Habitual patellar dislocation in extension in children with immature epiphysis: a report of three cases

Abstract Background Pediatric habitual patellar dislocation in extension (E-HPD) is a rare and specific form of patellar dislocation with limited reports in the literature. For children with immature epiphyses, the gold standard for E-HPD surgery has not been established, and the appropriate treatment is controversial. We report three cases of pediatric E-HPD with epiphyseal immaturity and explore the etiology, risk factors, and treatment of E-HPD in children. Methods This article describes three cases of children with E-HPD whose epiphyses were not closed because of skeletal immaturity. The children ranged in age from 7 to 11 years, and all were female. Two patients underwent a combination of medial patellofemoral ligament reconstruction and lateral retinacular release, and one chose to continue conservative treatment. Clinical outcomes were assessed using the Kujala, International Knee Documentation Committee (IKDC), Lysholm, and visual analog scale (VAS) scores and presence of patellar instability, and radiographic data were collected from medical records. Results One patient chose to continue conservative treatment, but the patellar dislocation did not improve. The other two patients were treated with medial patellofemoral ligament reconstruction and lateral retinacular release. Both patients had good outcomes with no recurrent dislocations during their respective 14- and 29-month follow-ups. All postoperative scores (Kujala, IKDC, Lysholm, and VAS for pain) significantly improved compared to preoperative levels.