Teenage Female with Knee Pain and Instability

Abstract

Congenital dislocation of the knee, result- ing from an absence of the cruciate ligaments, is  a condition affecting 0.017 per 1000 live births (1).  Although very rare, it has drawn the attention of or- thopaedic surgeons and radiologists because it is  associated with other congential anomalies. This paper presents abnormalities that are isolated to the knee and without evidence of associated syndrome. The absent anterior cruciate ligament (ACL) is associated with a hypoplastic posterior cruciate ligament (PCL), a shallow femoral notch, and hypoplastic tibial spines seen with radiographic and magnetic resonance imaging. The objective of this article is to review the clinical presentation and imaging fndings associated with congenitally absent ACL.