Lower limb discrepancy (leg length discrepancy,
LLD is a very common pediatric orthopedic disorder. Not only does it directly affect gait development, but in the long run, it can also lead to scoliosis, pelvic tilt, low back pain, excessive joint wear and tear, and asymmetric musculoskeletal development of the affected limb. There are many reasons for this phenomenon, as children’s bones are developing, and inflammation, tumors, congenital, trauma, deformities in other areas, etc. can lead to unequal growth. The following is an analysis of the common causes: 1, hip joint diseases, including congenital hip dislocation, slipped femoral epiphysis, femoral epiphysis necrosis, congenital hip inversion, congenital proximal femoral agenesis, sequelae of septic hip arthritis in infants, etc. 2, epiphyseal injury, many children have the experience of leg injury when they were young, various causes of epiphyseal trauma, that is, can lead to unequal length of the lower limbs, can also lead to deformity of the lower limbs. The long bones of the lower extremities are mainly the femur and tibia, and each bone has a growth plate, also known as the epiphyseal plate, which can lead to short legs or crooked legs as the child grows. 3, tumors, a variety of tumors, as long as they invade or affect the growth plate, will also lead to leg length or deformity, common childhood tumors that invade the epiphysis include: congenital multiple exophytic chondrosarcoma, multiple endophytic chondrosarcoma, etc. 4. Exogenous stimulation, including surgical stimulation, such as leg fracture, and finding that the leg on the fracture side becomes longer after doing fracture internal fixation surgery. Lower limb hemangioma, receiving various sclerotherapy injections, radiation therapy, etc., or shortening of the affected side due to soft tissue contracture and damage to the growth plate. 5. It is not uncommon for neurofibroma and hemangioma of the lower extremity to become excessively long due to more than normal nutrition of the affected limb. For example, in K-T syndrome, the affected limb is not short but long. In the case of neurofibroma, the nerve trunk becomes thick and coiled due to excessive innervation, resulting in the affected limb becoming longer and thicker. 6, unilateral congenital deformity, such as unilateral clubfoot, because the affected side muscle development is not complete, foot development is impaired, the calf is short and thin, resulting in unequal length. In addition, congenital tibial pseudarthrosis, congenital tibial curvature, congenital paraxial hemiplegia, including congenital fibular agenesis or tibial agenesis, these are common typical causes of lower limb inequality. 7, inflammation, long-term chronic childhood osteomyelitis, local inflammatory stimulation, enhanced blood supply, if the proximity of the epiphyseal plate, or local long-term high blood supply and high metabolic state, the affected limb will also become overgrown. And on the contrary, due to osteomyelitis resulting in bone destruction, bone loss or defect, and finally evolved into bone discontinuity, so that the leg will become shorter. 8, nerve damage, after nerve damage in childhood, such as damage to the common peroneal nerve, muscle dystrophy, eventually leading to thin and short calves. The legs or arms affected by the sequelae of polio are short. If the limbs are not innervated in development, they cannot be adequately nourished due to both vascular contraction function and muscle development, which eventually leads to unequal neurological limbs. 9, all kinds of idiopathic limb unequal length due to unknown reasons. In conclusion, there are many causes of lower limb inequality in children, and the affected limbs can be too long or too short. Basic screening and classification of the causes are very important for the development of surgical protocols and treatment plans.