High-energy pelvic ring injuries are among the most challenging problems in orthopedic trauma. They are frequently associated with hemodynamic instability, multiple organ injuries, substantial early mortality, and a high risk of long-term disability (1–3). The primary surgical goal is to restore pelvic ring symmetry and stability to allow early mobilization and to reduce chronic pain and functional impairment (4). Traditional open reduction and internal fixation (ORIF) can achieve anatomic or near-anatomic reduction but requires extensive soft tissue dissection, is associated with considerable blood loss and wound complications, and may be poorly tolerated in polytrauma patients (1, 4).

For these reasons, less-invasive strategies—particularly closed or limited-exposure reduction combined with percutaneous fixation—have increasingly been adopted (3, 5–7). However, conventional closed reduction techniques typically rely on Schanz pins, traction tables, or reduction frames, guided only by two-dimensional (2D) fluoroscopy (5, 8–10). These approaches are technically demanding, operator-dependent, and may still fail to achieve acceptable alignment, especially in markedly displaced or vertically unstable patterns. Surgeons must interpret complex three-dimensional (3D) deformities from 2D projections and maintain reduction manually under substantial soft tissue resistance, often at the cost of prolonged fluoroscopy and physical fatigue (5, 6, 11–13).

With the development of digital orthopedics, computer navigation and surgical robots have improved the precision of percutaneous screw placement, particularly in the sacroiliac and trans-sacral corridors (5, 14–16). However, the majority of systems focus on the fixation step rather than on actively performing the reduction maneuver itself. To address this gap, our group developed an intelligent robot-assisted fracture reduction (RAFR) system that integrates CT-based 3D planning, intraoperative CBCT registration, optical navigation, a table-mounted passive holding arm, an elastic traction device, and a force-controlled robotic arm (17–23). Preclinical studies in bone models and cadaveric specimens revealed that this system can execute planned reduction trajectories with high accuracy and repeatability (17–22).

Following these experimental validations and early clinical experiences, further clinical evidence in a broader patient cohort is needed. Therefore, the objective of this study was to describe the early clinical application of the RAFR system in 32 consecutive patients with fresh, unstable pelvic ring injuries, focusing on (1) reduction quality assessed by CT-based residual displacement and Matta grading, (2) perioperative parameters including operative time, blood loss, and fluoroscopic exposure, and (3) short-term functional outcomes.

In this single-center case series, we describe the early clinical application and safety profile of an intelligent robot-assisted fracture reduction (RAFR) system for fresh, unstable pelvic ring injuries. To the best of our knowledge, this represents one of the first comprehensive reports on a dedicated pelvic reduction robot applied to a human cohort. In 32 consecutive patients with Tile B/C fractures, closed reduction was successfully completed in all cases without conversion to open reduction. The system achieved a median CT-based residual displacement of 4.0 mm and an excellent-to-good Matta rate of 90.6%. These findings suggest that robot-assisted closed reduction is not only clinically feasible but also capable of achieving radiographic alignment comparable to the upper range of outcomes historically reported for conventional closed techniques (5–9). Crucially, the safety profile was favorable; no neurovascular injuries, implant malpositions, or severe soft tissue complications were observed. This initial success validates the system’s core design philosophy: combining the precision of computer-assisted planning with the mechanical stability of robotic manipulation to standardize minimally invasive pelvic surgery.

The evolution of pelvic fracture management has long been defined by a challenging trade-off between anatomic restoration and physiological preservation. Open reduction and internal fixation (ORIF) offers direct visualization and superior reduction quality but constitutes a significant trauma to the patient. Conversely, conventional manual closed reduction has the advantage of minimizing trauma but is notoriously unpredictable. It relies heavily on 2D fluoroscopy, which provides limited spatial information and demands strenuous physical effort from the surgeon to counteract strong muscle contractions. This often results in suboptimal reduction or operator fatigue, ultimately forcing a conversion to open surgery. Our robotic workflow effectively resolves this clinical conflict. By enabling high-precision reduction through minimal incisions, the RAFR system aligns with damage control principles—preserving the soft tissue envelope and minimizing blood loss—while delivering the reduction quality typically associated with open surgery. This “best of both worlds” approach potentially transforms acute unstable fractures from chaotic, high-morbidity cases into manageable, programmed procedures.

