The purpose of this study was to determine the normal angle of rotation of the axis of each finger using digital image analysis, whether the rotation of the digits is symmetrical in the two hands of an individual, and the reliability of this method.

Standardised digital photographic images were taken of thirty healthy volunteers. The palm of each hand was placed on a flat bench top with their fingers held in extension and adducted, to give an end-on image of all four fingers. Three independent observers analysed the images using Adobe Photoshop software. The rotational angle of each finger was defined as the angle created by a straight line connecting the radial and ulnar border of the nail plate and the bench top horizon.

The three observers showed Inter-Rater Reliability of 92%. The mean angles of rotation were: Index 13°, Middle 10°, Ring 5°, Little 12°. The differences in angle of rotation of the index and middle finger between the left and right hand were statistically significant (p=0.003, and p=0.002 respectively), demonstrating asymmetry between the two sides. The differences in angle of rotation of the ring and little finger of the left and right hand were not significantly significant (p= 0.312 and p=0.716 respectively).

In conclusion, symmetry was seen in the little and ring but not in the index and middle fingers. Digital image analysis provides a non-invasive and reproducible method of quantifying the rotation of normal fingers and may be of use as a diagnostic tool in the assessment and management of hand injuries.

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 purpose of the study was to objectively compare the effects of the scaphoid and Colles’ type casts on hand function. Currently there is no such published study.

Both casts are commonly used to immobilise suspected and radiologically proven undisplaced scaphoid fractures. There is no difference in non-union rates. The scaphoid incorporates the thumb in palmar abduction, whereas the Colles’ type cast leaves the thumb free. Although necessary for bone healing, immobilisation disrupts function and may require intensive corrective physiotherapy. Unnecessary immobilisation of uninvolved joints should be avoided when use does not compromise fracture stability.

We compared the effect of the two casts on hand function in 20 healthy right hand dominant volunteers using the Jebsen-Taylor Hand Function Test, which uses seven subtests designed to test tasks representative of everyday functional activities. Data were obtained through a mixed between and within subject design.

Using the Jebsen-Taylor Hand Function Test, median overall scoring in the Colles’ type cast was 2.5 times that obtained in the scaphoid. In timing individual subtests, the analyses show significant differences (p< 0001) between the presence and absence of a cast. When comparing the two cast types, mean times for all subtests are less in the Colles’ than in the scaphoid, with the difference reaching statistical significance in five out of seven subtests.

Having either type of cast significantly impairs handling and finger dexterity, and so affects activities of daily living. A scaphoid, however, is much more limiting than a Colles’ type cast. This makes it clearly more inconvenient for the patient with socioeconomic implications and occasionally issues of compliance during a long period of immobilisation.