Abstract
OBJECTIVE: The objective of the study was to evaluate the safety, feasibility, and radiographic outcomes of an intelligent robot-assisted fracture reduction (RAFR) system in the minimally invasive treatment of fresh, unstable pelvic ring injuries. METHODS: In this single-center retrospective case series, 32 consecutive patients with unstable pelvic ring injuries (Tile type B or C) treated between August 2024 and April 2025 underwent minimally invasive closed reduction and internal fixation using the RAFR system. The system combines preoperative computed tomography (CT)-based three-dimensional reduction planning, intraoperative cone-beam CT (CBCT) registration, an optical tracking system, a table-mounted passive holding arm, and a robotic arm with dual force-position monitoring. Operative time, intraoperative blood loss, and fluoroscopic exposures were recorded. Postoperative CT was used to measure residual displacement, which was graded according to Matta's criteria, and the excellent-to-good rate was calculated. Functional outcomes were assessed using the Majeed score at the final follow-up. RESULTS: All 32 procedures were completed using a closed, minimally invasive approach without conversion to open reduction. The median (IQR) operative time was 270 (225-311) min, blood loss was 150 (100-300) mL, and fluoroscopic exposures were 35 (30-45). The median residual displacement on CT was 4.0 (3.0-8.0) mm. According to Matta's criteria, 17 patients (53.1%) had excellent, 12 (37.5%) had good, and 3 (9.4%) had fair reductions, yielding an excellent-to-good rate of 90.6%. Two patients were lost to follow-up; among the remaining 30 patients, no major complications such as deep infection, implant failure, or iatrogenic neurovascular injury were observed, and the mean Majeed score was 76.7 ± 12.0. CONCLUSION: The RAFR system enabled closed reduction and percutaneous fixation of a heterogeneous cohort of unstable pelvic ring fractures with high rates of satisfactory reduction and favorable short-term functional recovery. These preliminary findings support the clinical feasibility and safety of robot-assisted closed reduction for unstable pelvic fractures and provide a basis for future comparative and multicenter studies.