Effect of age on radiographic outcomes of patients aged 6-24 months with developmental dysplasia of the hip treated by closed reduction

This study aimed to investigate the effect of age on the rates of redislocation, avascular necrosis (AVN) of the femoral head, and final radiographic outcomes in patients with developmental dysplasia of the hip (DDH) treated with closed reduction. A total of 308 hips (276 patients) with DDH treated with closed reduction were included and divided into three groups according to age (<12, 12-18, 18-24 months). Tonnis grade, rate of redislocation and AVN, Severin radiographic grade, and risk of surgery were evaluated on radiographs. Tonnis grade significantly increased with age (P < 0.001). Redislocation occurred in 17 (5.5%) and AVN occurred in 36 (11.7%) hips. The rate of redislocation and AVN was similar among the three age groups in all Tonnis grades. However, redislocation rate significantly increased with Tonnis grade (P = 0.027). Overall, 246 hips (79.9%) had satisfactory final outcomes, and 62 hips (20.1%) had unsatisfactory outcome; no difference was observed among three age groups. A total of 103 hips (33.4%) were found to be at risk for secondary surgery. The surgical risk (25%) in patients younger than 12 months was lower than that of older patients (12-18 months: 34.4%; 18-24 months: 37.9%). Logistic regression analysis also confirmed that age was not a risk factor for redislocation, AVN, or poor radiographic outcome. In conclusion, age has no significant impact on redislocation and AVN in patients aged 6-24 months with DDH treated by closed reduction. Although older patients have a higher risk developing residual acetabular dysplasia, secondary pelvic surgery provides favorable outcomes in most patients.