Purpose or Case Report: Cruciate ligament developmental variations are frequently encountered in pediatric musculoskeletal imaging. Some of these variations represent normal anatomic variants, whereas others result from pathological development and can result in pain and instability and may be associated with other abnormalities. The purpose of this educational poster is to review developmental variations in cruciate ligament anatomy that result in normal variants as well as congenital disease.

The normal prenatal and postnatal development of the cruciate ligaments is reviewed along with the associated stabilizing structures of the joint capsule. Several examples of normal anatomical variants are reviewed and demonstrated (e.g., triple bundle anterior cruciate ligament, variations in origin and insertion). Examples of the most common congenital anomalies are also presented (e.g., isolated absence, combined absence of both cruciate ligaments, hypoplasia, dysplasia of the intercondylar eminence) along with several associated developmental syndromes (e.g., nail-patella syndrome, tibial and fibular hemimelia, congenital knee dislocation). Several critical differential diagnoses (e.g., bucket handle meniscus tears) will be discussed given their impact on patient management.

A systematic approach is provided to help differentiate the various causes of abnormal cruciate ligament development using multimodality imaging. When available, longitudinal imaging, physical examination, and arthroscopic correlations are provided for clinical correlation. Possible complications are discussed to provide additional insight into patient care. Guidelines for reporting are provided to support patient care alongside referring providers. After viewing this module, readers will be able to better understand and differentiate cruciate ligament variants and congenital anomalies and better evaluate their impact on the patients for whom they care.
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