There are two specific aims of this study: to identify asymmetries in knee muscle strength, proprioception and dynamic joint loading in older patients with symptomatic, radiographically mild to moderate unilateral hip osteoarthritis without clinical knee osteoarthritis; and to explore the relationships of quadriceps muscle strength and proprioception to dynamic knee loading.

We are looking to enroll a total of 90 patients who are at least 40 years of age with symptomatic unilateral hip osteoarthritis of mild to moderate radiographic severity. Participants must have symptoms of mild to moderate hip osteoarthritis for more than one year according to the criteria of the American College of Rheumatology (and a radiographic criteria grade of 2 to 3 out of a maximum of 4). 

All patients will be interviewed and examined by the principal investigator. 

All subjects will have X-rays of the hips and knees and need to complete several questionnaires and a gait analysis. A gait analysis examines participants walking at several different speeds in front of a series of cameras and performing other activities of daily living, such as climbing stairs or rising from a chair.  The study doctor or study staff will test knee strength and will measure the sense of limb position and movements using a Cybex II (machine for measuring muscle strength). 

You may be eligible to participate in this study if you:

• Are at least 40 years of age
• Have been diagnosed with unilateral, mild to moderate hip osteoarthritis with a K-L X-ray grade of 2 to 3
• Do not have inflammatory rheumatic disease, diabetes mellitus or neurologic disease; or have had previous surgery or trauma to the lower extremity
• Are independently ambulatory (in order to perform the gait testing)

This is a partial list of eligibility requirements.