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This article has a correction

Please see: Br J Sports Med 2014;48:1068

Br J Sports Med doi:10.1136/bjsports-2012-091773
  • I-test

Question: I-test: a gymnast with anterior knee pain: not a typical case of jumper's knee

  1. Mario Maas
  1. Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
  1. Correspondence to Laura S Kox, Department of Radiology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; laurakox{at}hotmail.com

Case summary

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.

Imaging findings

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.

Figure 1

Sagittal T1-weighted MRI of the knee. The thick arrow shows an area of higher signal within the posterior part of the quadriceps tendon at the insertion on the patella. The thin arrow marks fat infiltration anterior to the suprapatellar bursa.

Figure 2

Sagittal proton density-weighted MRI of the knee. The arrow shows high signal at the attachment of the quadriceps tendon to the patella.

Question

  • What is the diagnosis?

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