Leg Length Discrepancy

What is leg length discrepancy?

If your child has one leg that’s shorter than the other, he or she has a condition called leg length discrepancy. The difference in length can range from a fraction of an inch up to several inches.

The greater the difference in leg length, the more a child must alter his or her normal posture and walking pattern. This can lead to a variety of symptoms, such as functional scoliosis, and hip, knee and ankle problems.

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There are generally two types of leg length discrepancies:

  • Structural discrepancy: This type occurs when either the thigh (femur) or shin (tibia) bone in one leg is physically shorter than the same bone in the other leg.
  • Functional discrepancy: This type occurs when the bone lengths are equal, but symmetry between the legs is thrown off by a problem in the foot, ankle, knee, hip or pelvis.

What are the symptoms of leg length discrepancy?

The symptoms of a leg length discrepancy vary widely from child to child based on the difference in leg length and the cause of the condition.

Some common symptoms include:

  • one leg that is shorter than the other (this is not always obvious)
  • problems with posture, such as a tilting shoulder
  • walking problems, such as limping or toe-walking
  • a knee that's chronically hyperextended on the short side and flexed on the long side
  • pain in the back, hip, knee or ankle

What are the causes of leg length discrepancy?

Structural leg length discrepancies occur when a child is born with legs that are of unequal length or has bowed tibias (shin bones). In most cases, there is no known cause for this.

Functional leg length discrepancy can occur when a child is born with a problem that alters alignment of the hips, such as coxa vara and developmental dislocation of the hip.

Other causes of leg length discrepancy may include:

  • fracture or other injury: an injury to the bone can slow down its growth, while the bone in the other leg continues to grow normally. Some fractures can also lead to overgrowth of bone during the healing process — this is common with injuries to the thighbone.
  • Osteomyelitis or other diseases of the bone: this can damage the growth plate in the bone, causing a discrepancy that occurs gradually over time.
  • Bone tumors and their treatments can affect bone growth.
  • Cerebral palsy and other neuromuscular problems: these conditions can cause problems with alignment and posture, possibly leading to a functional discrepancy.

How we care for leg length discrepancy

At Boston Children’s Hospital, the specialists in our Lower Extremity Program have treated many complex lower extremity conditions and can provide expert diagnosis, treatment and care for your child. We’ll work with you and your child to review the available options and decide the best course of treatment, based on your child’s individual needs.