Problems of encapsulation of total joint replacements

Area of Science:

• Biomaterials Science
• Orthopedic Engineering
• Tribology

Background:

• Particulate wear debris from artificial joints (metallic and plastic) and metal ions in body fluids pose health risks.
• Tissue ingrowth into artificial joints can impair function and longevity.
• Current joint replacement materials generate debris, necessitating improved solutions.

Purpose of the Study:

• To investigate encapsulation as a strategy to contain wear debris and prevent tissue ingrowth in artificial joints.
• To evaluate bioelastomers as potential capsule materials for artificial joints.
• To explore methods for reducing friction, wear, and improving the lifespan of artificial joints.

Main Methods:

• Testing various bioelastomers in simulated body fluid and lubricant environments.
• Utilizing three developed fatigue rigs to assess material performance.
• Investigating capsule shape optimization to minimize stress concentrations.
• Exploring electrophoresis for filtering wear debris.

Main Results:

• Bovine synovial fluid significantly increased the fatigue life of silicone rubber by tenfold.
• Specific capsule shapes are being investigated to reduce creasing-induced stresses.
• Electrophoresis demonstrated that Co-Cr-Mo alloy wear particles are attracted to negatively charged polymers.

Conclusions:

• Encapsulation of articulating parts offers a potential solution to mitigate adverse effects of wear debris and tissue ingrowth.
• Silicone rubber shows promise as a capsule material, particularly in a bovine synovial fluid environment.
• Electrophoretic filtration is a viable method for removing metallic wear particles from joint environments.