Click on Images for Enlarged View

Findings: Plain films of knees, AP and lateral. In this patient, there is evidence for healed Osgood-Schlatter disease in the right knee with a circumsribed ossicle within the patellar tendon. Fragmentation of the tibial tuberosity without clear edema most likely represents a subacute lesion.

Diagnosis: Osgood-Schlatter. Tibial tuberosity avulsion in the pubertal child due to tearing of the deep fibers of the patellar tendon insertion into the tibial tuberosity. This results in hemorrhage and cartilage avulsion.

Discussion: In the acute states, pretuberosity skin and subcutaneous edema is seen as well as infrapatellar fat pad edema. Edges of the patellar tendon are blurred. If the tibial tuberosity is ossified, one may see sliver-like or nodular avulsed fragments. If the tuberosity is still completely cartilaginous, one may see ossification of avulsed fragments in 2-4 weeks. Ossification of the contused patellar tendon may also occur subacutely as the edema decreases.

Late stages of the lesion have a variable appearance. Tuberosity fragments may or may not unite. Fragments are often located superior and anterior to the tuberosity. The patellar tendon may be thickened and may contain circumscribed ossicles. Fragments may also fuse to the tuberosity extending into the patellar tendon.

Soft tissue edema must be present in the acute stage of this lesion in order to make the diagnosis, since multiple ossification centers of the tibial tuberosity can be seen in normal patients. If edema is not present, this may represent residual of previous disease or normal variation.

References:
Ozonoff MB. Pediatric orthopedic radiology. Philadelphia:
W.B. Saunders Company, 1992.

Return to Pediatric Imaging Page