Assessment of vertebral fracture risk and therapeutic effects of alendronate in postmenopausal women using a quantitative computed tomography-based nonlinear finite element method.
A QCT-based nonlinear FEM was used to assess vertebral strength and mechanical parameters in postmenopausal women. It had higher discriminatory power for vertebral fracture than aBMD and vBMD. Alendronate effects were detected at 3 months, and marked bone density increases were noted in juxta-cortical areas compared to inner trabecular areas.


BACKGROUND
QCT-based finite element method (QCT/FEM) can predict vertebral compressive strength ex vivo. This study aimed to assess vertebral fracture risk and alendronate effects on osteoporosis in vivo using QCT/FEM.


METHODS
Vertebral strength in 104 postmenopausal women was analyzed, and the discriminatory power for vertebral fracture was assessed cross-sectionally. Alendronate effects were also prospectively assessed in 33 patients with postmenopausal osteoporosis who were treated with alendronate for 1 year.


RESULTS
On the age and body weight adjusted logistic regression, vertebral strength had stronger discriminatory power for vertebral fracture (OR per SD change: 6.71) than areal BMD and volumetric BMD. The optimal point for the vertebral fracture threshold was 1.95 kN with 75.9% sensitivity and 78.7% specificity. At 3 months, vertebral strength significantly increased by 10.2% from baseline. The minimum principal strain distribution showed that the area of high fracture risk decreased. At 1 year, the density of the inner cancellous bone increased by 8.3%, while the density of the juxta-cortical area increased by 13.6%.


CONCLUSIONS
QCT/FEM had higher discriminatory power for vertebral fracture than BMD and detected alendronate effects at 3 months. Alendronate altered density distributions, thereby decreasing the area with a high fracture risk, resulting in increased vertebral strength.
Imai
K
K
Department of Orthopaedic Surgery, School of Medicine, The University of Tokyo, Tokyo, Japan.
Ohnishi
I
I
Matsumoto
T
T
Yamamoto
S
S
Nakamura
K
K
D000368:Aged; D000369:Aged, 80 and over; D019386:Alendronate / Q000627:therapeutic use*; D044466:Asian People; D015519:Bone Density; D050071:Bone Density Conservation Agents / Q000627:therapeutic use*; D019245:Compressive Strength / Q000187:drug effects; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000293:injuries*; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000000981:diagnostic imaging*; D017698:Postmenopause; D011446:Prospective Studies; D011857:Radiographic Image Interpretation, Computer-Assisted; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D016103:Spinal Fractures / Q000209:etiology / Q000517:prevention & control*; D014057:Tomography, X-Ray Computed / Q000379:methods
D050071:Bone Density Conservation Agents; D019386:Alendronate
Spine (Phila Pa 1976). 2006 Jul 15;31(16):1789-94
16845352
Clin Biomech (Bristol, Avon). 1994 May;9(3):180-6
23916179
Bone. 2003 Oct;33(4):744-50
14555280
Bone. 1996 Feb;18(2):141-50
8833208
J Biomech. 1998 Feb;31(2):125-33
9593205
Spine (Phila Pa 1976). 2003 Mar 15;28(6):559-65
12642762
J Biomech. 2007;40(6):1381-91
16930610
J Bone Miner Res. 1997 Oct;12 (10 ):1721-8
9333134
Osteoporos Int. 1999;9(5):461-8
10550467
Bone. 2000 Nov;27(5):687-94
11062357
J Bone Miner Res. 2007 Dec;22(12):1885-92
17680721
N Engl J Med. 2003 Sep 25;349(13):1207-15
14500804
Spine (Phila Pa 1976). 2008 Jan 1;33(1):27-32
18165745
J Bone Miner Metab. 2001;19(6):331-7
11685647
N Engl J Med. 1995 Nov 30;333(22):1437-43
7477143
Am J Med. 1996 Nov;101(5):488-501
8948272
Calcif Tissue Int. 1989 Apr;44(4):243-50
2501006
Med Eng Phys. 2001 Apr;23 (3):165-73
11410381
BMJ. 1996 May 18;312(7041):1254-9
8634613
J Orthop Res. 1998 May;16(3):300-8
9671924
World Health Organ Tech Rep Ser. 1994;843:1-129
7941614
J Biomech. 2007;40(8):1745-53
17034798
J Biomed Mater Res B Appl Biomater. 2006 Jan;76(1):143-8
16047323
Radiology. 1991 Jun;179(3):669-74
2027972
Biomed Tech (Berl). 1998 Apr;43(4):82-8
9611393
Arch Intern Med. 2005 Aug 8-22;165(15):1762-8
16087825
Med Eng Phys. 2001 Nov;23(9):657-64
11755810
Phys Med Biol. 1999 Mar;44(3):751-64
10211808
J Bone Miner Res. 2007 Jan;22(1):149-57
17042738
Med Phys. 1999 Jul;26(7):1341-8
10435536
J Biomech. 1999 Oct;32(10 ):1013-20
10476839
Osteoporos Int. 1996;6(1):37-42
8845598
Bone. 2001 Aug;29(2):185-91
11502482
Am J Med. 2002 Mar;112(4):281-9
11893367
Lancet. 1996 Dec 7;348(9041):1535-41
8950879
JAMA. 2001 Feb 14;285(6):785-95
11176917
JAMA. 1998 Dec 23-30;280(24):2077-82
9875874
Bone. 2007 Mar;40(3):767-74
17174619
Osteoporos Int. 2005 Jun;16(6):642-50
15455195
J Bone Miner Res. 1994 May;9(5):687-93
8053398
J Clin Invest. 1993 Dec;92(6):2577-86
8254015
Arch Intern Med. 1997 Dec 8-22;157(22):2617-24
9531231