Question: I-test: a gymnast with anterior knee pain: not a typical case of jumper's knee
- Correspondence to Laura S Kox, Department of Radiology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands;
A 21-year-old male professional trampoline gymnast consulted his physician to evaluate his activity-related anterior knee pain, present since 4 weeks. The most likely diagnosis was patellar tendinopathy, often termed jumper's knee. However, his symptoms did not match this diagnosis since the pain was located in the proximal part of the left knee with weakness, instability when standing up and pain at the proximal patella. This forced him to discontinue trampoline jumping.
Examination of the left knee showed a painful swelling distally on the quadriceps muscle. Tenderness of the proximal border of the patella was reported. Extension was within normal range, flexion was limited and both were painful.
The differential diagnosis included rectus femoris lesion, quadriceps tendon rupture, quadriceps tendinopathy and fracture of the superior pole of the patella.
MRI (sagittal STIR and T1-weighted images and transversal T2-weighted, proton density and T2 fat-saturated images) revealed intact fibres of the quadriceps tendon. The posterior part of the tendon at the insertion on the patella showed a small area with increased MR signal (figures 1 and 2). Fat infiltration was found just anterior to the suprapatellar bursa, directly posterior to the tendon. A slight amount of oedema was seen at the base of the patella and in the subcutaneous soft tissue. No lesion of the patellar tendon was found.
What is the diagnosis?
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