Load transfer in bone after partial, multi-compartmental, and total knee arthroplasty

Area of Science:

• Biomechanics
• Orthopedic Surgery
• Biomedical Engineering

Background:

• Arthroplasty-associated bone loss is a clinical concern due to altered load transfer from stiff implants.
• Metallic implants disrupt the natural mechanical stimuli required for bone remodeling.

Purpose of the Study:

• To analyze how different knee arthroplasty types affect load transfer to bone.
• To compare load transfer in isolated partial knee arthroplasty (PKA), combined partial knee arthroplasty (CPKA), and total knee arthroplasty (TKA).

Main Methods:

• Utilized an experimentally validated, subject-specific finite element model.
• Simulated various arthroplasty types (unicondylar, bicompartmental, tricompartmental, total) under native and implanted conditions.
• Analyzed three load cases: gait, stair ascent, and sit-to-stand.

Main Results:

• Total knee arthroplasty (TKA) resulted in significantly higher mean strain shielding (30%) compared to PKA (4-7%) and CPKA (5-8%) during gait.
• Overstraining was observed in the proximal tibia with TKA (21%), while PKA/CPKA showed minimal overstraining (0-6%).
• TKA demonstrated greater variability in load distribution and sensitivity to load cases compared to PKA/CPKA.

Conclusions:

• Partial and multi-compartmental knee procedures promote more natural load transfer to bone than TKA.
• These findings suggest potential long-term bone health benefits for PKA and CPKA over TKA.
• Variability in bone loss post-TKA may relate to high-flexion activities influencing posterior condyle load.