Gender Specific Joints: The Wave of the Future

Jennifer Wider, M.D.
Society for Women’s Health Research
September 21, 2006

Many of us take our knees for granted without realizing how much strain is placed on them from everyday activities. As we walk, run, bend, twist and hustle, the knee -- which is the largest joint in the body -- takes a regular beating. But for the more than five million people who visit orthopedic surgeons each year for knee problems, these intricate, hinge-like joints can become more than a nuisance.

Knee problems can be debilitating and can result from a variety of things ranging from injuries to degenerative conditions to arthritis. According to the American Academy of Orthopedic Surgeons, joint replacement surgery is more common in the knee joint than any other joint in the body. Knee replacement surgery can alleviate pain and help to restore function in a damaged or diseased joint.

Recently, knee implants designed specifically for women have made their way into operating rooms around the country. The implants of the past were designed based on men’s knees. Often, smaller implants were used for women, but “a small percentage of women complained of persistent pain around the kneecap area,” according to Dr. Robert Bucholz, M.D., chairman of orthopedic surgery at University of Texas Southwestern in Dallas. 

Knee-related problems seem to affect women more often than men. One study in Europe found that women had more knee-related complaints than men at earlier ages. The same study revealed an increase in complaints as women approached and reached menopause, suggesting that hormonal fluctuations may play a role. 

One of the most common reasons for knee replacement surgery is damage to the joint from osteoarthritis, a degenerative condition caused by the breakdown and loss of cartilage in one or more joints in the body. The result is often pain, limited motion and partial loss of function. It is the most common type of arthritis and affects women over the age of 45 more often than men in the same age-range according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases.

Other studies have shown that female athletes are more likely to experience an injury of the anterior cruciate ligament (ACL) than male athletes who participate in the same sports. Researchers theorize that biological sex differences, including hormones, neuromuscular control and anatomical differences may explain the discrepancy.

“The distal femur of women’s knees is narrow and has less bony thickness to its anterior trough,” Bucholz said, referring to the bone that runs through the thigh. These anatomical gender differences mean that a knee replacement for men may not be optimal for women. “The pull of the quadriceps muscle is also different.”

Many in the field of orthopedics feel that these changes addressing differences between woman and men are long overdue. Because of the large number of people undergoing knee replacement surgery each year, and because women represent the majority of patients, sex-specific joint replacements may be the wave of the future. 

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Sources

Paradowski, P.T., et al. Knee complaints vary with age and gender in the adult population. Population-based reference data for the Knee injury and Osteoarthritis Outcome Score (KOOS). BMC Musculoskelet Disord. 2006. 7(1): p. 38.

Cowley, H.R., et al. Differences in neuromuscular strategies between landing and cutting tasks in female basketball and soccer athletes. J Athl Train. 2006. 41(1): p. 67-73.

Heitz, N.A., et al. Hormonal Changes Throughout the Menstrual Cycle and Increased Anterior Cruciate Ligament Laxity in Females. J Athl Train. 1999. 34(2): p. 144-149.

© September 21, 2006 Society for Women's Health Research