Small Femoral Nails and the Development of a Nonunion: A Case-Control Study.

Area of Science:

• Orthopedic surgery
• Trauma care
• Biomechanical engineering

Background:

• Locked intramedullary (IM) nails are standard for femoral shaft fractures.
• Femur nonunion risk is a concern following IM nailing.
• Nail-to-bone diameter mismatch is a potential risk factor.

Purpose of the Study:

• To investigate the association between IM nail diameter and femur nonunion.
• To determine if nail-to-bone diameter mismatch increases nonunion risk.
• To analyze this relationship in adult patients with AO/OTA 32 femoral shaft fractures.

Main Methods:

• Retrospective case-control study at a Level I trauma center.
• Included adult patients with AO/OTA 32 femoral shaft fractures treated with IM nails (2016-2022).
• Compared cases (nonunion surgery) with controls (healed fractures) using mRUSF, adjusting for smoking, open fractures, and comminution.

Main Results:

• 50 cases and 153 controls were analyzed.
• Wider femurs (>22 mm AP diameter at lesser trochanter) had increased nonunion odds with small IM nails (OR 2.1, P=.01).
• No significant association between nail diameter and nonunion was found in narrower femurs.

Conclusions:

• Larger IM nails (≥11 mm) may prevent nonunion in patients with wide femoral canals (≥22 mm).
• Nail diameter may not significantly impact nonunion risk in patients with narrower femoral canals.
• Optimizing IM nail selection based on femoral canal width is crucial for fracture healing.