Mini Case: Tibial Tuberosity Avulsion Fracture

At my clinic, we offer a rapid referral system where we provide free screens for patients in order to determine either a need for skilled physical therapy or possible referral to another practitioner. Recently, I had a 12 year old boy come for a screening due to knee pain. The patient reported that he had been practicing kicking footballs when on one kick, he felt a "pop" and developed severe knee pain in the planted leg. The patient denied any hx of knee pain prior to the incident. Pain was located over the tibial tuberosity and painful with palpation. Pain could also be increased with squatting or jumping and decreased with rest.

Due to the location of pain being only over the tibial tuberosity, I immediately had minimal suspicion of a ligament or meniscal tear. Objective testing confirmed my hypothesis: (-) Lachmann's, (-) Anterior Drawer, (-) Posterior Drawer, (-) Valgus/Varus Stress, (-) Extension Overpressure, (-) Joint Locking/Catching, (-) Joint Line Tenderness, (-) McMurray's, (+/-) Flexion Overpressure (pain located at tibial tuberosity). There was pain with resisted quadriceps contraction and with a stretch of the quadriceps. Based on the location of the patient's symptoms and tenderness at the tibial tuberosity, a potential diagnosis is Osgood-Schlatter's. The patient is in his adolescent years, there was increased prominence of bilat tibial tuberosities, and the location of the pain matches. However, there were several factors that made Osgood-Schlatter's less likely. It typically has an insidious onset and is often found bilaterally. This patient had a sudden development of pain with a "pop" and only had unilateral pain. With the negative ligament and meniscal testing and decreased likelihood of Osgood Schlatter's, my initial hypothesis of avulsion fx of the tibial tuberosity had moved up the list.

While there is no orthopedic test to specifically test for avulsion fractures of the tibial tuberosity, we can still use our clinical reasoning to come to this diagnosis by effectively ruling out other pathologies. One factor that stood out in this case was the patient's age. In the adolescent stage, this patient's growth plates had not closed yet. Patients this age are more susceptible to avulsion fractures in general. In school, we are taught to test for stress fractures using tuning forks or possibly ultrasound (ouch!), but the diagnostic accuracy is lacking. Needless to say, I referred the patient to an orthopedic surgeon who later confirmed an avulsion fracture. The patient will trial rest for 2-4 weeks before potentially initiating therapy.

-Chris

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