Abstract
BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.