Arthroscopic treatment of bilateral mandibular condylar cysts and associated osteoarthritis of the temporomandibular joints in a horse
Authors: Carmalt J. L., Reisbig N. A.
Journal: Equine Veterinary Education
Summary
# Editorial Summary: Bilateral Mandibular Condylar Cysts and Temporomandibular Joint Disease Unpredictable ridden behaviour, tongue protrusion at rest, and audible "clunking" during mastication prompted advanced diagnostic imaging in a horse that had already undergone unsuccessful arthroscopic surgery to the right temporomandibular joint (TMJ). Computed tomography revealed bilateral mandibular condylar bone cysts and marginal osteophytosis in both TMJs—pathology that had been missed on initial radiographic assessment—whilst diagnostic TMJ analgaesia demonstrated the joints' contribution to both a hindlimb lameness and the behavioural abnormalities. Arthroscopic debridement combined with intra-articular autologous protein solution injection produced temporary improvements in behaviour and the clunking sound, though clinical signs ultimately recurred, leading to euthanasia. This case illustrates that unilateral presentation on imaging can mask bilateral disease, and that TMJ pathology warrants consideration in horses presenting with unexplained dangerous behaviour alongside masticatory dysfunction or atypical movement patterns. The interconnected nature of TMJ proprioception, pain responses and behaviour emphasises the importance of thorough multimodal imaging and diagnostic analgaesia when initial treatment fails, particularly when safety concerns are paramount.
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Practical Takeaways
- •Consider TMJ pathology in the differential diagnosis for horses presenting with unexplained dangerous or unpredictable behaviour under saddle, particularly when accompanied by audible joint sounds or tongue protrusion
- •TMJ analgesia testing can help identify whether TMJ pain is contributing to lameness or behavioural signs before committing to arthroscopic surgery
- •Recognise that TMJ cysts and osteoarthritis may require multimodal treatment approaches and that surgical intervention alone may not resolve all clinical signs
Key Findings
- •Bilateral mandibular condylar cysts with TMJ osteoarthritis were identified as an underlying cause of dangerous ridden behaviour in a horse
- •TMJ analgesia altered both hindlimb lameness and behavioural components, demonstrating TMJ pain contribution to movement abnormality
- •Arthroscopic debridement and intra-articular autologous protein solution injection provided temporary resolution of behavioural signs and audible 'clunking' sound
- •TMJ pathology can present with complex clinical signs including tongue protrusion, audible joint sounds, and behavioural changes that may not fully resolve with surgical intervention