Case Description—3 horses were evaluated because of lameness and swelling of the stifle joint subsequent to trauma.
Clinical Findings—All horses had characteristic clinical signs of stifle joint pain and effusion. A medial patellar fracture and lateral collateral ligament avulsion fracture were visible ultrasonographically in each. Radiography, including standard as well as flexed lateromedial, cranioproximal-craniodistal oblique (skyline patellar), and laterally stressed caudocranial views, revealed similar findings.
Treatment and Outcome—Arthroscopic surgery to remove the patellar fracture was attempted in 1 horse with severe desmitis of the lateral collateral ligament; it remained lame afterward. The other 2 horses, with less severe collateral ligament damage, were managed conservatively and returned to athletic use, despite the lack of surgical intervention to repair the patellar fractures.
Clinical Relevance—Special radiographic views were necessary for diagnosis of medial patellar fracture and lateral collateral ligament avulsion fracture in the 3 horses. Ultrasonographic findings pertaining to the collateral ligament may be prognostically important in such situations. The severity of a fracture involving ligament avulsion may be the limiting factor in horses with this combined injury, and this factor should be considered prior to attempting surgical correction of patellar fractures.
