Acute Quadriceps Muscle Strains

Background There has been no research examining the magnetic resonance imaging findings, and in turn the prognosis, for a series of acute quadriceps muscle strains. Hypothesis The magnetic resonance imaging findings of acute quadriceps muscle strain injuries are helpful in predicting their prognosis. Study Design Causal-comparative study. Method Forty professional players of Australian Rules football were followed over 3 years. Magnetic resonance imaging examinations were performed within 24 to 72 hours of muscle-strain injury. Imaging features of muscle strain injury included the anatomical location, size (cross-sectional area and length), and site (proximal, middle, or distal). The time from injury to return to full training was termed the rehabilitation interval. Results 25 clinical quadriceps muscle strain injuries occurred, with 15 cases involving the rectus femoris. The rectus femoris injuries could be further categorized into cases with straining about the central tendon (n = 7, mean rehabilitation interval = 26.9 days) or cases with straining in the periphery (n = 8, mean rehabilitation interval = 9.2 days). Six cases involved one of the vastus muscles (mean rehabilitation interval = 4.4 days). Three players had normal magnetic resonance imaging examinations (mean rehabilitation interval = 5.7 days). Conclusions The rectus femoris–central tendon injury is the red flag diagnosis associated with a significantly longer rehabilitation interval. Clinical Relevance Magnetic resonance imaging is helpful in predicting the prognosis for acute quadriceps strains.