Optimal surgical component alignment minimizes TKR wear - An in silico study with nine alignment parameters

Area of Science:

• Biomedical Engineering
• Orthopedic Surgery
• Materials Science

Background:

• Preclinical mechanical wear testing of total knee replacements (TKRs) typically uses ideally aligned components under standardized walking conditions.
• Current testing methods often overlook the influence of implant alignment and different control regimes (force vs. displacement) on wear outcomes.

Purpose of the Study:

• To investigate the impact of nine component alignment parameters on TKR volumetric wear in silico.
• To develop a predictive model for TKR wear rate as a function of component alignment for both force and displacement control regimes.

Main Methods:

• Utilized a computational framework integrating Latin Hypercube sampling, finite element analysis, and a polyethylene wear model.
• Investigated nine alignment parameters (five femoral, four tibial) using two separate 300-point experimental designs for each control regime.
• Generated surrogate statistical models via stepwise multiple linear regression to predict wear.

Main Results:

• Wear at neutral alignment was 4.5 mm³/million cycles (displacement control) and 8.6 mm³/million cycles (force control).
• Force-control testing yielded a stronger predictive model (higher R², more terms, lower RMSE) compared to displacement-control.
• Transverse plane rotational mismatch of 15° can increase wear by up to 5 mm³/million cycles, nearly doubling neutral alignment wear.

Conclusions:

• Component alignment, particularly in the transverse plane, significantly influences TKR wear.
• Transverse plane alignment is a critical factor to consider when assessing the risk of TKR implant failure due to wear.
• The study highlights the importance of accounting for alignment variations in wear testing and clinical performance prediction.