Septic and aseptic post-operative discitis in the lumbar spine--evaluation by MR imaging.

PURPOSE

The aim of this study was to determine whether it was possible to differentiate septic from aseptic post-operative discitis in the lumbar spine by means of MR imaging.

MATERIAL AND METHODS

The study was a retrospective evaluation of 12 patients with prior lumbar discectomy and suspected post-operative discitis displaying low-back pain and typical MR findings. Six patients had elevated serum C-reactive protein (CRP) (septic) and 6 had normal CRP (aseptic). We used MR imaging to assess the distribution and degree of changes in the disc, in adjacent bone marrow, and in surrounding soft tissue.

RESULTS

Of the 6 patients with increased CRP levels, 3 had extensive MR changes typical of septic post-operative discitis: 1 found soon after surgery; 2 found later. The other 3 patients with septic discitis, who were examined in the early post-operative period, showed MR changes similar to those in the 6 patients with aseptic discitis.

CONCLUSION

Suspicion of septic post-operative discitis should be confirmed by MR imaging, serum CRP, and disc puncture. MR imaging is not reliable as the sole method for distinguishing septic from aseptic discitis in the early post-operative stage.