Stability Analysis of Plate-Screw Fixation for Femoral Midshaft Fractures

Area of Science:

• Orthopedic biomechanics
• Biomaterials engineering
• Surgical implant technology

Background:

• Achieving optimal implant fixation for rapid bone healing in transverse femoral fractures remains a challenge.
• The interplay between implant design, applied forces, and bone healing is not fully understood.
• Flexible and locked plating systems offer potential for balancing stability and flexibility in fracture fixation.

Purpose of the Study:

• To investigate the relationship between implant strength, working length, and interfragmentary strain (εIFM) on implant stability.
• To analyze the influence of screw configuration and type on the stability of locked compression plate (LCP) fixation for femoral midshaft transverse fractures.
• To correlate biomechanical characteristics with optimal bone healing outcomes.

Main Methods:

• Finite element analysis (FEA) was employed to model a transverse femoral fracture fixed with an LCP system.
• Simulations were conducted under varying compression loads (600 N to 900 N).
• Screw designs (conventional vs. locking) and penetration depths (unicortical vs. bicortical) were systematically evaluated using strain theory.

Main Results:

• Screw configuration significantly correlated with stability, particularly unicortical depth for both screw types under specific loads (700 N, 800 N).
• Interfragmentary strain (εIFM) was influenced by load and screw configuration, especially with bicortical conventional screws at 600 N.
• Lower interfragmentary strain (≤2%) indicated better stability, promoting callus formation and bony bridging.

Conclusions:

• Screw configuration is a critical factor in achieving primary stability for femoral midshaft transverse fractures.
• Understanding these biomechanical correlations aids in optimizing implant fixation for enhanced bone healing.
• The study provides valuable insights for the selection and placement of screws in orthopedic fracture management.