Dr Andrew Arnold discusses the two types of leg length differences, structural and functional.
Did you know that it is possible to have one leg longer than the other? In fact, not only is it possible, but it is also incredibly common, affecting approximately 80% of the population. But what causes it to happen and what are the effects of having a leg length discrepancy (or LLD)? Read on to learn more…
Leg length discrepancy is a condition where there is a noticeable difference in length between both lower limbs. This condition is also known as ‘unequal leg length’ or ‘leg length inequality’ (LLI).
Types of leg length discrepancy
There are two types of unequal leg length:
- Structural: Also referred to as ‘anatomical’. This type occurs because there is a physical difference in the length of the bones of the leg. The difference in length can either affect the thigh-bone (aka femur), or the shin-bone (aka tibia). The difference may be present from birth due to a developmental anomaly, or it may be acquired throughout life. Acquired causes of structural LLD include fractures, having a joint replacement or from the effect of a degenerative disease.
Many of us have very small differences between the lengths of our leg bones. If you were to measure 100 people in the street, approximately 90% of them would have differences in either the length of their thigh or shin-bones. Differences are usually minimal and have little to no effect on the gross structure or function of the body. Others have a greater difference which can lead to problems associated with posture and mobility.
- Functional: This type occurs not because of differences in bony length, but for all other reasons. The causes mainly stem from the body mechanics not functioning quite right, affecting the lower limb, which may include one sided muscle weakness/shortening, changes in joint positioning of the pelvis, hip, knee, ankle or foot, or excessively mobile joints. A common cause of functional LLD is a rotated (or ‘torsioned’) pelvis.
Effects of LLD
A very small LLD is easily absorbed by the body because the body is capable of making slight shifts and adjustments to compensate for the inequality from side to side. When an LLD is minimal there may be no symptoms at all. A person may be able to walk, jog, run, jump and go about their everyday lives with no impact from the LLD whatsoever.
When an LLD measures approximately 2cm (or more), the body finds it more difficult to deal with and this is when you may experience symptoms of pain and movement dysfunction, where you may need professional help (Hi! Did we hear a cry for help?!).
When you have one limb longer than the other, the forces exerted on the body when you move are absorbed unevenly, and more importantly, excessively on the lengthened side. This causes overloading of the lower limb joints, including the hip and knee, as well as joints further up the chain in the lower spine. It is thought this excessive loading over time can be a contributor to the development of osteoarthritis (OA) in these joints.
Treatment of LLD depends on the type and cause. No hands-on techniques or exercises will be able to change the length of a bone. Moderate to severe structural LLD’s are commonly treated using external supports, such as orthotics or built-up shoes. Where a visit to the chiro proves useful is when you have a functional LLD. We can use our magic touch and expert knowledge of the body and how it moves to loosen you up, untwist you and have you moving straight and even again.
Low back, hip or knee pain? It might be due to an LLD. At Cranbourne Family Chiropractic and Wellness Centre, we can help! Come and see us today!
- Murray, KJ. et al. 2015. Leg length discrepancy and osteoarthritis in the knee, hip and lumbar spine. The Journal of the Canadian Chiropractic Association. 59 (3). 226-237. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4593034/
- 2020. Leg length discrepancy. [Online]. Available from: https://www.physio-pedia.com/Leg_Length_Discrepancy. [Accessed 04 Oct 2020]
- American Academy of Orthopaedic Surgeons. 2016. Limb length discrepancy. [Online]. Available from: https://orthoinfo.aaos.org/en/diseases–conditions/limb-length-discrepancy. [Accessed 04 Oct 2020]
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