Distal Interlocking Screw Backout in New-Generation Retrograde Femoral Nails

Area of Science:

• Orthopedic surgery
• Biomedical engineering
• Trauma care

Background:

• Femur fractures require surgical fixation with intramedullary nails.
• Newer generation retrograde femoral nails aim to improve outcomes.
• Distal interlocking screw backout is a known complication.

Purpose of the Study:

• To compare the distal interlocking screw backout rates between the DePuy Synthes RFN-Advanced Retrograde Femoral Nail (RFNA) and the Stryker T2 Alpha Femur Retrograde Nail.
• To evaluate secondary outcomes including time to backout and reoperation rates.

Main Methods:

• Retrospective comparative study conducted at three Level 1 Trauma Centers.
• Included 103 adult patients with diaphyseal or distal femur fractures (OTA/AO 32-33).
• Compared outcomes between RFNA (n=24) and T2 Alpha (n=79) nails with a minimum 3-month follow-up.

Main Results:

• Higher distal interlocking screw backout rates were observed with the RFNA (38%) compared to the T2 Alpha (5.1%) (p<0.001).
• RFNA group had earlier backout (5 weeks vs. 19 weeks, p=0.013) and higher reoperation rates for screw removal (21% vs. 0%, p<0.001).
• These differences persisted across diaphyseal and metaphyseal fracture types.

Conclusions:

• The RFNA demonstrated a significantly higher incidence of distal interlocking screw backout and associated reoperations compared to the T2 Alpha.
• Findings suggest potential design or biomechanical differences influencing screw stability.
• Surgeons should consider these comparative outcomes when selecting retrograde femoral nails to mitigate complications.