Intraoperative validation of bone cut accuracy of a pinless smart touch-screen navigation system device in total knee arthroplasty

Purpose: Primary objective in most of the published literature on computer-assisted total knee arthroplasty (TKA) has so far been the comparison of axial alignment and components position, obtained either through navigation systems or through conventional instrumentation. We have found no studies aimed at assessing the intraoperative reliability of a navigation system in relation to bone cuts height. Aim of our study was therefore to establish bone cut accuracy of a pinless navigation system. Methods: From January 2014 to February 2016, 44 consecutive patients requiring total knee replacement (TKR) were enrolled in a prospective study. Primary end point of the study was to assess the accuracy of the DASH iPOD TOUCH Navigation System (Brainlab AG, Feldkirchen, Germany) by measuring the real thickness of both tibial and femoral osteotomies. We compared the data indicated by the navigation system with the intraoperative anatomical measurements done with the aid of a caliper. In addition, the radiographic alignment was compared with the data derived from the navigator. Results: The device proved to be precise. Differences between the two methods of measurement are distributed over a millimeter range. Radiological measurements showed that 95.5% of tibial components were within the range of 3° varus/valgus; same results were obtained by the navigation system; instead, 90.1% of femoral components were within the range of 3° varus/valgus based on the radiological measurement, whereas according to the navigation system, 86.4% were in this range. Conclusions: The DASH iPOD TOUCH Navigation System is a precise and reliable instrument to assist in TKA navigation.