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 ambulation, and the focus of this discussion will be about lower limb discrepancy.
Some limb-length differences are caused by actual anatomic differences from one side to the other (referred to as structural causes). The femur is longer (or shorter) or the cartilage between the femur and tibia is thicker (or thinner) on one side. There could be actual deformities in one femur or hip joint contributing to leg length differences from side to side. Even a small structural difference can amount to significant changes in the anatomy of the limb. A past history of leg fracture, developmental hip dysplasia, slipped capital femoral epiphysis (SCFE), short neck of the femur, or coxa vara can also lead to placement of the femoral head in the hip socket that is offset. The end-result can be a limb-length difference and early degenerative arthritis of the hip.
LLD do not have any pain or discomfort directly associated with the difference of one leg over the other leg. However, LLD will place stress on joints throughout the skeletal structure of the body and create discomfort as a byproduct of the LLD. Just as it is normal for your feet to vary slightly in size, a mild difference in leg length is normal, too. A more pronounced LLD, however, can create abnormalities when walking or running and adversely affect healthy balance and posture. Symptoms include a slight limp. Walking can even become stressful, requiring more effort and energy. Sometimes knee pain, hip pain and lower back pain develop. Foot mechanics are also affected causing a variety of complications in the foot, not the least, over pronating, metatarsalgia, bunions, hammer toes, instep pain, posterior tibial tendonitis, and many more.
Leg length discrepancy may be diagnosed during infancy or later in childhood, depending on the cause. Conditions such as hemihypertrophy or hemiatrophy are often diagnosed following standard newborn or infant examinations by a pediatrician, or anatomical asymmetries may be noticed by a child's parents. For young children with hemihypertophy as the cause of their LLD, it is important that they receive an abdominal ultrasound of the kidneys to insure that Wilm's tumor, which can lead to hypertrophy in the leg on the same side, is not present. In older children, LLD is frequently first suspected due to the emergence of a progressive limp, warranting a referral to a pediatric orthopaedic surgeon. The standard workup for LLD is a thorough physical examination, including a series of measurements of the different portions of the lower extremities with the child in various positions, such as sitting and standing. The orthopaedic surgeon will observe the child while walking and performing other simple movements or tasks, such as stepping onto a block. In addition, a number of x-rays of the legs will be taken, so as to make a definitive diagnosis and to assist with identification of the possible etiology (cause) of LLD. Orthopaedic surgeons will compare x-rays of the two legs to the child's age, so as to assess his/her skeletal age and to obtain a baseline for the possibility of excessive growth rate as a cause. A growth chart, which compares leg length to skeletal age, is a simple but essential tool used over time to track the progress of the condition, both before and after treatment. Occasionally, a CT scan or MRI is required to further investigate suspected causes or to get more sophisticated radiological pictures of bone or soft tissue.
Non Surgical Treatment
The non-surgical intervention is mainly usedfor the functional and environmental types of leg length discrepancies. It is also applied to the mild category of limb length inequality. Non-surgical intervention consists of stretching the muscles of the lower extremity. This is individually different, whereby the M. Tensor Fascia latae, the adductors, the hamstring muscles, M. piriformis and M. Iliopsoas are stretched. In this non-surgical intervention belongs also the use of shoe lifts. These shoe lifts consists of either a shoe insert (up to 10-20mm of correction), or building up the sole of the shoe on the shorter leg (up to 30-60mm of correction). This lift therapy should be implemented gradually in small increments. Several studies have examined the treatment of low back pain patients with LLD with shoe lifts. Gofton obtained good results: the patients experienced major or complete pain relief that lasted upon follow-up ranging from 3 to 11 years. Helliwell also observed patients whereby 44% experienced complete pain relief, and 45% had moderate or substantial pain relief. Friberg found that 157 (of 211) patients with LBP, treated with shoe lifts, were symprom-free after a mean follow-up of 18 months.
leg length discrepancy lifts
Surgery is another option. In some cases the longer extremity can be shortened, but a major shortening may weaken the muscles of the extremity. In growing children, lower extremities can also be equalized by a surgical procedure that stops the growth at one or two sites of the longer extremity, while leaving the remaining growth undisturbed. Your physician can tell you how much equalization can be attained by surgically halting one or more growth centers. The procedure is performed under X-ray control through very small incisions in the knee area. This procedure will not cause an immediate correction in length. Instead, the LLD will gradually decrease as the opposite extremity continues to grow and "catch up." Timing of the procedure is critical; the goal is to attain equal length of the extremities at skeletal maturity, usually in the mid- to late teens. Disadvantages of this option include the possibility of slight over-correction or under-correction of the LLD and the patient?s adult height will be less than if the shorter extremity had been lengthened. Correction of significant LLDs by this method may make a patient?s body look slightly disproportionate because of the shorter legs.