Prediction of Clinically Significant Leg-Length Discrepancy in Congenital Disorders

Leg-length discrepancy greater than 2 to 2.5 cm can potentially have an adverse effect on our walking and standing mechanisms and requires proper correction involving surgical treatment. However, for minor leg-length discrepancy in childhood, decision making for the indications for and timing of epiphysiodesis is difficult because of unpredictable final discrepancy. The purpose of this study was to analyze longitudinal changes of minor leg-length discrepancy in congenital disorders and to determine earlier predictive values for the clinically significant discrepancy. Twenty-one patients with congenital disorders who had minor leg-length discrepancy less than 2 cm at the first presentation were retrospectively evaluated. The patients were divided into 2 groups according to leg-length discrepancy at latest follow-up: the significant group (n=11) had 25 mm or more of leg-length discrepancy and the minor group (n=10) had less than 25 mm of leg-length discrepancy. The authors evaluated longitudinal changes of leg-length discrepancy within the first 10 years by mixed-effects regression model. All patients showed monotonically increasing leg-length discrepancy with age, except for 2 (neurofibromatosis type 1 and macrodactyly of the foot) who demonstrated fluctuating leg-length discrepancy. Mean annual rate of leg-length discrepancy change in the significant group was 2.1 mm across the first decade of life and was significantly larger than that in the minor group (difference in slope, 1.3 mm; P<.0001). In minor leg-length discrepancy associated with congenital disorders, the incidence of clinically significant leg-length discrepancy can be predictable by the annual rate of leg-length discrepancy change in the first decade of life.