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In medicine, a leg length discrepancy is defined as a difference in the length of the lower limbs from the foot to the hip. In the case of a true leg length discrepancy, which is anatomically determined, a difference in bone length can be observed. In addition, there is the functional form, which arises due to misalignments of individual joints or contractures (loss of length) of the capsular-ligamentous apparatus and the muscles. Anatomical leg length discrepancy is caused by accelerated, delayed or absent growth. This may involve a change in the shape of the pelvis or a shortening of the lower or upper leg. Anatomical leg length discrepancy may be caused by congenital malformations. The congenital growth disorders associated with this condition are referred to as osteochondrodysplasias. In this group of conditions, the abnormalities may be localised in the metaphyses, epiphyses, endosteum or periosteum. Overall, this results in increased or decreased bone growth.

However, tumour-related conditions of the lower limbs can also result in an anatomical leg length discrepancy. Bacterial and non-bacterial inflammations could also be considered as possible causes. This also applies to neuro-orthopaedic conditions associated with paralysis, which affect bone supply and thus growth.

However, trauma to the lower limb is considered the most common cause. This includes injuries to the growth plate (epiphysis) and fractures. Radiation therapy as part of cancer treatment or a systemic disease leading to altered metabolic processes may also be considered as triggers.

Various treatments are employed for functional and anatomical leg length discrepancies. In the case of the functional form, for example, surgical lengthening of the limbs would not be considered. In addition to a possible surgical soft-tissue procedure, the focus is primarily on intensive treatment of the soft tissues. An existing leg length discrepancy can also be corrected conservatively using custom-made orthopaedic insoles. A differential diagnosis based on a treadmill analysis is generally advisable. Minimal leg length discrepancies are rarely accompanied by symptoms, as they can be easily compensated for. A slight pelvic tilt is also hardly noticeable. However, even a mild pelvic tilt should by no means be underestimated, as it can lead to scoliosis or a short-leg limp.

Custom-made insoles are a suitable way of compensating for this. A leg length discrepancy of less than 1 cm is very common; around two in three people are affected by it. Greater differences in leg length could have serious consequences for the skeletal and muscular systems and would lead to lumbar scoliosis and a significant pelvic tilt. At a later stage, this could result in a counter-curvature of the cervical and thoracic spine. This abnormal curvature of the spine becomes fixed in 90 per cent of cases and would therefore persist. The severe pelvic misalignment would result in the knee on the longer side being permanently bent, whilst the shorter side would develop a pes cavus posture. The abnormal strain on the hip joint and the spine would be followed by osteoarthritis of the vertebral joints, the formation of osteophytes and increased wear and tear of the intervertebral discs. A difference in leg length may be accompanied by the following pain symptoms:

– hip, neck, head and knee pain

– Spinal and shoulder discomfort

– Thoracic spine and sacroiliac joint blockages

– Dizziness, migraine

– tennis elbow

– Eye pressure

– Tinnitus

– Migraines

In cases of significant pelvic misalignment due to a large difference in leg length, surgical procedures may be considered, involving leg lengthening, shortening or the replacement of bone segments.

A leg length discrepancy can be treated in the short term using microcurrent and LED light; however, this success is usually not long-lasting, as, in our view, a leg length discrepancy is not the cause but rather the effect of biomechanical problems. Therefore, treatment should be approached and administered in a more complex and systemic manner.

Microcurrent and LED light therapy can be used very effectively and sustainably for biomechanical disorders; however, this should be done with a holistic approach rather than a short-sighted focus on merely correcting leg length.