A tangential radiographic projection for investigation of the equine temporomandibular joint.
Authors: Townsend Neil B, Cotton Johanna C, Barakzai Safia Z
Journal: Veterinary surgery : VS
Summary
# Editorial Summary: Tangential Radiography of the Equine Temporomandibular Joint Imaging the equine temporomandibular joint (TMJ) presents a genuine technical challenge—standard radiographic projections inevitably superimpose overlying structures, obscuring the articular surfaces—yet the TMJ is increasingly recognised as a source of clinical signs including quidding, headshaking, and performance issues. Townsend and colleagues developed and optimised a novel tangential radiographic projection using cadaveric skulls (n=11), strategically placing contrast medium and anatomical markers to identify the ideal beam angle, which four independent observers then ranked across three different angulations (75°, 70°, and 65° to the dorsal plane). The 70° angle proved significantly superior (P<0.001) with no significant interobserver variation, and the technique successfully translated to standing sedated horses, producing excellent-quality images without safety concerns. By isolating the lateral TMJ compartment without superimposition, this projection meaningfully expands the diagnostic toolkit available in primary practice, offering a practical, affordable intermediate step between clinical examination and ultrasonography before pursuing advanced imaging at referral centres. Farriers and practitioners managing horses with suspected TMJ pathology now have an evidence-based radiographic protocol worth incorporating into their diagnostic algorithms.
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Practical Takeaways
- •Use a 70° tangential projection to the dorsal plane when radiographing the equine TMJ in standing sedated horses—this angle provides the clearest, most consistent images
- •This technique can be incorporated into your clinical workup for horses with quidding or headshaking to help identify TMJ pathology before referral for CT or MRI
- •The method is reliable and reproducible, meaning multiple practitioners can obtain consistent images for comparison and monitoring
Key Findings
- •A tangential radiographic projection at 70° to the dorsal plane provides optimal visualization of the equine TMJ without superimposition of surrounding structures (P<0.001)
- •The technique was successfully and safely performed in standing sedated horses with excellent image quality
- •No significant interobserver variation was found, indicating high reproducibility of the technique
- •Tangential radiography complements clinical examination and ultrasonography for TMJ assessment before advanced imaging referral