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.
