Distal locking screw migration in the depuy-synthes retrograde femoral nail-advanced-an unexpected consequence of an implant upgrade.

AIMS

The Retrograde Femoral Nailing Advanced (RFNA) system is a new generation of retrograde femoral nail (RFN) introduced to extend the range of distal fractures treated by intramedullary (IM) nailing. There is concern that the rate of distal interlock screw back-out may be higher for the RFNA. This study aims to highlight a higher-than-expected incidence of distal locking screw migration.

METHOD

Patient and implant data were prospectively collected from theatre and electronic patient records. The study focused on monitoring the migration of distal locking screws, treating each screw as an "at-risk" unit for analysis.

RESULTS

We report a high rate of distal locking screw migration in the Depuy-Synthes RFNA, with 16 (8.1 %) of screws migrating out of the 197 distal locking screws implanted. Per patient screw migration was seen in 11 (16.9 %) of the 65 patients studied. Oblique screws had a higher backing out rate of 13.7 % (10 out of 73) compared to the 4.8 % (6 out of 124) rate for transverse screws.

CONCLUSION

We found a higher-than-expected rate of screw migration in this new generation nail. The oblique screws were more often affected. We hypothesize that the screw orientation alongside the new polymer inlay contributes to this effect. The use of an end cap and the locking attachment washer (LAW) seems to reduce the rate of migration. The study highlights the importance of a local metalwork governance process in identifying unexpected adverse implant events. We recommend that early user centers prospectively monitor new trauma implants.