Hip dysplasia looks different depending on age. In infants, the most visible signs are uneven skin folds on the thighs or buttocks, one leg appearing shorter than the other, and limited movement when spreading the legs apart. In older children and adults, hip dysplasia shows up less as something you can see and more as something you can feel: a limp, deep groin pain, and a hip that clicks or catches during movement.
What It Looks Like in Infants
Most parents first notice hip dysplasia by looking at their baby’s skin folds. Normally, the creases on the back of both thighs and buttocks mirror each other. In a baby with hip dysplasia, one side often has extra folds or folds that sit at different heights. For example, the gluteal crease on the affected side may sit lower than the other, or one thigh may show two distinct skin creases while the opposite thigh is smooth. These asymmetries happen because the ball of the hip joint isn’t sitting properly in its socket, which shifts the surrounding soft tissue.
Skin fold asymmetry alone doesn’t confirm dysplasia. Some perfectly healthy babies have uneven creases. But when it appears alongside other signs, it’s a strong reason to investigate further.
A second visible clue is leg length. When you lay a baby on their back and bend both knees with the feet flat, the knee on the affected side may sit noticeably lower than the other. This is called the Galeazzi sign, and it reflects the femur sitting higher in the pelvis than it should because the hip socket isn’t holding it in place properly.
The third thing parents and pediatricians look for is limited range of motion. When you gently spread a baby’s bent legs apart (like opening a book), both hips should open to roughly the same degree. If one side resists or doesn’t open as far, that restricted movement can indicate the hip isn’t seated correctly. During well-baby checkups, doctors perform specific hands-on tests to feel for a telltale “clunk” as they gently push the hip in and out of the socket. That clunk is the femoral head slipping out of or back into the joint, and it’s distinct from the small, harmless clicks that many newborn hips produce.
What Imaging Reveals
Because the physical signs can be subtle or absent entirely, ultrasound is the standard screening tool for babies under six months. The key measurement is the alpha angle, which reflects how well the bony roof of the hip socket covers the femoral head. A normal hip has an alpha angle above 60 degrees. In newborns up to three months old, angles between 50 and 59 degrees are considered immature but acceptable as long as the hip is maturing on schedule. After three months, that same 50 to 59 degree range crosses into true dysplasia. Angles in the mid-40s indicate a more unstable joint that typically needs treatment.
For older children whose bones have hardened enough for X-rays, doctors look at the shape and depth of the hip socket and how much of the femoral head it covers. A shallow, steep socket that leaves too much of the ball exposed is the hallmark image of dysplasia at any age.
How It Shows Up in Toddlers and Children
If dysplasia isn’t caught in infancy, walking often makes it visible. A child with one affected hip will typically limp. When they stand on the affected leg, the opposite side of the pelvis drops downward because the muscles around the unstable hip can’t hold the pelvis level. This creates a distinctive swaying walk where the child leans their upper body over the weak hip with each step to compensate. In children with both hips affected, the gait looks more like a waddle, with the pelvis rocking side to side.
Parents sometimes notice their child stands with the affected leg turned outward or that one leg looks shorter when the child is standing straight.
Adult Symptoms and the C-Sign
Adults with undiagnosed or undertreated hip dysplasia usually present with pain rather than a visible deformity. The pain is most often felt in the front of the hip, deep in the groin. It’s not a surface-level ache like a muscle strain. Patients frequently describe it as feeling like it comes from deep inside, almost like bone pain, and it tends to radiate outward.
When adults point to where it hurts, many instinctively cup one hand over the front and side of the hip in a C-shape, with the thumb wrapping behind and the fingers curving around the groin. Orthopedic specialists recognize this “C-sign” as a strong indicator that the problem is inside the joint itself rather than in the surrounding muscles or tendons.
The pain typically starts during or after activity, especially walking, running, or prolonged standing. Over time it can begin appearing during everyday tasks or even at rest. Sitting for long periods, getting in and out of a car, and crossing the legs often become uncomfortable. Some adults also notice a catching, clicking, or locking sensation in the hip during movement. This usually means the ring of cartilage lining the edge of the hip socket (called the labrum) has started to tear under the abnormal stress. Labral tears from dysplasia produce a sharp, stabbing pain in certain positions layered on top of the deeper constant ache.
The Limp and Gait Changes in Adults
Adults with hip dysplasia often develop the same pelvic drop seen in children, known as a Trendelenburg gait. When you stand on one leg, the muscles on the outside of your standing hip are supposed to keep your pelvis level. In a dysplastic hip, those muscles can’t generate enough force to do the job because the joint geometry is off. The result is that your opposite hip drops every time you take a step on the affected side.
To compensate, most people unconsciously lean their torso over the weak hip during each step. This shifts their center of gravity closer to the joint and reduces the load on it. The lean might be subtle at first, but it becomes more pronounced as the joint deteriorates. Without the lean, the pelvis drops sharply, which actually increases stress on the already struggling hip. Over years, this altered walking pattern can cause secondary pain in the lower back, the opposite knee, or the IT band on the affected side.
What Happens if It Goes Untreated
A shallow hip socket concentrates weight-bearing forces onto a smaller area of cartilage than a normal hip does. That accelerated wear eventually leads to osteoarthritis, often decades earlier than the typical age-related kind. Among adults who already have both hip dysplasia and early signs of arthritis, roughly one in three will need a hip replacement within ten years. Many adults who need hip replacements in their 30s, 40s, or 50s trace the cause back to dysplasia that was never identified or that was only partially treated in childhood.
The progression isn’t always linear. Some people with mild dysplasia stay active for years with minimal symptoms, while others with more severe socket shallowness develop pain and joint damage relatively quickly. The factors that seem to accelerate the timeline include high-impact activities, higher body weight, and the presence of labral tears that destabilize the joint further.