Findings: Image #1 is a plain film of the lateral right knee demonstrating increased sclerosis in the region of the tibial tuberosity with minimal associated fragmentation.

Image #2 and Image #3 are axial and sagittal reconstructed CT images of the right knee, respectively. These images demonstrate mild fragmentation of the anterior tibial tubercle at the insertion site of the patellar ligament.

Image #4 is a sagittal T1 weighted MRI. The right knee demonstrating decreased signal in the region of the tibial tuberosity at the insertion of the patellar ligament.

Image #5 is a coronal STIR image demonstrating a region of increased signal in the anterior epiphysis consistent with marrow edema.

Diagnosis: Osgood Schlatter’s disease.

Discussion: Osgood Schlatter’s disease is an entity that occurs most often in adolescent boys between the ages of 11 and 15. It most commonly affects males who are involved in sports activities. Although the disease is most commonly unilateral, bilaterality is not uncommon. Clinically the patient presents with swelling and tenderness over the proximal aspect of the anterior tibia. Oftentimes, a firm mass-like density can be palpated over the anterior tibial tuberosity. Although initial radiographs of the knee may demonstrate soft tissue swelling, ossific abnormalities are usual early in the course of the disease. After three to four weeks, an ossific density in the region of the tibial tuberosity may become evident (consistent with a small avulsed fragment). In addition, there will be indistinctness of the interpatellar tendon as well as osseous irregularity of the tibial tuberosity.

The pathologic findings are most consistent with repetitive microtrauma at the insertion of the patellar ligament causing fragmentation. In addition, bone marrow edema may be identified if MRI is obtained (as was presented in this case).

Reference:
Resnick D. Bone and Joint Imaging W. B. Saunders, Philadelphia. 1996;969-970.

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