Bone mineral density in patients with ossification of the posterior longitudinal ligament. Minimal decrease of bone mineral density with aging.
METHODS
Bone mineral density of individuals with ossification of the posterior longitudinal ligament and that of normal people was determined by dual-energy x-ray absorptiometry.


OBJECTIVE
To determine whether bone mineral density in the people with ossification of the posterior longitudinal ligament is higher than that in normal individuals even in body parts other than the spine, and to evaluate the relation between bone mineral density and age in patients with ossification of the posterior longitudinal ligament.


BACKGROUND
It is unknown whether the bone mineral density of patients with ossification of the posterior longitudinal ligament is greater in body parts other than the spine. If so, it provides a basis for the theory that certain systemic factors are involved in the pathogenesis of ossification of the posterior longitudinal ligament. Because bone mineral density decreases physiologically after middle age, the influence of age must be considered in evaluating bone mineral density.


METHODS
In the rib area and upper and lower limb areas, which are not affected by ossification of the spinal ligament, bone mineral density of 45 men with ossification of the posterior longitudinal ligament of the cervical spine was compared with that of 25 men without ossification of the posterior longitudinal ligament (normal group).


RESULTS
Bone mineral density was higher in the group with ossification of the posterior longitudinal ligament in each part and significantly higher in the rib and lower limb areas (rib: P < 0.01, lower limb: P < 0.05). The age-related decrease was significantly less in the group with ossification of the posterior longitudinal ligament (rib: P < 0.01, upper limb: P < 0.05, lower limb: P < 0.01).


CONCLUSIONS
Systemic factors that increase bone mineral density appear to be involved in the pathogenesis of ossification of the posterior longitudinal ligament, and these factors may be activated after middle age.
Mamada
T
T
Department of Orthopaedic Surgery, Faculty of Medicine, University of Tokyo, Japan.
Nakamura
K
K
Hoshino
Y
Y
Saita
K
K
Kurokawa
T
T
D015502:Absorptiometry, Photon; D000368:Aged; D000375:Aging / Q000502:physiology*; D015519:Bone Density / Q000502:physiology*; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017887:Ossification of Posterior Longitudinal Ligament / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology*