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Spinal Fusion 
Panel findings and recommendations: 
 -   In the absence of fracture, dislocation, or complications of tumor or infection, the use of spinal fusion is not recommended for the treatment of low back problems during the first 3 months of symptoms or after 3 months not meeting the Posner Criteria for instability. (Strength of Evidence = A.) 
 -   Spinal fusion should be considered following decompression at a level of increased motion due to degenerative spondylolisthesis.  (Strength of Evidence = C.)  
 -   The Posner Criteria of instability is an elective indication for fusion in symptomatic activity limited patients providing a reasonable surgical outcome compared to fusion for ideal discographic or intuitive reasons. (Strength of Evidence = B.) 
  Lumbar spinal fusion surgeries use bone grafts, and are sometimes combined with metal devices, to produce a rigid connection between two or more adjacent vertebrae.  The therapeutic objective of spinal fusion surgery for patients with low back problems is to prevent any movement in the intervertebral spaces between the fused vertebrae, thereby reducing pain and any neurologic deficits.  Various theoretical rationales are given for the use of fusion in patients with low back problems.  One theory postulates that in cases of significant spinal instability (abnormally increased motion at an intervertebral level), fusion prevents painful compression of the neural structures.  Another controversial theory holds that, in some cases, back symptoms arise from the disc itself and fusion relieves symptoms by greatly reducing forces compressing the disc. 
Spinal Fusion for lost structural integrity or instability 
Literature Reviewed     Evidence on Efficacy    Potential Harms and Costs      Summary of Findings     Author's Example 
Spinal Fusion for lost structural integrity or instability   
Literature Reviewed.  Of the 129 articles screened for this topic, 3 met criteria for review.346,349,350  In addition, a meta-analysis article was reviewed.351  Other articles contained information used by the panel, but did not meet article selection criteria. 352, 353, 354, 355, 356 
  Evidence on Efficacy.    One RCT evaluated the rate of fusion with and without Knodt rods in patients with a diagnosis of multiple level foraminal stenosis.349 All patients were treated by wide decompressive laminectomy, foramenotomy and bilateral-lateral fusion from L3 to the sacrum.  The rates of fusion, patient-reported functional status, and the lengths of postoperative hospital stays were not significantly different between the two groups. 
  A controlled trial by Herkowitz and Kurz346 compared laminectomy with and without fusion in patients with chronic symptoms (mean symptom duration 3.0 years) who did not improve after nonoperative treatment and who had a positive imaging finding (myelogram and either CT or MRI) consistent with degenerative spondylolisthesis and spinal stenosis.  Internal fixation using metal devices was not done as part of the fusion procedure. Following surgery, the fusion group reported significantly greater pain relief in the back and legs than did the nonfusion group.  At mean followup of 3.0 years, excellent or good outcome rates were significantly greater for the fusion group than for the nonfusion group (96 percent compared with 44 percent). 
  The third study meeting review criteria was a nonrandomized trial comparing laminectomy with and without Knodt rod fusion in patients with chronic symptoms, leg pain or neurologic deficit, who did not improve after 3 months of conservative care and who had a positive imaging finding (EMG and myelogram or CT) for a herniated disc.350  At long-term followup (mean followup time of 4.9 years for the fusion group and 3.7 years for the non-fusion group), the percentages of patients reporting satisfactory results (excellent or good) were not significantly different between the two groups.  There are serious design problems with this study, such as the fusion group having a significantly longer mean duration of preoperative symptoms: 5.7 years compared with 1.3 years.  Numerous studies now find hardware for elective fusion to add nothing but complications. 349a-h   
  An attempted meta-analysis on this topic351 found only four nonrandomized studies comparing surgery with and without fusion for herniated disc350,353,354,356  Three of the four trials reported no significant difference in results between the two groups.  One trial did report significantly better results with fusion, but the treatment groups were not comparable.  The fusion group had significantly more abnormal findings on x-ray, fewer positive straight leg raising tests, longer duration of pain, and fewer workers' compensation patients.356 
 Potential Harms and Costs.  Turner, Ersek, Herron, et al.351 indicated that complications are frequent with lumbar spinal fusions. Based on a review of a large case series, the mean rates for the most common reported complications were 7.3 percent for instrumentation failure and 10.8 percent for bone graft donor site pain.  The mean rates for other complications were 0.2 percent for in-hospital mortality, 1.5 percent for deep infection, 1.6 percent for superficial infection, 3.7 percent for deep vein thrombosis/thrombophlebitis, 2.2 percent for pulmonary embolus, 2.8 percent for neural injury, 2.0 percent for graft extrusion, and 8.7 percent for other complications.  Spinal fusion is also considered an expensive procedure. 
  Summary of Findings.  There appeared to be no good evidence from controlled trials in 1994 that spinal fusion alone is effective for treatment of any type of low back problems in the absence of spinal fractures or dislocation.  In the opinion of the panel, there may be two conditions where spinal fusion could be effective.  The first is in cases of combined degenerative spondylolisthesis, stenosis, and radiculopathy where patients have decompressive laminectomy for spinal stenosis symptoms.346, Fischgrund et al.`97  The second situation is in some young patients (generally under age 30) with significant spondylolisthesis and severe leg pain who may receive some benefit from stabilization procedures, although this has not been proven in controlled trials. Spondylolisthesis surgery has been further clarified by Moller et al.`00, Eckman et al.`05, Carragee et al.`06. 
  Although the usual reasons stated for doing spinal fusion for degenerative problems are instability of the spine and disc disease, there is lack of scientific agreement on how to define spinal instability. Spondylolisthesis is often implicated as a cause of instability, but it may or may not have any detectable abnormal motion and the extent to which this contributes to low back symptoms is controversial.  Moreover, there is no good evidence that patients who undergo fusion will return to their prior functional level.  It appears that fusion is not commonly considered for adults within the first 3 months of symptoms except for fracture or dislocation. 346, 350 
One of the spinal implants manufacturers sued the AHCPR in 1994 for being biased before the Guide #14 was even released.  I suppose the panel was biased feeling there should be data weighting benefit v. harm before proposing expensive procedures with considerable risk.  We now have such data from the prospective studies about both implants and fusion for back pain. See Fusion Caveat and Surgical Discussion. Reliable data since 1994 condemns the use of elective lumbar fusion other than after extensive spinal stenosis decompressions in the presence of degenerative spondylolisthesis or those patients meeting the Posner Criteria for Instability. 
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