The impact of adjacent level disc degeneration on health status outcomes following lumbar fusion.
METHODS
A retrospective review of patient outcomes after lumbar spinal fusion.


OBJECTIVE
To determine whether patients with a fusion ending adjacent to a "degenerated disc" (DDD group) had worse clinical outcomes than patients with fusions ending adjacent to "normal" discs (NL group).


BACKGROUND
Although it has been suggested that creating a rigid motion segment adjacent to a degenerated segment may negatively impact clinical outcomes after lumbar fusion, this question has not been addressed to our knowledge in the English literature.


METHODS
Twenty-five consecutive patients treated with lumbar fusion for degenerative instability who had preoperative lumbar spine magnetic resonance imaging, who completed health status questionnaire Short Form 36 (SF-36), and were seen in the office for radiographic follow-up at least 2 years following surgical treatment formed the study group. The magnetic resonance images were reviewed independently by two spine surgeons and rated for the presence of any degenerative changes. Statistical analysis of the SF-36 data was performed with chi2 and Mann-Whitney U testing.


RESULTS
Of the 25 patients, 20 were fused adjacent to at least one degenerated level (DDD group), whereas 5 were fused adjacent to a normal level (NL group). At follow-up, SF-36 scores were higher for the DDD group in all eight subgroups, contrary to the research hypothesis. A power analysis demonstrated with at least 98% certainty that if patients in the DDD group had even a 10% lower score in any of the 8 SF-36 subgroups, this study would have detected it.


CONCLUSIONS
This retrospective review of patients who underwent lumbar fusion for degenerative instability demonstrated no adverse impact on clinical outcomes when the lumbar fusion ended adjacent to a degenerative motion segment. Although a power analysis validated these results with 98% certainty, larger prospective studies are needed to confirm that there is no benefit to include degenerated adjacent segments in a lumbar fusion for degenerative instability.
Throckmorton
Thomas W
TW
The Vanderbilt University Spine Center, Department of Orthopaedics and Rehabilitation, Nashville, Tennessee, USA.
Hilibrand
Alan S
AS
Mencio
Gregory A
GA
Hodge
Arleen
A
Spengler
Dan M
DM
D000328:Adult; D000368:Aged; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D007403:Intervertebral Disc / Q000473:pathology; D008159:Lumbar Vertebrae / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013122:Spinal Diseases / Q000175:diagnosis / Q000601:surgery*; D013123:Spinal Fusion; D016896:Treatment Outcome