Surgical accuracy of open platform image-based robotic-assisted total hip arthroplasty

Precise acetabular cup positioning is critical for the success and longevity of total hip arthroplasty (THA). Robotic-assisted systems enhance placement accuracy, with closed-platform systems being well-established. A pertinent question is whether newer open-platform systems, which offer implant flexibility, achieve comparable accuracy. This study evaluates the radiographic accuracy of a novel, open-platform robotic system (Yuanhua KUNWU) in achieving the planned acetabular component position.

A multi-centre retrospective review of 87 consecutive primary robotic THA procedures performed using the KUNWU system was conducted. Pre-operative CT-based planning defined the target acetabular inclination (AI) and anteversion (AV). The primary outcome was the deviation between the planned position and the post-operative CT-measured position. Secondary outcomes included the proportion of cups within the Lewinnek and Callanan safe zones and the accuracy of leg length and offset restoration.

The mean deviation from the planned position to the post-operative CT was -2.7° for inclination (95% CI: -3.7° to -1.8°, P < 0.001) and 1.0° for anteversion (P = 0.058). Overall, 80.5% (70/87) of cups were placed within the combined Lewinnek and Callanan safe zones. A significant difference was found in combined offset (mean 2.79 mm, P = 0.002) but not in leg length discrepancy (P = 0.302). Interobserver reliability was excellent for all measurements.

The KUNWU open-platform robotic system facilitates accurate and reliable acetabular cup positioning, with minimal deviations from the pre-operative plan and a high rate of placement within the classic safe zones. These results support its use as a precise tool for component positioning in THA.