Screening Methods for Woven Materials as Artificial Cartilage

In the orthopedics industry, there exists a void in the continuum of care associated with joint pain due to cartilage damage and wear. Currently, patients are asked to endure joint pain with only over-the-counter pain medication to ease discomfort. When the pain becomes unbearable, joint surgery is performed. As the average age of joint replacement recipients decreases, the necessity of revision surgeries increases due to limited hardware life spans. Revision surgeries are more traumatic and require longer recovery times than primary replacements. Although some procedures, like unicondylar knee replacements and hip resurfacing, are less invasive and preserve more tissue than total joint procedures, a minimally invasive short-term cartilage replacement is desired. A synthetic plug of a three-dimensionally woven material has been forwarded as a possible solution to delay the need for a total joint replacement while effectively relieving pain. Once implanted, micro-motion between fibers within the device will be experienced during each loading cycle. The minimization of wear during these events is important not only to avoid device failure but also to minimize a biological response. In the current work, various screening methods for fiber materials are evaluated and range from simple mechanical property testing using an atomic force microscope (AFM), direct fiber-on-fiber wear using a rig test, to pin-on-disk accelerated life wear testing. It is found that direct fiber-on-fiber wear tests provide distinguishable rankings of fiber materials according to wear coefficient and identify polyethylene terephthalate (PET) and ultra-high-molecular-weight polyethylene (UHMWPE) as candidates for further investigation. Pin-on-disk tests have allowed the wear mechanisms of three-dimensional fabrics to be explored and provide insight for further optimization of weave parameters and fiber materials.