There are many types of thumb hypoplasia, with more obvious ones like "floating thumb," where only a small part of the thumb is connected to the palm by tissue, making the abnormality noticeable at birth.
However, type II thumb hypoplasia can sometimes be harder to detect and may be overlooked by parents. This is because type II thumb hypoplasia often doesn't have a striking difference in appearance from a normal thumb. But once you understand its characteristics, it's easy to diagnose, and the surgery is straightforward and targeted accordingly.
1. Small first web space
IEven though type II thumb hypoplasia might seem "okay," the thenar muscle is underdeveloped, so this area feels less full to the touch. The thumb may appear thinner, and the angle at which the child can open the thumb-index gap is limited.
Difficulty opening the thumb-index gap
If the child has a small first web space, they will not be able to grasp objects freely, relying instead on their fingers to pinch. Parents can carefully observe their child's grasping posture when playing with toys and test the thumb's opening angle.
2.Loose joint capsule
Children with type II thumb hypoplasia usually have poor stability in the metacarpophalangeal joint. If parents touch the child's fingers, they may feel noticeable looseness. This could cause the child to have difficulty holding a pen or carrying water steadily.
Loose joints
3. Lack of opposition function(palm)
Due to the absence of the thenar muscle, the child's thumb can only flex but lacks opposition.
Opposition is the ability of the thumb to touch each of the other fingers (pinky, ring, middle, and index), which is crucial for grasping objects securely in daily life.
Therefore, if you notice that the child cannot open their hand fully or hold larger objects steadily, it is important not to ignore it and to contact a doctor promptly.
For type II thumb hypoplasia, during surgery, the goal is to open up the thumb-index gap, strengthen joint stability, and most importantly, reconstruct the opposition function. This ensures that after surgery, with proper functional exercises, the child can gradually regain both a better appearance and improved hand function.
Whether it's type II thumb hypoplasia or a "floating thumb," both affect the child's hand function. Since hands are crucial in daily life, parents should ensure their baby gets examined after birth and should be attentive to changes in the child's hands and feet, never neglecting them!