Angular stable locking in a novel intramedullary nail improves construct stability in a distal tibia fracture model

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Traumatology

Background:

• Intramedullary nailing is standard for unstable distal tibia fractures.
• Conventional nails may lead to delayed healing, malunion, or nonunion due to insufficient distal fragment fixation.
• A novel angular stable nailing concept aims to reduce nail toggling, screw migration, and secondary loss of reduction.

Purpose of the Study:

• To biomechanically evaluate a novel angular stable intramedullary nail concept.
• To compare its performance against a conventional nail in treating unstable distal tibia fractures.
• To assess construct stability under dynamic loading in a cadaveric model.

Main Methods:

• Ten pairs of human cadaveric tibiae with simulated AO/OTA 42-A3.1 fractures were used.
• Specimens underwent reamed intramedullary nailing with either a conventional Expert Tibia Nail (ETN) or the novel Tibia Nail Advanced (TNA) system.
• Biomechanical testing involved quasi-static and cyclic axial/torsional loading until construct failure, monitored by motion tracking.

Main Results:

• The TNA system demonstrated significantly lower initial nail toggling in flexion compared to ETN.
• After 5000 cycles, TNA showed significantly reduced interfragmentary movements, particularly in flexion and shear displacement.
• Cycles to failure, defined by 5° varus and 5° flexion, were significantly higher for the TNA system.

Conclusions:

• The novel angular stable intramedullary nail concept offers enhanced construct stability for unstable distal tibia fractures.
• It maintains stability over time, reduces the number of locking screws, and better resists loss of reduction under dynamic loading.
• This approach provides a biomechanically superior alternative to conventional locking methods.