Declining incidence of low-trauma knee fractures in elderly women: nationwide statistics in Finland between 1970 and 2006

Summary The study assessed the recent secular trend in the incidence of low-trauma knee fractures among older Finns in the years 1970-2006. The clear rise in women's fracture incidence from early 1970s until the late 1990s was followed by a declining fracture rate. Exact reasons for the decline are unknown, but a cohort effect toward a healthier female population with improved functionality and reduced risk of injurious slips, trips and falls could partly explain the phenomenon. Introduction Although low-trauma fractures of elderly adults have been recognized as a major public health concern in modern societies with aging populations, fresh nationwide information on their secular trends is sparse. Methods We determined the current trend in the number and incidence (per 100,000 persons) of low-trauma knee fractures among elderly people in Finland, an EU country with a well-defined white population of 5.3 million, by taking into account all persons 60 years of age or older who were admitted to our hospitals for primary treatment of such fractures from 1970 to 2006. Results The number and incidence of low-trauma knee fractures among 60-year-old or older Finnish women sharply rose between 1970 and 1997, from 218 (number) and 55 (incidence) in 1970 to 733 and 124 in 1997. However, thereafter both the number and incidence of fractures have continuously declined so that there were only 626 fractures in these women in 2006 (incidence 94). In the age-adjusted fracture incidence, the findings were similar. During 1970-1997, the age-adjusted incidence of low-trauma knee fractures in our elderly women clearly rose (from 60 to 118), but thereafter, this incidence declined to 85 in 2006. In men, the fracture incidence did not show consistent trend changes over time (30 in 1970 and 36 in 2006). Conclusions The sharp rise in the incidence of low-trauma knee fractures in Finnish elderly women from early 1970s until late 1990s has been followed by a declining fracture rate. Exact reasons for this are unknown, but a cohort effect toward a healthier aging female population with improved functional ability and reduced risk of injurious slips, trips and falls cannot be excluded.