Efficacy of 3D-Printed Patient-Specific Axial Alignment Guides for Minimally Invasive Intramedullary Nailing of Complex Femoral Diaphyseal Fractures

Introduction: Minimally invasive osteosynthesis (MIO) techniques preserve biological integrity and enhance fracture healing. A primary challenge in MIO is the lack of direct fracture visualization. Interlocking nails (ILNs) are often used for long bone fracture MIO. Accurate rotational alignment is not controlled during ILN fixation and relies on anatomic landmark identification and intraoperative fluoroscopy. This study aimed to evaluate 3D-printed patient-specific guides (PSGs) for facilitating axial alignment during ILN placement in a cadaveric femoral fracture model and compare them to a freehand technique. We hypothesize that PSGs would result in improved axial alignment compared with the freehand technique.

Materials and Methods: Six cadaveric dogs were used. Preoperative CT scans were used to design 3D-printed PSGs that engaged the I-Loc ILN jig. A diaphyseal fracture was created and fractures were stabilized using an ILN with freehand or PSG technique. Pre- and postoperative radiographic alignment were compared using the femoral neck angle of anteversion (FAA).

Results: The freehand technique yielded FAA that was significantly different from the native anatomy (p = 0.02, mean difference 16.02 degrees ± 2.86) and the guided technique resulted in a similar FAA to native anatomy (p = 0.82, mean difference 6.93 degrees ± 2.86). PSG use was associated with an FAA closer to the native femoral anatomy than the freehand technique (p = 0.004).

Discussion/Conclusion: These findings suggest that PSGs enhance alignment accuracy, offering an improvement over the freehand technique and supporting our hypothesis. PSGs offer a method for achieving axial alignment without fluoroscopy, potentially enhancing clinical outcomes in MIO.

Acknowledgment

The authors would like to thank ACCESS Specialty Animal Hospital for financial support of this study.

Publication History

Article published online:
15 July 2025