HEALTHNET

How is leg length discrepancy developed?

Leg length discrepancy is a condition of unequal lengths of the lower legs...

(Posted on 12 July 2007)

Q1. How is leg length discrepancy developed?

A1. Leg length discrepancy is a condition of unequal lengths of the lower legs. There are generally two types of leg length discrepancies.

Structural leg length discrepancy occurs when there is genuine shortening or lengthening of either thigh (femur) and/or shin (tibia) bone in one leg.
Functional leg length discrepancy occurs when leg lengths are equal but altered mechanics above the leg, which in turn gives an impression of asymmetry of the legs.

Structural leg length discrepancy is usually caused by interference of normal bone growth of the lower legs. Some children are born with unequal leg lengths or bowed shin bones which manifested by a leg length discrepancy. Increased blood flow to one leg (e.g. bone tumor), injury or infection involving growth plate (e.g. osteomyelitis) and inflammation of joint (e.g. juvenile rheumatoid arthritis or haemophilia) may inhibit or stimulate bone growth and can cause leg length discrepancy. Structural inequality can occur from fractures which damage the cells responsible for bone growth. Some fractures may also lead to overgrowth of the bone during healing process and result in the affected leg growing longer than normal. Overgrowth is common among children with femoral fractures.

The causes of functional leg length discrepancy are often biomechanical due to an abnormal alignment or deformities of the spine, hip, knee or ankle joint, or due a tilted or rotated pelvic, so that one hip appears to be higher than the other. Functional leg length discrepancy can also be present at birth in children with altered alignment of the hips as in coax vara and developmental dislocation of the hip. Neuromuscular problems like poliomyelitis or cerebral palsy can also lead to a functional discrepancy.

Q2. What are the symptoms of a leg length discrepancy?

A2. The symptoms of a leg length discrepancy vary widely. Always consult your doctor or physiotherapist for a diagnosis.

Some people may not be aware of the discrepancy up to 2cm. However, others may walk with a waddling walking pattern where the hips seem to move up and down as the body tries to compensate for the discrepancy. Some people may develop other deformities which help to compensate for the condition. Toe walking on the short side to decrease the swaying, rotation of the leg while walking, high foot arch on the short side, flattening of the foot arch on the long side, excessive pronation of the forefoot or bunion formation are some common compensatory signs. Walking with limping gait increases energy expenditure during ambulation. This will put more stress onto one leg, leading to functional scoliosis (abnormal curvature of the spine). With poor posture, joint motion may become dysfunctional with associated muscle imbalance, which can cause pain to the back, hip, knee or ankle.

Q3. What are the treatments?

A3. A slight leg length discrepancy below 2 centimeters is hardly noticeable by most people, as the body may compensate for the condition by altered biomechanics.

For inequality of 2 - 2.5 centimeters, a shoe lift (orthotics) can be used. A proper shoe lift can help to level the pelvis and equalize the length of the two legs that allow people to walk normally. Physiotherapy treatment options such as stretching, strengthening exercises, gait retraining and other techniques may help to improve joint flexibility and stability, and alleviate pain and disabilities caused by the discrepancy.

Surgical treatments, such as lengthening or shortening procedures, may be required for people with severe discrepancy. Much planning is required in managing a child with leg length discrepancy. The doctor may need to continually monitor the child's growth over a period of time and estimate the discrepancy at maturity before considering any surgical procedures. Treatments for leg length discrepancy are highly specific for individuals and should be determined by your doctor or physiotherapist after a thorough assessment.

Source: Quality HealthCare