Sinding-Larson-Johansson (SLJ) syndrome and distal femoral cortical irregularity
Presentation
Gymnast with pain, limited right knee motion, with tenderness and swelling over the lower patella.
Patient Data
Rx right knee
The lateral radiograph of the knee shows a tiny avulsed fracture fragment arising from the inferior aspect of the patella and a cortical irregularity projected on the posterior aspect of the supracondylar femoral metaphysis.
MRI Right knee
PD fat sat sagittal images provide a better definition of the avulsed fragment at the inferior pole of the patella that shows marrow edema. There's also the thickened and edematous proximal patellar tendon with edema of the Hoffa's fat pad, near the lower pole of the patella.
Mild edema can be also appreciated at the distal insertion of the quadriceps muscle tendon. In addition, there is an ovoid cortical lesion on the posterior and medial aspect of the supracondylar femoral metaphysis, localized to the attachment of the medial head of the gastrocnemius muscle referring to distal femoral cortical irregularity.
Menisci and ligament are normal. There is no joint effusion.
Case Discussion
Repetitive stress on the patellar tendon can make the growth plate within the knee become inflamed and irritated (traction apophysitis). On radiographs, one or more foci of ossification can be seen at the lower pole of the patella. MRI shows an abnormal signal in the lower patella with irregular cortical margins and bone fragmentation. Thickening of the proximal patellar tendon and diffuse edema of the Hoffa’s fat pad are common findings while distal femoral cortical irregularity is an occasional finding.
Case courtesy Dr.ssa Laura Braccaioli
Radiographer: TSRM Fabio Imola