Leg length discrepancy in children with hip pathology. How important is it?

BACKGROUND: Length inequality of the lower limbs is a common secondary deformity in pathologies such as congenital hip dislocation and Perthes' disease. Treatment can shorten or lengthen the affected limb, but no clear patterns have been identified. The different authors' opinions on the impact of leg variance in patients with hip joint pathology and the need to correct this inequality prompted us to analyse and conduct a study on this issue. AIM: To evaluate the inequalities of lower limb length in patients with unilateral congenital hip dislocation and Perthes' disease after surgical intervention. MATERIALS AND METHODS: The study included 38 patients with unilateral pathology of the hip joint: 27 girls, 11 boys; 26 patients with congenital hip dislocation, 12 with Perthes disease. 12 patients (32%) underwent surgical treatment on the left hip, and 26 patients on the right (68%). The average age was 9 years (±2.24). Duration of observation up to 7 years (average 28 months ± 21). The minimum follow-up period was 6 months, the maximum was 84 months. RESULTS: A positive Trendelenburg test was noted in 21 patients (10 with Perthes disease and 11 with hip dislocation). In patients with congenital hip dislocation, the affected limb was shortened by 2.3 cm (1.7–2.9) in 16 patients, lengthened by 1.6 cm (1.3–1.9) in 10 patients. In patients with Perthes disease, shortening of the affected limb occurred in 9 patients by an average of 1.9 cm (1.2–2.6), and in 3 patients there was a lengthening of the limb by an average of 1.5 cm (0.7–2.0). The formation of positional hip subluxation was revealed in 8 patients with limb lengthening on the affected side. After statistical analysis, it was revealed that acquired shortening of the operated limb occurs more often (ratio 25 to 13, p=0.019). The dependence of the change in length on pathology was noted as statistically insignificant (p=0.525). There was no dependence of changes in the length of the lower limb on the patient’s gender (p=0.657), however, a statistical dependence on age was revealed (p=0.049). CONCLUSION: From our point of view, correction of residual length inequality is reasonable, as it allows correcting the development of secondary complications, reducing the degree of positional subluxation of the femoral head, improving the balance of the gluteal muscles, and reducing the severity of gait disorders, which for many patients is even more important than joint stability.