Do Floor Activities Increase Knee Osteoarthritis?

Osteoarthritis (OA) of the knee is common in older adults around the world. In this study from Thailand, researchers explore the link between lifelong floor activities and knee OA. Floor activities included squatting, lotus position, side-knee bending, and kneeling. Side-knee bending is sitting on the floor with both knees bent and one leg (hip) turned in and the other rotated out.

Nurses conducted a survey of 288 women and 288 men from southern Thailand who were over the age of 40. Average daily duration of these four floor activities was recorded. Based on the number of minutes per day in each position, the researchers calculated the average lifetime floor activity exposure for each person.

Other data collected included age, body mass index (BMI), and tobacco use (smoking). They found the lotus position was the most common floor activity. Side-knee bending was next. Average time in floor activity each day was about one hour for all subjects.

There was a positive link between lifetime floor activity exposure and knee OA. People who spent the most time in squatting, lotus, and side-knee bending had twice the risk of knee pain and OA. The risk of OA increased with age in women who were overweight.

Using X-rays, the researchers matched the type of arthritic problem with the positions used most often. The effect of these positions appears to be on the entire joint, not just one side or the other.

The authors suggest these finding show that habitual flexed positions of the knees can overload the joint. The result is damage to the meniscus and/or the joint cartilage. All of these changes may lead to OA. Changing or avoiding floor activities may help reduce the risk of knee OA in this group of southeast Asians.