Open‑Platform Robotic Knee Replacement Hits High Mark for Accuracy Across Multiple Implants

A new multicenter study suggests that open-platform robotic systems can achieve high alignment accuracy in total knee arthroplasty (TKA) across a range of implant types, potentially offering surgeons greater flexibility without compromising precision. Published in Arthroplasty, the retrospective analysis evaluated 114 consecutive robotic-assisted knee replacements using the Yuanhua KUNWU system at three high-volume centers in China.

Unlike conventional closed-platform robotic systems, which are typically locked to a single implant brand, open-platform systems allow surgeons to select from multiple implant models. This flexibility could be especially valuable in cases with complex anatomy or when tailoring procedures to specific alignment philosophies. However, whether open platforms can match the accuracy of closed systems has remained an open question.

In this study, the KUNWU robot was used with four different implant designs: DePuy Attune, Zimmer Biomet Persona, Smith & Nephew Legion, and Zhengtian Irene. Postoperative radiographs were used to measure several key alignment parameters, including the hip–knee–ankle (HKA) angle, femoral and tibial component coronal angles, and posterior tibial slope.

Across all cases and implant types, over 90% of knees achieved alignment within 3 degrees of the preoperative surgical plan—widely considered the clinical threshold for acceptable accuracy. Mean deviations were minimal: 1.32° for HKA angle, −0.55° for the femoral coronal angle, and +0.19° for the tibial coronal angle. The posterior tibial slope averaged a −0.42° deviation. While some of these differences reached statistical significance, the authors note they were too small to be clinically meaningful.

The system also demonstrated high interobserver reliability, with intraclass correlation coefficients above 0.77 and Cronbach’s alpha values exceeding 0.87 for all alignment measures.

Although the findings are promising, the authors caution that the retrospective design and uneven distribution of implant types limit generalizability. Long-term clinical outcomes such as implant survival and patient-reported satisfaction were not assessed. The study also lacked a control group using manual or closed-platform techniques.

Still, the results support the growing viability of open-platform robotic assistance in knee arthroplasty. As surgeons increasingly look to personalize implant selection and alignment strategies, a system capable of combining precision with versatility could offer a practical advantage—particularly in institutions aiming to reduce dependence on single-vendor solutions.

Further prospective, controlled trials are needed to determine whether the short-term alignment accuracy observed in this study translates into better long-term functional outcomes and implant longevity.