Published 1/1/2014

What's Your Diagnosis?

In this feature, AAOS Now publishes a series of images, challenging readers to diagnose the condition depicted.

The images for this month’s challenge were submitted by Marc Biggers, MD, a resident member at the University of Tennessee–Campbell Clinic.

Dr. Biggers writes that a 15-year-old high-school football player was seen with a 1-week history of anterior knee pain. The youth states that the pain began after he sustained a hit to his knee during a game. The only physical examination finding is tenderness to palpation over his tibial tuberosity. A lateral radiograph (Fig. 1) and lateral and coronal MRIs (Figs. 2, 3) are obtained. What’s your diagnosis?

Images (PDF)

Answer to this month’s challenge is below
According to Marc Biggers, MD, who submitted the case, the diagnosis is Osgood-Schlatter disease. More interesting, however is the incidental finding of dorsal defect of the patella.

Dorsal defect of the patella is a benign subchondral lesion of unknown etiology. The lesion usually is located in the superolateral region of the patella and appears as a rounded radiolucency with sclerotic margins on radiographs. MRI can be used to differentiate dorsal defect from osteochondritis dissecans of the patella. Because the dorsal defect does not involve articular cartilage, it usually does not require treatment or surgery.

Send AAOS Now your case
Do you have a challenging case you’d like to submit for publication? Email a short case description and any accompanying images to