Leg Length Discrepancy

Leg length discrepancy, the unequal length of the lower limbs, or “symmetrical limb size unequal” (that is, the difference in the length of the legs) can be classified into the category of biomechanics, which can be divided into two types:

1. Structural leg length discrepancy: The measured values of the long leg bones (tibia and femur) are different, and there are many pathogenic factors, including developmental abnormalities, fractures, degenerative diseases, cancer, or tumor changes, etc.

The common reasons are rough as follows:

(1) Hip joint diseases,

(2) Epiphyseal injury, the child accidentally falls, or the parent does not pay attention to it or is afraid of being scolded and does not say it. In short, many patients have experienced leg injuries when they were young.

(3) Tumors, all kinds of tumors, as long as they invade or affect the growth plate, will also cause the length or deformity of the legs.

(4) Exogenous irritation. Such causes include surgical irritation.

(5) Malunion or non-union after trauma, malunion due to poor fixation after trauma, or fracture in poor blood supply such as middle and lower tibial fractures and non-union, and shortening of the affected limb.

(6) Neurofibromas and hemangioma of the lower extremities are not uncommon because the nutrition of the affected limb exceeds normal and becomes too long.

(7) Unilateral congenital malformations, such as unilateral clubfoot varus, due to impaired muscle development, impaired foot development, short and thin calves, resulting in unequal length. In addition, congenital prosthetic joints of the tibia, congenital flexure of the tibia, congenital paraxial Hemi-limb deformities (hemimelia), including congenital fibula or tibial abscess, are common typical causes of the unequal length of lower limbs the reason.

(8) Inflammation, chronic childhood osteomyelitis, local inflammation stimulation, increased blood supply, if it is close to the epiphyseal plate, or if the local area is in a state of high blood supply and high metabolism for a long time, the affected leg will become overgrowth. On the contrary, due to osteomyelitis, bone destruction, bone loss or defect, and finally evolved into nonunion, so that the legs will become shorter.

(9) Nerve damage (paralysis). After childhood nerve damage, such as common peroneal nerve damage, muscular dystrophy, eventually, lead to thin and short calves. With brachial plexus injury, such as obstetric paralysis, the sick arm is short in addition to not moving. The well-known sequelae of polio (poliomyelitis sequelae) affect the legs or arms, all of which are short. In short, if the limbs are not innervated by nerves during development, the vasoconstriction function and muscle development cannot be adequately nourished, which will eventually lead to unequal length of the nerve limbs.

(10) All kinds of unexplained, idiopathic limbs are not of equal length, which is how they are born. There is no clear cause of the disease.

2. Functional leg length discrepancy: identification and treatment are more complicated, and there are many pathological factors, such as body compensation related to trauma, soft tissue shortening, joint contracture, ligament laxity, force line problems, and foot biology problems (Unilateral excessive pronation, pelvic rotation and abnormal pelvic position in gait, etc.)

The reasons are rough as follows:

(1) Gluteal muscle contracture is generally considered to be related to hip muscle injection. Simple gluteus maximus contracture generally does not cause pelvic tilt. However, there is an adduction disorder in the hip joint extension position when the gluteal muscles are involved. The muscular tissue contracture stretches the relatively active and free anterior and lateral sides of the ilium. Disrupted the balance of the pelvis. When the lower limbs are close together, the pelvis is tilted to the affected side and the healthy side is tilted upward so that the lower limbs are parallel, which is manifested as a tilt of the pelvis and the appearance of the lower limb on the affected side is longer. Since this unequal length of the lower limbs is caused by the tilt of the pelvis, the actual lengths of the two lower limbs are measured to be equal. The lower limbs are not equal in length.

(2) Hip synovitis is a common disease in childhood, manifested as claudication, which may or may not is accompanied by limb pain. In mild cases, the hip joint examination was normal. Severe cases may have pelvic tilt, that is, the affected limb looks longer than the healthy side.

(3) Hip sprains occur in children around 7-10 years old. They often sprain the hip joints due to slapstick, rubber band jumping, jumping, or dancing. They often have typical symptoms such as false unequal length of the lower limbs and pain.

(4) In scoliosis, the spine is bent to one side, which may be S-shaped or C-shaped (usually bends to the right in the upper back and the left in the lower back), which usually causes the pelvis to tilt and the hips on both sides are uneven. , Resulting in the symptoms of pseudo-length lower limbs.

(5) Trauma may also cause the pelvis to tilt, resulting in a leg length discrepancy.

In addition, the leg length discrepancy is also a common complication after hip replacement. It may be true unequal length or false unequal length.

Common symptoms of the leg length discrepancy

1. Knee joint pain: Pain may occur on the inside, outside, or front side. Knee pain and excessive pronation are often present on one side of the long leg.
2. Non-structural scoliosis (functional and postural scoliosis) and primary scoliosis.
3. Pain in the neck and shoulders.
4. Back pain (including “lumbar disc herniation”).
5. Foot pain, bunions on one side of the long leg due to excessive compensatory pronation.
6. Ankle pain: related to supination on one side of the short leg or excessive pronation on the side of the long leg.
7. Hip joint pain (forward or backward twisting of the pelvis), and hip joint pain or acetabular wear are prone to appear on one side of the long leg. If left untreated, it may cause the patient to require hip replacement surgery in the future.

The leg length discrepancy can also affect the muscles, blood vessels, and nervous system.

Measurement methods

There are more than one assessment methods, and doctors can choose the technique that best suits their specific situation.

1. The patient lies on his back, puts the limbs in a symmetrical position, relaxes, and measures the anterior superior iliac spine to the medial malleolus tip
2. The patient lies on his back, puts the limbs in a symmetrical position, relaxes, and measures the greater trochanter to the tip of the lateral malleolus
3. Lying on the patient’s back, place the limbs in a symmetrical position, relax, mark the inner ankle tips of the legs with a marker, and then stick them together to measure the distance between the two marking lines.

(The premise of the above three evaluation methods is to ensure the neutral position of the bilateral iliac bones)

4. The unequal length of the lower limbs can be scanned by X-ray/CT

Treatment

In the diagnosis and evaluation, any “pain indication” of the patient is very important, and attention should be paid to ensure that the treatment plan is suitable for the patient’s biomechanical abnormal symptoms. If the patient has hip compensation, the pelvis needs to be adjusted or loosened, combined with stretching and strength exercises to correct the abnormality. If the patient has a structural leg length discrepancy, and it is not caused by recent trauma, a heel pad needs to be added to the shorter side of the structure. It is recommended that the height of the heel pad is 50% (adult) of the measured difference. For example: if the measured difference is 8mm, add a 4mm heel pad during the initial treatment-this will reduce possible compliance issues.

Below Heel lift with adjustable height is quite suitable for people who have a leg length discrepancy

Heel lift – Adjustable Orthopedic for Leg Length Discrepancy

Material: Natural leather + High-quality rubber construction

Size: S M L

Feature:
1)1 lift for 3 heights, adjustable height by two removable 1/8″ thick rubber layers, self-adhesive glue between each layer.
2)helping absorb shock at heel strike
3)Natural leather guarantees excellent durability and Latex-free

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