No abstract

1976 through 1992, 30,003 primary knee arthroplasties and their revisions have been recorded in a nation-wide Swedish study. We report on the structure of the register, demographic data and survivorship. We found that operations for osteoarthrosis (OA) counted for the increase in number of arthroplasties in contrast to rheumatoid arthritis (RA), where the number had slightly declined. For primary operations, the total knee prostheses have practically eliminated other types in RA and are steadily gaining popularity in OA at the expense of the unicompartmental prostheses. Total knee replacements showed gradually improving survival even in unchanged designs while the unicompartmental prostheses don't, partly because of newly introduced inferior designs. We also found that failed unicompartmental prostheses were best replaced with a tricompartmental prosthesis and that a total revision was to be preferred when a tricompartmental tibial component failed. The risk of the most devastating complications, e.g., infection, leading to extraction of the prosthesis or arthrodesis has decreased considerably also in the last years.

BMI is an important predictor of osteoarthritis even within normal BMI. A decreased risk of osteoarthritis of the hip was found in smokers, but the effect was weak compared to that of BMI or age. Contrary to studies of radiographic osteoarthritis our study indicates higher risk of hip than of knee osteoarthritis.

Objectives-The aim was to examine the relation between osteoarthrosis of the knee leading to prosthetic surgery among men and women and overweight, smoking, and hormone therapy. Methods-A case-referent study was performed with a study base of all men and women, born 1921-1938, living in 14 counties in Sweden during 1991-95. The cases (n=625) were identified through the Swedish Knee Arthroplasty Register. The referents (n=548) were randomly selected through the central population register from the same counties. Detailed information on general health status, height, weight, smoking habits, medication, use of hormones, specific physical loads from occupation and housework, and sports activities was collected by a telephone interview and a postal questionnaire. The cases were classified in terms of high, medium or low/non-exposure to the factors studied, according to the distribution of variables among the referents. Results-Women with high body mass index (BMI) at the age of 40 had a relative risk of 9.2 (95%CI 5.3, 16.0) of developing severe knee osteoarthrosis later in life, and for men at the same age the relative risk was 3.9 (95%CI 2.3, 6.4). Smokers were less likely to develop severe knee osteoarthrosis compared with nonsmokers. Oestrogen therapy for women over 50 showed an increased relative risk of 1.8 (95%CI 1.2, 2.6), while use of oral contraceptives did not influence the risk . Conclusion-Overweight is a risk factor for knee osteoarthrosis leading to prosthetic surgery in men and women, with the strongest relation for women. Oestrogen therapy after 50 increased the relative risk, while smoking decreased it. (Ann Rheum Dis 1999;58:151-155) The results of diVerent studies on the impact of constitutional and lifestyle factors for the development of knee osteoarthrosis have partially been inconsistent. [1][2][3][4][5][6][7][8][9][10][11][12] Overweight is the most consistent risk factor identified, and the eVect seems to be strongest in women. Smoking has in certain studies shown a negative association with knee osteoarthrosis, [1][2][3] and in others no association. 4 There are some clinical, laboratory, and epidemiological studies suggesting that there is a relation between sex hormones and the development of osteoarthrosis.8-10 However, some epidemiological investigations have concluded that oestrogen use is not associated with knee osteoarthrosis. 12The aim of this study was to examine the relation between osteoarthrosis of the knee leading to prosthetic surgery among men and women, and overweight, smoking, and hormone therapy. Methods STUDY POPULATION AND DESIGNThe study base comprised all men and women born 1921 to 1938, and living in 14 counties in Sweden during 1991-95. The relation between constitutional and lifestyle factors and the development of severe knee osteoarthrosis in men and women was studied using the case-referent method in the study base.The cases had undergone prosthetic knee replacement during 1991-93 because of clinically significant primary tibiofemoral osteoarthrosis. ...

No abstract