DEXA T-score Concordance and Discordance Between hip and Lumbar Spine / 대한척추외과학회지

OBJECTIVE: To evaluate the concordance, or discordance, of the osteoporotic diagnosis between femur neck and lumbar spine, using DEXA T-scores and the WHO classification. MATERIALS AND METHODS: The BMD (Define?) on both hips and of the lumbar spine of 718 Korean females were measured. The mean age of the subjects was 55.5 years (31-91). The BMD data were obtained from 3 hip regions and from the lumbar spine, anteroposteriorly, using dual-energy x-ray absorptiometry (Lunar). The BMDs of femur neck and the L2-4 vertebrae were classified into normal (a T-score >-1), osteopenia (-1 < or = T-score < -2.5) and osteoporosis (-2.5< or =T-score) using the WHO definitions. RESULTS: There was significant correlation between the femur neck and lumbar BMDs (r=0.772). However, the discordance rate was 33% for all the cases, but this was 20% in the subjects below 50 of age, 31% in the subjects in their 50's, 47% in their 60's and 42% when 70 or above. The discordance rates of the normal, osteopenic and osteoporotic groups were 21, 54 and 17% respectively, with the highest discordance rate in the osteopenia group. Among the 649 persons in the normal or osteopenia groups, in relation to the femur neck BMD, there were 67 (10.3%) in the osteoporotic group with L2-4 BMD. But the reverse situation was only 12 persons from 594 (2.0%). (Eds note: this whole section makes little sense? What were the BMDs? The last sentence is completely meaningless.) CONCLUSIONS: The discordance rate between the femur neck and lumbar spine was as high as 33%, and was the highest in the osteopenia persons in their 60's. Therefore, in these persons the BMD of both sites should be checked together, but if not, the lumbar BMD should be checked first.

Circumferential Bending Test of Lumbar 4-5 Segment and Biomechanical Investigation of Stability for Anterior Lumbar Interbody Cages and Supplemental Posterior Instrumentation / 대한척추외과학회지

STUDY DESIGN: Compare the effectiveness of three types of cages used in each case separately with that of cages supplemented by posterior fixation such as transfacet screws and transpedicular screws. OBJECTIVES: To determine whether any important information could be obtained when anterolateral and/or posterolateral bending is imposed. SUMMARY OF LITERATURE REVIEW: Most lumbar spine biomechanical bending tests have been performed on flexion-extension and lateral bending only. MATERIALS AND METHODS: Flexibility was tested through the unconstrained eccentric compression-bending of isolated L4-L5 motion segments. A total of sixteen fresh frozen human cadaveric lumbosacral spine specimens(range of ages : 42+/-13 years 12 males and 4 females) were tested in this investigation. In each case bending load was applied in flexion(0 degree direction), then in 30 degree increments around the transverse plane until flexion was repeated at the 360 degree loading direction. Specimens underwent anterior interbody instrumentation with three different types of cage at L4-5 in three groups, respectively. After testing the interbody fusion constructs, the L4-L5 segments were first stabilized posteriorly using transfacet screws and then retested using transpedicular screw instrumentation. RESULTS: In the intact model, the increase in deflection angle was twice compared with that of the previous point starting from 120 degree up to 150 degree. The pure extensional motion showed the largest deflection angles which are 3.5 times higher than those in pure flexion in average. All three types of cages showed the similar results that were obtained from the intact model.