Leg Length Discrepancy
What is it?
Leg Length Discrepancy (LLD) or Lower Limb Discrepancy is a condition of unequal lengths of the lower limbs. The discrepancy may be in the femur, or tibia, or both. In some conditions, the whole side is affected, including the upper limbs. However, it is the discrepancy of the lower limbs that causes problems with walking, and the focus of this discussion will be about lower limb discrepancy.
Causes of leg length discrepancy
Previous Injury to a Bone in the Leg
A broken leg bone may lead to a limb length discrepancy if it heals in a shortened position. This is more likely if the bone was broken in many pieces. It also is more likely if skin and muscle tissue around the bone were severely injured and exposed, as in an open fracture.
Broken bones in children sometimes grow faster for several years after healing, causing the injured bone to become longer. A break in a child's bone through the growth center near the end of the bone may cause slower growth, resulting in a shorter leg.
Bone Infection
Bone infections that occur in children while they are growing may cause a significant limb length discrepancy. This is especially true if the infection happens in infancy. Inflammation of joints during growth may cause unequal leg length. One example is juvenile arthritis.
Bone Diseases (Dysplasias)
Bone diseases may also cause limb length discrepancy. Examples are:
- Neurofibromatosis
- Multiple hereditary exostoses
- Ollier disease
Other Causes
Other causes include inflammation (arthritis) and neurologic conditions.
Sometimes the cause of leg length discrepancy is unknown, particularly in cases involving underdevelopment of the inner or outer side of the leg, or partial overgrowth of one side of the body. These conditions are usually present at birth, but the leg length difference may be too small to be detected. As the child grows, the limb length discrepancy increases and becomes more noticeable. In underdevelopment, one of the two bones between the knee and the ankle is abnormally short. There also may be related foot or knee problems.
Hemihypertrophy (one side too big) or hemiatrophy (one side too small) are rare limb length discrepancy conditions. In these conditions, the arm and leg on one side of the body are either longer or shorter than the arm and leg on the other side of the body. There may also be a difference between the two sides of the face. Sometimes no cause can be found. This is known as an "idiopathic" difference.
Symptoms
Many people walk around a leg length discrepancy of up to 2 cm and not even know it. However, discrepancies above 2 cm become more noticeable, and a slight limp is present. Even up to 3 cm a small lift (orthotic) compensates very well, and many patients are quite happy with this arrangement.
Beyond 3 cm however, the limp is quite pronounced, and medical care is often sought at that point. Walking with a short leg gait increases energy expenditure during ambulation. It also puts more stress on the long leg, and causes functional scoliosis.
Dr. Crosby can diagnose any leg length discrepancy and offer you treatment to improve your quality of life. Call today!
Courtesy of The American Academy of Orthopaedic Surgeons and www.orthoseek.com
