Subject-specific finite element model with an optical tracking system in total hip replacement surgery

Area of Science:

• Orthopedic Surgery
• Biomechanical Engineering
• Medical Device Design

Background:

• Intra-operative peri-prosthetic femoral fractures are a significant complication in total hip arthroplasty (THA).
• Fracture incidence is highest during the implant insertion phase of THA.
• Understanding the biomechanics of implant impaction is crucial for fracture prevention.

Purpose of the Study:

• To combine subject-specific finite element analysis (FEA) with optical tracking to analyze bone strain and impaction forces during THA.
• To simulate intra-operative loading scenarios using FEA with varying implant-bone interface friction.
• To investigate the biomechanical effects of different friction coefficients on the femur during THA implant insertion.

Main Methods:

• Subject-specific FEA models were created for the ABG II femoral stem.
• A 3D optical tracking system experimentally measured hammer velocity during simulated impaction.
• Quasi-static explicit and dynamic loading simulations were performed using friction coefficients of 0.1 and 0.4.

Main Results:

• The lower friction coefficient (0.1) resulted in higher anterior bone strains compared to the higher friction coefficient (0.4).
• A lower friction coefficient led to greater implant displacement relative to the femur.
• Maximum mallet swing velocity was measured at 1.5 m/s prior to impact.

Conclusions:

• Implant-bone interface friction significantly influences intra-operative biomechanics during THA.
• Lower friction conditions during impaction may increase the risk of femoral fracture due to elevated strains.
• FEA combined with experimental tracking provides valuable insights into THA complications.