SURGICAL RESULTS OF LUMBAR SPINAL STENOSIS - A COMPARISON OF PATIENTSWITH OR WITHOUT PREVIOUS BACK SURGERY

Study Design. This retrospective study was designed to investigate the effects of previous back surgery in patients undergoing surgical proc edure for lumbar spinal stenosis. Objectives. The authors evaluated th e results of singly operated and repeat surgery patients operated on f or lumbar spinal stenosis, and compared prognostic factors correlated with the results for these two groups. Summary of Background Data. Rep eat back surgery is generally not as successful as a first operation, but few studies evaluate the effects of previous back surgery on the s urgical outcome of patients with lumbar spinal stenosis. Methods. The subjective disability of singly operated and repeat surgery patients a s assessed by the Oswestry questionnaire was compared with clinical da ta and myelographic findings to identify factors predictive of outcome . Results. The mean Oswestry score was 31.0 for singly operated patien ts 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 rep eat 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 significan tly to poor outcome in the repeat surgery group, but not in the singly operated group. The optimum time interval for achieving successful re sults from subsequent surgery is at least 18 months after previous sur gery. In the regression analysis, the prognostic preoperative variable s for good outcome was block stenosis on myelography in the singly ope rated patients and age over 50 years and no coexisting disease in the repeat surgery patients. Conclusions. Previous back surgery had a high ly significant worsening effect on the outcome of patients reoperated on for lumbar spinal stenosis. Not even a very well-established diagno sis of lumbar spinal stenosis, as confirmed by myelography and during surgery, could guarantee as successful a surgical outcome in the repea t surgery patients as that in the singly operated patients.