Why Does One Leg Feel Longer Than the Other?
One leg can feel longer for two reasons. The bones may really differ in length. Or a tilt in the pelvis or spine may make the legs look uneven. A true difference means one bone is actually shorter. An apparent difference means the bones are the same length, but something higher up in the body pushes them out of line. Standing imaging is the most reliable way to tell which type you have.
Key points
- A leg length discrepancy can be a true bone difference, or an apparent one caused by the position of the pelvis or spine.
- Pain often shows up in the back, hip or knee on the side opposite the shorter leg, because the body compensates.
- Scans taken lying down can miss alignment shifts that only appear when you stand and bear weight.
- An EOS standing scan measures both legs from hip to ankle in a single image, under weight, with about 90% less radiation than a standard X-ray.
- Knowing the type and size of the difference helps your clinician choose the right next step.
Most people have a small difference between their legs. It is surprisingly common and often causes no trouble at all. But when the difference is large enough, or when your body cannot adjust to it smoothly, you may start to notice pain, tiredness or an uneven walk that gets worse over time.
The tricky part is working out what is really going on. Is one bone actually shorter? Or is a tilted pelvis making it seem that way? The answer changes what you do about it.
What is the difference between a true and an apparent leg length discrepancy?
A true discrepancy means the thigh bone or shin bone on one side is physically shorter than on the other side. An apparent discrepancy means the bones are the same length, but something else makes one leg sit higher or lower than the other. This is usually a pelvic tilt, a curved spine or tight muscles around the hip.
A true difference is structural. One bone grew shorter, or was made shorter by a fracture, surgery or a growth-plate problem in childhood. The bones themselves are unequal. This is confirmed by measuring the full leg on imaging taken while you stand.
An apparent difference is positional. The bones are the same length, but a tilted pelvis or uneven hips make one leg work as though it is shorter. Muscle imbalance, scoliosis or a stiff joint can all cause this effect. Standing imaging shows the tilt that a tape-measure test in the clinic may miss.
Many people have a mix of both. A small true difference can make the pelvis tilt, which then adds an apparent difference on top. This is why measuring the whole chain, from the ground up, matters so much.
How do I know if one leg is longer than the other?
You may notice everyday clues before a clinician ever measures you. These are the most common signs.
One trouser leg drags on the ground or needs shortening more than the other, even on straight-cut trousers.
The sole of one shoe wears down faster, especially on the outer edge.
Your pelvis dips clearly to one side with every step, so your walk looks uneven.
An ache on one side of the lower back or hip, often worse after long walks or standing.
The longer leg often takes more load. This can lead to knee tiredness or pain that seems to have no clear reason.
None of these signs on its own proves a leg length difference. But if you recognise two or three together, it is worth looking into.
What causes uneven legs?
Several things can make one leg sit higher or shorter than the other. Some are present from birth. Others develop over time.
One leg may simply grow slightly more than the other during childhood.
A broken thigh or shin bone can heal slightly shorter if the broken pieces overlap.
Joint replacement surgery can slightly change the working length of the leg.
A tilted pelvis or a curve in the spine shifts the hip sockets, creating an apparent difference.
Tight hip flexors or adductors on one side can pull the pelvis down, copying the effect of a shorter leg.
Your body is a connected chain from your feet to your head. When one link changes, other links compensate. That is why pain from a leg length difference can show up in your back, your opposite hip or even your neck, far from the actual problem.
Why does standing imaging matter for a leg length difference?
Standing imaging captures how your body really works under gravity. When you lie down for a standard X-ray, CT scan or MRI, your muscles relax and your pelvis flattens. The alignment shift that causes your symptoms can then disappear from the picture completely.
An EOS scan takes a single, full-length image of your skeleton from your ankles to your hips (or higher) while you stand naturally. This lets the radiographer see the true position of every bone under real load. At ScanAlign, full-body standing imaging, we use EOS technology that gives about 90% less radiation than a standard X-ray, around ten times less.
