A study published in the Journal of Spinal Disorders and Techniques examined the risk factors for radiographic L5-S1 disc height reduction after lumbar posterolateral floating fusion surgery.
The researchers examined 86 patients who underwent the procedure from 2007 to 2010 with a two- to six-year follow-up. The average patient age was 65.4 years old, and the patients were almost evenly split male and female.
Here are five findings from the study:
• 30.2 percent of the patients had disc height reduction
• Patients without disc height reduction had significantly more levels fused
• L1-S1 sacrolumbar alignment changed after patients without disc height reduction underwent surgery
• Height for discs posterior to the L5-S1 intervertebral disc before surgery was significantly greater in patients without disc height reduction
• Fusing more than three levels was a significant risk factor for L5-S1 disc height reduction
"Surgical methods and fusion levels should be chosen after considering their association with L5-S1 disc height reduction," concluded the study authors. A study recently published in Spine found obese individuals had a reduced average total disc height when compared with non-obese patients. The average height in obese patients was 1.04 cm, compared with 1.14 cm. The total disc height in obese patients was 4.16 cm, compared with 4.57 cm.
However, the study authors found no significant relationship between reduced disc heights and obesity at the lumbosacral junction, despite the differences identified at L1-L2 and L3-L4. These researchers also found average disc heights were negatively associated with recent pain.
The type of procedure used may also impact postoperative disc height. A May 2014 article published in the Journal of Spinal Disorders & Technique reported radiographic findings showed disc replacement improved disc space and segment height range of motion. A 2009 study showed no disc height loss in disc replacement or spinal fusion groups, but reoperation rates were lower among disc replacement patients.
Another article published in the July issue of Spine examining anterior lumbar interbody fusion for degenerative disc disease found the two-year postoperative disc height was significantly greater than the preoperative disc height at the fused level. Another 2011 study on ALIF found decreased disc space height adversely aggravates the adjacent segment degeneration.
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