 - Metabolic bone disease such as osteoporosis to a degree that spinal instrumentation is contra-indicated Males over 55 years of age, females over 50 years of age andor subjects that in the investigators opinion are medical indicative of osteoporosis e.g. early menopause, steroid use, etc. are required to have a DEXA scan; If the DEXA scan is -2.5t in the spine, the patient must be excluded 