RESEARCH - High systemic BMD increases risk of incident knee OA and JSN, but not radiographic progression of existing OA: MOST

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Ann Rheum Dis. Published Online First: 15 January 2009.

doi:10.1136/ard.2008.099531

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Extended Report

High systemic bone mineral density increases the risk of incident knee

OA and joint space narrowing, but not radiographic progression of

existing knee OA: The MOST study

C Nevitt 1*, Yuqing Zhang 2, M Kassim Javaid 3, Tuhina Neogi

2, R Curtis 4, Jingbo Niu 2, E McCulloch 1, Neil Segal

5 and T Felson 2

1 University of California, San Francisco, United States

2 Boston University Medical Center, United States

3 University of Oxford, United Kingdom

4 University of Alabama at Birmingham, United States

5 University of Iowa, United States

Abstract

Objectives: Previous studies suggest that high systemic bone mineral

density (BMD) is associated with incident knee OA defined by

osteophytes, but not with joint space narrowing (JSN), and are

inconsistent regarding BMD and progression of existing OA. We tested

the association of BMD with incident and progressive tibiofemoral OA

in a large, prospective study of men and women ages 50-79 with, or at

risk for, knee OA.

Methods: Baseline and 30-month weight-bearing PA and lateral knee

x-rays were scored for K-L grade, JSN and osteophytes. Incident OA was

defined as the development of K-L grade 2 at follow-up. All knees were

classified for increases in grade of JSN and osteophytes from

baseline. The association of gender-specific quartiles of baseline BMD

with risk of incident and progressive OA was analyzed using logistic

regression, adjusting for covariates.

Results: The mean age of 1,754 subjects was 63.2 (SD, 7.8) and BMI

29.9 (SD, 5.4). In knees without baseline OA, higher femoral neck and

whole body BMD were associated with an increased risk of incident OA

and increases in grade of JSN and osteophytes (p < 0.01 for trends);

adjusted odds were 2.3 to 2.9-fold greater in the highest vs. the

lowest BMD quartiles. In knees with existing OA, progression was not

significantly related to BMD.

Conclusions: In knees without OA, higher systemic BMD was associated

with a greater risk of the onset of JSN and K-L grade 2. The role of

systemic BMD in early knee OA pathogenesis warrants further

investigation.

http://ard.bmj.com/cgi/content/abstract/ard.2008.099531v1?papetoc

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