Functional disability secondary to acute low-back pain, chronic low-back pain, lumbar stenosis, and lumbar disc disease may be reliably and validly assessed using functional outcome surveys that are valid, reliable, and responsive. Outcome instruments supported by Class I and Class II medical evidence for the evaluation of low-back pain include the Spinal Stenosis Survey of Stucki, Waddell-Main, RMDQ, DPQ, QPDS, SIP, Million Scale, LBPR Scale, ODI, and CBSQ. Many of these outcome measures have been applied to patients who have been treated with lumbar fusion for degenerative lumbar disease and have proven to be valid and responsive; however, the reliability of these instruments has never been specifically assessed in the lumbar fusion patient population. Patient satisfaction surveys have been used to measure outcome following lumbar fusion. Their usefulness resides in their insight into patient attitudes toward the treatment experience but is limited because of their inability to measure responsiveness and the lack of information on their reliability.