Open reduction (OR) alone and OR plus Pemberton periacetabular osteotomy (PPO) techniques are commonly used in the treatment of developmental dysplasia of the hip at walking age. However, discussions on the timing of acetabular osteotomy are still ongoing. The aim of the present study was to compare the results of patients who underwent Ferguson OR (FOR group) and OR plus PPO group. Between 2008 and 2017, we performed surgery on the hips, which we thought were used for closed reduction but could not be reduced as closed, or that the reduction was not stable. Patient follow-up was ≥12 months. The study included 75 hips of 57 patients of which 20 (26.7%) patients with FOR and 55 (73.3%) patients with PPO. Preoperative and postoperative acetabular indices (AIs), additional surgical intervention rates, and avascular necrosis (AVN) rates were compared. The Kalamchi-McEwen classification system was used to evaluate AVN. The average age of the patients was 12.38 (9-14) months. The mean follow-up period was 38.95 (12-140) months. AVN developed in 21 (24%) hips (6 (8%) type 1, 13 (17.3%) type 2, and 2 (2.7%) type 3). AVN developed in 7 (35%) hips in the FOR group and 14 (25.5%) hips in the PPO group. No statistically significant difference was found between the two groups (p=0.416). Revision surgery was performed in 2 (3.7%) cases of the PPO group and 6 (31.5%) cases of the FOR group. Statistically, the PPO group had less revision surgery (p=0.004). The PPO group had an AI of 13.33° (5°-27°) that was significantly lower (p<0.001) than that of 27.98° (18.39°) of the FOR group. Ferguson and Pemberton techniques are current and effective in the treatment of patients with developmental hip dysplasia at walking age. There was no significant difference between the two groups when examined from the point of view of AVN, but the results of PPO surgery were found to be better with respect to AI and revision surgery.