Two-year outcome after lumbar microdiscectomy versus microscopic sequestrectomy -: Part 2:: Radiographic evaluation and correlation with clinical outcome

Study Design. Single-center randomized prospective study at a university hospital. Objective. The aim of the present study was to assess disc morphology radiologically 2 years after surgery in a cohort of prospectively randomized patients undergoing microdiscectomy ( D) or microscopic sequestrectomy ( S) to compare the results and to correlate this data with clinical outcome. Summary of Background Data. Simple fragment excision in cases of herniated lumbar discs has been repeatedly reported as an alternative to standard microdiscectomy, and according to the literature clinical results of both techniques seem to be comparable. As sequestrectomy, however, avoids any additional damage to the disc, the fate of the intervertebral space over time may well differ between the 2 procedures and may potentially even have an impact on outcome. Respective postoperative radiological data are not available so far. Material and Methods. This radiological evaluation represents a 2-year follow-up study by magnetic resonance imaging of a previously reported cohort of 84 patients harboring lumbar disc herniations that were randomized to D and S in equal parts. Disc and nondisc characteristics such as disc desiccation, loss of disc height, and endplate changes plus form, size, and location of canal-compromising disc lesions were assessed by a blinded neuroradiologist. Pre- and postoperative radiological data were compared and correlated with clinical outcome. Results. There was a high incidence of relevant ( >= 4 mm) postoperative protrusions/extrusions of 66% in group D and 68% in group S ( NS). The presence of a protrusion/extrusion, however, did not correlate with low back pain or sciatica. Loss of disc height over time was more common in group D ( 63%) than in group S ( 38%; P < 0.05) and endplate degeneration also increased significantly more in group D ( 47 vs. 14% in group S; P < 0.01). A significant correlation was present between Modic type endplate changes and low back pain. Conclusion. Nondiscal pathologies, in particular Modic type endplate changes, seem to play an important role in the etiology of unfavorable clinical outcome after surgery for disc herniations. Sequestrectomy demonstrated significantly less postoperative disc degeneration than standard microdiscectomy after 2 years and may thus represent an attractive treatment alternative.