Rotational Alignment of the Finger Nails in a Normal Population

Author(s): Bansal R, Craigen MAC

Source: J Hand Surg 32B: 80-84, 2007.

Summary:

The authors measure the alignment of the nails in the hands of 100 normal adults with the interphalangeal joints extended and the metacarpophalangeal (MCP) joints at 0 and 90 degrees.  When examining hands in MCP joint extension, only 17% of hands had all nails parallel (i.e., 5 degrees or less difference in rotation): this improved to 56% with the MCP joints flexed.  When comparing matching fingers from the two hands, 76% of little, 83% of ring, 77% of middle, and 80% of index nails matched.

This study demonstrates that the inclination of the fingernails to the horizontal plane varies within a hand and between hands.  The authors caution against examination of the injured hand alone when assessing finger rotation following fracture.  Although matching fingers in the two hands may be a more reliable method of assessing for malrotation, variation in nail plate alignment is expected in approximately 20% of normal individuals.  Rotational alignment may be better determined by active finger motion and/or passive wrist flexion and extension.

Nail, Rotation, Alignment, Finger, Flexion, Extension

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