Early complications of a novel retrograde intramedullary femoral nail in the treatment of femur fractures.

OBJECTIVES: To determine the early implant failure rate of a novel retrograde intramedullary femoral nail.

METHODS: Design: Retrospective matched case control.

SETTING: Academic level 1 trauma center.

PATIENTS SELECTION CRITERIA: Patients 18 years and older with an acute AO/OTA 32-A, 32-B, 32-C, and 33-A fracture or periprosthetic distal femur fracture from April 2018 to April 2022 were included in the study. The two interventions compared were the Synthes Expert Retrograde/antegrade femoral nail (RAFN or control implant) versus the next generation RFN-Advanced retrograde femoral nail (RFNA or experimental implant) (Synthes, West Chester, PA).Outcome Measures and Comparisons: Early implanted-related complications between the experimental and control implants were assessed including locking screw backout, screw breakage, intramedullary nail failure, need for secondary surgery, and loss of fracture reduction.

RESULTS: 314 patients were identified with a mean age of 31.0 years and 62.4% of the patients being male. Open fractures occurred in 32.5% of patients with 3.8% of injuries being distal femur periprosthetic fractures. 56 patients in the experimental group and 258 patients in the control group. Mean follow-up was 46.8 weeks for the control cohort and 21.0 weeks for the experimental cohort. Distal interlocking screw backout occurred in 23.2% [13 of 56] of experimental group patients and 1.9% [5 of 258] of control group patients (p<0.0001). Initial diagnosis of interlocking screw back out occurred at an average of 3.2 weeks post-operatively (range, 2-12 weeks). 54% of patients that sustained screw back-out underwent a secondary operation to remove the symptomatic screws (12.5% of all patients treated with the experimental implant required an unplanned secondary operation due to screw backout). A logistic regression model was used to predict screw back out and found the experimental implant group was 4.3 times as likely to experience distal locking screw backout compared to the control group (p=0.01).

CONCLUSIONS: The RFNA implant was associated with a significantly higher rate of screw back-out with a substantial number of unplanned secondary surgeries compared to the previous generation of this implant.

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