[Spastic equinus foot]

Pes equinus is the most common deformity in cerebral palsy. A primarily dynamic pes equinus without shortening of the calf muscle in many cases turns into a structural pes equinus. This is due to insufficient linear growth of the calf muscle compared to bone growth. Structural pes equinus has to be distinguished from marked, compensatory and forefoot pes equinus. Conservative as well as operative treatment options are often applied in combination or sequentially. In dynamic pes equinus botulinum toxin A is the therapy of choice. Only slight structural pes equinus may improve under botulinum toxin A injection with and without additional casting. Usually, structural pes equinus requires operative treatment or lengthening of the gastrocnemius and/or soleus muscle (operation according to Baumann). Because of its side effect of inducing loss of power of the calf muscle, lengthening of the Achilles tendon should only be performed with caution. Especially in bilateral spastic cerebral palsy, the increased risk of causing talipes calcaneovalgus and crouch gait has to be considered.