Leg length discrepancy is characterized by an acquired or congenital difference in the length of the lower extremities (legs). Approximately 40 to 75 percent of the population is affected by leg length discrepancy, although it only becomes clinically relevant when it exceeds 1 to 2 centimeters.
What is leg length discrepancy?
Leg length discrepancy refers to a difference in length between the two lower extremities. Generally, a distinction is made between a real or anatomic leg length difference and a functional leg length difference. While the anatomical leg length difference is caused by a real existing length difference of the leg bones, a functional leg length difference is mainly caused by contractures of the joints, the capsular ligament apparatus or the muscles as well as by malpositions of the hip joint. As a rule, a minimal leg length difference does not lead to any complaints, but can cause a compensatory spinal curvature or a shortening limp. A more pronounced leg length difference causes a static change of the musculoskeletal system, which is not infrequently accompanied by a pelvic obliquity and/or scoliosis (lumbar scoliosis, cervicothoracic scoliosis). In addition, pointed foot posture, intervertebral disc wear, osteophyte formation, and spondyloarthrosis may be observed with leg length discrepancy.
Causes
Anatomic leg length discrepancy is generally due to congenital malformations resulting from congenital growth disorders of the lower extremities (osteochondrodysplasias), which can manifest in the epiphyses (growth plates), metaphyses (tubular bone section between the epiphysis and the bone shaft), periosteum (periosteum), and/ or endost (inner periosteum) and result in unilaterally reduced bone growth. In addition, tumors (neurofibromatosis Recklinghausen; enchondromatosis, osteochondromatosis), tumor-like diseases (fibrous dysplasia) and (a)septic inflammations (osteomyelitis, juvenile polyarthritis) can also cause a leg length discrepancy via bone mass loss. Neuroorthopedic diseases such as poliomyelitis (polio) can also induce leg shortening via bone mineralization. Functional leg length differences, on the other hand, are due to genetically or traumatically induced luxations (dislocations) or contractures of the knee, hip, or upper ankle joints.
Symptoms, complaints, and signs
The difference in the length of the legs in itself is often not visible to the naked eye and does not cause any discomfort in the first place. The complaints and their symptoms arise from the existing asymmetry in the body and especially in the musculoskeletal system. In this way, different muscle groups, tendons and joints are subjected to different levels of stress, which sooner or later can lead to one-sided overload and pain. External signs of a leg length discrepancy can be a crooked posture, general postural defects or a pelvic obliquity. These factors are usually easily visible, but as long as no complaints occur, they are rarely investigated for their causes. Leg length differences are also noticeable in the wear of street shoes. Usually, one of the shoes is more worn than the other, especially in the ball and heel area. If you compare heels of a pair of shoes with each other, you will often also notice that the two shoes have different wear patterns. If the leg length difference is greater than 2.5 centimeters, discomfort can occur even when sitting for long periods of time, because the legs are supported on the floor with different amounts of force. Here, too, the person affected often adopts a protective posture and bends the upper body far forward. This malposition is very easy to recognize and diagnose visually.
Diagnosis and course
Leg length discrepancy is usually diagnosed by clinical or manual measurement of the lower extremities while sitting, standing, and lying down. An examination of the pelvis and spine allows conclusions to be made about structural changes resulting from compensatory adaptation processes. Nomograms can be used to predict and graphically display the expected difference in length as well as postoperative bone growth in affected individuals who are still in the growth phase. The diagnosis is confirmed by imaging procedures.Differences in length can thus be determined comparatively accurately by radiography (e.g., standing leg radiograph) and computed tomography. In the course of sonographic leg length determination, the joint gaps can be localized with the aid of distance markers and the lengths of the tibia and femur can be determined. With early prognosis and initiation of therapy, both forms of leg length discrepancy have a good prognosis and course. However, if left untreated, leg length discrepancy can lead to pelvic obliquity and scoliosis.
Complications
In general, leg length differences are medically important only when the leg difference is greater than two centimeters. Smaller differences do not lead to complications and are usually not treated. In most cases, the affected person cannot perform everyday tasks easily, since, for example, even ordinary standing is no longer possible. This can be counteracted by insoles in shoes and is mainly used for smaller leg length discrepancies. If the leg length difference is more pronounced, the shoes can be orthopedically prepared so that the leg length difference is compensated. In this case, there are no other complications. The leg length difference often severely restricts the patient’s growth. This leads to short stature in many of those affected. This can have a negative effect on the psyche, especially in childhood, as children are often bullied because of this. Psychological problems and reduced self-esteem can also result from the leg length difference itself. Treatment of the symptom itself is not possible. However, it is useful to identify the leg length discrepancy in early childhood, as operations can be performed here to accelerate growth and thus compensate for the differences.
When should you go to the doctor?
The greater the leg length difference, the more important treatment is. Minimal differences do not cause discomfort, or only now and then. In that case, targeted gymnastics or an over-the-counter heel elevator will help. In case of permanent pain in the hip, pelvis or lumbar spine, treatment by an orthopedic specialist is necessary. Only he is able to diagnose the leg length discrepancy and its effects on the skeletal system. For infants and toddlers, the pediatrician is the first point of contact. He will detect an existing leg length discrepancy during the preventive examinations and initiate an immediate therapy. In most cases, the little ones do not have any complaints afterwards in adulthood. If the difference occurs after a trauma, immediate treatment is necessary. Permanent damage can only be minimized or completely stopped in this way. Diseases affecting the musculoskeletal system can lead to pelvic obliquity. In this case, treatment by a specialist is also necessary. Therapy is focused on the underlying disease and its consequences.
