Last updated: 11/24/2009

LLD is a common problem that is frequently discovered during the growing years. A medical history specific to the problem of limb length discrepancy, is taken by the treating physician to provide information as to the cause of discrepancy, previous...

treatment, and neuromuscular status of the limb. The patient is first evaluated standing on both legs to assess pelvic obliquity, relative height of the knees, presence of angular deformity, foot size, and heel pad thickness. Overall discrepancy is assessed by having the patient stand with the shorter leg on graduated blocks until the pelvis is leveled. Examination is then performed with the patient prone, hips extended and knees flexed to 90 degrees. In this position, the respective lengths of the femur and tibia segments of the two legs can be compared, and the relative contribution of the difference within each segment to the overall LLD can be roughly assessed.

Imaging studies, such as x rays, are the diagnostic tool of choice to fully evaluate the patient. A leg series of x rays shows the overall picture of the affected leg. The extent of LLD and required alignment can be measured with precision, and bone abnormalities involving specific parts of the leg can also be seen. The x rays are usually repeated at six to 12 month intervals to establish the growth pattern of the limbs. When several determinations of limb length have been compiled, the remaining growth and the ultimate discrepancy between the legs can be calculated, and a treatment plan selected based on predicting future growth and discrepancy, which is in turn dependent on an accurate record of past and present growth. Treatment is rarely started solely on the basis of a single determination of the existing discrepancy in a skeletally immature child. CT scans are not performed routinely but may be helpful in confirming the diagnosis or more accurately measure the amount of discrepancy.

For LLD patients with a nonfunctional foot, most physicians recommend amputation. In patients with a functional foot, the surgical procedure recommendations generally fall into one of the following three groups:

• The first group involves patients with a leg discrepancy less than 10%. There is little disagreement that these patients can benefit from lengthening procedures.
• The second group involves patients with a leg discrepancy exceeding 30%. Amputation is usually recommended for these patients.
• The third group involves patients a discrepancy ranging between 10 and 30%. Lengthening more than 4 in (10 cm) in a leg with associated knee, ankle, and foot abnormalities is very complex. At skeletal maturity, an average lower-extremity length is often 31.5–39.4 in (80–110 cm) and a 10% discrepancy represents 3.1–4.3 in (8–11 cm).

In the case of leg lengthening, the patient is also seen and evaluated for the design of the external fixator before surgery.

One week before surgery, patients are usually scheduled for a blood and urine test. They are asked to have nothing at all to eat or drink after midnight on the night before surgery.