Abstract
Study Design. A reliability study of the Modic classification.
Objective. To determine the reliability and reproducibility of the Modic classification for lumbar vertebral marrow changes.
Summary of Background data. In 1988, Modic with colleagues described two degenerative stages of vertebral marrow and endplate morphology. These were Type I (inflammatory phase) and Type II (fatty phase). Later in 1988, he added a third variety; Type III where there was marked sclerosis adjacent to the endplates. No formal reliability or reproducibility studies had been performed on the Modic classification.
Methods. This study involved five independent observers of differing spinal experience using the Modic classification to grade fifty sagittal T1 and T2 weighted MRI scans. The observers repeated the assessment at three weeks. Intra- and inter-observer reliabilities were assessed using kappa statistics.
Results. There were 7 type I, 40 type II, 1 type III and 2 normal levels. The individual intra-observer agreement was substantial or excellent with kappa values ranging from 0.71 to 1.00. The overall inter-observer agreement was excellent with a kappa value of 0.85. There was complete agreement in 78% of the levels, a difference of one type in 14% and a difference of two or more in 8% of levels. The level of experience of the observer did not correlate with a better score.
Conclusions. We have shown that the Modic classification is both reliable and reproducible. It is simple and easy to apply for observers of varying clinical experience. We therefore recommend its use in clinical research and practice.
These abstracts were prepared by Mr. Brian J C Freeman FRCS (Tr & Orth). Correspondence should be addressed to him at The Centre for Spinal Studies and Surgery, University Hospital, Queens Medical Centre, Nottingham NG7 2UH.
