Fact-sheet: Patellofemoral impingement
Updated on 09/30/2019 at 6:19 PM
View all RADEOS cases associated with this fact-sheet
Definition
Impingement between the patellar tendon, the patella, and the anterior aspect of the lateral femoral condyle, resulting in inflammation of the underlying fat
Clinical features
Lateral patellofemoral pain on knee extension
Transient patellar dislocation
Ultrasound
Hyperechogenicity and thickening of the inferolateral patellar fat
Pain reproduced on ultrasound palpation
MRI
Edematous PD hyperintensity and T1 hypointensity of the lateral infrapatellar fat.
Assessment for morphologic factors predisposing to transient patellar dislocation:
- Patella alta (Caton-Deschamps index > 1.2),
- TT-TG distance at the upper limits of normal,
- Trochlear dysplasia, patellar dysplasia,
- Short distance between the posterior aspect of the patellar tendon and the anterior aspect of the femoral trochlea (3 mm).
In chronic involvement, fibrous or osteochondral metaplasia may be observed.