Is high level of disability an indication for spinal fusion? Analysis of long-term outcome after posterior lumbar interbody fusion using carbon fiber cages.

OBJECTIVE

Posterior lumbar interbody fusion is a recognized 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.

METHODS

Sixty-five consecutive patients who underwent posterior lumbar interbody fusion using carbon cages and pedicle fixation between 1993 and 2000 were recruited and contacted with a postal survey. Clinical outcome was assessed by the postoperative clinical findings and complications and the fusion rate, which was assessed using the scoring system described by Brantigan and Steffee. Functional outcome was measured by using improvement in the Oswestry Disability Index, return to work, and satisfaction with the surgical outcome. The determinants of functional relief were analyzed against the improvement in disability using multiple regression analysis.

RESULTS

The mean postoperative duration at the time of the study was 4.4 years. Overall radiologic fusion rate was 98%. There was a significant improvement in Oswestry Disability Index (P < 0.01). There was 84% satisfaction with the surgical procedure and 61% return to predisease activity level and full employment. We found preoperative level of disability to be the best determinant of functional recovery irrespective of age or the degree of psychological morbidity and litigation (P < 0.01).

CONCLUSION

The combination of posterior lumbar interbody fusion and posterior instrumented fusion is a safe and effective method of achieving circumferential segmental fusion. A direct relationship between preoperative level of disability and functional recovery suggests that disability should be measured preoperatively and spinal fusion should be performed to alleviate disability caused by degenerative spine.