Treating Leg-Length Inequality

By Mark Charrette, DC

An early suspicion of leg-length inequality (“short leg”) may arise from a
patient’s clinical exam, spinal X-rays or the existence of recurrent
subluxations. If leg-length inequality is suspected, perform an accurate
examination to determine the amount of difference and influence this discrepancy
has on the patient’s spine and gait. Next, determine the source of the
inequality, so the correct treatment can be provided. Finally, determine by
evaluation whether the treatment has sufficiently addressed the problem.

Begin by examining the patient in the upright, weight-bearing position.
Measurements of leg-length discrepancy obtained in non-weight-bearing positions
have been
found to be unreliable.¹ In the upright posture, positioning
errors and measurement confusions are not a factor. Accurate
clinical determinations are then possible² and effective
chiropractic care can proceed. Since the lower extremities provide foundational
support for the pelvis during standing and walking, it is not surprising that
they can have a profound effect on both pelvic and spinal alignment.

Anatomical or Functional?

When one leg is shorter, there is often pelvic unleveling with a compensatory lumbar curve to the short side.³ Gait
will be somewhat altered in an attempt to make up the difference. Eventually,
specific degenerative changes will occur in the spine and hip
joints.^4-5 A leg-length difference (measured while standing) 5-9 mm
or over results in a higher incidence of low back pain.⁶ Athletes and
those who spend a lot of time on their feet may develop chronic symptoms with
just 3 mm of discrepancy.⁷

There are two possible causes of a short leg, and each needs different
treatment. An anatomical short leg is caused by a difference in the
length and/or size of the structures between the femur head and the ground. This
is sometimes found after a fracture or surgery, but is most often the result of
asymmetrical growth. A functional short leg develops secondary to a
difference in the supporting structural alignment between the femur head and the
ground. The most common cause is excessive pronation on one side, but knee
valgus may also be a causative factor.

Postural Examination

Before beginning treatment of a short leg condition, perform a weight-bearing
postural examination of the pelvis and lower extremities. Position the patient
in bare (or stocking) feet on an unyielding, level surface. Tell the patient to
stand relaxed in a “normal upright posture.”⁸ Palpate the
iliac crests⁹ and the lumbar spine to determine if there is any
pelvic unleveling and a compensatory lateral curvature. If either is found, see
whether the greater trochanters and knee joints are level; then evaluate the
knee alignment for valgus and the feet for asymmetrical hyperpronation.

If there is evidence of a functional short leg, see if the pelvis and spinal
imbalances can be temporarily corrected by having the patient roll onto the
outsides of both feet. As you palpate the levels of the iliac crests and greater
trochanters, ask the patient to relax and return to a normal stance. If the
pelvis dips down or rotates forward on the side of greater foot pronation, this
shows the effect of the foot imbalance on the pelvis and lumbar spine. A lack of
significant asymmetry in the lower extremity alignment reveals an anatomical
difference.

Orthotic or Lift?

When evidence exists of a difference in lower extremity alignment (such as
excessive pronation), providing symmetrical support is the most effective
treatment. This is accomplished by supplying custom-made, corrective orthotics
for both feet. It is important to recognize the functional short leg, since
providing a lift instead of an orthotic will likely perpetuate the
associated sacroiliac subluxations.¹⁰ Only the standing postural
exam, with careful evaluation of lower extremity alignment, permits this
determination. If there is any doubt, the safest approach is to fit the patient
initially with custom-made orthotics. If a leg-length discrepancy persists after
wearing the orthotics for several weeks and receiving chiropractic adjustments,
a heel lift can then be easily added to the orthotic for complete
correction.

When an anatomical difference in leg length affects the alignment of the
pelvis and spine, chiropractic care should include the recommendation of an
appropriate amount of lift under the heel. Since some asymmetry is tolerated by
the body (most reliable studies find that about 5 mm is the limit),¹¹
an exact correction of the difference measured at the femur heads is not needed.
The exception may be athletes (such as long distance runners), who spend many
hours a day exercising and competing on their feet.

For most patients, undercorrection (to within about 3 mm) is the best way to
ensure a good response while avoiding any negative reactions. If the amount of
lift needed exceeds 6 mm (the difference measured at the femur heads is more
than 10 mm), the additional lift must be built onto the shoe, since a lift in
excess of 6 mm will push the foot out of most shoes. This is done by adding half
of the heel lift amount to the sole of the shoe, so the foot is not excessively
plantarflexed during stance and gait.

Determine the Source of the Shortening for Best Results

Once a patient with a short leg has been properly examined, the source of the
lower extremity shortening can be identified, and effective treatment can be
provided. In many cases of functional short leg, as evidenced by radiographic
study, the use of scientifically designed, custom-made orthotics has been shown
to help eliminate musculoskeletal deficiencies and improve patient
outcomes.¹² Those few patients with a true anatomical leg-length
discrepancy will need to be supplied with an appropriate lift. The additional
time required to determine the source of the short leg will be repaid in more
effective chiropractic care and adjustments that last.

References

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   study of 288 consecutive chronic LBP patients. Clin Biomech,
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6. Friberg O, 1987, Op Cit.
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