ANALYSIS OF CLINICAL RESULTS OF DISCAL PROSTHESES AS A FUNCTION OF THE TYPE OF DEGENERATIVE DISCOPATHY

Abstract

Purpose of the study: Discal arthroplasty is warranted as a part of the treatment of discopathy to guarantee mobility after disc removal. Depending on the type of discopathy, the diseased disc can be classified into different categories: absence of herniation (H0), disc herniation (H1), recurrent disc herniation (H2), post discectomy syndrome (H3), or stenosis of a single unit (including grade 1 degenerative spondylolisthesis) (St-SPd). The purpose of this study was to compare clinical outcome after discal arthroplasty for these different clinical situations.

Material and methods: This was a prospective study of 152 patients who underwent a single-stage operation for insertion of a lumbar disc prosthesis. Pain was assessed with a visual analog scale for the lumbar level (VAS-L), and for radicular pain (VAS-R) and the Oswestry index (ODI). Patients were classified as follows: 39 H0, 52 H1, 22 H2, 29 H3, 10 ST-SPd).

Results: Outcome in patients in groups H0, H1, and St-SPd, i.e. first-intention surgery patients, presented equivalent results for lumbar and radicular pain and for function: VAS-L and VAS-R declined concomitantly. Results at three months postop were equivalent to those observed at 24 months. Patients in groups H2 and H3 who had had prior operation(s) for posterior discectomy experienced rapid relief of lumbar pain but radicular pain persisted postoperatively (6 to 12 m).

Discussion: These data confirm the excellent results obtained with single-level disc replacement as assessed by VAS and ODI. The persistence of radiculalgia which then resolves several months later in patients with a history of discal surgery can be explained by the combination of chronic compression, postoperative adherences and restored disc height. In the present series, none of the patients required complementary surgery for posterior radicular release.

Conclusion: Discal arthroplasty provides satisfactory results for the different stages of discal disease. The procedure should however be undertaken with prudence for patients who have had prior surgery. A perfect analysis of other factors involved should be helpful in chosing the most appropriate technique and avoid the development of postoperative radiculalgia. The present results could be usefully confirmed with a long-term randomized prospective study comparing discal prosthesis with fusion for the treatment of discal disease.