Intermediate patellar ligament desmopathy often occurs in conjunction with other stifle abnormalities

Intermediate patellar ligament (IPL) desmopathy is a relatively uncommon injury previously reported to have a poor prognosis for return to athletic activity. There is little documentation of the clinical and ultrasonographic features, clinical significance, and outcome for return to work following IPL injury in horses. The aim of this retrospective descriptive study was to describe the clinical and ultrasonographic features of IPL desmopathy, its association with other injuries of the stifle, and outcome for return to work following injury. Forty-two stifles with an ultrasound diagnosis of IPL desmopathy over a 5-year time period were included. Data regarding signalment, clinical presentation, diagnostic imaging findings, treatment, and outcome are described. Intermediate patellar ligament desmopathy occurred most commonly in the midbody (35/42; 83%) of the ligament and lesions were predominantly hypoechoic discrete tears (31/42; 74%) that were obliquely oriented in a craniolateral to caudomedial direction (28/42; 67%). Rarely (1/42; 2%) was IPL desmopathy the only ultrasonographic abnormality detected. Of 13 horses that underwent recheck ultrasound examination, the majority (11/42; 85%) either did not improve or worsened ultrasonographically. Despite this, of 25 horses with long-term follow-up, 23 (92%) returned to work, 16 at the same level or higher. A variety of treatments were utilized. The clinical significance of IPL desmopathy is difficult to determine because it is usually found in conjunction with other stifle abnormalities. Although IPL desmopathy rarely shows ultrasonographic improvement over time, prognosis can be good for return to work.