Background: Oncologic resections and reconstructions of the pelvis are among the most challenging procedures in orthopedic surgery due to complex anatomy, tumor variability, and the need for precise margins.Patient-specific instrumentation (PSI) created with 3D printing has emerged as a promising solution, but accurate intraoperative referencing remains difficult.This study evaluates the use of novel acetabular-referencing PSI cutting guides for pelvic tumor resections and reconstructions.Methods: Five patients (mean age 57.2 years) underwent pelvic resections with acetabular-referencing PSI between 2019 and 2023.Each guide incorporated a hemispherical feature seating within the acetabulum after femoral head removal.Postoperative CT reconstructions were compared with preoperative plans to assess resection accuracy, implant alignment, operative time, and margin status.Results: All patients achieved negative gross margins; two had microscopically positive margins (one planned).Mean operative time was 8 hours 52 minutes, including two complex procedures.Mean deviations were 8.32 mm for center of rotation (CoR) and 7.37 mm for center of gravity (CoG).Directional CoR deviations averaged 2.62 mm anteroposteriorly, 6.30 mm mediolaterally, and 3.92 mm superoinferiorly.Angular deviations averaged 1.88 in anteversion and -2.54 in inclination.All implants were positioned within or near accepted thresholds for pelvic reconstruction accuracy.Conclusions: Acetabular-referencing PSI enabled reproducible guide placement and accurate osteotomies in complex pelvic resections without increasing operative time.This technique offers a reliable alternative to surface-contoured guides and may enhance precision in oncologic reconstruction by mitigating challenges of intraoperative interfacing.Larger studies with long-term follow-up are needed to confirm functional outcomes and implant survivorship.
Lau et al. (Sun,) studied this question.