[Single portal arthroscopic-assisted reduction technique in the treatment of irreducible developmental dislocation of the hip in infants and toddlers].

Objective: To investigate the efficacy of single-portal arthroscopic-assisted reduction technique in the developmental dislocation of the hip in infants. Methods: From January 2014 to December 2016, 12 dislocated hips in 12 children with a median age of 14 months (10 to 20 months) were treated with single-portal arthroscopic-assisted reduction technique. The indication for intervention was failure of closed reduction after bilateral adductor and unilateral iliopsoas release under anesthesia. Adductor and iliopsoas tendon were released routinely through a medial approach. Through the same medial approach a single-portal arthroscopic-assisted reduction technique was selected, with a medial sub-adductor portal for both 4.0 mm cannulated system with a 30° arthroscope and the instruments. After assessing of the intraarticular structures, the hypertrophic ligamentum teres and acetabular pulvinar were resected, and transverse acetabular ligament (TAL) was incised and a limited release of the capsule was performed prior to reduction of the hip. Arthrography was performed after reduction in all children. Safe zone angle and the medialization ratio on the arthrogram were compared pre and post arthroscopic reduction. Acetabular index were compared at two time points: before operation and at the latest follow-up with paired t test. Results: All hips were reduced with single-portal arthroscopic procedures. The reduction was confirmed on arthrography. With a median follow-up of 26 months (18 to 36 months), all 12 hips remained stable. Safe zone angle increased from 18.5°±3.8° to 61.9°±6.5° immediately after arthroscopic reduction(t=-28.944, P<0.01); and the medialization ratio on the arthrogram increased from 62%±20% to 104%±16% immediately after arthroscopic reduction (t=-3.519, P<0.05). The mean acetabular index decreased from 40.6°±5.0° to 29.4°±5.0° at the latest follow-up (t=5.463, P<0.01). However, Kalamchi-MacEwen type Ⅰ avascular necrosis was developed only in 1 case, and residual dysplasia was observed in 2 hips. Conclusions: Single-portal arthroscopic-assisted reduction technique is a safe and effective treatment for developmental dislocation of the hip in infants and toddlers.