We evaluated treatment results of 22 children (32 hips) with idiopathic hip dislocation after walking age in two Dutch academic hospitals. The Tönnis classification was used preoperatively. Outcome was measured using the Severin and Kalamchi classification. The mean age at treatment was 24 months and the mean follow-up was 6.8 years. In 24 hips (73%), a perfect outcome was found (Kalamchi score≤1 and Severin score of 1). A fair or a poor outcome according to Severin (≥3) was found in five hips (15%). Treatment of a hip dislocation beyond 18 months of age usually results in adequate hip development with limited avascular necrosis.
Level of evidence: Level III.