What does a pre or post axial radial hemimelia birth defect involve?

A pre- or post-axial radial hemimelia is characterized by the absence or malformation of the radius, which is one of the two long bones in the forearm. This condition can manifest either in a pre-axial (before the radial axis in anatomical terms) or post-axial (after the radial axis) manner.

In specific terms, when we refer to "missing radius," we highlight that individuals may have either a complete absence of the radius or significant underdevelopment of this bone. The condition also involves effects on the hand, often leading to functional impairment. The mention of the "ulnar side of the hand" relates to the positioning of the other major bone in the forearm, which is the ulna, that remains present but may experience structural compensation or alteration in function due to the absence of the radius.

Understanding the terminology is critical: "pre-axial" and "post-axial" indicate the location in relation to the body's anatomical axes, and in this context, it is specifically the radius that is affected, leading to the noted consequences in the anatomy and functionality of the hand and wrist.