gms | German Medical Science

Objectives: Robotic-assisted surgery has been recently introduced to improve the follow-up of knee arthroplasty by enhancing the surgeon’s ability to better restore normal kinematics.Robotic-assisted uni-condylar knee arthroplasty (UKA) aims to provide improved surgical bone resection and alignment accuracy, optimized component positioning and knee balancing, with the goal of improving patient clinical and functional outcomes. These advantages focus therefore on improving the reproducibility of UKA surgeries, lowering (if not eliminating) eventual differences among high- and low-volume surgeons.

In order to provide a reference for the surgeons interested in performing operations with robotic assistance (and also to surgeons already performing them), the purpose of the current study is to investigate and quantify the reproducibility of the in vivo measurements performed with a robotic system: in order to achieve this goal, the intra- and inter-observer variability of a series of measurements obtained with a MAKO system was therefore analyzed and compared among differently skilled operators.

Methods: Five consecutive patients were analyzed for this study and underwent robotic-assisted UKA at our Institution, using a semi-active robotic system. A group of 26 patients who previously underwent the same typology of operation was used as control for BMI and age.

Three different observers with different experience levels (high volume surgeon, low volume surgeon and orthopedic resident) were involved to independently perform the measurements of two parameters of the preoperative knee (i.e. the Hip-Knee-Ankle angle (HKAa) and the Internal-External Rotation of the limb) at 0°, 30°, 60°, 90° and 120° degrees of knee flexion. Inter and intra-observer comparisons were performed.

Results and conclusion: The results of the comparison of the 5 patients involved in the study with the control group of 26 consecutive patients equally treated with robotic UKA showed that the sample chosen represents a homogeneous cohort as no statistically significative difference was found in terms of age (p value 0.44) and BMI (p value 0.33).

The variability in the measurements obtained from the intra-observer and inter-observer comparisons is reported in Table 1 [Tab. 1] (for HKAa) and Table 2 [Tab. 2] (for internal-external rotations).

This study demonstrated the high intra and inter-observer reproducibility of the measurements of knee HKAa and internal-external rotation obtainable in a clinical environment with the use of a MAKO robotic system, highlighting the great reliability of the robotic system in acquiring the data then used for the operation itself. Furthermore, the fact that the inter-observer variability was not remarkably high provides a significant insight on the required level of experience with the robotic system required to actually perform the measurement with this technique.