Retrospective analysis of oblique and straight distal sesamoidean ligament desmitis in 52 horses

Background Injuries to the oblique (ODSL) or straight (SDSL) distal sesamoidean ligaments are a recognised cause of distal limb lameness in the horse. However, there are only limited publications addressing common diagnostic features and prognosis. Objectives (a) Report findings on ultrasonography and standing low-field magnetic resonance imaging (sMRI) in horses with ODSL or SDSL injury; (b) Identify clinical variables associated with lesion type and (c) Identify factors associated with return to soundness in horses with ODSL or SDSL injury. Study design Retrospective case series. Methods Horses with a primary diagnosis of ODSL or SDSL injury confirmed with a combination of diagnostic analgesia and detection of a lesion on imaging (ultrasonographic +/- advanced imaging) were included. Return to soundness and performance follow-up data were obtained. Results Fifty-one horses were included. SDSL injuries were more common in the forelimb (13/21, 62%), while ODSL injuries had equal frequency in fore- (15/30, 50%) and hindlimbs (15/30, 50%). ODSL injuries were more likely than SDSL injuries to affect the proximal third of the ligament (OR =13; 95% CI 2.3-74.3; p = 0.004) and often presented with periligamentar swelling (20/30;67%) and focal pain (22/28;79%). Lesions were frequently detected using ultrasonography (35/42;83%) and sMRI examination (18/25;72%). Only 27/49 cases (55%) returned to soundness, with only 15/49 (31%) returning to intended use. There were no significant associations between outcome and clinical features or treatment. Main limitations There was no comparative gold standard to validate lesions such as high-field MRI or histopathology. Conclusions In contrast to previous studies, ODSL and SDSL injuries were readily identified ultrasonographically using appropriate views, and with sMRI. Given the limited availability, cost and general anaesthetic risks associated with high-field MRI, more focus should be placed on optimising the ultrasonographic examination. Owners of affected horses should be informed of the guarded prognosis for return to full use.

Automated summary

This study reports findings on ultrasonography and standing low-field magnetic resonance imaging in horses with oblique or straight distal sesamoidean ligament injuries, identifying clinical variables associated with lesion type and factors associated with return to soundness. Despite no significant associations between outcome and clinical features or treatment, owners of affected horses should be informed of the guarded prognosis for return to full use.