Use of computer-assisted hexapod external fixators for complex foot and ankle reconstructions - An analysis of functional outcomes and complications.

Introduction: Foot and ankle pathology can often require complex surgical reconstruction. Until recently, circular external fixators such as the Ilizarov frame have proven to be useful, yet they fall short when progressive, precise corrections are required. Computer-assisted hexapod external fixators seek to address many of the shortfalls of traditional circular fixators. However, evidence for their use is scarce. The objective of this work was to evaluate the functional and quality of life outcomes and post-operative complications of patients treated with computer-assisted hexapod external fixation.

Methods: A retrospective, observational study was conducted. All cases were treated with either a TrueLok hex (TL-HEX) or a Taylor Spatial Frame (TSF) fixator. Primary outcomes were post-operative improvement in 12-Item Short Form Survey (SF12) and American Orthopaedic Foot and Ankle Score (AOFAS) scores, and complications following Paley's classification.

Results: A total of 59 patients with complex foot and ankle conditions using 64 external fixation frames were included. The median sum of both SF12 score domains improved from a preoperative score of 63.6 to 91.3 at last follow-up (p < 0.001). Median AOFAS improved from a preoperative score of 35 to 75.5 at last follow up (p < 0.001). Functional improvement was not affected by the choice of external fixator. Complications occurred in 49 cases (77 %). The most common post-operative complications included pin tract complications in 37 (58 %) cases, joint rigidity in 24 (38 %) and axial deviation in 9 (14 %).

Conclusions: Computer-assisted hexapod external fixation is an effective technique to correct complex foot and ankle deformities and leads to a marked improvement in post-operative functional and quality-of-life outcomes with a high minor complication rate.