Distal Interlocking Screw Backout in New-Generation Retrograde Femoral Nails.

OBJECTIVES

To compare distal interlocking screw backout rates between 2 new-generation retrograde femoral nails: the DePuy Synthes RFN-Advanced Retrograde Femoral Nail (RFNA) and the Stryker T2 Alpha Femur Retrograde Nail (T2 Alpha).

DESIGN

Retrospective comparative study.

SETTING

Three Level 1 trauma centers.

PATIENT SELECTION CRITERIA: Patients aged ≥18 years who underwent operative fixation with the RFNA or T2 Alpha for a diaphyseal or distal femur fracture [Orthopaedic Trauma Association/Arbeitsgemeinschaft für Osteosynthesefragen (OTA/AO) 32-33] between November 2022 and August 2024 with a minimum follow-up of 3 months.

OUTCOME MEASURES AND COMPARISONS: The primary outcome was the distal interlocking screw backout rate. Secondary outcomes included time to backout and reoperation rates for screw removal. Outcomes were compared between the RFNA and T2 Alpha.

RESULTS

A total of 103 patients [median age 59 years (IQR: 38-73), 61% women] were included, comprising 63 OTA/AO 32 and 40 OTA/AO 33 fractures, with 24 treated with the RFNA and 79 with the T2 Alpha. Backout rates were higher in the RFNA group [38% (95% CI: 20%-59%) vs. 5.1% (95% CI: 1.6%-13%), P < 0.001]. Stratified by fracture location, backout rates remained higher in the RFNA group for both diaphyseal [6/20 (30%) vs. 1/43 (2.3%), P = 0.003] and metaphyseal fractures [3/4 (75%) vs. 3/36 (8.3%), P = 0.008]. Time to backout was earlier in the RFNA group [5 weeks (IQR: 3-6) vs. 19 weeks (IQR: 14-31), P = 0.013]. Reoperation rates for screw removal were higher in the RFNA group (21% vs. 0%, P < 0.001). The median follow-up for the overall cohort was 27 weeks (IQR: 18-41).

CONCLUSIONS

The RFNA was associated with a higher rate of distal interlocking screw backout, an earlier time to backout, and an increased reoperation rate for screw removal compared with the T2 Alpha. These findings can guide surgeons in implant selection and highlight the need for solutions to mitigate distal interlocking screw backout in the RFNA.

LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.