17-Year-Old Runner with Shin Pain

DISCUSSION

In conjunction with the patient history, the bone findings were typical of shin splints. Shin splints appear as an interrupted linear, longitudinal pattern of mild increased uptake along the posterior medial cortex of the long bone, best seen on medial or lateral views.

The pattern of uptake in shin splints reflects the actual underlying physiology. During the phase of running at which the foot extends before pushing off the ground, the gastrocnemius and soleus muscles contract. These calf muscles provide additional power for running when they extend the foot for longer times, as can be seen in running techniques such as sprinting. The extra power involved places greater stress on the soleus, which attaches directly to the posteromedial tibial cortex. This increased stress leads to increased tension and pulling of the muscle on the periosteum of the tibia, resulting in stress along the diaphysis (1,2). The linear pattern (on the delayed phase of the bone scan only) thus represents periostitis along the insertion of these muscles (3).

In contrast, a stress fracture has increased perfusion and blood pool activity on 3-phase bone scanning. On the delayed phase, it appears as a fusiform focus of intense increased radiotracer uptake of varying thickness, depending on the grade (3). The tibia is the most common site of stress fracture in athletes.

Plain radiographs are often the first line of investigation; however, fractures will not begin to appear on radiographs until 7–10 d after the initial insult. Radiography has low sensitivity for stress fractures, and the findings are always negative for patients with shin splints (4).

Medial tibial stress syndrome is often diagnosed by clinical presentation alone. Depending on the severity and location, stress fractures may be treated with rest; ice; elevation; slow, non–weight-bearing, rehabilitative exercises; immobilization with a cast or splint; or, in more severe cases, surgery. Patients with shin splints often resume physical activity gradually, as tolerated, usually within 1 wk but sometimes in as long as 3 mo. The time until patients with stress fractures resume physical activity is relative but is usually approximately 3 mo for low-intensity activity and up to 6 mo for full intensity (4).