Leg Length Discrepancy After Knee Replacement Surgery

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Overview

Differences between the lengths of the upper and/or lower legs are called leg length discrepancies (LLD). A leg length difference may simply be a mild variation between the two sides of the body. This is not unusual in the general population. For example, one study reported that 32 percent of 600 military recruits had a 1/5 inch to a 3/5 inch difference between the lengths of their legs. This is a normal variation. Greater differences may need treatment because a significant difference can affect a patient's well-being and quality of life.Leg Length Discrepancy

Causes

A number of causes may lead to leg length discrepancy in children. Differences in leg length frequently follow fractures in the lower extremities in children due to over or under stimulation of the growth plates in the broken leg. Leg length discrepancy may also be caused by a congenital abnormality associated with a condition called hemihypertrophy. Or it may result from neuromuscular diseases such as polio and cerebral palsy. Many times, no cause can be identified. A small leg length discrepancy of a quarter of an inch or less is quite common in the general population and of no clinical significance. Larger leg length discrepancies become more significant. The long-term consequences of a short leg may include knee pain, back pain, and abnormal gait or limp.

Symptoms

The symptoms of limb deformity can range from a mild difference in the appearance of a leg or arm to major loss of function of the use of an extremity. For instance, you may notice that your child has a significant limp. If there is deformity in the extremity, the patient may develop arthritis as he or she gets older, especially if the lower extremities are involved. Patients often present due to the appearance of the extremity (it looks different from the other side).

Diagnosis

The doctor carefully examines the child. He or she checks to be sure the legs are actually different lengths. This is because problems with the hip (such as a loose joint) or back (scoliosis) can make the child appear to have one shorter leg, even though the legs are the same length. An X-ray of the child?s legs is taken. During the X-ray, a long ruler is put in the image so an accurate measurement of each leg bone can be taken. If an underlying cause of the discrepancy is suspected, tests are done to rule it out.

Non Surgical Treatment

Structural leg length discrepancy can be treated with a heel lift in the shorter leg?s shoe, if the leg length is greater than 5 mm. The use and size of the heel lift is determined by a physical therapist based on how much lift is needed to restore proper lumbopelvic biomechanics. In certain cases, surgical intervention may be needed to either shorten or lengthen the limb. An important component to any surgical procedure to correct leg length discrepancies is physical therapy. Physical therapy helps to stretch muscles and maintain joint flexibility, which is essential in the healing process. For a functional leg length discrepancy no heel lift is required, but proper manual therapy techniques and specific therapeutic exercise is needed to treat and normalize pelvic and lower extremity compensations. The number of treatments needed to hold the pelvis in a symmetrical position is different for each patient based on their presentation and biomechanical dysfunctions in their lower back, pelvis, hip, knee, and foot/ankle. If you have pain in your lower back or lower extremity and possibly a length discrepancy; the two symptoms could be related. A good place to start would be a physical therapy evaluation to determine whether you have a leg length discrepancy and if it could be contributing to your lower back pain, hip pain, knee pain, or leg pain.

LLL Shoe Insoles

Surgical Treatment

Surgical options in leg length discrepancy treatment include procedures to lengthen the shorter leg, or shorten the longer leg. Your child's physician will choose the safest and most effective method based on the aforementioned factors. No matter the surgical procedure performed, physical therapy will be required after surgery in order to stretch muscles and help support the flexibility of the surrounding joints. Surgical shortening is safer than surgical lengthening and has fewer complications. Surgical procedures to shorten one leg include removing part of a bone, called a bone resection. They can also include epiphysiodesis or epiphyseal stapling, where the growth plate in a bone is tethered or stapled. This slows the rate of growth in the surgical leg.
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