Genetic factors contribute more to hip than knee surgery due to osteoarthritis - A population-based twin registry study of joint arthroplasty. Magnusson, K., Scurrah, K., Ystrom, E., Ørstavik, R. E., Nilsen, T., Steingrímsdóttir, Ó A., Ferreira, P., Fenstad, A. M., Furnes, O., & Hagen, K. B. Osteoarthritis and Cartilage, December, 2016.
doi  abstract   bibtex   
OBJECTIVE: To explore and quantify the relative strengths of the genetic contribution vs the contribution of modifiable environmental factors to severe osteoarthritis (OA) having progressed to total joint arthroplasty. DESIGN: Incident data from the Norwegian Arthroplasty Registry were linked with the Norwegian Twin Registry on the National ID-number in 2014 in a population-based prospective cohort study of same-sex twins born 1915-60 (53.4% females). Education level and height/weight were self-reported and Body Mass Index (BMI) calculated. The total follow-up time was 27 years for hip arthroplasty (1987-2014, 424,914 person-years) and 20 years for knee arthroplasty (1994-2014, 306,207 person-years). We estimated concordances and the genetic contribution to arthroplasty due to OA in separate analyses for the hip and knee joint. RESULTS: The population comprised N = 9058 twin pairs (N = 3803 monozygotic (MZ), N = 5226 dizygotic (DZ)). In total, 73% (95% confidence intervals (CI) = 66-78%) and 45% (95% CI = 30-58%) of the respective variation in hip and knee arthroplasty could be explained by genetic factors. Zygosity (as a proxy for genetic factors) was associated with hip arthroplasty concordance over time when adjusted for sex, age, education and BMI (HR = 2.98, 95% CI = 1.90-4.67 for MZ compared to DZ twins). Knee arthroplasty was to a greater extent dependent on BMI when adjusted for zygosity and the other covariates (HR = 1.15, 95% CI = 1.02-1.29). CONCLUSION: Hip arthroplasty was strongly influenced by genetic factors whereas knee arthroplasty to a greater extent depended on a high BMI. The study may imply there is a greater potential for preventing progression of knee OA to arthroplasty in comparison with hip OA.
@article{magnusson_genetic_2016,
	title = {Genetic factors contribute more to hip than knee surgery due to osteoarthritis - {A} population-based twin registry study of joint arthroplasty.},
	issn = {1522-9653},
	doi = {10.1016/j.joca.2016.12.015},
	abstract = {OBJECTIVE: To explore and quantify the relative strengths of the genetic contribution vs the contribution of modifiable environmental factors to severe osteoarthritis (OA) having progressed to total joint arthroplasty.
DESIGN: Incident data from the Norwegian Arthroplasty Registry were linked with the Norwegian Twin Registry on the National ID-number in 2014 in a population-based prospective cohort study of same-sex twins born 1915-60 (53.4\% females). Education level and height/weight were self-reported and Body Mass Index (BMI) calculated. The total follow-up time was 27 years for hip arthroplasty (1987-2014, 424,914 person-years) and 20 years for knee arthroplasty (1994-2014, 306,207 person-years). We estimated concordances and the genetic contribution to arthroplasty due to OA in separate analyses for the hip and knee joint.
RESULTS: The population comprised N = 9058 twin pairs (N = 3803 monozygotic (MZ), N = 5226 dizygotic (DZ)). In total, 73\% (95\% confidence intervals (CI) = 66-78\%) and 45\% (95\% CI = 30-58\%) of the respective variation in hip and knee arthroplasty could be explained by genetic factors. Zygosity (as a proxy for genetic factors) was associated with hip arthroplasty concordance over time when adjusted for sex, age, education and BMI (HR = 2.98, 95\% CI = 1.90-4.67 for MZ compared to DZ twins). Knee arthroplasty was to a greater extent dependent on BMI when adjusted for zygosity and the other covariates (HR = 1.15, 95\% CI = 1.02-1.29).
CONCLUSION: Hip arthroplasty was strongly influenced by genetic factors whereas knee arthroplasty to a greater extent depended on a high BMI. The study may imply there is a greater potential for preventing progression of knee OA to arthroplasty in comparison with hip OA.},
	language = {eng},
	journal = {Osteoarthritis and Cartilage},
	author = {Magnusson, K. and Scurrah, K. and Ystrom, E. and Ørstavik, R. E. and Nilsen, T. and Steingrímsdóttir, Ó A. and Ferreira, P. and Fenstad, A. M. and Furnes, O. and Hagen, K. B.},
	month = dec,
	year = {2016},
	pmid = {27986619},
	keywords = {Arthroplasty, Heritability, Osteoarthritis, Twins},
}

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