Abstract
Introduction: It is said that God gave us paired bilateral anatomical structures so that the trauma surgeon can compare the injured side with its uninjured counterpart. The axial rotational alignment of fingers, when disrupted by injury, may lead to scissoring. During examination, comparison is made between the rotational alignment of injured and uninjured fingers. This assumes that the rotational alignment of the fingers is symmetrical. A study was performed to ascertain normal rotational alignment, and establish whether this assumption is valid.
Materials and Methods: Standardised digital images were taken with fingers in extension. These were analysed using the angle-measuring tool on Adobe Photoshop software. The rotational angle used was that between a line joining the radial and ulnar borders of the nail plate, and the horizontal.
Results: Mean angles of rotation were 13° for the index finger, 10° for the middle, 5° for the ring and 12° for the little. Differences in the angle for ring and little fingers between the sides were not significant; these fingers are symmetrical. Index and middle fingers demonstrated statistically significant asymmetry of 2.6° (SD +/− 4.2°).
Discussion: Previous work has sought to quantify rotational alignment in cadavers or using wire markers and fluoroscopy. A new method, using digital photography and image analysis is described. We determined mean angles, showing symmetry of the ring and little but asymmetry of index and middle. Previous work has suggested that up to 10° of rotation can be tolerated. With only 2.6° of difference, clinical comparison of sides remains appropriate.
The abstracts were prepared by Major SA Adams. Correspondence should be addressed to Major M Butler, CSOS, Institute of Naval Medicine, Crescent Road, Alverstoke, Hants PO12 2DL
