[CAS-guided correction arthrodesis of the tarsometatarsal and midfoot joints].

OBJECTIVE: Restoration of a stable and plantigrade foot in deformities at the midfoot (between the Chopart and tarsometatarsal (TMT) joint) and/or the TMT joint and concomitant degenerative changes. INDICATIONS: Deformities and concomitant degenerative changes at the midfoot and/or TMT joint. CONTRAINDICATIONS: Active local infection or relevant arterial insufficiency. SURGICAL TECHNIQUE: Supine position and dorsomedian and dorsolateral approach to the midfoot and TMT joint. Placement of dynamic reference bases (DRB) in the talus and distal shaft of the 1(st) metatarsal. Two-dimensional (2D) image acquisition for navigation. Definition of axes of the talus and 1st metatarsal, and of the extent of correction. Exposition of midfoot and TMT joints and removal of remaining cartilage. Transplantation of autologous, cancellous, and cortical bone if necessary. Computer-assisted surgery (CAS)-guided correction and internal fixation with 3.5 mm screws (e.g. 3.5 mm cortical screw, Synthes, Umkirch, Germany) and plates (e.g. 3.5 mm LCDCP, Synthes, Umkirch, Germany). Three-dimensional (3D) image acquisition for analysis of the accuracy of the correction and implant position. Insertion of drains and layerwise closure. POSTOPERATIVE MANAGEMENT: Partial weight bearing (15 kg) in cast shoe for 6 weeks, followed by full weight bearing in a stable standard shoe. After 12 weeks, pedography and production of insole orthoses based on the pedographic data.
RESULTS: From September, 1(st) 2006 to September, 30(th) 2008, 32 correction arthrodeses at the midfoot/TMT joint were performed. The accuracy was assessed by intraoperative 3D imaging. All achieved angles/translations were within a maximum deviation of 2° when compared to the planned correction. Complications associated with CAS were not observed. In all 31 cases without navigation failure, a timely fusion was observed.