High-Accuracy reduction of comminuted diaphyseal femur fractures using on-site 3-D-printed guides.

Purpose Persistent malalignment-especially rotational error-after fixation of comminuted femoral shaft fractures compromises function and often necessitates revision surgery. This study evaluated whether point-of-care, patient-specific three-dimensional printed reduction guides can reproducibly restore native femoral length, coronal-sagittal alignment and axial rotation in a cadaveric model simulating highly comminuted shaft fractures.Methods Ten freshfrozen human legs were CTscanned, virtually reduced, and fitted with patientspecific guides printed in a sterilizable medical resin. A 2 cm midshaft segment was resected to simulate a comminuted fracture. Each construct was reduced with the guides and stabilized with a locking compression plate. Postoperative CT volumes were superimposed to the preoperative plan to quantify absolute deviations in length, coronal (varus/valgus), sagittal (procurvatum/recurvatum), and axial rotation.Results All reductions were completed without technical difficulty. Mean ± SD absolute errors were 1.50 ± 1.08 mm in length, 0.92 ± 0.41° in the coronal plane, 1.33 ± 1.34° in the sagittal plane, and 4.33 ± 1.88° in rotation-well within acceptable clinical limits.Conclusion On‑site printed, patient‑specific guides achieved high accuracy in a comminuted femoral fracture model. Clinical studies are required to determine whether this accuracy translates into improved patient outcomes.