Recently, I have seen many cases of scoliosis caused by unequal length of the lower limbs. It is necessary to educate everyone.

What is scoliosis caused by unequal length of the lower limbs?

Generally, significant lower limb symptoms may only occur when the unequal length of the lower limbs exceeds 2cm, and surgical intervention may be necessary.

But when the length of the lower limbs is not equal to 0.5-2.0cm, the child will not experience any symptoms, but it can cause lumbar scoliosis. This type of scoliosis is called functional scoliosis caused by unequal length of the lower limbs (structural LLD). If functional scoliosis is not intervened for a long time, it will worsen during rapid growth and transform into structural scoliosis, increasing the difficulty of correction.

Is adolescent idiopathic scoliosis caused by unequal length of the lower limbs?

Let's talk about the answer first, no

The type of lumbar curvature in adolescent idiopathic scoliosis often causes pelvic tilt, but if a full length lower limb X-ray is taken, the difference in length between the two lower limbs generally does not exceed 0.3cm. The etiology of scoliosis caused by unequal length of the lower limbs is more clear and belongs to a type of secondary scoliosis.

Sekiya, T., Aota, Y., Yamada, K.et al.Evaluation of functional and structural leg length discrepancy in patients with adolescent idiopathic scoliosis using the EOS imaging system: a prospective comparative study.Scoliosis13, 7 (2018). https://scoliosisjournal.biomedcentral.com/articles/10.1186/s13013-018-0152-4

How to distinguish whether scoliosis is caused by unequal length of the lower limbs or idiopathic scoliosis?

If it is chest curvature, it is basically not caused by unequal length of the lower limbs;

If it is a waist bend, please follow the steps below to evaluate

1. Assess the posture. If the child's FBT test is negative and the angle of curvature is small, but there is a noticeable pelvic tilt, be careful that it may be caused by unequal length of the lower limbs. It should also be noted that 80% of the unequal length of the lower limbs is due to elongation of the right lower limb. If it is an abnormality on the left side, the possibility of unequal length of the lower limbs is not high.

The FBT test is negative, and there is a slight curvature of the waist. If there is a noticeable pelvic tilt in the posture, it should be highly suspected that the lower limbs are not of equal length

2. To evaluate X-rays, if the functional LLD (height distance between the femoral heads on both sides seen in pelvic coronal plain films) exceeds 1cm, it is necessary to take a full length lower limb X-ray to identify the presence of unequal length of the lower limbs.

Functional LLD (height distance between the femoral heads on both sides seen in pelvic coronal plain film) exceeding 1cm

Raczkowski JW, Daniszewska B, Zolynski K. Functional scoliosis caused by leg length discrepancy. Arch Med Sci. 2010 Jun 30;6(3):393-8. doi: 10.5114/aoms.2010.14262. PMID: 22371777; PMCID: PMC3282518.

3. Evaluate the full length film of both lower limbs. If the structural LLD (difference in length between the two lower limbs) exceeds 1cm, it can be basically determined that there is unequal length between the two lower limbs

If the structural LLD exceeds 1cm, it can be clearly defined as functional scoliosis caused by unequal length of the lower limbs

How to treat scoliosis caused by unequal length of lower limbs?

When the unequal length of the lower limbs is less than 2cm, internal raised insoles can be worn to correct scoliosis. After wearing corrective insoles, scoliosis will not be corrected immediately, and 80% will show some improvement within about one month. The unequal length of both lower limbs exceeds 2cm and may require surgical intervention.

Patients with structural scoliosis, large angle scoliosis, or concomitant chest curvature caused by long-term unequal length of the lower limbs may require rehabilitation training, brace treatment, etc. to correct existing scoliosis.

After being diagnosed with scoliosis caused by structural LLD, wearing an elevated insole and training for one month, the body posture has partially improved