Study design: This retrospective study was designed to investigate the effects of previous back surgery in patients undergoing surgical procedure for lumbar spinal stenosis.
Objectives: The authors evaluated the results of singly operated and repeat surgery patients operated on for lumbar spinal stenosis, and compared prognostic factors correlated with the results for these two groups.
Summary of background data: Repeat back surgery is generally not as successful as a first operation, but few studies evaluate the effects of previous back surgery on the surgical outcome of patients with lumbar spinal stenosis.
Methods: The subjective disability of singly operated and repeat surgery patients as assessed by the Oswestry questionnaire was compared with clinical data and myelographic findings to identify factors predictive of outcome.
Results: The mean Oswestry score was 31.0 for singly operated patients and 40.9 for repeat surgery patients (P = 0.0001). The outcome was excellent-to-good in 67% of singly operated patients and in 46% of repeat surgery ones (P < 0.0017). Severe myelographic findings correlated significantly with good outcome in the singly operated group but not in the repeat surgery group. Coexisting disease contributed significantly to poor outcome in the repeat surgery group, but not in the singly operated group. The optimum time interval for achieving successful results from subsequent surgery is at least 18 months after previous surgery. In the regression analysis, the prognostic preoperative variables for good outcome was block stenosis on myelography in the singly operated patients and age over 50 years and no coexisting disease in the repeat surgery patients.
Conclusions: Previous back surgery had a highly significant worsening effect on the outcome of patients reoperated on for lumbar spinal stenosis. Not even a very well-established diagnosis of lumbar spinal stenosis, as confirmed by myelography and during surgery, could guarantee as successful a surgical outcome in the repeat surgery patients as that in the singly operated patients.