For a closer look at how EOS captures the whole leg in one calibrated image, read more about EOS scanning for leg length discrepancy.
Want to find out whether a standing scan could explain your symptoms before you plan a trip to London?
Book a free video consultationWhen MRI is the better choice. EOS is excellent at showing bones, joints and overall alignment. If your clinician suspects a soft-tissue problem, such as a disc problem, nerve compression or a muscle tear, MRI is usually the more suitable test. The two scans answer different questions, and sometimes they work well together.
What can be done about a leg length difference?
The right next step depends entirely on the type and size of the difference, and on whether it is causing symptoms. ScanAlign is a diagnostic imaging clinic, not a treatment provider. Our role is to give you and your clinician an accurate picture of what is happening.
Once the measurements are clear, your treating clinician may consider options such as a heel lift, physiotherapy to address pelvic tilt or, in more significant cases, a referral to an orthopaedic specialist. The key point is that the imaging comes first. Without it, any approach is guesswork.
So before you start a treatment, or change the one you are on, it is worth getting a detailed diagnosis. Knowing whether the cause sits in your pelvis, your legs or your spine changes what will actually help.
If you would like to book a leg length measurement, you can start with a free video consultation from home to discuss whether a standing scan is right for you.
Important. If you have sudden numbness, weakness in one or both legs, or any loss of bladder or bowel control, get urgent medical help. Contact your doctor straight away or go to your nearest emergency department. These symptoms need immediate assessment, not a routine scan.
Frequently asked questions
Very common. Studies suggest that most adults have some measurable difference between their legs. In most cases the difference is small and causes no problems at all.
Yes. A tilted pelvis moves one hip socket higher than the other, so the leg on that side works as though it is shorter. This is called an apparent leg length discrepancy. Standing imaging can show the tilt clearly.
A tape-measure test in the clinic gives a rough guide, but it depends on finding exact bony landmarks through skin and muscle. The position of the pelvis can also affect it. Imaging while standing is more precise, because it measures the bones directly under load.
No. ScanAlign is a private, self-pay clinic. You can refer yourself. We recommend starting with a free video consultation so we can check that a standing scan is the right test for you.
An EOS scan uses about 90% less radiation than a standard X-ray, around ten times less. This makes it one of the lowest-dose options available for full-length skeletal imaging.
It can. When one leg is effectively shorter, the pelvis tilts and the spine curves to compensate. Over time, this puts extra strain on the lower back muscles, joints and discs, which can contribute to pain.
When you lie down, gravity no longer acts on your skeleton in the same way. Your muscles relax, your pelvis can flatten out, and any tilt or compensation your body uses while upright disappears from the image. A standing scan captures your real, weight-bearing alignment.
The price for patients travelling from abroad is confirmed during the free video consultation. You can read more on our FAQs and cost page.
Absolutely. Uneven hips and a leg length difference often go together. One can cause the other, or both can come from the same underlying alignment problem. A full standing image helps sort out how they are linked.
You speak with a member of the team, who will ask about your symptoms and history. They will tell you whether a standing EOS scan is likely to be useful, and explain what the appointment involves. There is no obligation to book.
Find out what is really going on
A standing EOS scan can measure both legs precisely, under your own body weight, and show whether your pelvis or spine is compensating. Start with a free, no-obligation video consultation from home.
Book a free video consultationSources
- Knutson, G.A. (2005). Anatomic and functional leg-length inequality: a review and recommendation for clinical decision-making. Chiropractic & Osteopathy, 13, 11.
- Sabharwal, S. & Kumar, A. (2008). Methods for assessing leg length discrepancy. Clinical Orthopaedics and Related Research, 466(12), 2910–2922.
- NHS. Lower limb length discrepancy overview. NHS Conditions. Available at: nhs.uk.
Written by Abbas Dhami (Specialist Diagnostic Radiographer)
This page is general information and not a diagnosis.
ScanAlign is the trading name of CoreMed Solutions Ltd and operates under The Harley Street Hospital's CQC licence.