ROTTERDAM, The Netherlands—Varus alignment of the knee precedes the development of knee osteoarthritis (OA) in many patients, doubles the risk of knee OA in overweight patients, and increases the risk 5-fold for whose who are obese, according to data from researchers at Erasmus Medical Center, in Rotterdam, The Netherlands. Lead author G. M. Brouwer, MSc, writes in Arthritis & Rheumatism,¹ "An increasing degree of varus alignment is associated not only with progression of knee OA but also with development of knee OA. However, this association seems particularly applicable to overweight and obese persons."

"[T]he report by Brouwer et al is important: as the first report of a relationship between malalignment and incident idiopoathic knee OA, as the first report of a relationship between a local mechanical factor and incident idiopathic knee OA, and as a confirmation that malalignment influences knee OA progression, especially in patients who are overweight," Leena Sharma, MD, writes in an accompanying editorial.² Dr. Sharma, with the Arthritis Division at Northwestern University's Feinberg School of Medicine, in Chicago, Illinois, also notes that the results of this study suggest that more attention should be paid to "strategies to improve load distribution in malaligned knees" as a way to reduce the incidence of knee OA.

The Brouwer study comprised 1501 randomly selected participants from the Rotterdam open-population, prospective cohort study on the incidence of and risk factors for chronic disabling diseases. Knee OA at baseline and at a mean follow-up of 6.6 years was scored by Kellgren/Lawrence grading, and knee alignment at baseline was measured by the femorotibial angle on radiographs.

At baseline, 38% of 2664 knees had normal alignment, 26% had varus alignment, and 36% had valgus alignment. Varus alignment, however, was associated with an overall 2-fold increased risk in development of knee OA, which was attributable to increased knee OA in overweight and obese subjects but not in subjects of normal weight [see table].

Table: Knee Alignment and Risk of Knee OA

Weight	Varus vs Normal Alignment	Valgus vs Normal Alignment