# Leg length difference

> One leg is slightly longer than the other. Small differences are common and usually harmless; a heel lift or shoe insert is the usual first step.

Guide in [Foot shape and posture](https://footanklelowerlimb.com.au/learn/topics/foot-shape-and-posture), from Foot Ankle Lower Limb: https://footanklelowerlimb.com.au/learn/leg-length-difference
Reviewed by Andrew Schox, BSc(Hons) PGradDipPod MPod (Podiatrist) on 1 November 2026.
Next review by 1 November 2027.

- **Small differences are common and usually harmless.** Nearly everyone has one leg slightly longer than the other.
- **Structural and functional differences are not the same.** One lies in the actual length of the bones; the other is an unevenness that is seen or felt while the bones are alike.
- **Treatment usually starts with a lift in the shoe,** sized to the measured difference.
- **Surgery is an elective choice,** kept for larger differences.

## What is a leg length difference, and how common is it?

A leg length difference (leg length discrepancy) means the left and right legs are different lengths [1]. Nearly everyone has a small one, usually under 1 cm, and it usually needs no action on its own [1][2].

A structural difference means the leg bones really are different lengths [1][3]. A functional difference means the legs look uneven, or feel uneven to the person, but the bones match [3][4]. Tight soft tissues, stiff joints or a tilted pelvis can cause it [5].

Walking may change above 1 cm [6]. A difference of 2 cm or more may cause problems, and over 2 cm is rare, about 1 in 1000 [7]. Where it starts to matter isn't agreed [6]. Up to 90% of children have some difference, but one that matters is rare [8].

## What causes a leg length difference, and who gets it?

A structural difference can be present from birth or develop later [3]. Differences usually arise during childhood growth, and a fracture or a problem with a growth plate (the area at the end of a bone that controls how long it grows) may cause unequal leg lengths [1]. If one bone grows slowly or stops growing while its pair keeps going, a difference results [9]. Infection and past injury can also cause one [3].

Functional differences can come from tight soft tissues, stiff joints, a tilted pelvis or the way the foot works [5]. Most structural differences have no known cause [10]. It isn't due to anything you did.

## What does a leg length difference feel like, and how is it diagnosed?

In children, a leg length difference is often not noticed until their walking changes, pain appears, or function is limited [8]. It can appear as a limp or toe-walking, back, hip, knee or ankle pain, or a sloping shoulder line [3].

The most common way to measure is with a tape measure from the front hip bone to the inside ankle bone, comparing left and right [1]. Using the average of at least 2–3 measurements is advised [3]. A tape measure and standing blocks are useful screening tools, though it isn't clear how their accuracy compares with imaging such as CT [3][11]. A standing X-ray is the most accurate method, though it is seldom needed [1].

Pain near the area doesn't prove the difference is the cause, so it's worth looking for other reasons too [12][4].

## What helps first?

A small difference usually needs no treatment. The usual first step is a heel lift, shoe insert or insole (a lift) matched to a difference that has been measured in millimetres [1][2][10]. For differences up to 2 cm, a lift inside the shoe may be used [10]. Larger differences may need the shoe sole built up [1]. Wear the lift with supportive shoes. If you're on your feet for work, it's worth talking about correcting the difference [1].

Lifts may ease pain and improve how you move for many adults with painful joint or muscle problems [13]. How well they work is uncertain, though, and the best amount of correction isn't clear yet [13][14]. Treatment is always your choice [15].

A child's hip, thigh or knee pain shouldn't be put down to leg length.

## What helps if a lift isn't enough?

If a lift hasn't been enough, or the difference is large, a surgeon can talk through the options with you. Surgery is always an elective choice, and the size of the difference alone doesn't decide it [15]. A difference of more than 5–6 cm may need surgery [1].

In a growing child, closing the growth plate of the longer leg slows its growth, and this has been used for predicted differences of 2–5 cm [16]. Lengthening the shorter leg is another option [17].

Surgery carries real risks of complications, so ask for clear counselling first [7][16][17].

## What is the outlook, and can it come back?

The outlook depends on the size and cause of the difference, and on age. Small differences mostly stay harmless, while 2 cm or more is more likely to cause problems [7]. In children, minor differences are usually benign, but a larger one can point to an underlying cause [8].

A difference has been linked with low back pain, scoliosis and hip or knee osteoarthritis [13]. These are associations, so a difference shouldn't be assumed to explain new or worsening symptoms [6][13].

If your child is still growing, it helps to watch the difference over time. It isn't clear yet whether lifts or other treatments change the long-term outcome, or stop a difference returning or progressing [14].

## What can make it serious?

- Your child walks on tiptoe and also can't stand with heels down, has one side different from the other, has very bulky calves, or seems unusually stiff or unsteady.
- You have lost weight without trying.
- You have pain at night or at rest that doesn't settle.
- Your child has a limp that hasn't improved after a week, limps without pain, or doesn't want to put weight on their foot.
- Your child has a fever with a limp or a painful, red, hot or swollen joint, or seems very unwell with foot or leg pain.
- Your child suddenly has severe pain in one joint and is limping.

## Common questions

### Can a leg length difference cause back, hip or knee pain?

It has been linked with back pain, sciatic nerve pain, changes in walking and joint instability, but a link doesn't prove the difference is the cause. Pain in these areas can have other reasons, so it shouldn't be assumed to come from the difference.

### Why do I feel uneven after a hip replacement?

After a hip replacement, adults often notice a difference of more than 10 mm. Sometimes the legs measure the same and it is a sensation of being uneven. A tilted pelvis or tight buttock muscles after surgery can add to that feeling. It can affect recovery and how happy you are with the result if you have symptoms.

