Developmental dysplasia of the hip

Although the etiology of developmental dysplasia of the hip (DDH) has not been rigorously evaluated, it is generally believed that genetic, hormonal, and/or mechanical factors play a role. Observational studies have shown that infants with a family history of DDH have an increased relative risk of the condition; however, most cases occur in children with no family history. It is believed that those with DDH have increased ligamentous laxity, and that this is most pronounced at the time of delivery. Intrauterine confinement and positioning may play a role given that infants born breech, first-born infants, and large infants have been shown to have a higher relative risk of the condition.[4]Bialik V, Bialik GM, Blazer S, et al. Developmental dysplasia of the hip: a new approach to incidence. Pediatrics. 1999;103:93-99. http://www.ncbi.nlm.nih.gov/pubmed/9917445?tool=bestpractice.com [5]Shipman SA, Helfand M, Moyer VA, et al. Screening for developmental dysplasia of the hip: a systematic literature review for the US Preventive Services Task Force. Pediatrics. 2006;117:e557-e576. http://www.ncbi.nlm.nih.gov/pubmed/16510634?tool=bestpractice.com

The hip is a ball and socket joint that is not fully developed at birth. Much of the development of the hip joint occurs in utero and within the first several months of life. Normal development of the hip joint requires appropriate alignment and contact between the ball of the femoral head and the socket of the acetabulum. In persistent DDH, the anatomic relationship between the femoral head and the acetabulum is incorrect, leading to abnormal development. In severe cases, a dislocated femoral head leads to the development of a false acetabulum in the pelvis. Persistently poor alignment of the ball and socket during the development of the hip joint can lead to premature arthritis in the joint; however, this outcome is not universal and typically does not occur for several decades.[6]Wedge JH, Wasylenko MJ. The natural history of congenital disease of the hip. J Bone Joint Surg Br. 1979;61-B:334-338. http://www.ncbi.nlm.nih.gov/pubmed/158025?tool=bestpractice.com [7]Schwend RM, Pratt WB, Fultz J. Untreated acetabular dysplasia of the hip in the Navajo: a 34 year case series followup. Clin Orthop Relat Res. 1999;364:108-116. http://www.ncbi.nlm.nih.gov/pubmed/10416399?tool=bestpractice.com [8]Pratt WB, Freiberger RH, Arnold WD. Untreated congenital hip dysplasia in the Navajo. Clin Orthop Relat Res. 1982:169;69-77. http://www.ncbi.nlm.nih.gov/pubmed/7067235?tool=bestpractice.com

Clinical terms

• Hip dysplasia: a radiographic finding alone showing an imperfect degree of coverage of the femoral head by the acetabulum.

• Hip subluxation: partial articulation of the joint surfaces. Clinically, this manifests as a hip that has a greater degree of laxity than normal with provocative testing, reflecting greater than normal movement of the femoral head within the acetabulum, but which is not fully dislocated or dislocatable.

• Hip dislocation: the femoral head sits fully outside of the acetabulum, either at rest or with provocative testing.

• Fixed prenatal dislocation (teratologic): typically associated with multiple deformation, and/or neurologic conditions, or other syndromes (e.g., arthrogryposis), where more invasive intervention is usually required to attempt a reduction.