gms | German Medical Science

Objectives: External fixators are traditionally used for tibial lengthening by distraction osteogenesis. Recently intramedullary lengthening nails (ILN) have provided a more comfortable and equally safe alternative for tibial lengthening. During the lengthening procedure the development of ankle equinus deformity can become a relevant complication. Persistent impairment of the patients' gait may result in prolongated treatment including additional surgery. To prevent ankle equinus using ILN Belthur MV et al. [1] proposed temporary ankle arthrodesis by extraarticular insertion of a canulated calcaneotibial screw during the lengthening period.

Methods: Temporary extraarticular arthrodesis of the ankle joint via a canulated calcaneotibial screw was performed in a series of six patients treated with antegrade tibial ILN (PRECICE). Through guidance of a K-wire a canulated screw was implanted in retrograde technique, obliquely from the upper lateral edge of the calacaneal tuber to the lateral posterior aspect of the distal tibia. The screws were inserted with the ankle in neutral position. The patients were mobilized nonweight bearing using crutches. The screws remained in situ during the distraction period and were removed after six weeks of consolidation. When radiographic follow up proved sufficient callus formation full weight bearing was approved. Movement of the ankle joint was assessed clinically. Alignment of the hindfoot was measured by the lateral tibiocalcaneal angle (LTCA) in plain radiographs.

Results and conclusion: This procedeure was performed on a total of six patients with relative tibial shortening due to fibular hemimelia (n=2), congenital tibial pseudarthrosis (n=1), idiopathic leg length discrepancy (LLD) (n=2), posttraumatic LLD (n=1) and contralateral hemihypertrophy (n=1). In 5/6 patients the (LTCA) displayed no signifcant alternation throughout the lengthening procedure (+/- 5°). In 1/6 the ILN and the screw had to be removed due to insuffciency of the callus plus proximal nail dislocation and the procedure was changed to external fixation. Preoperative ankle range of motion was regained within six months of screw removal. No neurovascular complications were encountered, and no patients experienced equinus contracture. Temporary extraarticular arthrodesis of the subtalar und ankle joint is a reliable method to prevent ankle equinus when performing tibial lengthening using ILN.