Leg Length and Osteoarthritis

At least 20 million people in the United States have osteoarthritis. This prevalent type of arthritis is most simply age-related wear-and-tear of joints. As people age, cartilage that protects the body’s joints breaks down, leading to joint pain and stiffness. Osteoarthritis normally appears after middle age and can cause significant disability if not treated. However, most osteoarthritis is manageable with over-the-counter pain relief, physical therapy and exercise. Physical activity is also the most effective prevention for osteoarthritis; maintaining a healthy body weight and avoiding injury can reduce the risk of developing osteoarthritis. Now, a new study reported in the Annals of Internal Medicine claims that leg length discrepancy is a modifiable risk factor that mitigates the risk of osteoarthritis.

It is estimated that 85% of the world’s population has some sort of leg length discrepancy. This inequality in leg length can range from barely noticeable and less than 1 cm to 6 cm or more. The discrepancy may be functional or congenital, in which a person is born with an anatomical discrepancy in the length of their limbs. An acquired discrepancy, on the other hand, is related to injuries, conditions or diseases that alter the body’s posture and gait. Most often, acquired leg length discrepancy is related to pronation — a slight inward roll of the foot during a normal walking or running gait. Anatomical discrepancies can be corrected through surgical procedures, if the discrepancy is great and likely to cause considerable disability. Acquired discrepancies can often be corrected with athletic conditioning and stretching programs, or by wearing arch supports, heel lifts or similar orthotic devices. Whatever the cause of leg length inequality, it usually results on back and joint pain, depending on the severity of the discrepancy.

The authors of the Annals study examined more than 3000 individuals aged 50 to 79 years who had or were at risk for osteoarthritis. Leg length was measured using full-limb radiography. The results indicate that a greater leg length discrepancy is associated with more prevalent osteoarthritis of the knee. Participants with a leg length inequality of more than 1 cm showed signs of osteoarthritis on the radiographs more often than participants with a leg length discrepancy of less than 1 cm (53% vs. 36%); symptomatic radiographic osteoarthritis also occurred more frequently in the first group (30% vs. 17%). The participants with greater leg length discrepancies also experienced symptomatic (15% vs. 9%) and progressive osteoarthritis (29% vs. 24%) of the knee more often than the comparison group, with or without radiographic confirmation of osteoarthritis.

Several related studies have confirmed these findings, and also reported that osteoarthritis of the hip may be related to leg length discrepancy, though the findings failed to reach statistical significance. These analyses call for the investigation of leg-lengthening treatments related to osteoarthritis. However, the term “modifiable risk factor” that is used by many of the studies’ authors calls to mind things like eating habits, smoking or physical activity. Still, simple fixes for leg length inequality — physical activity and stretching — are themselves modifiable risk factors for osteoarthritis. It is likely not efficient to measure every persons’ limbs within a centimeter in order to recommend a healthy lifestyle to avoid osteoarthritis. And, as the current study shows, leg length equality does not guarantee freedom from osteoarthritis or joint pain.

While the findings are likely accurate, this study is another in a long line of reports that seems not to report ground-breaking findings, but, basically, confirms that everyone should be living an active, healthy lifestyle and get plenty of physical activity. There are certainly people who have congenital limb defects and discrepancies that are not modifiable without surgery or other structural interventions, but osteoarthritis of the knee is probably not the most significant concern facing these patients.

Stay healthy, get plenty of exercise, avoid injury as much as possible and prevent a multitude of age-related conditions and diseases.

References

Ahmad R, Sharma V, Sandhu H, Bishay M. Leg length discrepancy in total hip arthroplasty with the use of cemented and uncemented femoral stems. A prospective radiological study. Hip Int. Jul-Sep 2009;19(3):264-267.

Golightly, Y., Allen, K., Helmick, C., Renner, J., & Jordan, J. (2009). Symptoms of the knee and hip in individuals with and without limb length inequality Osteoarthritis and Cartilage, 17 (5), 596-600 DOI: 10.1016/j.joca.2008.11.005

Golightly, Y., Allen, K., Renner, J., Helmick, C., Salazar, A., & Jordan, J. (2007). Relationship of limb length inequality with radiographic knee and hip osteoarthritis Osteoarthritis and Cartilage, 15 (7), 824-829 DOI: 10.1016/j.joca.2007.01.009

Harvey WF, Yang M, Cooke TD, et al. Association of leg-length inequality with knee osteoarthritis: a cohort study. Ann Intern Med. Mar 2;152(5):287-295.