Outcomes of Triceps Surae Lengthening Surgery in Children With Charcot-Marie-Tooth Disease: A Multisite Investigation

Background: Orthopaedic surgical intervention in children with Charcot-Marie-Tooth (CMT) often includes triceps surae lengthening (TSL) and foot procedures to address instability and pain due to equinus and cavovarus deformities. These surgeries may unmask underlying weakness in this progressive disease causing increased calcaneal pitch and excessive dorsiflexion in terminal stance leading to crouch. The purpose of this study was to evaluate changes in ankle function during gait following TSL surgery in children with CMT. Methods: Nineteen participants (11 male; age 12.8, SD 3.6 y) with CMT underwent gait analysis and clinical examination preoperatively and postoperatively to determine the outcomes of (1) triceps surae lengthening (TSL) and (2) plantar fascia release with bony foot surgery with or without TSL. TSL was performed in limbs with limited passive dorsiflexion range of motion (ROM) and decreased peak dorsiflexion in terminal stance, with gastrocnemius recession (GR) being preferred over tendo-Achilles lengthening (TAL) in cases with smaller dorsiflexion deficits. Passive dorsiflexion ROM, gait kinematics and kinetics, and foot posture index (FPI) were examined within and across surgical groups using linear mixed models. Results: Dorsiflexion ROM, peak dorsiflexion in terminal stance and mid-swing, and peak nondimensional plantar flexor moment improved significantly after both GR (n=8 limbs) and TAL (n=11 limbs) (P≤0.02). After plantar fascia release with bony foot surgery (n=20 limbs), FPI changed significantly, indicating reduced cavovarus regardless of whether TSL was done (P<0.05). Passive and dynamic dorsiflexion and ankle kinetics (moment and power) increased only when concomitant TSL was done (P≤0.04). Conclusions: In patients with increased equinus due to reduced passive dorsiflexion range of motion, TSL is an effective surgery for reducing excessive equinus in terminal stance and mid-swing, decreasing toe-walking, and improving swing phase clearance. It can be combined with extensive foot surgery to correct cavovarus deformity without leading to excessive dorsiflexion in terminal stance and crouch gait. Clinical gait analysis is an important tool to help identify appropriate candidates for TSL based on the key indicator of peak dorsiflexion in terminal stance. Level of Evidence: Level IV.