| Articular cartilage damage caused by degenerative joint disorders leads to pain and immobility for approximately seventy million people in the US. Many treatments are available, but all have limitations. In this study, mechanical durability of new implant materials was evaluated. Friction, compression, shear, and durability characteristics were obtained. Simple, progressive, bench top tests were developed based on knee kinematics and kinetics. Biomaterials were evaluated using these tests and ranked in relationship to fresh bovine cartilage.; Compression tests were used to evaluate the biomaterials at physiologic loads and loading rates. Tissue engineering constructs did not have the mechanical strength to survive this environment. At 5 MPa of stress, unconfined compression tests showed no significant moduli differences between the tested biomaterials and fresh cartilage. Sterilized cartilage and PVAc biomaterial confined compressive moduli were significantly higher than fresh cartilage, while the devitalized cartilage modulus was significantly lower.; Cyclic compression tests were conducted up to 1.5 million cycles. Sterilized cartilage, devitalized cartilage, and PVAc-Y average reliabilities were the same or higher when compared to fresh cartilage. PVAc-X had inferior reliability, but withstood approximately 20,000 cycles before recording a failure. Constant shear testing demonstrated that sterilized cartilage, devitalized cartilage, and PVAc performances were equivalent to that of fresh cartilage. Combining cyclic compression and shear in a wear test yielded slightly different results, with devitalized cartilage and PVAc-X and PVAc-Y showing lower average reliability than fresh cartilage. Sterilized cartilage outperformed fresh cartilage in this test, with higher average reliability and more cycles before failure of a specimen.; A new set of tests has been designed specifically to characterize soft tissues and soft tissue replacements. Material fracture and fatigue were common forms of failure under stresses similar to articular joints. Material surface wear was not prominent for any of the materials tested. While current forms of tissue engineered cartilage have a fraction of the strength needed for the demanding knee joint, other polymeric cryogels and sterilized allografts can perform to levels similar to normal cartilage in these mechanical tests. We propose a similar set of mechanical tests be applied to development and verification of soft tissue replacements. |
