Experience with minimally invasive nucleus replacement

More than 5 million Americans suffer from chronic low-back pain, making it the leading cause of lost workdays in the United States and one of the most expensive health care issues today (1). Although the causes of low-back pain remain unclear, it is believed that approx 75% of cases are associated with degenerative disc disease (1). It is generally believed that dehydration of the degenerated nucleus pulposus (NP) leads to a reduction in hydrostatic pressure on the internal surface of the annulus, resulting in an abnormal stress state in the tissue and, consequently, a breakdown of the annular tissue seen macroscopically as fissures and tears. This manifests as chronic and debilitating pain owing to tissue impingement on nerve roots and presents as a herniated or ruptured disc. Current treatment options, such as discectomy and fusion, are fairly successful in reducing pain but do not restore normal biomechanical function to the disc. The likely out come of these procedures is further degeneration of either the initially affected disc (for discectomy) or adjacent segments (for fusion). Degenerative disease of the spine is one of if not the leading musculoskeletal disorder confronting our health system. The spine provides the major structural element of the neck and trunk while protecting the spinal cord. Spinal degeneration is an irreversible process leading to loss of mechanical integrity with the potential for neurological compromise. Clinical manifestations of degenerative spine disease are variable and graded and are categorized into a variety of diseases. These diseases include mechanical cervical and lumbar pain such as internal disc disruption, acute spinal instability, herniated NP, degenerative spondylolisthesis, degenerative scoliosis, and spinal stenosis.