Discitis after lumbar disc surgery. Features of "aseptic" and "septic" forms.

Two major types of postoperative discitis have been previously described: septic discitis and "avascular" or "chemical" discitis. Percutaneous discal biopsy is an important way of distinguishing these entities. In a retrospective study of 25 cases of postoperative discitis, three groups have been analyzed with bacteriologic and histologic tests: a group of nine patients (group A) with positive discal bacteriologic cultures; a group of eight patients (group B) with typical septic histologic tests but negative bacteriologic discal procedures; and a group of eight patients (group C) in whom the histologic picture was reminiscent of a mechanical process. No group was unique in any clinical and radiologic parameter. Group A and group B were quite similar in biological features, but group C had erythrocyte sedimentation rate and C-reactive protein serum levels significantly lower than groups A and B (P less than 0.01). After 4 weeks, these differences were still present. This study confirms that there are two main features of postoperative discitis that can be recognized by histologic and biological tests, allowing for different treatments.