**Core Concept:** Developmental Dysplasia of Hip (DDH) is a spectrum of conditions characterized by abnormal development of the hip joint, leading to instability, dislocation, or abnormal bone growth. The hip joint is a ball-and-socket joint, and DDH disrupts the normal anatomy, resulting in potential long-term complications like osteoarthritis and pain.

**Why the Correct Answer is Right:** Developmental Dysplasia of Hip is a common pediatric musculoskeletal disorder, affecting newborns and infants. It is classified into two main types: Acetabular Dysplasia and Developmental Dislocation of the Hip (DDH). In Acetabular Dysplasia, the acetabulum (socket) is shallow and poorly formed, causing instability. In Developmental Dislocation of the Hip, the head of the femur (thigh bone) fails to properly settle into the acetabulum, resulting in dislocation.

**Why Each Wrong Option is Incorrect:**

A. False: DDH is a congenital condition. While it can occur in newborns, it is not limited to infants and can affect children and adults as well.
B. False: DDH does not involve the knee joint or ligaments, which are unrelated to hip joint integrity.
C. False: DDH is not a result of poor muscle tone, but rather a developmental issue affecting the hip joint.
D. False: DDH is not solely a result of poor mother's posture while breastfeeding. While posture can worsen the condition, it is not the sole cause.

**Clinical Pearl:** Early detection and intervention are crucial for successful treatment in DDH. Clinical examination, such as the Ortolani or Barlow test, can identify hip instability during the first few months of life. If left undiagnosed or untreated, DDH can lead to long-term complications, including arthritis, pain, and limited mobility.