Clinical imaging study and meta-analysis of ossification of the ligamentum flavum

Abstract

Objective To study the clinical epidemiology of ossification of ligamentum flavum(OLF)and evaluate its characteristics of prevalence,morphology,and distribution in a common population.Some factors associated with its occurrence were analyzed by meta-analysis.Methods A total of 1736 southern Chinese volunteers were recruited by open invitation.T2 weighted MRI sequences of whole spine in all participants were obtained.OLF was identified as an area of low signal intensity located in the posterior part of the spinal canal,and subsequently confirmed by CT scan.The distribution of OLF was classified into three types:isolated type,continuous type and non-continuous type.The morphology of the lesion was classified into triangular,round and beak shapes based on the pattern of ossification on T2 weighted sagittal MRIs.Literatures about OLF were searched in Ovid Medline,PubMed,Embase and Chinese BioMedical Literature Database from January 1980 to January 2010.Results OLF was identified in 66 volunteers including 52 females and 14 males.According to the new classification of the study,there were 45 cases of single type (68.2%),11 cases of continuous type(16.7%)and 10 cases of non-continuous type(15.2%).In 92 OLF,there were 17 triangular shape(18.5%)and 75 rounded shape according to morphological classification.A literature review showed that there were only 4 reports related to the prevalence of OLF.Conclusion This study demonstrated that morbidity rate of OLF is about 3.8% in southern Chinese population.The incidence is related to age and gender.It is necessary to perform whole spine MRI examination to detect the multiple level and noncontinous type. Key words: Ligamentum flavum; Spine; Meta-analysis