Introduction: The importance of isolated gastrocnemius contracture in disorders of the foot and ankle has been established in recent years. The aim of this study is to describe the proximal anatomical approach to the medial and lateral heads of gastrocnemius and to compare the sizes of the medial and lateral heads of the gastrocnemius.

Method: 15 cadaveric knees were dissected using a posterior approach 1cm below the level of the skin crease. Proximity of cutaneous nerves and major vessels was noted. The heads of the gastrocnemius were dissected from their origin and the cross sectional anatomy was defined.

Results: Approach to the medial head of gastrocnemius is safe. Conversely the variable anatomy of the nerves in the approach to the lateral head means that extreme care must be taken if complications are to be avoided. The aponeurosis of the medial head of gastrocnemius was 2.4 times the cross-sectional area compared to the lateral head.

Conclusion: In this study we describe a safe posterior approach to the medial aponeurosis of gastrocnemius and also describe the different sizes of the medial and lateral gastrocnemius heads. We propose that the release of the medial head alone is safe and likely to be efficacious in the surgical treatment of isolated gastrocnemius tightness that has failed non-operative treatment.