DO VERTEBRAL END PLATE CHANGES PREDICT BETTER OUTCOME FOLLOWING LUMBAR INTERBODY FUSION: A PROSPECTIVE STUDY WITH MINIMUM 2 YEAR FOLLOW UP

Abstract

Study Design: Prospective cohort study

Summary of Background data: A definite link between Modic end plate changes and discogenic low back pain has yet to be established. However, current prospective data indicates that Modic changes strongly correlate with the pain provocation of lumbar discography and improved clinical outcome following instrumented posterolateral fusion. Consequently, there is recent heightened awareness using this radiological entity in the selection of patients for interbody fusion or total disc replacement.

Objective: To prospectively evaluate whether Modic changes can predict improved clinical outcome following antero-posterior lumbar interbody fusion using femoral ring allograft.

Methods: A cohort of chronic low back pain patients were investigated with MRI and lumbar discography. Twenty-six patients with disco-graphically-proven concordant pain reproduction were prospectively entered into the study. Clinical results were collected using the Oswestry Disability Index (ODI), Visual Analogue Scale (VAS) and Short Form 36 Health Questionnaire (SF-36) at the pre-operative and two-year follow up. The minimal clinically important difference (MCID) was taken as 10 points for ODI, 2 points for VPAS, and 7 points for the physical function and bodily pain subset of the SF-36 questionnaire.

Results: MRI scans evaluated for the level fused revealed 13 patients with no end-plate changes (Type 0), whilst 2 patients had Modic Type I and 11 had Modic Type II changes. MCID in ODI were achieved in Type 0, Type 1 and Type 2, but improvement in VAS only was achieved in the Type 0 and Type 1. For SF-36, the MCID of 7 points was reached in most domains for all types of Modic change. There was no statistical difference in clinical outcome between those patients with Modic Type 0 and those with Modic type I or II.

Conclusion: This prospective study shows that Modic changes do not predict improved clinical outcome following antero-posterior interbody fusion using the femoral ring allograft.