Clubfoot is usually diagnosed in one of two ways: during a routine prenatal ultrasound or through a physical exam right after birth. About 80% of cases are isolated birth defects with no known cause, while the remaining 20% are linked to other conditions like spina bifida or genetic syndromes. The diagnostic process is straightforward in most cases, but distinguishing severity and ruling out related conditions takes a trained eye.
Prenatal Detection by Ultrasound
Many parents first learn about clubfoot before their baby is born. Ultrasound can detect the characteristic foot positioning as early as the first trimester, though it’s more commonly spotted during the routine anatomy scan around 18 to 20 weeks. A systematic review of 13 studies found that the earliest diagnoses occurred in the first trimester, while the latest were made around week 28.
Prenatal detection isn’t perfect. The false-positive rate for isolated clubfoot on ultrasound ranges from 10 to 40% across studies, meaning the foot may appear turned inward on the scan but look normal at birth. One single-institution study found a false-positive rate of about 7%, suggesting that experienced imaging centers tend to be more accurate. If clubfoot is suspected on ultrasound, doctors will typically look for other structural abnormalities to determine whether the foot is an isolated finding or part of a broader condition.
Physical Exam at Birth
The definitive diagnosis happens after delivery. A doctor examines the newborn’s foot for four overlapping deformities, sometimes remembered by the acronym CAVE: the arch is abnormally high (cavus), the front of the foot turns inward (adductus), the heel tilts inward (varus), and the foot points downward as if the baby is standing on tiptoe (equinus). In a true clubfoot, these positions are rigid and can’t be fully corrected by gently moving the foot.
The exam follows a careful sequence. The doctor palpates the heel to check whether the heel bone can be felt in its normal position or seems “empty,” meaning it’s pulled up and hidden by tight tissue. They check whether the outer edge of the foot is straight or bowed outward. They test how far the foot can be moved in three directions: rotation, upward bending at the ankle, and correction of the heel’s inward tilt. The muscles are assessed for tone, and the hips, knees, elbows, and shoulders are all examined to rule out dislocations or deformities in other joints.
Babies need to be relaxed during the exam, and the foot should be manipulated gently. There’s no substitute for what an experienced examiner can feel with their hands. For instance, unusual stiffness in the hindfoot can suggest a bony bridge between bones that wouldn’t show up on an X-ray in a newborn.
Positional vs. Structural Clubfoot
Not every foot that looks turned at birth is a true clubfoot. One of the most important distinctions the exam makes is between a positional (or postural) clubfoot and a structural one. Positional clubfoot happens when the foot was simply held in an awkward position in the womb. The foot may look inverted and turned inward, but it feels supple, has no deep skin creases, and the calf is a normal size. Most importantly, it can be gently moved into a fully corrected position by hand.
Structural clubfoot is different. The foot is rigid, the ankle’s range of motion is limited, and the deformity can’t be passively corrected. There are often deep creases on the sole or behind the heel, and the calf on the affected side is noticeably thinner. Severity varies: some structural clubfeet are relatively soft and partially reducible, while others are stiff and completely fixed in position. That spectrum is why scoring systems exist.
Scoring Severity
Once clubfoot is confirmed, doctors score its severity to guide treatment decisions and track progress over time. The two most widely used systems are the Pirani score and the Dimeglio classification.
The Pirani score evaluates six physical signs: the depth of the crease behind the heel, whether the heel feels empty, rigidity of the downward pointing, the depth of the crease on the inner sole, curvature of the foot’s outer border, and the position of a key bone on the top of the foot (the talus). Each sign is scored 0 for normal, 0.5 for moderate deformity, or 1 for severe deformity, giving a total between 0 and 6. A higher number means a more severe case. This score is checked repeatedly throughout treatment to measure improvement.
The Dimeglio classification uses a 20-point scale based on four measurements: how far down the foot points, how far the heel tilts inward, how much the foot can be rotated, and how much the forefoot angles inward relative to the hindfoot. Higher scores again indicate more rigid, harder-to-correct deformities. Both systems help predict how many casts a baby will need and whether a minor surgical procedure on the Achilles tendon is likely.
When X-Rays Are Used
Clubfoot is primarily a clinical diagnosis, meaning the physical exam is the main tool. X-rays are not routinely needed to confirm the diagnosis in a newborn, partly because many of the foot bones haven’t fully hardened yet and don’t show up well on film. However, imaging becomes useful in certain situations: when the foot doesn’t respond to treatment as expected, when surgery is being considered, or when doctors need an objective measurement of the bone alignment.
When X-rays are taken, two views of the foot are standard. On the top-down view, the angle between the two main hindfoot bones normally falls between 25 and 40 degrees; an angle below 25 confirms hindfoot varus. The angle measuring forefoot alignment on the same view is normally 0 to 20 degrees, with anything above 20 indicating forefoot adduction. On the side view, the arch angle is normally 0 to 4 degrees, with higher values confirming cavus, and the angle between the shinbone and heel bone normally falls between 60 and 90 degrees, with anything above 90 indicating equinus. These measurements give a precise, reproducible picture of each component of the deformity.
Screening for Associated Conditions
Because about 20% of clubfoot cases occur alongside other conditions, the initial diagnosis includes screening for broader problems. Conditions commonly associated with non-isolated clubfoot include spina bifida (specifically myelomeningocele), distal arthrogryposis (a group of conditions causing joint stiffness), and various chromosomal abnormalities.
This is why the newborn exam extends beyond the foot itself. Checking the hips for dislocation, the spine for dimples or tufts of hair that could signal spinal cord issues, and the other joints for unusual stiffness helps determine whether the clubfoot is truly isolated. When clubfoot is detected prenatally, a detailed ultrasound of the rest of the baby’s anatomy is typically performed to look for other anomalies. If the clubfoot appears isolated on imaging and at birth, the prognosis is generally better and treatment is more predictable than when it’s part of a syndrome.