Guideline update for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 2: assessment of functional outcome following lumbar fusion.

Assessment of functional patient-reported outcome following lumbar spinal fusion continues to be essential for comparing the effectiveness of different treatments for patients presenting with degenerative disease of the lumbar spine. When assessing functional outcome in patients being treated with lumbar spinal fusion, a reliable, valid, and responsive outcomes instrument such as the Oswestry Disability Index should be used. The SF-36 and the SF-12 have emerged as dominant measures of general health-related quality of life. Research has established the minimum clinically important difference for major functional outcomes measures, and this should be considered when assessing clinical outcome. The results of recent studies suggest that a patient's pretreatment psychological state is a major independent variable that affects the ability to detect change in functional outcome.