Bilateral Recurrent, Atraumatic Anterior Knee Dislocations in a Pediatric Patient With Congenital Absence of the Anterior Cruciate Ligament.

An 8 yo 15 kg male child with an undiagnosed congenital syndrome presented with painful, recurrent atraumatic bilateral knee dislocations. Recurrent dislocations were reduced in the emergency department and were never associated with neurovascular compromise. Magnetic resonance imaging identified congenital agenesis of the anterior cruciate ligament (ACL) bilaterally. He underwent staged bilateral physeal-sparing ACL reconstructions with autograft iliotibial band and had no subsequent dislocations during 14 month follow-up. To our knowledge, this is the only reported case of atraumatic spontaneous bilateral knee dislocations in a patient with bilateral congenital absence of the ACL. This case describes a novel indication for physeal-sparing ACL reconstruction in a rare clinical entity.