Improved method for planning intramedullary guiding rod entry point in total knee arthroplasty.

BACKGROUND

To study the accuracy of using the deepest point of the intercondylar notch (DPIN) as a reference point for femoral intramedullary (IM) guiding rod entrance in total knee arthroplasty (TKA) with 3-D reconstruction in Chinese subjects.

METHODS

A total of 50 normal femurs in 25 Chinese subjects (mean age 25.6 ± 2.9 years; range 18-29 years) were chosen from the lower extremities computed tomography digital imaging and communications in medicine (DICOM) database for this study. The DICOM data were imported into Mimics 10.0 software. A cylinder (radius = 4 mm; length = 20 cm) was used to simulate ideal insertion of a IM guiding rod into the femoral canal. DPIN was taken as a reference point for calculating the relative position of the rod's entry point.

RESULTS

The mean rod entry point position in the coronal plane was 2.94 ± 1.12 mm (range 0.79-4.91 mm) medial and 6.01 ± 2.09 mm (range 2.49-9.51 mm) anterior to the DPIN, with no significant difference between sides. All potential angle errors were below 2°.

CONCLUSION

The results of this study show that the DPIN can serve as a reference for surgeons using an IM guide system in TKA.