Idiopathic Congenital Dislocation of the Knee: Case Series of Spontaneous Reduction.

Introduction: Idiopathic congenital dislocation of the knee (CDK) represents a distinct clinical category. Grade III CDK, defined as knee flexion <30° has a poor prognosis. The standard of care is "as soon as possible" manipulation and casting. Waiting for spontaneous reduction is not regarded as an accepted treatment strategy. The purpose of this study is to report on the occurrence of spontaneous reduction in idiopathic grade III CDK. Materials and Methods: This prospective cohort study included consecutive cases of idiopathic CDK treated from April 2020 to August 2025. Inclusion criteria were: Absence of neuromuscular or genetic diseases, diagnosis of grade III CDK, and follow-up until full recovery. Results: Seven knees in five female patients with grade III CDK were included; two had bilateral CDK. All pregnancies were full-term with cephalic presentation; one infant was delivered by cesarean section. Four neonates were firstborn. Hip ultrasound showed dysplasia in three patients, bilateral in two, and unilateral in one. Spontaneous full reduction occurred in six out of seven knees before 1 month of age. In the remaining knee, the flexion gradually improved to 30°, after which reduction was prompted by casting once for 2 weeks at 11 weeks of age. All knees regained a normal, stable range of motion. Bilateral dysplastic hips normalized spontaneously in one patient, while the other two required fewer than 6 weeks of splinting. Conclusion: These findings suggest a potential role for observation in the management of idiopathic grade III CDK. In this cohort, all infants were non-breech, had no foot deformities, or teratologic etiology. Significance of study: A period of observation is warranted for idiopathic CDK. In this series, six out of seven knees reduced spontaneously, and the remaining knee required only a brief period of casting at approximately 3 months of age.