of a rostral portal under visual guidance. Nasotracheal intubation of the live horses allowed mandibular manipulation, which is required for complete visualization of the joint.

Results: A novel injection technique allowed consistent arthrocentesis of the DMJ. The joint could be completely explored by using both portals and manipulation of the mandible. Variations in the medial joint capsule were observed between horses along with a cyst of the mandibular condyle in one horse. The only complication consisted of damage to the parotid salivary gland, which occurred in three cadaver heads. No communication was found between the joint compartments of the TMJ.

Conclusion: Correct portal placement and intraoperative manipulation of the mandible were critical and allowed complete exploration and debridement of the DMJ.

Clinical Significance: Determining the independence of the TMJ joint compartments has clinical ramifications for the diagnosis and treatment of clinical disorders. Most TMJ pathology, notwithstanding sepsis, is identified within the DMJ. Arthroscopic exploration of the DMJ is possible and may help manage these conditions.