Anatomical aspects of the gastrocnemius aponeurosis and its insertion: a cadaveric study.

Anatomical variation in the attachment of the gastrocnemius muscle to the soleus muscle has not been studied previously. The gastrocnemius muscle may insert directly onto the tendinous superficial surface of the soleus; however, in most cases, the distal end of the gastrocnemius aponeurosis extends for a variable distance as a thin, tendinous sheet void of muscular attachments. Surgeons performing a gastrocnemius recession may target the exposed inferior portion of the aponeurosis that is not directly covered by muscle. This is the subject of this anatomical study. Fifty-three embalmed cadaveric specimens were dissected to measure the length of the gastrocnemius aponeurosis medially and laterally. Three aponeurosis length categories were subjectively developed according to the ease with which a surgeon might release the gastrocnemius from the soleus: long aponeurosis (minimum aponeurosis length greater than 10 mm; 53% of specimens); short aponeurosis (9%), and direct attachment of the gastrocnemius muscle to the soleus on the medial side, lateral side, or both (38%). The typical gastrocnemius aponeurosis in the sample was distinctly shorter medially and longer laterally. For aponeuroses in the long aponeurosis category, the median length medially was 22.5 mm and median length laterally was 51 mm. In the short aponeurosis category, median medial length was 5 mm and lateral length was 22 mm. The lateral length was 1.8 times greater than the medial length for the long aponeurosis and 5 times greater for the short aponeuroses. Understanding the variation of the gastrocnemius aponeurosis will aid the surgeon in choosing a recession technique, performing the procedure, and preventing iatrogenic complications.