The accessory soleus muscle as a cause of persistent equinus in clubfeet treated by the Ponseti method : A report of 16 cases.

Encountering an accessory soleus muscle in children undergoing surgical release for clubfeet is not a frequent occurrence and only a few reports could be traced in literature. The purpose of this study is to report a series of 20 observations in 16 patients with idiopathic clubfeet treated by the Ponseti technique where the accessory soleus muscle was responsible in preventing full ankle dorsiflexion after Achilles tendon tenotomy. Following its division, adequate dorsiflexion could be achieved. To our knowledge this is the largest series published to date on this topic. In addition, we discuss the frequency and epidemiology, as well as the anatomy of the accessory soleus muscle, its innervation and embryology. The mean age at presentation was 40.7 days (range : 6 to 210 days). The accessory soleus tendon was observed in 6 right and 6 left feet, 4 feet had bilateral involvement. The average ankle dorsiflexion after complete tendo Achilles tenotomy was 2.50 (SD: 638), and after sectioning of the accessory soleus tendon, it was 19.50 (SD: 559) (p < 0.001). Correction was obtained in all patients, after 3 to 10 casts. In conclusion, the recognition of an accessory soleus muscle, in patients with clubfeet, is important, and its release is necessary to fully correct the deformity. Failure to recognize this muscle may lead to persistent hindfoot deformity.