How to determine if your baby's hand is type III or type IV thumb dysplasia

Type III thumb dysplasia is characterized by partial dysplasia of the metacarpal bones of the thumb, especially the proximal metacarpal bones. The thenar muscles dominated by the median and ulnar nerves are significantly affected, with limited movement of the metacarpal and interphalangeal joints, resulting in significant dysplasia and instability of the thumb, and a small appearance. Type IV thumb dysplasia thumb also known as floating thumb, no metacarpal bone or only metacarpal bone remains, and the palm is connected to a loose leather tube, the size of the thumb varies greatly, but mostly located in the radial or remote end.