Radiographic imaging of muscle strain injury.

We reviewed our experience with computed tomography and magnetic resonance imaging of acute muscle strain injury. We imaged 50 athletes (average age, 28 years; range, 17 to 42) who had an acute muscle strain involving either the adductor, hamstring, quadriceps, or triceps surae muscles. Computed tomography (axial imaging) was used from 1982 to 1987 for 27 athletes. Spin-echo magnetic resonance imaging (axial, coronal, sagittal imaging) was used from 1987 to 1991 for 23 athletes. Computed tomography and magnetic resonance imaging localize the strain injury to a single muscle within a group of synergists; the adductor longus, rectus femoris, and medial head of gastrocnemius muscles are most prone to strain injury. A disruption occurs predictably at the myotendinous junction; fluid collects at the disruption site and dissects along the epimysium and subcutis. Muscle tissue remote from the myotendinous junction clearly demonstrates extensive injury with abundant magnetic resonance imaging signal changes consistent with edema and inflammation. Follow-up computed tomographic and magnetic resonance imaging studies can clearly demonstrate atrophy, fibrosis, and calcium deposition.