[Distribution of MRI signal alterations of the cartilage endplate in pre-operated patients with special focus on recurrent lumbar disc herniation]. / Verteilungsmuster von (Modic-)Signalveränderungen an den vertebralen Endplatten voroperierter Patienten und ihr Bezug zu Rezidivvorfällen.

ABSTRACT

PURPOSE: To study the location of (Modic) MR signal alterations (SA) of the cartilage endplate (CEP) in pre- and non-operated segments L3-S1 with special focus on the presence of recurrent lumbar disc herniation (RLDH). MATERIALS AND METHODS: In a retrospective study the MR images of vertebrae L3-S1 of 65 consecutive patients with a history of microdiscectomy were evaluated. Of the 190 segments studied, 67 were pre-operated. These were divided into a group with recurrent lumbar disc herniation (RLDH) (n = 19) and a group without evidence of RLDH (n = 48). Non-operated segments (n = 123) were also considered as a separate group. In these three groups the prevalence of different Modic types was determined using the sag. T1- and T2-weighted images, and, in particular, the distribution of SA at the upper and lower CEP was examined by evaluating the sag. T2-weighted images. In order to achieve this, each CEP was divided into nine regions. RESULTS: Pre-operated segments showed significantly more frequent (p < 0.001) and more expansive (p < 0.001) SA than non-operated segments. Non-operated segments showed SA less frequently in the central region of both upper and lower CEP (p = 0.056 and p = 0.015, respectively). In operated segments without RLDH, the upper CEP had significantly more SA on the operation side than in the mid-sagittal and contra-lateral regions (p = 0.016, p = 0.037) and significantly more on the operation side of the lower CEP than in the contra-lateral region (p = 0.027). Operated segments with RLDH did not show an emphasis of SA on the operation side. In this group SA occurred significantly more often in the central and ventral mid-sagittal regions of the upper CEP than in the pre-operated segments without RLDH. CONCLUSION: 1. There are different patterns of signal alterations in the three groups. 2. The importance of the central region of the CEP for the integrity of the disc is strongly supported by the low incidence of signal alterations in this location in non-operated segments. 3. There are clear indications for the influence of the operation on the development and distribution of signal alterations. 4. In pre-operated segments signal alterations occurring in the central and ventral mid-sagittal regions of the upper CEP can be indicative of the development of RLDH.