Obesity and Joint Replacement Surgery: CJRR Update

Nicole de Guia, Program Lead, CJRR
Cassandra Linton, Project Lead, CJRR
Canadian Institute for Health Information
Toronto, ON

The Canadian Joint Replacement Registry (CJRR) has recently published topical studies and reports using data voluntarily submitted by almost 500 surgeons across Canada in every province and one territory. To date, over 103,000 procedures have been captured in the CJRR database, and the database continues to grow with increased interest in submissions by electronic files as well as by paper.

Obesity and Joint Replacement Surgery
A recently published CJRR study showed evidence of a cross-sectional relationship between obesity and joint replacement surgery using Canadian data¹. When compared to the 2004 Canadian adult population, 46% of joint replacement patients (hip and knee) in the CJRR sample (N=17,244) were classified as obese, compared to 23% of Canadian adults in this category. Those considered overweight made up roughly the same percentage as the Canadian adult population, with 35% and 36%, respectively. Obese persons were found to be over three times as likely to undergo joint replacement surgery (RR=3.12, 95% CI, 2.993.25), and overweight persons were one and a half times more likely (RR=1.53, 95% CI, 1.461.60), when compared to those in the acceptable weight category in 2003-04. This work supports the findings of many studies in which obesity has been strongly implicated as a risk factor for knee osteoarthritis and in some studies, for osteoarthritis of the hip.

Factors Affecting Early Revisions
One of the benefits of a national joint arthroplasty registry is the ability to report longitudinally on patients. The CJRR recently released an Analysis-in-Brief that investigated factors influencing the time to early revision based on 179 patients with both a primary and subsequent revision procedure captured in the CJRR between May 1, 2001 (the start of data collection) and March 31, 2004².

The study first compared reasons for revision, analyzed by joint, between the early revision patients and all revision patients (n=4,238) in the CJRR database (latter includes cases in which only the revision, but not the primary procedure was captured). For early knee revisions, the most common reasons for revision were aseptic loosening (19%), implant fracture (15%) and infection (11%); for hip, instability (39%), infection (25%) and bone fracture (18%). By comparison, aseptic loosening was by far, the most common reason noted for all revisions in the CJRR (57% for hip and 49% for knee).

Survival analyses using the Cox Proportional Hazard model showed evidence that hip replacement patients were more likely to undergo early revisions than knee replacement patients, after adjusting for joint (hip versus knee), age, gender, primary diagnosis, and cement use (P<0.0001, Log-Rank test). The hazard of early revision for hip replacements was found to be 3.6 times the hazard for knee replacements (P<0.0001, Chi-square test).

Get involved in CJRR!
CJRR continues to work with orthopaedic surgeons and their staff across the country to collect data to produce timely and relevant studies and reports such as those mentioned in this article. Join the many orthopaedic surgeons across Canada who are involved in this grassroots, national initiative. For more information about CJRR, please visit our web site at www.cihi.ca/cjrr or contact us at Cette adresse email est protégée contre les robots des spammeurs, vous devez activer Javascript pour la voir. .