An Analysis of the Prognostic Factors Affecing the Clinical Outcomes of Conventional Lumbar Open Discectomy : Clinical and Radiological Prognostic Factors

STUDY DESIGN This is a retrospective study. PURPOSE We wanted to examine the clinical and radiological prognostic factors affecting the postoperative clinical outcome of patients with lumbar disc herniation and who underwent open discectomy. OVERVIEW OF LITERATURE Conventional open discectomy has been widely used as a treatment regimen for the management of lumbar disc herniation. Still, much controversy exists regarding the factors that affect the postoperative clinical outcomes. METHODS The current study was conducted on 40 patients who were diagnosed with lumbar disc herniation by the senior surgeon of our department from March 2004 to June 2007. These patients were refractory to conservative treatment and they could be followed up for more than one year following their surgical treatments. Preoperatively, after postoperative year 1 and at the final follow-up, a comparison was made for the Oswestry disability index (ODI) scores and the visual analogue scale (VAS) scores that indicated low back pain and radiating pain. For identifying prognostic factors, an analysis was also performed for such factors as age, gender, the operated level, the duration of preoperative low back pain and radiating pain, a smoking history, the body mass index and whether the surgery was revision or the primary operation. A radiological analysis, based on the preoperative plain flexion-extension radiography, was performed for the presence of mild segmental instability of < 3 mm, spondylolysis and disc space narrowing. Pfirrmann's degenerative grade of the disc, the degree of herniation and whether a herniation was central or massive on the magnetic resonance imaging scans. RESULTS At the final follow-up, the ODI was significantly higher in the cases of revision as compared with the cases of primary operation. The female gender also had a tendency for a poor ODI as compared with that of the men, but this had only borderline statistical significance. There was significant correlation between the preoperative ODI and the preoperative VAS indicating radiating pain. At a final follow up, the low back pain VAS score was significantly lower in the extruded cases as compared with that of the protruded or sequestrated cases. CONCLUSIONS Following an analysis for detecting the prognostic factors of open discectomy, the final clinical outcome was found to be poor for the revision surgery cases. In regard to the type of herniation, the degree of low back pain was relatively lower at a final follow-up for the extruded cases as compared with that for the protruded or sequestrated cases. Open discectomy surgery should be performed after evaluating the patients' various prognostic factors that could affect the final clinical outcome.