Runner's Bump

Runners who average more than 30 miles per week occasionally develop a mass on the tibialis anterior tendon sheath that may be mistaken for a tumor.

The mass typically presents after a minor change in the training program or an insignificant injury. Patients are in their middle adult years. The lesion increases in size with running and activities and decreases in size with rest and elevation. Pain is usually mild enough to allow continuation of the running program, which in turn leads to the persistence of the lesion.

On examination, a soft, mobile lesion surrounds the tibialis anterior tendon at the level where the tendon makes impinges on the shoelaces or the tongue of the shoe. The tendon itself retains normal caliber and function. In some cases the lesion can be partially eliminated by compressive massage, but recurs promptly.

MRI shows a intermediate signal on T1 weighted images and hyperintensity on T2 weighted sequences. Treatment is by recognition of the origin of the problem, education of the runner, and padding, changing, or repositioning the laces and the tongue of the shoe to minimize the forces on the area.

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