Magnetic resonance imaging findings of injuries to the calf muscle complex

The objective was to describe the imaging findings following acute injury to the calf musculature. We retrospectively reviewed 59 MR examinations in patients who sustained injuries to the calf muscle from April 2001 to September 2004 (48 men, 11 women), with an average age of 31 and 47 years respectively (range in men 20-53; range in women 33-63). Attention was directed to the frequency of muscle involvement, the location of the injury within the musculotendinous unit and the extent of the injury. A total of 79 separate sites of strain injury were identified (39 solitary, 20 dual). Of the 39 isolated strains, injury to the gastrocnemius was most common (19 out of 39; 48.7%), preferentially involving the medial head in 18 cases and the lateral head in 1 case. The soleus was also commonly involved (18 out of 39; 46.2%), with 2 cases (5.1%) of distal avulsions of the plantaris. Of the 20 dual injuries, a combination of gastrocnemius injury with soleus injury was the most frequent finding (12 out of 20; 60%). Dual injuries of both heads of the gastrocnemius muscles were demonstrated in 4 cases (20%), with the soleus and tibialis posterior injured in 3 cases (15%). A combination of soleus and flexor hallucis longus injury was seen in 1 case (5%). This retrospective study utilizing MRI demonstrates that the medial head of the gastrocnemius is the most commonly injured muscle of the calf, closely followed by the soleus, the latter finding rarely reported in the sonographic literature. Dual injuries of the calf muscle complex occur much more commonly than previously reported and may be of prognostic significance. (orig.)