A family with a 36 month child with proximal femoral focal d…

A family with a 36 month child with proximal femoral focal deficiency has been using an equinus prothesis for ambulation.  Poor foot integrity, limited ankle mobility (0-10 degrees of ankle dorsiflexion and 0-20 degrees of ankle plantar flexion), and knee instability on the involved limb are causing the prosthesis to fit poorly, which is leading to pain and skin breakdown.  Which procedure listed below has the best potential to improve function and mobility for this child?