Vertebral strength changes in rheumatoid arthritis patients treated with alendronate, as assessed by finite element analysis of clinical computed tomography scans: a prospective randomized clinical trial.
OBJECTIVE
Finite element analysis of clinical computed tomography (CT) scans provides a noninvasive means of assessing vertebral strength that is superior to dual x-ray absorptiometry (DXA)-measured areal bone mineral density. The present study was undertaken to compare strength changes, measured using this newer method, in rheumatoid arthritis (RA) patients who were treated with alendronate (ALN) versus those who were not.


METHODS
Thirty female RA patients without radiologic signs of L3 compression fractures or a history of osteoporosis medication were enrolled in a prospective randomized clinical trial. Patients were randomly assigned to the ALN group (5 mg orally, once daily) or the control group not receiving antiresorptive treatment. All patients were evaluated by DXA and quantitative CT at baseline and reevaluated after a mean of 12.2 months. Nonlinear finite element analysis was performed on the CT scans (n = 29 available for analysis) to compute an estimate of vertebral compressive strength and to assess strength changes associated with changes in the trabecular compartment and the outer 2 mm of bone (peripheral compartment).


RESULTS
On average, vertebral strength was significantly decreased from baseline in the control group (n = 15) (median change -10.6%; P = 0.008) but was maintained in the ALN group (n = 14) (median change +0.4%; P = 0.55), with a significant difference between the 2 groups (P < 0.01). Strength decreased more rapidly within the trabecular bone, and ALN treatment was much more effective in the peripheral than the trabecular compartment.


CONCLUSIONS
Our results indicate that patients with RA can lose a substantial amount of vertebral strength over a relatively short period of time, and this loss can be prevented by ALN, primarily via its positive effect on the outer 2 mm of vertebral bone.
Mawatari
Taro
T
Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan. taro@ortho.med.kyushu-u.ac.jp
Miura
Hiromasa
H
Hamai
Satoshi
S
Shuto
Toshihide
T
Nakashima
Yasuharu
Y
Okazaki
Ken
K
Kinukawa
Naoko
N
Sakai
Shuji
S
Hoffmann
Paul F
PF
Iwamoto
Yukihide
Y
Keaveny
Tony M
TM
D000328:Adult; D000368:Aged; D019386:Alendronate / Q000627:therapeutic use*; D001172:Arthritis, Rheumatoid / Q000188:drug therapy*; D050071:Bone Density Conservation Agents / Q000627:therapeutic use*; D019245:Compressive Strength; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D008875:Middle Aged; D011446:Prospective Studies; D013131:Spine / Q000502:physiology*; D014057:Tomography, X-Ray Computed / Q000379:methods*
D050071:Bone Density Conservation Agents; D019386:Alendronate