### How much leg length difference is too much?

There is no agreed size. Under 1 cm is normal and usually needs no action. Some people's walking may change once the difference passes 1 cm, and the chance of problems rises from about 2 cm. A measurement alone doesn't decide treatment; how you feel and move matters too. A podiatrist can help you work out what suits you.

## Further reading

- [Leg length difference on Clindice](https://clindice.com/leg-length-difference)
- [Leg Length Discrepancy](https://kidshealth.org/en/parents/leg-length-discrepancy.html), KidsHealth (Nemours)
- [Leg lengthening and shortening: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/002965.htm), MedlinePlus
- [The Radiological X-ray Exam: Leg Length Measurements](https://www.esht.nhs.uk/wp-content/uploads/2022/01/0951.pdf), NHS
- [Limping in children](https://www.nhs.uk/symptoms/limp-in-children/), NHS
- [Green Amber Infection (SA/OM) red Flags Malignancy red flags](https://frimley-healthiertogether.nhs.uk/application/files/1916/2385/1021/CS45385_NHS_LIMP_Pathway_Primary_and_Community_Care__April_2021.pdf), NHS

## Sources

1. ORTHOPAEDIC · vrab-tacra.gc.ca. https://www.vrab-tacra.gc.ca/sites/default/files/2022-01/ORTHO2019EN.pdf
2. Leg length discrepancy · Dorset HealthCare University NHS Foundation Trust. https://www.dorsethealthcare.nhs.uk/our-services-and-sites/physical-health/orthotics-insoles-braces-and-supports/leg-length-discrepancy
3. Overview and Spinal Implications of Leg Length Discrepancy: Narrative Review · Applebaum A, Nessim A, Cho W · Clinics in Orthopedic Surgery · 2021. https://doi.org/10.4055/cios20224
4. Leg Length Discrepancy After Total Hip Arthroplasty: A Review of Clinical Assessments, Imaging Diagnostics, and Medico-Legal Implications · Bianco Prevot L, Tronconi LP, Bolcato V et al. · Healthcare (Basel, Switzerland) · 2025. https://doi.org/10.3390/healthcare13121358
5. Assessment of Pediatric Limb Length Inequality · Wynes J, Schupp A · Clinics in Podiatric Medicine and Surgery · 2022. https://doi.org/10.1016/j.cpm.2021.09.004
6. Relationship and significance of gait deviations associated with limb length discrepancy: A systematic review · Khamis S, Carmeli E · Gait & Posture · 2017. https://doi.org/10.1016/j.gaitpost.2017.05.028
7. Are percutaneous epiphysiodesis and Phemister technique effective in the treatment of leg-length discrepancy? A systematic review · Tirta M, Hjorth MH, Jepsen JF et al. · Journal of Pediatric Orthopedics · 2024. https://doi.org/10.1097/bpb.0000000000001160
8. Something Doesn't Look Right: Recognizing and Managing Limb-Length Discrepancy · Marsh D, Said M, Mackey C et al. · Pediatrics in Review · 2026. https://doi.org/10.1542/pir.2025-006863
9. Limb length discrepency - Limb Reconstruction - Oxford University Hospitals · ouh.nhs.uk. https://www.ouh.nhs.uk/limbreconstruction/information/conditions/limb-length-discrepancy/
10. Scoliosis and Lower Limb Inequality: To Lift or Not to Lift, That Is the Question · Colonna S, Casacci F, Borghi C · Cureus · 2024. https://doi.org/10.7759/cureus.58443
11. Methods for assessing leg length discrepancy · Sabharwal S, Kumar A · Clinical Orthopaedics and Related Research · 2008. https://doi.org/10.1007/s11999-008-0524-9
12. Anatomic and functional leg-length inequality: a review and recommendation for clinical decision-making. Part I, anatomic leg-length inequality: prevalence, magnitude, effects and clinical significance · Knutson GA · Chiropractic & Osteopathy · 2005. https://doi.org/10.1186/1746-1340-13-11
13. Shoe Lifts for Leg Length Discrepancy in Adults With Common Painful Musculoskeletal Conditions: A Systematic Review of the Literature · Campbell TM, Ghaedi BB, Ghogomu ET et al. · Archives of Physical Medicine and Rehabilitation · 2018. https://doi.org/10.1016/j.apmr.2017.10.027
14. Leg Length Discrepancy: The Natural History (And What Do We Really Know) · Gordon JE, Davis LE · Journal of Pediatric Orthopedics · 2019. https://doi.org/10.1097/bpo.0000000000001396
15. Leg Length Discrepancy- Treatment Indications and Strategies · Vogt B, Gosheger G, Wirth T et al. · Deutsches Arzteblatt International · 2020. https://doi.org/10.3238/arztebl.2020.0405
16. Staples, tension-band plates, and percutaneous epiphysiodesis screws used for leg-length discrepancy treatment: a systematic review and proportional meta-analysis · Tirta M, Hjorth MH, Jepsen JF et al. · Acta Orthopaedica · 2024. https://doi.org/10.2340/17453674.2024.41104
17. Aesthetic lower limb lengthening techniques: a systematic review of efficacy, complications, and patient satisfaction · Giorgino R, Cornacchini J, Sillmann YM et al. · Journal of Orthopaedic Surgery and Research · 2025. https://doi.org/10.1186/s13018-025-05808-x

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This is general information, not advice about your own situation. To discuss your issues, book with one of our podiatrists. In an emergency, call 000.