The limbus and the neolimbus in developmental dysplasia of the hip.

UNLABELLED: The limbus and the neolimbus are both pathological lesions that form in response to a developmentally dislocated hip. An understanding of these structures is integral to treatment of developmental dysplasia of the hip (DDH). Yet, we believe the current peer-reviewed orthopaedic literature and orthopaedic textbooks commonly fail to correctly use or define these terms. The neolimbus is best defined as a hypertrophied ridge of fibrocartilage in the superolateral region of the acetabulum caused by pressure from the dislocated hip on this region. The limbus is the labrum that is hypertrophied with fibrous and fibrocartilaginous overgrowth, and is a potential block to concentric reduction of a dysplastic hip. We review the early and current literature in an attempt to clarify the use of the terms limbus and neolimbus and provide an overview of the importance and treatment of these abnormal structures associated with DDH. LEVEL OF EVIDENCE: Level V, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.