Assessment of segmental spinal motion has been and continues to be a difficult clinical problem. X-ray measurement error of up to 10 degrees for simple measurements for flexion, extension and side bending have been recorded. It is extremely difficult to measure small changes in vertebral alignment that may prove to have clinical significance. The measurement accuracy of the RSA technique far exceeds any manual techniques to date. RSA allows the surgeon to monitor spatial relationships within the spine over time with a much higher accuracy then conventional techniques.

This is a non-randomized prospective study design looking at the use of RSA in spinal surgery patients. Subjects in this study will undergo their indicated surgery. Prior to closure, they will be implanted with tantalum beads, which will serve as landmarks when the RSA film pairs are taken post-operatively. The subjects will have standard post-operative x-rays 6 weeks-3 months post-op and again at 12 months post-op. Yearly visits after this are anticipated for 5-10 years with proper funding.

Inclusion Criteria:

• Patients undergoing Spinal fusion or discectomy

Exclusion Criteria:

• pregnant women