Computer-Assisted Surgery-(CAS-)Guided Correction Arthrodesis of the Subtalar Joint

Restoration of a stable and plantigrade foot in deformities at the hindfoot and concomitant degenerative changes at the subtalar joint. Deformities at the hindfoot and concomitant degenerative changes at the subtalar joint. Active local infection or relevant vascular insufficiency. Prone position and posterolateral approach to the subtalar joint. Placement of dynamic reference bases in talus and calcaneus through stab incisions. Two-dimensional image acquisition for navigation. Definition of the axes of talus and calcaneus, and of the extent of correction. Exposure of the subtalar joint and removal of remaining cartilage. Computer- assisted surgery-(CAS-)guided correction and transfixation of the corrected position with two 2.5-mm Kirschner wires. Transplantation of autologous cancellous and cortical bone, if necessary. Three-dimensional (3-D) image acquisition for analysis of the accuracy of the correction and planning of the drillings for the screws. CAS-guided drilling and insertion of the screws. 3-D image acquisition for analysis of the accuracy of the correction implant position. Wound closure in layers. 15 kg partial weight bearing in an orthosis (e.g. Vacuped TM, OPED Inc., Valley, Germany) for 6 weeks, followed by full weight bearing in a stable standard shoe. From September 1, 2006 to August 31, 2008, 26 correction arthrodeses were performed. The accuracy was assessed by intraoperative 3-D imaging. All achieved angles/translations were within a maximum deviation of 2A degrees/2 mm when compared to the planned correction. Complications that were associated with CAS were not observed. In all 25 cases that completed 2-year follow-up, timely fusion was registered.