Uneven thigh or gluteal creases in an infant are a common concern for new parents. While these asymmetries can sometimes indicate an underlying medical condition, they are frequently a benign finding. This article clarifies when this physical variation is a normal part of development and when it warrants professional medical attention. Understanding this distinction helps parents monitor their baby’s growth.
Anatomical Variation and Normal Findings
In most cases, uneven thigh or gluteal creases are purely cosmetic and do not signify a health concern. The skin folds reflect the infant’s soft tissue, specifically the distribution of fat and how the skin naturally bunches. This variation in fat distribution is common and can be influenced by the baby’s position or the natural contours of their legs and buttocks.
Creases are not a reliable standalone indicator of a problem, occurring in up to 25% of healthy infants. The depth, number, and alignment of these folds can differ slightly without any underlying issue with the hip joint. For instance, one inner thigh may display an extra crease because the fat padding is slightly thicker there. These creases often become less noticeable as the child grows and body fat distribution changes.
Uneven Creases and Developmental Dysplasia of the Hip
Asymmetric skin folds are one physical sign associated with Developmental Dysplasia of the Hip (DDH). DDH is a condition where the hip’s ball-and-socket joint does not form correctly. This means the ball at the top of the thigh bone (femoral head) does not sit securely within the hip socket (acetabulum). This abnormal formation can range from a shallow socket to a completely dislocated hip.
The presence of uneven creases alone is considered a weak link to DDH. Studies indicate that asymmetric folds are present in only a fraction of infants diagnosed with the condition. The asymmetry may occur because displacement of the thigh bone causes relative leg shortening, creating a surplus of soft tissue that folds unevenly. Since DDH is not painful for babies, observing uneven creases is a valuable starting point for evaluation.
A healthcare provider looks for other, more reliable physical signs of DDH during routine examinations. These include limited range of motion, particularly difficulty spreading the legs apart (abduction), or a noticeable difference in leg length when the knees are bent (Galeazzi sign). A clinician may also observe an outward-turning leg or feel a palpable “clunk” or “pop” when moving the hip, indicating instability. DDH is more common in girls, firstborn children, and babies born in the breech position. These risk factors prompt closer monitoring.
Medical Assessment and Diagnostic Tools
A healthcare professional performs a thorough physical examination when uneven creases or other risk factors are present. For newborns and young infants, the primary diagnostic tools are specific physical maneuvers checking for joint instability. The Ortolani test involves gently moving the hip into a reduced position. The Barlow maneuver attempts to gently dislocate an unstable hip.
These tests are performed with the infant lying on a flat surface. The examiner feels for a distinct sensation indicating the femoral head moving in or out of the socket. The sensitivity of these maneuvers decreases after two to three months of age as the infant’s ligaments tighten. If the physical exam suggests instability or if risk factors are present, diagnostic imaging is used to confirm or rule out DDH.
For infants under four to six months of age, an ultrasound is the preferred imaging technique. This is because the hip joint is still largely composed of cartilage, which does not show up well on X-rays. Ultrasound allows the clinician to visualize the hip joint in real-time and assess the stability and structure of the socket. For infants older than six months, when the bones have begun to ossify, plain X-rays are used for diagnosis. If confirmed, early treatment often involves a Pavlik harness, which holds the hip in a stable position to encourage normal development. Prompt detection and treatment prevent problems like early-onset arthritis later in life.