Overgrowth of the Lower Limb after Treatment of Developmental Dysplasia of the Hip

Abstract

Background: During treatment of developmental dysplasia of the hip (DDH), overgrowth of the affected leg can sometimes develop. However, little was studied about this phenomenon. The purpose of this study was to evaluate the incidence of leg length discrepancy by overgrowth and investigate the risk factors for overgrowth in patients treated for DDH.

Methods: One hundred and seven patients who were treated for unilateral DDH and reached skeletal maturity were included in this study. Overgrowth was assessed on standing anteroposterior radiographs of the hip by measuring the difference in the height of femoral heads. Significant overgrowth was defined when the affected femoral head was higher than the contralateral side by more than 10 mm. The associations among treatment modalities, age at treatment, radiologic parameters, and development of significant overgrowth were retrospectively analyzed.

Results: Significant overgrowth was found in 45 patients (42%). Binary logistic regression analysis revealed that anterolateral open reduction (OR) and femoral osteotomy were the significant and independent risk factors for overgrowth (p = 0.032 and p = 0.011, respectively). In the femoral osteotomy group, the incidence of overgrowth was higher in patients who underwent femoral osteotomy at the age of 2 to 4 years than those who underwent femoral osteotomy in other age range (87% and 13%, respectively

p = 0.021). In the non-femoral osteotomy group, anterolateral OR and center-head distance discrepancy (CHDD) over 7.4% around the age of 3 years were significant risk factors for overgrowth (p = 0.024 and p = 0.002, respectively).

Conclusion: Overgrowth of the affected leg is a commonly encountered problem during treatment of DDH. Patients who underwent femoral osteotomy, especially at the age of 2 to 4 years, as well as the patients who underwent anterolateral OR or who showed large CHDD around the age of 3 years may require careful follow-up for development of overgrowth.