Palmar/plantar ligament injuries in five horses: Clinical findings, comparative diagnostic imaging, therapy and outcome

Summary Background Diagnosing palmar/plantar ligament injuries in horses is challenging and has been reported only rarely, primarily using ultrasonography. Objectives To describe presentation, diagnosis, treatment and outcomes of horses with full‐thickness palmar/plantar ligament injuries. Study Design Case series. Methods Five horses (three forelimbs, two hindlimbs) with palmar/plantar ligament tears were included. Clinical findings and comparative imaging features were evaluated using contrast radiography (three cases), ultrasonography (three cases), standing helical computed tomographic tenography (CTT) or arthrography (CTA) (four cases) and standing low‐field magnetic resonance imaging (MRI) (three cases). All horses underwent tenoscopic and/or arthroscopic debridement of the lesions. Results Tenoscopy revealed a slit‐like communication between the metacarpophalangeal/metatarsophalangeal joint and digital flexor tendon sheath (DFTS) in all cases, with fibrillation of the intersesamoidean ligament and/or proximal scutum. Concomitant axial sesamoiditis was identified in two cases. CTT/CTA consistently demonstrated synovial communication as linear contrast medium accumulation with flow into the adjacent synovial structure. Contrast radiography showed a characteristic horizontal linear contrast accumulation proximal to the proximal sesamoid bones (two cases) and direct communication between the DFTS and metatarsophalangeal joint (one case). Low‐field MRI identified the lesion within the palmar/plantar ligament (two cases) and axial sesamoiditis (two cases). Ultrasonography detected a plantar ligament tear in only one case and failed to identify the lesion in the remaining two cases. Main Limitations Small sample size, limited or missing long‐term follow‐up and lack of histopathology, which precluded differentiation between traumatic and degenerative injury. Conclusion CTT/CTA was the most reliable imaging modality for the definitive diagnosis of complete palmar/plantar ligament tears in these horses. Hyperextension is the proposed injury mechanism, but the absence of histopathology limits aetiologic clarification. An association with axial sesamoiditis is possible and warrants investigation in a larger cohort. Based on these cases, prognosis for return to pre‐injury performance appears guarded to poor.