Hip dysplasia is diagnosed differently depending on age, ranging from hands-on physical exams in newborns to imaging studies in older children and adults. The process starts with recognizing risk factors or symptoms, then confirming the diagnosis with the right test at the right time.
Newborn Physical Exam
Most cases of hip dysplasia are first detected in the hospital within days of birth. Pediatricians perform two specific maneuvers on every newborn’s hips during routine checkups, and these exams continue at well-child visits through the first year of life.
The Ortolani maneuver checks whether a dislocated hip can be guided back into the socket. The examiner gently lifts and rotates the infant’s thigh outward, feeling for a distinct “clunk” as the ball of the femur slides back into place. This is a tactile sensation of movement, not just an audible click. Many newborns have harmless clicking sounds in their hips from soft tissue; what matters is the feeling of the hip actually relocating.
The Barlow maneuver does the opposite. It tests whether a hip that’s currently in the socket can be pushed out with gentle pressure. If the hip slides out of place, that confirms instability. Together, these two tests can identify hips that are dislocated, dislocatable, or subluxed (partially out of position). They’re most reliable in the first few weeks of life, before the muscles around the hip tighten up and make subtle instability harder to detect.
Another useful sign is the Galeazzi test. With the baby lying on their back, the examiner bends both hips and knees, then compares knee heights. If one knee sits lower than the other, the hip on that side may be dislocated. Doctors also look for asymmetric thigh skin folds or limited range of motion when spreading the legs apart, though these signs are less specific on their own.
Who Needs Imaging
Not every infant gets a hip ultrasound. The American Academy of Pediatrics recommends serial clinical exams for all babies, but reserves imaging for those with specific risk factors. Female infants born in the breech position should get hip imaging. For boys born breech or girls with a family history of hip dysplasia, imaging is optional but worth discussing. Universal ultrasound screening for all newborns is not recommended in the United States.
If anything feels abnormal on the physical exam, imaging is the next step regardless of risk factors. The type of imaging depends entirely on the child’s age.
Ultrasound for Infants Under 6 Months
Ultrasound is the primary imaging tool for babies younger than about 4 to 6 months. At this age, the hip socket and femoral head are mostly cartilage, which doesn’t show up well on X-rays. Ultrasound can visualize soft tissue directly and measure how well the socket covers the femoral head.
The most widely used interpretation system is the Graf classification, which measures two angles on the ultrasound image. The alpha angle reflects the shape of the bony roof of the socket. A normal hip (Graf Type I) has an alpha angle greater than 60 degrees, meaning the bony socket is deep enough to hold the femoral head securely.
If the alpha angle falls between 50 and 59 degrees, interpretation depends on age. In a baby younger than 3 months, this is classified as an “immature” hip (Type IIa), which often develops normally on its own with monitoring. The same measurement in a baby older than 3 months is considered true dysplasia (Type IIb) and typically requires treatment. As alpha angles drop further below 50 degrees, the hip progresses through more severe categories: Type IIc (the socket is critically shallow), Type III (the femoral head has dislocated), and Type IV (severe dislocation where the femoral head is pushed far from its normal position).
This age-dependent interpretation is important. A mildly abnormal ultrasound at 6 weeks may just need a follow-up scan, while the same finding at 4 months calls for intervention.
X-Rays for Older Babies and Children
Once a child reaches about 4 to 6 months of age, the hip bones have calcified enough to show clearly on X-rays, making them the preferred imaging method. Radiologists look at several landmarks to assess hip position and socket development.
One key measurement is Shenton’s line, a smooth curve drawn along the bottom edge of the femoral neck and the top of the pelvic bone near the hip socket. In a normal hip, this curve flows unbroken. A disrupted or “broken” Shenton’s line means the femoral head has shifted out of its proper position, either upward, sideways, or both. After age 3 or 4, any disruption of this line on any view of the hip indicates an abnormal relationship between the femoral head and the socket.
Other X-ray measurements assess how shallow or steep the socket is and whether the femoral head is centered within it. These measurements help classify severity and guide treatment decisions.
Diagnosing Hip Dysplasia in Adults
Hip dysplasia isn’t always caught in childhood. Some people reach their teens or twenties before symptoms appear. The most common complaint is activity-related groin pain, often felt deep in the front of the hip during or after exercise. Some people describe a sense of instability, as if the hip might give way. These symptoms often develop because the shallow socket puts extra stress on the soft tissue rim (labrum) that lines the edge of the socket, eventually causing a labral tear.
For adults, diagnosis starts with a physical exam that tests range of motion and reproduces pain in specific positions. X-rays then confirm the shape of the socket and how much coverage it provides to the femoral head. The same landmarks used in children, including Shenton’s line and socket angle measurements, apply here.
MRI and Arthrogram for Soft Tissue Detail
When doctors suspect damage to the labrum or need to see structures that don’t appear on X-rays, MRI provides the clearest picture. In some cases, a contrast agent is injected into the hip joint before the scan (an MRI arthrogram), which outlines the labrum, cartilage, and ligaments in sharp detail. This can reveal labral tears, cartilage damage, or inversion of the labrum into the joint, all of which affect treatment planning.
For infants being treated with closed reduction (repositioning the hip without surgery), an arthrogram performed during the procedure helps the surgeon evaluate how well the femoral head sits in the socket and whether the labrum is folded inward and blocking full reduction. These findings can predict long-term outcomes.
What the Diagnosis Looks Like at Each Age
- Newborn to 6 weeks: Physical exam with Ortolani and Barlow maneuvers at birth and early well-child visits. Ultrasound if risk factors are present or exam is abnormal.
- 6 weeks to 6 months: Continued physical exams plus ultrasound as needed. Mildly abnormal findings may be monitored with repeat scans.
- 6 months to 2 years: X-rays become the primary tool. A child who starts walking late, walks with a limp, or has asymmetric leg length may be evaluated at this stage.
- Older children and teens: X-rays and possibly MRI if pain or instability develops. The diagnosis sometimes comes as an incidental finding or after a sports injury.
- Adults: X-rays to confirm socket shape, often followed by MRI arthrogram to assess labral and cartilage damage before deciding on treatment.
Early detection matters because treatment is simplest in the first few months of life, when a soft brace can guide normal socket development. The later the diagnosis, the more likely that surgical correction or joint preservation procedures will be needed.