Influence of lifetime hip joint force on the risk of self-reported hip osteoarthritis: a community-based cohort study.
OBJECTIVE
To investigate the influence of cumulative lifetime hip joint force on the risk of self-reported medically-diagnosed hip osteoarthritis (OA).


METHODS
Prospective cohort.


METHODS
General population.


METHODS
Members of Canadian Association of Retired Persons, community-dwelling.


RESULTS
Health-professional diagnosed hip OA, self-reported.


METHODS
Exposure data on lifetime physical activity type (occupational, household, sport) and dose (frequency, intensity, duration) was collected in 2005. Subjects were ranked in terms of a 'cumulative peak force index' (CFPI), a measure of lifetime mechanical hip joint force. Multivariable survival analyses were performed to obtain adjusted effects for mean lifetime exposure and during 5-year age periods.


RESULTS
Of 2918 subjects aged 45-85, 176 (6.03%) developed hip OA during the 2-year follow up (43 men, 133 women). The highest quintile of mean lifetime hip CPFI (HR 2.32; 95% CI 1.31-4.12), and high hip force in three age periods (35-39, 40-44, 45-49) were independently associated with hip OA. Previous hip injury was an approximate five-fold risk for development of hip OA across all models. In analysis by activity domain (occupation, sport, household), there was a trend (non-significant) for the highest quintile of occupational force, but not sport or household, to be associated with hip OA.


CONCLUSIONS
A newly proposed measure of lifetime mechanical hip force was used to estimate the risk of self-reported, medically-diagnosed hip OA. While there are important limitations, this prospective study suggests that lifelong physical activity is generally safe. Very high levels of lifetime force from all domains combined, and in particular from occupational forces, may be important in the etiology of hip OA.
School of Population and Public Health, University of British Columbia, 5804 Fairview Avenue, Mather Building, Vancouver, BC V6T 1Z3, Canada. cratzlaf@interchange.ubc.ca
C R
CR
Ratzlaff
G
G
Steininger
P
P
Doerfling
M
M
Koehoorn
J
J
Cibere
M H
MH
Liang
D R
DR
Wilson
J M
JM
Esdaile
J A
JA
Kopec
D000328:Adult; D000368:Aged; D001835:Body Weight; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D015207:Osteoarthritis, Hip / Q000503:physiopathology*; D011446:Prospective Studies; D012307:Risk Factors; D013314:Stress, Mechanical; D011795:Surveys and Questionnaires; D013997:Time Factors