Are your legs the same length or is one shorter or longer than the other? It’s possible that you have a leg length discrepancy and aren’t aware of it. Slight differences in length between the right and left leg might not be noticeable or increase the risk of injury or orthopedic problems. However, a significant difference in leg length between the two sides may increase the risk of orthopedic issues, especially if it is pronounced.
How common is this problem? Seventy percent of the population has a discrepancy in leg length. However, the difference in length between the two legs may be so slight that it’s unlikely to cause problems. In fact, orthopedists don’t agree about when a leg length discrepancy needs treatment. But research suggests that even a modest difference in leg length may increase the risk of orthopedic problems.
Leg Length Discrepancy and Arthritis
People who have one leg that’s longer than the other by only 2 centimeters may be at higher risk of developing knee and hip osteoarthritis. Primarily a degenerative form of arthritis, some cases of osteoarthritis also have an inflammatory component. Since it’s mainly a degenerative joint disease, it’s not surprising that the incidence increases with age, but your anatomy may also play a role in whether you develop arthritis of the hips or knees. According to a study, having a leg length discrepancy of as little as 2 centimeters increases the risk of hip and knee osteoarthritis and may also predict the severity of this form of arthritis if it develops.
A 2-centimeter leg length discrepancy is equivalent to a difference in leg length of around ¾ of an inch. When there’s this degree of difference in leg length, it causes greater asymmetry when walking and it’s the longer leg that bears more weight. Over time, the extra burden can cause degeneration of the joint in the knee or hip on that side. However, some orthopedists recommend correcting leg lengths as minor as 1/8 of an inch, especially if the person participates in sports or spends a lot of time on their feet.
The best scenario is that you discover a leg length discrepancy early in life. However, many people reach adulthood with a significant difference in leg length and are unaware of it. In fact, the journal Podiatry Today points out that leg length differences are one of the top three causes of running injuries and also contribute to other training injuries.
One clue as to a possible discrepancy in leg length is repeated overuse injuries, especially ones that fail to respond to treatment. If you do any type of training, you’ve probably been sidelined by one or more overuse injuries, especially if you don’t vary your training, but a repeated history of back, hip, or knee injuries should raise a red flag. Differences in leg length place added stress on the entire posterior chain when you run or walk. Leg length discrepancy can contribute to orthopedic problems such as medial tibial stress syndrome, patellofemoral pain syndrome, patellar tendonitis, and foot problems, including plantar fasciitis. Having a significant difference in leg length can also trigger back pain due to unequal joint angles created by asymmetrical lumbosacral facet joint angles. Such inequality increases the risk of arthritis in the lumbar and sacral portions of the spine.
What Causes a Difference in Leg Length?
A structural leg length discrepancy can originate from childhood and come from one or more bones in the leg being shorter one side. For example, an injury to the growth plate of a bone in the leg in a child can stop one leg from growing before the growth process is completed. Some children are also born with a congenital difference in the length of the leg bones on each side. Spinal problems such as scoliosis or a history of a bone fracture are also possible contributors.
Functional leg length discrepancies are common with scoliosis and are characterized by an asymmetrical pelvis where one iliac crest is higher than the other. People who have had trauma to the hip can develop pelvic asymmetry. You can determine if you have an asymmetrical pelvis by placing one hand on each of your anterior iliac crests. If one hand is higher than the other, there’s asymmetry, also known as pelvic obliquity. Sometimes, leg length discrepancy is caused by an inflexible pelvis or lack of flexibility in the feet or ankles. Weakness in these areas can also cause a functional change in leg length.
Treatment of Differences in Leg Length
If you have a history of repeated overuse injuries or suspect you have a difference in leg length, it’s best to see a sports medicine physician or orthopedist for evaluation. They can determine if you have a discrepancy, how significant it is, and whether it’s functional or structural. Depending upon how severe it is, how physically active you are, whether you have back pain, and if you have repeated overuse injuries, they may or may not recommend treatment.
What does treatment consist of? In cases of structural leg length discrepancies, you may only need an orthotic that you place in your shoe or a heel lift to correct the discrepancy and improve your gait. If the cause is functional, the condition may respond to physical therapy, particularly stretching, to correct the pelvic imbalance.
When physicians discover a leg length discrepancy of 2 centimeters or more during childhood, they sometimes recommend surgery. It’s difficult to get an exact measure of the discrepancy through a physical exam, so some physicians recommend a CT scan. The surgery involves stapling the growth plate on the longer bone to stop it from growing. This will allow the shorter leg to catch up. Of course, it’s too late to do that in an adult! Still, if you have repeated injuries or chronic back, hip, or knee pain, find out whether a leg length discrepancy is contributing. A heel lift or physical therapy may help you lower your risk of knee arthritis as well as the risk of training injuries.
References:
· WebMD.com. “Having Shorter Leg Ups Arthritis Risk”
· Podiatry Today. “Detecting and Treating Leg Length Discrepancies”
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