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What is your diagnosis?

The most likely diagnosis is Sinding-Larsen-Johansson syndrome (SLJS) which is a traction apophysitis of the inferior pole of the patella/proximal patellar tendon.  It most commonly occurs in active 10-13 year olds and is more common in boys. XR will frequently show a calcification in the proximal patellar tendon as it does in this case.

• Pearl: Osgood Schlatter is a traction apophysitis at the distal patellar tendon and is more common than SLJS. They share a very similar pathophysiology and patient population.

What is the mechanism of injury?

Although rarely associated with an acute injury, there may be an inciting factor such as kicking, increase in training volume, or direct trauma. It is generally an overuse disorder similar to other traction apophysitis. In particular, SLJS is associated with kicking and jumping activities.

What physical exam findings are expected?

There will be tenderness at the patellar tendon origin on the inferior pole of the patella. There may also be focal swelling and occasionally erythema at the origin site. There should not be any loss of active knee extension which would suggest a more severe etiology of pain such as a patellar sleeve avulsion or patellar tendon rupture. 

Which imaging modalities can be used?

X-ray is the diagnostic modality of choice. Lateral knee XR may show a calcification in the proximal patellar tendon although it may also be normal in certain cases. Ultrasound may be used to assess integrity of the patellar tendon and to evaluate for other etiologies such as patellar tendinosis. Seldomly, if the diagnosis is unclear or there is no significant improvement over time, MRI may be used for diagnosis.

What is the management in the ED?

ED management is generally supportive with recommendations for relative rest, NSAIDs, and activity modifications. SLJS is a self limited syndrome and should resolve over weeks to months. Main focus, especially if presenting with acute onset pain, is to rule out other etiologies such as fracture.

When do you consult orthopedics?

Orthopedics should not be consulted in the ED for SLJS, but follow up with sports medicine or orthopedics can and should be arranged for evaluation and to ensure resolution of symptoms over time.