Anatomic study of the gastrocnemius-soleus junction and its relationship to the sural nerve

Background: Gastrocnemius recession is performed for equinus contracture of the ankle and as an adjunct treatment for various foot pathologies. Successful release relies on many factors, including a thorough knowledge of the anatomy of the gastrocnemius-soleus junction and its relationship to the sural nerve which may be vulnerable to iatrogenic injury. Neither the average width of the tendon at the gastrocnemius-soleus junction, the anatomy of the sural nerve with respect to the gastrocnemius-soleus junction, nor appropriate landmarks for accurate incision placement at this level to avoid undesirable vertical extension, however, have yet to be acceptably defined. Methods: Fourteen fresh-frozen cadavers were dissected and the width of the tendon at the gastrocnemius-soleus junction, the distance of the sural nerve from the lateral border of the tendon at this level, the length of the fibula, and the distance from the distal tip of the fibula to the gastrocnemius-soleus junction were measured. Results: The average width of the gastrocnemius-soleus complex at the junction was 58 mm (range, 44-69 mm), the average distance of the sural nerve from the lateral border of the gastrocnemius-soleus complex at the level of the gastrocnemius-soleus junction was 12 mm (range, 7-17 mm), the average percentage of this distance as compared to the entire width of gastrocnemius-soleus junction was 20% (range, 13%-27%), and the ratio of the distance of the gastrocnemius-soleus junction from the distal tip of the fibula divided by the length of the fibula was 0.5 (range, 0.5-0.6). Conclusion: These results provide some guidelines as to the approximate size of the gastrocnemius-soleus complex at the site of gastrocnemius recession along with the location of the sural nerve at the musculotendinous junction. Also, the results indicate that the fibula can serve as a reproducible anatomic landmark to enable localization of the gastrocnemius-soleus junction at the time of gastrocnemius recession.