Hypothesis: terminal transverse limb defects with "nubbins" represent a regenerative process during limb development in human fetuses.

BACKGROUND

Terminal transverse limb defects with nubbins occur in one arm at one of several levels (distal humerus, proximal forearm, wrist, and at the metacarpal-phalangeal joint in the hand). The associated nubbins contain osteocartilaginous tissue and small nails and are not associated with evidence of amnion disruption.

METHODS

We present affected newborn infants whose terminal transverse limb defects are at one of these three levels: proximal forearm, elbow, or metacarpal-phalangeal joint.

RESULTS

We hypothesize that the presence of residual digit-like structures reflects a regenerative process that has occurred during limb development in these infants.

DISCUSSION: Only limited regeneration of digit-like structures can occur in the human fetus.