The leg length discrepancy means there is inequality of the length of the lower limbs. It is also called as limb length inequality. The problem is extremely common with 23% of the general population having a discrepancy of 1 cm or more

Leg length discrepancy causes compensatory gait abnormalities, degenerative arthritis of the lower extremity and lumbar spine. In addition to the length inequality, these patients may also have angular and torsional deformities that may influence their functional leg lengths. For example, flexion contractures around the knee and hip can cause apparent shortening of the leg.

Hip abduction contracture and ankle equinus causes functional lengthening.

Small leg length discrepancy is well compensated by body and hardly requires any treatment. Bigger differences need to be equalized to prevent osteoarthritis , scoliosis and backache in later life.

Causes of Leg Length Discrepancy

The causes can generally be divided into two broad categories: congenital and acquired.

Congenital limb length inequality

• Longitudinal deficiency of the fibula
• Hemihypertrophy syndromes
• Klippel-Trénaunay-Weber syndrome
• Skeletal dysplasias.
• Proximal femoral focal deficiency
• Developmental dysplalsia of hip
• Unilateral clubfoot
• Vascular malformation
• Congenital pseudarthrosis of the tibia
• Ollier’s disease

Paralytic disorders

• Spasticity (cerebral palsy)
• Poliomyelitis
• Spina bifida
• Spinal dysraphism

Acquired

• Physis disruption
  • infection
  • trauma
  • tumor
  • Malunion of fracture

Functional Effects of Limb Length Discrepancy

• Back pain
  • increased prevalence of back pain
• Osteoarthritis
  • decreased coverage of femoral head on long leg side leads to osteoarthritis
• Structural scoliosis
  • Limb length discrepancy increases the incidence of structural scoliosis
• Inefficient gait

Classification of Limb Length Discrepancy:

• Static
  • malunion of femur or tibia
• Progressive
  • Physeal growth arrest
  • Congenital
    • Absolute discrepancy increases
    • Proportion stands the same

Treatment of Leg Length Discrepancy

Goals of treatment are

• Leg length equality within 1 cm
• Level pelvis
• Functional improvement

In certain cases small leg length inequality may be beneficial to the patient especially in neuromuscular disorders to aid in clearance in the swing phase of gait.

Depending on the severity of the difference, different treatments can be used for correction of the inequality.

Treatment of leg length inequality involves many different approaches. Non operative treatment involves use of shoe raises or orthotics.

Surgical approach deals with the problem by

• Correction of deformity if present
• Shortening of the normal leg
• Lengthening of affected leg
• Combination of shortening and lengthening.

Non-operative Treatment

An inequality < 2cm projected at maturity is generally without any functional problems. Often, surfices. Up to 1 cm can be inserted in the shoe. For larger leg length inequalities, the shoe must be built up.

Leg length inequalities beyond 5 cm are difficult to treat with a shoe lift.

A foot-in-foot prosthesis can be used for larger leg length inequalities but is often not tolerated well. It is often used as temporary measure.

Surgical Treatment

Shortening of long side

Epiphysiodesis of femur, tibia, or both

Epiphysiodesis inhibits the growth of the limb and can be used to correct 2-5 cm of projected limb length discrepancy.

It can be performed only in skeletally immature patients where growthpotential is still present.

Because the procedure effectively shortens the longer leg and is usually done on the uninvolved side, it may be unappealing to the patient and family.

It can be used alone or with limb lengthening of short limb.

Shortening of Mature Limb

This involves ostectomy and removal of bone segment followed by fixation of remaining fragments with desirable fixation device.

Limb lengthening of short side

It is contemplated in cases > 5 cm projected discrepancy. It can be  combined with a shortening procedure (epiphysiodesis, ostectomy) on long side when the discrepancy is large [>8 cmm]

Lengthening is usually done by corticotomy and gradual distraction

The limits of lengthening depend on patient tolerance, bony consolidation, maintenance of range of motion, and stability of the joints above and below the lengthened limb.

Numerous fixation devices are available, such as the ring fixator with fine wires, monolateral fixator with half pins, or a hybrid frame.

There are multiple signs and symptoms for leg length discrepancy (LLD). Some are obvious and some are subtle. There are differences between individuals on the extent and causes of leg length discrepancy (LLD). The difference in length between the two legs may vary from 3 and a half to 4 percent. These differences often determine the impact that may be experienced by different individuals. Signs and symptoms usually experienced in the patients with leg length discrepancy (LLD) include:

• If the difference in leg length discrepancy (LLD) is 3 cms and higher, difference will be easily noticed as the person walks.
• The person affected with leg length discrepancy (LLD) will need to exert more energy to walk.
• Some people may experience some pain in the lower back, ankle, or hip as they walk. Some studies have collaborated this, while other have refuted this.
• The person’s posture will be highly affected, causing him/ her to hold the longer leg on the knee for support.
• The person’s gait will be adversely affected, which will be obviously noticed.

The risk factors for leg length discrepancy (LLD) include:

Patients might have serious dissimilarities in the length of the legs as an effect brought by Leg Length Discrepancy (LLD) due to:

• Infection.
• Birth defects.
• Injuries.
• Accidents and other causes.

Leg length discrepancy (LLD) with very high difference can become complicated and lead to severe orthopaedic conditions like lower back pain, scoliosis, or arthritis, if left untreated.

• The patient may experience complications due to contractures of the muscles while having to constantly stand on their toes of the shorter leg for support.
• Another complication is that the shorter side of their body is often lowered down and suddenly lifted by the longer side, causing them to have abnormal gait that goes up and down.
• The abnormal gait can cause the child to be highly disturbed psychologically.
• The patient is often ridiculed and teased by other children, hindering the child’s social life.
• Most patients with leg length discrepancy (LLD) have to constantly support the shorter leg on the knee while standing, causing them to bend often or they may have to stand on their toes.