ARTHRITIS & RHEUMATISM Vol. 56, No. 9, September 2007, pp 2993–2998 DOI 10.1002/art.22850 © 2007, American College of Rheumatology Varus Foot Alignment and Hip Conditions in Older Adults K. Douglas Gross, 1 Jingbo Niu, 2 Yu Qing Zhang, 2 David T. Felson, 2 Christine McLennan, 2 Marian T. Hannan, 3 Kenneth G. Holt, 4 and David J. Hunter 2 Objective. Mechanical strain on the hip can result from varus malalignment of the foot. This study was undertaken to explore the cross-sectional relationship between varus foot alignment and hip conditions in a population of older adults. Methods. The Framingham Osteoarthritis Study cohort consists of a population-based sample of older adults. Within this sample, we measured forefoot and rearfoot frontal plane alignment using photographs of a non–weight-bearing view of both feet of 385 men and women (mean age 63.1 years). Each foot segment was categorized according to the distribution of forefoot and rearfoot alignment among cases of ipsilateral hip pain, trochanter tenderness, hip pain or tenderness, and total hip replacement (THR). The relationship of foot align- ment to these conditions was examined using logistic regression and generalized estimating equations, ad- justing for age, body mass index, sex, and physical activity. Results. The mean  SD rearfoot varus alignment was 0.7  5.5 degrees, and the mean  SD forefoot varus alignment was 9.9  9.9 degrees. Subjects in the highest category of forefoot varus alignment had 1.8 times the odds of having ipsilateral hip pain (P for trend  0.06), 1.9 times the odds of having hip pain or tenderness (P for trend < 0.01), and 5.1 times the odds of having undergone THR (P for trend  0.04) com- pared with those in the lowest category. No significant associations were found between rearfoot varus align- ment and any hip conditions. Conclusion. Forefoot varus malalignment may be associated with ipsilateral hip pain or tenderness and THR in older adults. These findings have implications for treatment, since this risk factor is potentially mod- ifiable with foot orthoses. Approximately 14% of adults 60 years of age report having hip pain on most days (1). Despite this prevalence, we know little about the etiology of most hip conditions. Medical management remains largely depen- dent on palliative drugs and, in the case of radiographic findings, total hip replacement (THR). In spite of costly treatment, some pain or tenderness often persists. In the effort to develop safer, cheaper, and more effective treatment options, it is essential that we deepen our appreciation of etiologic pathways and draw attention to modifiable risk factors. One potentially important source of repetitive stress on the hip is varus foot malalignment. Forefoot and rearfoot varus malalignments are frontal plane malalignments that alter the foot’s orientation to the ground. Excessive forefoot or rearfoot varus alignment can disrupt the closed chain functioning of the lower limb and strain proximal tissues. Excessive varus align- ment of the forefoot has been associated with overuse injuries of the foot (2), shank (3), and knee (4). Biome- chanical models (5,6) anticipate that varus malalignment may present even greater risk for overload of the hip. However, no previous studies have evaluated the rela- tionship of forefoot or rearfoot varus alignment to hip conditions. Moreover, all previous studies of foot align- ment and proximal pain (2–4) have sampled younger adults, in whom the risk of hip pain is minimal. The purpose of this study was to assess the relationship of Supported by the Boston University Aging Research Center Pilot Project Grant program. The Framingham Osteoarthritis Study is supported by the NIH (grants AR-47785 and AG-18393). The Fra- mingham Heart Study also is supported by the NIH (grant N01-HC- 25195 from the National Heart, Lung, and Blood Institute). 1 K. Douglas Gross, PT, ScD: Boston University School of Medicine, and Boston University Sargent College of Health and Rehabilitation Sciences, Boston, Massachusetts; 2 Jingbo Niu, DSc, Yu Qing Zhang, DSc, David T. Felson, MD, MPH, Christine McLennan, MSc, David J. Hunter, MBBS, PhD: Boston University School of Medicine, Boston, Massachusetts; 3 Marian T. Hannan, MPH, DSc: Institute for Aging Research, Hebrew Senior Life, and Division on Aging, Harvard Medical School, Boston, Massachusetts; 4 Kenneth G. Holt, PT, PhD: Boston University Sargent College of Health and Rehabilitation Sciences, Boston, Massachusetts. Address correspondence and reprint requests to K. Douglas Gross, PT, ScD, Boston University School of Medicine, 650 Albany Street, Room X200, Boston, MA 02118. E-mail: grossd@bu.edu. Submitted for publication March 28, 2006; accepted in revised form May 18, 2007. 2993