Abstract
Degenerative disc disease in the lumbar spine is marked by a dehydration of the intervertebral disc and loss of biomechanical function of the spinal unit. Since the current surgical procedures are ineffective in restoring natural biomechanical function back to the diseased disc, researchers have looked to replace the intervertebral disc. These designs are flawed in that they either don’t restore natural movement back to the spinal unit, require surgeries that are highly invasive, or they further promote disc degeneration of adjacent spinal levels. Recently, researchers have sought to only replace the central portion of the disc called the nucleus pulpous. A potential nucleus replacement could mimic a healthy nucleus pulpous in restoring healthy biomechanical function to the spinal unit. A hydrogel, poly (vinyl alcohol) (PVA), has been investigated to serve as a nucleus replacement. However, semi crystalline PVA suffers dissolution under physiological conditions and for this reasons are tested others hydrogels (HEMA) which are biocompatible, maintain the liquid transport function, the shape and the size of intervertebral disc and are very good shock-absorbent. Keywords: prosthesis, hydrogel, HEMA, intervertebral disc