Treatment and therapy
Therapeutic measures depend on the extent of the specific leg length discrepancy present. For example, length differences of up to one centimeter do not usually require therapy if the patient is free of symptoms. To compensate for the difference, shoe inserts or adjustments to the ready-made shoe (heel cushions, heel wedges) are used. Length differences of no more than three centimeters can be compensated with the help of an orthopedic shoe adjustment (heel elevation with sole compensation). For more pronounced length differences (3 cm or more), orthopedic custom shoes or custom shoes with inner shoes or footbed orthoses are recommended. In addition, a length difference of up to 12 centimeters can be compensated for with inner shoes that place the foot of the shorter leg in a pointed foot position and have adapted heel rolls. In the case of a high degree of leg length discrepancy, the patient may be fitted with platform shoes or orthopedic leg orthoses, which fix the foot on a synthetic foot in the pointed foot position. In general, shortening or lengthening compensatory measures are possible within the framework of surgical interventions, which are considered in the case of an anatomically determined difference of not less than 3 centimeters. In this context, temporary clamping or permanent obliteration of epiphyses that have not yet closed in order to reduce the growth of the affected bone (epiphysiodesis) is a comparatively simple standard procedure for affected individuals whose growth phase has not yet been completed.In addition, after completion of the growth phase, the longer limb can be shortened osteotomically or the shorter limb can be lengthened by an external fixator or an extension intramedullary nail. Functionally induced leg length discrepancies should also receive additional causal treatment to eliminate the triggering factor as much as possible.
Outlook and prognosis
The prognosis of leg length discrepancy depends on several factors. First, it is important to take accurate measurements to distinguish an anatomic leg length difference from a functional one, because an anatomic leg length difference is treated differently than a functional one. For example, in a functional one, a shoe raise would do more harm than good. The spine can usually still compensate well for a difference of less than 2 cm, but beyond that the prognosis depends on treatment as early as possible. If the pelvic obliquity caused by a difference in leg length is not treated, back pain and spinal curvature (scoliosis) may result. If the shortening of the leg can be treated by appropriate measures while the child is still growing, the prognosis is good and in most cases no surgical intervention is necessary. If shoe insoles or elevations are prescribed, the prospect of improvement is positive if they are worn regularly. If leg shortening is diagnosed at a later stage, the prospects depend on whether the imbalance has already caused long-term wear and tear on the joint. In most cases, physiotherapeutic measures are then necessary in addition to treatment of the leg length discrepancy in order to relieve muscle tension and joint overload. The longer the leg length discrepancy persists, the greater the risk of osteoarthritis due to joint wear.
Prevention
Congenital anatomical leg length discrepancy cannot be prevented as a rule. Since surgical compensation during the growth phase is associated with fewer complications, the length difference should be diagnosed early. Leg length discrepancies caused by secondary causes can be prevented, if necessary, by consistent treatment of the underlying disease.
Follow-up care
In cases of hip misalignment, compensation can be achieved manually. In this case, no follow-up care is required. After fitting insoles or heel cushions, respectively, or adjusting the sole of the shoe, the leg length discrepancy may be compensated. Follow-up care ensures that it is to a sufficient degree and that the gait is correct. It must be checked at regular intervals whether the measures taken still sufficiently compensate for the leg length difference. Surgical measures are also conceivable in the case of leg length discrepancy. As expected, follow-up care must be performed more frequently and with greater care. If pain occurs, the aftercare must be particularly careful. The cause of the pain must be determined or eliminated. If the leg length discrepancy occurred after the insertion of a hip prosthesis, follow-up care must ensure that it is corrected as quickly as possible. Even small differences in leg length can trigger hip misalignment. Therefore, preventive care includes informing the patient about possible leg axis misalignments. He must know that these are not always avoidable and that they can be compensated for in aftercare. Aftercare is also important because the operated patient can claim compensation for pain or leg length discrepancies about which he or she was not adequately informed.
What you can do yourself
In the case of a leg length difference, the development of suitable therapeutic measures should always be carried out in cooperation with a physician. However, the discomfort associated with legs of different lengths can also be reduced by self-help measures and some home remedies. For example, a slight difference can often be compensated by special footwear. In the case of larger differences, medical clarification should be sought as soon as possible. The sooner the leg length difference is detected, the sooner suitable treatment can be started. This can often prevent possible malpositions and other complaints. Physiotherapeutic measures and sporting activity can help to counteract back and hip pain that may have already developed. In particular, targeted fascia training and yoga exercises such as the pigeon help to strengthen the “weak” leg and compensate for malpositions.People with a leg length difference should also pay attention to a healthy lifestyle. A fit musculoskeletal system on the one hand and a strong immune system on the other help to combat pain in the long term and prevent psychological complaints. If psychological or physical secondary symptoms have already set in, a therapist must be consulted. In general, acceptance and an open approach to the leg length difference are important for recovery.
