Evaluating the accuracy of a new robotically assisted system in cadaveric total knee arthroplasty procedures

Abstract

Background: Robot-assisted total knee arthroplasty (TKA) has been shown to facilitate high-precision bone resection, which is an important goal in TKA. The aim of this cadaveric study was to analyze the accuracy of the target angle and bone resection thickness of a recently introduced robotic TKA system.

Methods: This study used 4 frozen cadaveric specimens (8 knees), 2 different implant designs, navigation, and a robotic system. The 4 surgeons who participated in this study were trained and familiar with the basic principles and operating procedures of this system. The angle of the bone cuts performed using the robotic system was compared with the target angles from the intraoperative plan. For each bone cut, the resection thickness was recorded and compared with the planned resection thickness.

Results: The mean angular difference for all specimens was less than 1°, and the standard deviation was less than 2°. The mean difference between the planned and measured angles was close to 0 and not significantly different from 0 except for the difference in the frontal tibial component angle, which was 0.88°. The mean difference in the hip-knee-ankle axis angle was - 0.21°± 1.06°. The mean bone resection difference for all specimens was less than 1 mm, and the standard deviation was less than 0.5 mm.

Conclusions: The results of the cadaveric experimental study showed that the new TKA system can realize highly accurate bone cuts and achieve planned angles and resection thicknesses. Despite the limitations of small sample sizes and large differences between cadaveric and clinical patients, the accuracy of cadaveric experiments provides strong support for subsequent clinical trials.

Keywords: Accuracy; Bone resection; Cadaveric study; ROPA TKA system; Robotic surgery; Total knee arthroplasty.

Fig. 1

(A) The illustration of the ROPA TKA robot system. (B) The schematic diagram of the placement of the ROPA TKA robot system in the operating room

Fig. 2

The operator performs preoperative planning using specialised software to determine the ideal resection thickness and angle to obtain a balanced and well-aligned TKA.

Fig. 3

The schematic diagram of intraoperative calibration and osteotomy. (A) and (B): The calibration of femoral and tibial on the ROPA TKA system. (C) The robotic arm of the ROPA TKA robotic system is fixed in the desired position determined by the surgical plan based on the operator’s intraoperative planning. Once the cutting jig is set and fixed in the correct position, the surgeon performs the cuts

Fig. 4

(A) The illustration of intraoperative adjustment of osteotomy parameters according to the soft tissue condition of the specimen. (B) The chematic diagram of intraoperative tibial osteotomy on the ROPA TKA system

Fig. 5

Measurement of HKA, FFC, FTC, FVA. (A) Line a was the femoral mechanical axis, and line b was the tibial mechanical axis; the medial angle formed between them was recorded as the HKA. (B) Line c was the line across the bottom of the femoral condyles, line d was the line across the bottom of the tibial plateau on the anteroposterior radiograph; the lateral angle between line a and line c was recorded as FFC, and the medial angle between line b and line d was recorded as FTC. (C) Line e was the anatomical axis of the femur, the acute angle between line a and line e was recorded as FVC.

Fig. 6

Graphical representation of angle (A) and thickness (B) differences