Experimental micromechanics of the cement-bone interface.

Area of Science:

• Biomaterials Science
• Orthopedic Biomechanics
• Materials Science

Background:

• Cement fixation is common for implants, but its micromechanical behavior at the bone interface is poorly understood.
• Local interfacial motion significantly influences implant fixation and longevity.

Purpose of the Study:

• To quantify the micromechanics of the cement-bone interface using digital image correlation.
• To investigate interfacial motion, compliance, strength, and damage mechanisms under tensile and compressive loading.

Main Methods:

• Laboratory-prepared cemented total hip replacements were subjected to quasistatic tensile and compressive loading.
• Digital image correlation (DIC) techniques were employed to measure local displacement and strain at the cement-bone interface.

Main Results:

• Majority of displacement localized at the cement-bone contact interface.
• Interface was more compliant in tension than compression, with significant hysteresis due to sliding.
• Tensile strength correlated inversely with compliance and directly with contact area.
• Loading beyond ultimate strength caused microcracking and damage in both cement and bone, with more damage to cement.
• Interface opening/closing could facilitate particle transport.

Conclusions:

• The cement-bone interface exhibits complex micromechanical behavior, including significant sliding and damage.
• The mechanical support of the cement mantle by surrounding bone may be suboptimal.
• These findings have implications for implant longevity and the design of preclinical tests.