Suspended patient-specific instrument-assisted femur-first osteotomy for fixed-bearing unicompartmental knee arthroplasty: technical note and preliminary clinical results

This study designed a novel suspended patient-specific instrument (SPSI), described its design rationale and the surgical workflow of femur-first osteotomy based on this instrument, and explored its feasibility and early clinical outcomes in fixed-bearing unicompartmental knee arthroplasty (UKA). Ten patients with anteromedial osteoarthritis of the knee were included, all of whom underwent UKA with SPSI-assisted femur-first osteotomy. Operative time, blood loss, and postoperative complications were recorded. The resting pain VAS score and the objective knee component of the 2011 revised KSS were compared preoperatively and at 3 months postoperatively, and prosthetic positioning parameters were assessed via X-ray. All surgeries were completed successfully without abandonment of the SPSI or severe complications. The median operative time was 75.00 (70.00, 96.75) minutes, and the median blood loss was 50.00 (50.00, 62.50) ml. At 3 months postoperatively, the VAS score decreased significantly from 5.50 (5.00, 6.25) preoperatively to 0.50 (0.00, 1.00) ( p = 0.005), while the KSS score improved significantly from 44.40 ± 4.67 preoperatively to 80.90 ± 5.45 ( p < 0.001). Satisfactory prosthetic positioning parameters were achieved, with a femoral coronal angle of 89.70 ± 6.78°, a tibial coronal angle of 86.80 ± 2.20°, a femoral sagittal angle of 8.40 ± 1.89°, and a tibial sagittal angle of 82.00 ± 2.49°. The SPSI enables accurate localization of femoral prosthesis peg holes, and the femur-first osteotomy workflow optimizes the surgical field and simplifies intraoperative steps. Current preliminary data indicate this novel workflow may serve as a feasible alternative for fixed-bearing UKA, though comparative analysis and long-term survivorship data remain absent.