OBJECTIVETo explore the prevalence, distribution and clinical significance of high-intensity zone (HIZ) in anterior annulus fibrosus (AF) in comparison with HIZ in posterior AF of lumbar disc.

METHODSAccording to the diagnosis and location of HIZ, 610 lumbar magnetic resonance images with entire clinical materials were divided into control group (without HIZ), anterior AF group (HIZ), posterior AF group (HIZ) and anterior & posterior (AP) AF group (HIZ). The incidence of HIZ was summarized. The clinical data, such as male/female ratio, age, and body weight, prevalence of low back pain (LBP) and distribution of HIZ, were compared and analyzed between the groups.

RESULTSThree hundred and fifteen cases shown no HIZ (51.6%), 95 cases presented HIZ in anterior AF (15.6%, 119 discs), 159 cases presented HIZ in posterior AF (26.1%, 189 discs) and 41 cases presented HIZs in both anterior and posterior AF (6.7%, 96 discs). There was significant difference between the prevalence of HIZ in anterior AF and that in posterior AF (P < 0.01). The male/female ratio and body weight of each groups showed no difference (P > 0.05), and the age was proved to be statistically different between four groups (P < 0.01, control group < posterior AF group < AP AF group < anterior AF group). HIZs in anterior AF often occurred at L(1,2)-L(4,5), whereas, they usually developed at L(3,4)-L(5)S(1) in posterior AF. The incidence of LBP in control group, anterior AF group, posterior AF group, AP AF group were 40.0%, 52.6%, 55.4% and 65.8%, respectively. The LBP prevalence of control group was lower than that of other three groups (P < 0.05), and the prevalence of last three groups showed no difference (P > 0.05).

CONCLUSIONSCompared with HIZ in posterior AF, the HIZ in anterior AF of lumbar disc has a lower prevalence, often develops in elder patients and in upper motion segments. It also indicates an obvious relation to LBP as the former.