Bodily Oddities

Clinodactyly

Also called: Curved little finger · Bent pinky

A finger that curves sideways toward its neighbours, most often the little finger leaning toward the ring finger. Between 1% and 20% of people have it, and on its own it is harmless.

Bones and joints Variation Structural
Try it Genetic

How common

1–20% of people Uncommon · 1–10% Depends on the cutoff angle used. Mild curves are common.

Do you have this?

These are answers from visitors, not a study.

How it works

Each finger has three small bones called phalanges. The middle one is normally a short rectangle. In clinodactyly the middle bone is wedge-shaped, shorter on one side than the other1. The bone above it tilts toward the short side, so the fingertip points sideways. Doctors count it when the curve is more than 10 degrees from straight1. The little finger is affected most often, and it usually leans toward the ring finger.

The shape is set before birth and does not get worse after the bones stop growing. It is usually on both hands. Most cases are inherited in a dominant pattern, so one parent often has it too1.

Reports of prevalence run from 1% to about 20%, depending on how much curve is counted1. A slight bend is common and most people with it never notice.

A more marked curve is one of the many small physical signs seen in Down syndrome, and it is on the list of checks doctors make on newborns2. That link worries some parents. On its own, in a person with no other signs, a curved little finger means nothing beyond a curved little finger1.

A different condition, camptodactyly, is a finger bent forward at the middle joint that cannot straighten fully. That is a tendon and ligament problem rather than a bone shape3.

Try it

  1. Lay one hand flat on a table with the fingers together.
  2. Look at the little finger from above. In most people it lies straight. In clinodactyly the top two segments angle toward the ring finger.
  3. Spread the fingers. The curve stays, because it is in the bone and not the joint.
  4. Check the other hand. Both hands usually match.

Sources and further material

  1. Encyclopedia Clinodactyly
  2. Encyclopedia Down syndrome
  3. Encyclopedia Camptodactyly The forward-bent finger that is often confused with clinodactyly.
Bones Variation

Hitchhiker's thumb

A thumb whose top joint bends back past 50 degrees, once taught as a simple recessive gene. Thumb angle is really a smooth range, and the genetics are not that simple.

24–36% of people
Bones Variation

Morton's toe

A second toe that looks longer than the big toe because the first metatarsal bone in the foot is short. It is common, and it is the foot shape seen on classical Greek statues.

3–22% of people
Bones Variation

Webbed toes

Two toes joined by skin, most often the second and third, in about 1 in 2,000 to 3,000 babies. The toes usually work normally and many people leave them as they are.

About 1 in 2,000–3,000 births