According to the International Hip Dysplasia Institute
Developmental Dysplasia of the Hip (DDH)
Developmental Dysplasia of the Hip or DDH is generally the preferred term for babies and children with hip dysplasia since this condition can develop after birth. DDH is a medical term for general instability, or looseness, of the hip joint. Doctors use a number of different terms for hip dysplasia depending on severity and time of occurrence. These names include:
- Hip Dysplasia
- Developmental Dislocation of the Hip (DDH)
- Hip Dislocation
- Developmental Dysplasia of the Hip (DDH)
- Acetabular Dysplasia
- Congenital Dislocation of the Hip (CDH)
The term Congenital Dislocation of the Hip (CDH) tends to refer to a defect where something is missing or added to normal tissues. In the case of DDH, the infant/child’s joint is otherwise normal except for the instability.The hip is a “ball-and-socket” joint that is held together by ligament
The ball is called the “femoral [fem-er-uhl] head” which is the top of the femur or thigh bone.
The socket is called the “acetabulum” [as-i-tab-yuh-luhm] and is a part of the pelvis.
The femoral head fits into the acetabulum creating the hip joint. This joint is normally held tightly in place by the surrounding ligaments and joint capsule.
Hip dysplasia has a wide range of severity. In some children the ligaments around the hip joint are loose allowing the hip to subluxate. This is when the ball is no longer centered in the socket. Other times the ball is slightly or completely dislocated from the socket.