Longer Legs a Bigger Pain
 It has long been known that heavy use of our knees and legs can later contribute to the development of knee osteoarthritis (OA). But new research suggests that increased leg length may predispose taller people to knee OA later on in life, specifically those of Chinese . Prior to the research recently conducted by Hunter et al and published in the May 2005 issue of Arthritis Rheumatology, the association between knee height and OA was never closely investigated.
The reasoning behind the claim is that with increasing leg length there is additional amounts of torque on the knee. This extra torque is a burden, stressing the bones of and around the knee. In contrast to body height, which may change with age, knee height is constant, making knee height a more appropriate metric of stature.
For this study, a sample of residents 60 years and older living in Beijing, China was selected at random. Subjects answered questions about joint symptoms to assess pain levels and radiographs of their knees were taken. A knee joint with a Kellgren/Lawrence grade of 2 or higher was defined as having radiographic OA. The Kellgren Lawrence scale was first developed in 1957; a 2 on this scale indicates minimal yet present osteophytes, while higher levels indicate higher levels and greater narrowing of joint space. Following the assessment, the subjects were considered to have symptomatic OA when both radiographic OA and self-reported pain were present in the same joint. For knee height, a sliding broad-blade caliper to measure each personŐs right leg. Later, logistic regression analyses were calculated to assess whether knee height was associated with existing radiographic and symptomatic OA.
A total of 1,006 men, the mean age being approximately 68 years, and 1,500 women, 67 years old on average, participated in this study. Higher knee height was found to be associated with an increasing prevalence of both radiographic and symptomatic OA, especially among Chinese women. In contrast to Chinese men, increasing knee height was significantly associated with symptomatic knee OA in women, with women in the highest quartile of knee height demonstrating a 2.2 fold greater odds of symptomatic knee OA than women in the lowest quartile of knee height. Also among women with knee pain, higher knee height was associated with more severe knee pain independently of the severity of radiographic OA.
The researchers suggest that a longitudinal study is certainly appropriate to further examine the risk of taller stature on the progression of OA symptoms. In particular, the factors contributing to increased knee pain and symptomatic knee OA in taller women but not in men require further study and exploration.
Article References
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15880346&dopt=Citation, site accessed on 07/31/05
http://www.hopkins-arthritis.som.jhmi.edu/news-archive/2005/knee_height_knee_pain.html, site accessed on 07/31/05
http://www.orthopaedic.ed.ac.uk/handoa/sld013.htm, site accessed on 07/31/05
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