High-resolution ultrasound (US) has helped to characterize the "tennis leg injury" (TL). However, no specific classifications with prognostic value exist. This study proposes a medial head of the gastrocnemius injury classification based on sonographic findings and relates this to the time to return to work (RTW) and return to sports (RTS) to evaluate the prognostic value of the classification. 115 subjects (64 athletes and 51 workers) were retrospectively reviewed to asses specific injury location according to medial head of the gastrocnemius anatomy (myoaponeurotic junction; gastrocnemius aponeurosis (GA), free gastrocnemius aponeurosis (FGA)), presence of intermuscular hematoma, and presence of gastrocnemius-soleus asynchronous movement. Return to play (RTP; athletes) and return to work (RTW; occupational) days were recorded by the treating physician. This study proposes 5 injury types with a significant relation to RTP and RTW (P < .001): Type 1 (myoaponeurotic injury), type 2A (gastrocnemius aponeurosis injury with a <50% affected GA width), type 2B (gastrocnemius aponeurosis with >50% affected GA width), type 3 (free gastrocnemius aponeurosis (FGA) tendinous injury), and type 4 (mixed GA and FGA injury). The longest RTP/RTW periods were associated with injuries with FGA involvement. Intermuscular hematoma and Gastrocnemius-soleus asynchronous motion during dorsiflexion and plantarflexion were observed when the injury affected >50% of the GA width, with or without associated FGA involvement, and this correlated with a worse prognosis. The proposed classification can be readily applied in the clinical setting although further studies on treatment options are required.
Keywords: medial head of gastrocnemius; muscle classification; prognostic value; return to play; tennis leg; ultrasound.
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