Quantitative-MRI analysis of the effects of retrograde nailing on vascularity of the distal femur: A cadaveric study.

Background: Distal femur fractures remain treatment challenges with a considerable postoperative non-union rate. Concern remains that surgery may compromise osseous vascularity. This study aimed to determine effects of retrograde femoral intramedullary nailing (RFIN) on distal femur vascularity, and the locations of the middle genicular artery terminal branches in relation to the standard RFIN entry point.

Methods: Five lower limb cadaveric pairs were obtained (ten specimens). Experimental limbs were randomly assigned, and contralateral limbs served as controls. An 11 mm femoral nail was implanted in experimental specimens. Controls only underwent a medial parapatellar incision with capsulotomy. Quantitative pre- and post-contrast-MRI was performed to assess arterial contributions to distal femur regions. Osseous vascularity was further evaluated with contrast-CT imaging. Next, specimens were injected with latex medium, and dissection was performed to assess extraosseous vasculature.

Results: No statistically significant differences were found with quantitative-MRI in experimental and control groups for the entire distal femur or individual regions. The experimental group demonstrated a small mean decrease of 1.4% in distal femur arterial contributions. CT and anatomic dissection confirmed maintenance of middle genicular artery terminal branches. On average, 3.3 (±1.3) terminal branches entered along the posterior intercondylar notch. A mean distance of 15.2 mm (±6.9 mm) was found between the posterior RFIN entry point and these terminal branches.

Conclusions: RFIN did not significantly alter arterial contributions to the distal femur or disrupt the middle genicular artery terminal branches. However, care must be taken to ensure nail entry point accuracy given proximity of the entry point to terminal branches.