First-in-human prospective pilot study of a bipolar dual-center total wrist arthroplasty: early mechanical stability and clinical outcomes

Purpose Total wrist arthroplasty (TWA) is limited by implant loosening, instability, and non-physiological load transfer, partly because most contemporary implants rely on a single center of rotation and do not preserve native wrist kinematics. This first-in-human pilot study evaluated the feasibility, early mechanical stability, and clinical outcomes of a novel bipolar dual-center TWA system designed to preserve radiocarpal and midcarpal motion. Methods This prospective single-center pilot case series included five consecutive patients with end-stage wrist arthritis treated with a bipolar dual-center TWA implant using cement fixation, as per the device’s intended use. The outcome measures included pain assessed using the pain subscale of the Patient-Rated Wrist Evaluation (PRWE) questionnaire (normalized to a 0–10 scale), total PRWE score, DASH score, range of motion, grip strength, radiographic implant stability, complications, and reoperation. Clinical outcomes were assessed at the most recent follow-up visit. Results The mean follow-up was 19.2 months (range, 12–24 months), with 24-month data available for three patients. Implant survivorship was 100%, with no loosening, migration, dislocation, or implant revision observed on radiographs. One patient experienced a traumatic postoperative fall without loss of implant fixation. The mean PRWE-derived pain score improved from 9.0 to 3.0, and the mean PRWE total improved from 84.6 to 23.2 at the final follow-up. The mean DASH score improved from 79.0 to 29.5, with substantial inter-patient variability (final range, 0–91.7). All five patients met the predefined responder criterion of ΔPRWE ≥ 20 combined with radiographic stability. Three patients with positive preoperative signs of carpal tunnel syndrome subsequently underwent carpal tunnel release 4–8 months postoperatively, with symptomatic improvement in all patients. One intraoperative carpal fracture was managed without component revision surgery. The mean wrist flexion improved from 13° to 37°, and extension improved from 11° to 32°. Conclusions This first-in-human pilot study demonstrated the technical feasibility and early mechanical stability of the bipolar dual-center TWA concept. All patients met the predefined wrist-specific responder criteria with stable mechanical implant fixation. These findings support further investigation of the dual-center concept in larger studies with longer follow-up periods.