Arthroscopic approach and intra-articular anatomy of the equine atlanto-occipital joint.

OBJECTIVE: To develop arthroscopic approaches to the atlanto-occipital (A-O) and describe associated arthroscopic anatomy. STUDY DESIGN: Experimental ex vivo study and clinical case report. ANIMALS: Ten equine cadaver joints and 1 clinical case. METHODS: CT arthrograms of 8 A-O joints were performed to determine the placement of an arthroscopic portal. Arthroscopy was performed via dorsal and/or ventral approaches (dorsal or ventral to the longissimus capitis tendon) in 10 cadaveric A-O joints and the A-O joint of a 2-week-old foal with septic arthritis. Accessible cartilage was debrided in 3 cadaver joints. Accessibility and risks were assessed by review of arthroscopic images, postoperative necropsy, and computed tomography (CT). RESULTS: Dorsal and ventral outpouchings of the A-O joint were identified with CT. Arthroscopy of the dorsal pouch provided access to 50% of the dorsocranial occipital condyle and 15% of the dorsocranial atlas articular surfaces. Joint distension caused displacement of the dura. Dura perforation occurred with a blind dorsal approach in 2 of 5 joints. Dura perforation did not occur after ultrasonography-guided approaches. Arthroscopic debridement of septic arthritis and osteomyelitis was successful in 1 clinical case. CONCLUSION: Approaches to the A-O joint were determined from CT examinations. The cranial aspect of the dorsal pouch of the A-O joint was accessed via arthroscopic triangulation in all horses of this study. Ultrasound-guided joint access prevented perforation of vital structures, including the spinal canal. CLINICAL SIGNIFICANCE: Advanced imaging improves the diagnosis of A-O joint pathology. Descriptions of arthroscopic anatomy and accessibility provide important information for surgical intervention.

Neovascularisation in chronic tendon injuries detected with colour Doppler ultrasound in horse and man: implications for research and treatment.

Recent research on chronic painful Achilles tendons in humans using ultrasonography and immunohistochemistry, has demonstrated an association between neurovascular ingrowth and tendon pain. In horses, chronic debilitating tendon conditions are well-known to be very difficult to treat, and the background to impaired function and pain is not scientifically clarified. In a collaborative research project between the Sports Medicine Unit in Umeå and Strömsholm Equine Hospital, grey-scale ultrasonography (US) and colour Doppler (CD) examination were performed in ten horses with chronic tendon injuries (>3 months) and a control group of six healthy and asymptomatic horses. In all symptomatic tendons, but not in any of the tendons in the control group, neovessels were seen in the area with structural tendon changes. The neovessels found in the horse tendons looked similar to what has recently been presented in human Achilles tendons. These findings motivate evaluation of the same treatment, a sclerosing injection that was demonstrated recently to give promising results in the treatment of chronic Achilles tendon injuries (tendinosis) in humans.