IS HIGH LEVEL OF DISABILITY AN INDICATION FOR SPINAL FUSION? ANALYSIS OF LONG TERM OUTCOME AFTER POSTERIOR LUMBAR INTERBODY FUSION USING CARBON FIBRE CAGES

Abstract

Posterior lumbar interbody fusion is a well described procedure for the treatment of back pain associated with degenerative disc disease and segmental instability. It allows decompression of the spinal canal and circumferential fusion through a single posterior incision.

Sixty-five consecutive patients who underwent posterior lumbar interbody fusion (PLIF) using carbon cages and pedicle fixation between 1993 and 2000 were recruited and contacted with a postal survey.

Clinical outcome was assessed by the assessment of postoperative clinical findings and complications and the fusion rate, which was assessed using standard X-rays with the scoring system described by Brantigan and Steffee. Functional outcome was measured by using improvement in the Oswestry Disability Index, PROLO score, return to work and satisfaction with the surgical outcome. The determinants of functional relief were analysed against the improvement in disability using multiple regression analysis.

The mean postoperative duration at the time of the study was 4.4 years. The response rate to the survey was 84%. Overall radiological fusion rate was ninety eight percent. There was a significant improvement in Oswestry Disability Index P< 0.001. There was 85% satisfaction with the surgical procedure and 58% return to pre-disease activity level and full employment. In the presence of near total union rate we found preoperative level of disability to be best the determinant of functional recovery irrespective of age or the degree of psychological morbidity (p< 0.0001).

The combination of posterior lumbar interbody fusion (PLIF) and posterior instrumented fusion is a safe and effective method of achieving circumferential segmental fusion. This procedure gives sustained long-term improvement in functional outcome and high satisfaction rate. Direct relationship between preoperative level of disability and functional recovery suggests that spinal fusion should be performed to alleviate disability caused by degenerative spine.