A key differentiator of our system is its departure from the trial-and-error methodology of manual reduction (5, 7, 8). Traditional techniques remain heavily dependent on repeated fluoroscopic checks and manual manipulation, which leads to prolonged radiation exposure for the surgical team. In contrast, our workflow reconfigures the procedure around 3D imaging and computer-assisted planning. By mirroring the intact hemipelvis to create a patient-specific target, we eliminated the need for invasive fiducial markers and replaced subjective estimation with deterministic trajectory execution. Mechanically, the system’s functional separation between contralateral stabilization and ipsilateral reduction is a critical innovation. The contralateral hemipelvis is anchored via passive arms, providing a rigid mechanical reference that resists the forces applied during reduction. Clinically, this configuration is advantageous because the pins used for stabilization can often be incorporated into the definitive fixation (e.g., for INFIX constructs), thereby simplifying the construct and minimizing additional trauma (21, 23). Furthermore, unlike a human assistant who may fatigue, the robotic arm maintains the reduced position indefinitely. This “static hold” capability is vital; it allows the surgeon to insert guide wires and screws with precision, free from the urgency of losing the reduction, thereby significantly reducing the risk of screw malposition and neurovascular injury.

The versatility of the RAFR system is further highlighted by its application in non-standard patient populations. Our cohort included a 6-year-old patient with a severely displaced, unstable pelvic fracture following a traffic accident. Pediatric pelvic fractures present unique challenges: extensive open exposure is undesirable due to growth plate risks, and standard adult plates are often ill-suited to pediatric anatomy. Using the robotic system, we achieved anatomic reduction and performed percutaneous K-wire fixation. The robot’s ability to execute fine, scale-adjusted maneuvers allowed for a fixation strategy that was minimally invasive yet stable enough to permit early mobilization. Follow-up revealed excellent functional recovery. This case suggests that the system’s benefits—precision planning and soft tissue preservation—may be particularly amplified in pediatric trauma or other scenarios where standard implants and exposures are contraindicated.

While the system automates the reduction maneuver, safe implementation requires a rigorous “surgeon-in-the-loop” workflow. Our early experience revealed several technical nuances critical for success. First, image quality is paramount. Preoperative protocols must include bowel preparation to minimize intestinal gas, which can obscure bony landmarks on intraoperative fluoroscopy and CBCT. Additionally, close coordination with the anesthesia team is essential during the registration scan; controlling respiratory excursion ensures that the optical tracking of the anterior superior iliac spine (ASIS) remains accurate. Second, tracker stability is the Achilles’ heel of any navigation system. We encountered one instance of tracking drift due to loosening of the reference frame, necessitating re-registration. Rigorous fixation of trackers to the bone cortex is non-negotiable. Third, force management requires a hybrid approach. The robotic arm is safety-limited to a maximum force. In cases of fracture impaction or interlocking fragments, this limit may be exceeded, causing the robot to pause. We found that a collaborative strategy is effective: the surgeon performs a manual “unlocking” maneuver to disengage the fragments, after which the robot resumes its trajectory to complete the fine reduction. This synergy ensures that the robot does not blindly force a reduction against osseous resistance, acting as an essential haptic safety layer. Finally, contingency planning remains vital. Despite the high success rate, the complexity of the integrated software-hardware architecture means that technical faults are possible. A strictly defined protocol for converting to manual or open reduction must be in place, ensuring patient safety is never compromised by equipment downtime.

This study has several important limitations. First, it is a retrospective single-center case series with a relatively small sample size and no concurrent control group treated with conventional manual or open reduction. Therefore, the findings should be interpreted as preliminary evidence of feasibility and short-term safety rather than as proof of superiority over existing techniques. Second, the follow-up duration was limited to approximately 3 months, precluding assessment of long-term outcomes such as post-traumatic arthrosis, implant longevity, or late functional decline. Third, the current RAFR workflow requires an intact or minimally displaced contralateral hemipelvis as a template, and patients with bilateral severe comminution or deformity were excluded; the results therefore may not be generalizable to the most complex bilateral patterns. Future multicenter comparative studies, ideally randomized where feasible, are needed to confirm these early findings, define the specific fracture patterns and patient subsets most likely to benefit from robot-assisted closed reduction, and evaluate cost-effectiveness and learning-curve effects.

This case series reveals that an intelligent robot-assisted fracture reduction system can be safely integrated into the minimally invasive management of fresh, unstable pelvic ring injuries, achieving high rates of satisfactory CT-based reduction and encouraging early functional outcomes without conversion to open surgery. While these results support the feasibility of this approach, they should be considered as a foundation for further research. Larger multicenter studies with control groups and longer follow-up are required to clarify the comparative effectiveness, indications, and implementation strategies for robot-assisted closed reduction in pelvic ring trauma.