Presentation
History of chronic lateral knee pain and instability.
Patient Data
The sagittal images demonstrates increased signal by oedema within the fat below the caudal margin of the patella as well as moderate patella alta. The T2 axial image demonstrates decreased signal within fat interposed between the lateral aspect of the patellar tendon and the lateral trochlear ridge. Mild lateral patellar subluxation is present as indicated by the off-midline positioning of the patellar tendon. The cruciate ligaments, collaterals and menisci are normal. The patellar tendon, cruciate ligaments, collateral ligaments and menisci are normal. There is no joint effusion. A small pedunculated osteochondroma of the posteromedial surface of the tibia is noted.
Case Discussion
On MRI, a focal area of high signal or oedema on STIR or T2 weighted sequences is present at the inferolateral aspect of the patellofemoral joint, specifically the lateral portion of the infrapatellar fat pad. Associated findings of lateral patellar subluxation and/or patella alta are frequently present.
Radiographer: TSRM Fabio Imola