Conflict-free screw map for retrograde nail and lateral LCP (LISS-type) plate constructs in distal femur fractures with lateral comminution: technical note and early case series

Abstract

Distal femur fractures with significant lateral comminution often challenge single-implant fixation, particularly in osteoporotic or high-energy cases. This technical note describes a reproducible method combining a retrograde femoral nail with a lateral LCP (LISS-type) plate using the Conflict-Free Screw Map, a predefined system of safe plate holes (A and B) that align with the distal interlocking bolts of the nail and prevent implant collision. After provisional reduction, the retrograde nail is inserted but left without distal locking, allowing submuscular placement of the lateral plate beneath vastus lateralis. Once the plate is secured following the conflict-free map, definitive distal nail locking is completed, creating a load-sharing, torsion-resistant construct without the need for medial augmentation. Seven patients (mean age 72 years, OTA/AO 33-A3, C2, C3) were treated between 2021 and 2024 using this technique. The mean operative time was 2 hours 20 minutes, and all fractures achieved radiographic union at a mean of 12 weeks (10–16). No infections, mechanical failures, or screw conflicts occurred, and mean final knee motion was 0–115°. The Conflict-Free Screw Map simplifies implant coexistence, reduces surgical exposure, and enhances reproducibility of dual-implant constructs. This nail–plate configuration provides a stable, biologically friendly solution for distal femur fractures with lateral comminution, allowing early mobilization and consistent union outcomes.