gms | German Medical Science

Objectives: Augmented Reality is a powerful tool and has already shown its potential in a wide spectrum of surgical procedures, including orthopaedics. This technology indeed allows, through the use of a dedicated visor, to visualize a series of information and/or images superimposed to the user's field of vision; thanks to this feature, therefore, it was introduced as a surgical assistant tool. This single-center study, focused on total knee arthroplasty, aims to evaluate the intra-operative outcomes of the surgeries performed with AR assistance in terms of time required for the operation and difference between the pre-planned positioning and the achieved one, defined in terms of tibial implant varus and slope angles.

Methods: Seventy-six consecutive patients were selected for this study. Pre-planning was performed according to the augmented reality protocol and the aimed varus and slope angles were defined and used to instruct the device, which will then guide the Surgeon intra-operatively to perform the tibial cuts. Total Knee Arthroplasty was performed starting from the tibial cut with the assistance of AR tools, and the time required to perform the calibration, registration, and fixation of the resection block was recorded. The varus and slope angles achieved were then recorded to perform the comparison with the pre-planned ones, allowing to determine the average and standard deviation of the differences. The femoral cuts were then performed using the tibial ones as reference.

Results and conclusion: The average usage time of the AR tool was 5 min (SD 1 min). Comparing planned and achieved varus angles, results showed an average difference of 0.59 degrees (SD 0.55 degrees); a difference of 0.70 degrees (SD 0.75 degrees) was instead measured for the slope. In detail, for varus angles the differences were below 1 degree for 96% of the cases (and between 1 degrees and 2 degrees for the rest of the cases). Concerning the slope, 89% of the cases were under 1 degree, 9% between 1 degrees and 2 degrees, and 2% with more than 2 degrees.

The results showed very good accuracy of the surgical cuts according to the pre-planned ones, and limited increase in surgery duration when compared to traditional approaches. These outcomes highlighted therefore the potential of this new technology as a valid and competitive option to be considered by the surgeons, if compared to other recent technological tools.