Computer-assisted tibia preparation for total ankle arthroplasty: a cadaveric study.

BACKGROUND: Most surgeons performing total ankle arthroplasty (TAA) suggest that accurate tibial preparation perpendicular to the tibial shaft axis improves outcomes. Recent studies demonstrate that computerized surgical navigation significantly improves the accuracy of tibial preparation in total knee arthroplasty (TKA).

METHODS: We performed the tibial preparation for TAA in seven matched pairs of cadaver lower extremities. One set of matched pairs was prepared using the conventional external tibial alignment guide/cutting block from the Scandanavian Total Ankle Replacement system (STAR, Waldemar Link GmbH & Co., Hamburg, Germany) under fluoroscopic guidance. The second set of matched pairs was prepared using the VectorVision((R)) navigation system (BrainLAB, Munich, Germany), with currently available computed tomography (CT)-based TKA software. Pre-operative CT data were used to assess the tibial mechanical axis. In both groups, accuracy of the tibial plafond preparation relative to the tibial shaft axis in both the coronal and sagittal planes was determined by fluoroscopic, radiographic and CT analysis.

RESULTS: Mean values of the tibial cut for the set of matched-pair tibiae prepared by the conventional surgical method ranged across the three imaging assessment techniques in the ranges 89.3-89.6 degrees (coronal plane, anteroposterior) and 90.3-90.4 degrees (sagittal plane, lateral). For the computer-navigated set, the values were 89.7-89.9 degrees (coronal) and 89.1-89.4 degrees (sagittal). Comparison between the conventional and computer-navigated tibial measurements were not different at the 95% confidence interval (CI) for CT, fluoroscopy or radiographic assessments.

CONCLUSIONS: Our results demonstrate that accuracy of TAA tibial preparation using computer-navigation equals that of the conventional technique performed by a foot and ankle surgeon experienced in TAA. We anticipate that this investigation will encourage the development of computer-navigation applications specific to TAA, with the potential of improving accuracy over conventional methods.