Excessive scissoring or overlap of fingers can cause discomfort, weaken grip strength, and affect cosmesis. The treatment
of little finger fractures is guided by the degree of scissoring or rotational deformity perceived in the digit. The purpose
of this study is to assess the variation of little finger scissoring or overlap in the normal population using standard clinical
examination. We evaluated 80 uninjured little fingers in 40 normal patients. The digital images of photographed hands, taken
in both extension and flexion, were used to evaluate the overlap percentage of the adjacent fingernail as a proxy for rotation
of the digits. Paired
t tests were used for statistical analysis. The average fingernail overlap was 25%±20%, ranging from 0% to 71%. The average
overlap on the left hand was significantly less at 21%±18% as compared to 30%±21% on the right (
P<.01). The average variation between hands in individuals was 16%±13%.
This study confirms that overlap or scissoring of the little finger varies between the hands of a given individual. Our results
question the usefulness of assessing rotational deformity of the little finger by checking for overlap and comparing with
the contralateral side. This has implications not only in assessing patients for possible surgery, but also in planning and
performing surgical reductions of acute fractures and for correction of malunions.
Drs Lahey, Patel (Archit), Kang, and Choueka, and Mr Patel (Mihir) are from the Department of Orthopedic Surgery, Maimonides
Medical Center, Brooklyn, New York.
Drs Lahey, Patel (Archit), Kang, and Choueka and Mr Patel (Mihir) have no relevant financial relationships to disclose.
Correspondence should be addressed to: Archit Patel, MD, Department of Orthopedic Surgery, 927 49th St, Brooklyn, NY 11219
Scissoring or overlap of fingers can lead to patient reports of discomfort, decreased grip strength, and cosmetic deformity.
Scissoring of the digits on flexion has long been described as an accurate clinical tool to predict functional impairment
As a result, the basis of acceptable treatment is influenced by the degree of scissoring, or rotational deformity perceived
in the digit. It is commonly accepted that the tip of a finger in the flexed position should touch adjacent fingers as they
approach the base of the thenar eminence, but should not overlap.
Degree of rotation and function is determined by comparison to the unaffected hand. Tan et al
demonstrated in a recent article that 90% of normal patients had overlap of at least 1 finger using a specialized device
to standardize hand position. These findings, while important, are not always clinically applicable. In the office, surgeons
are left with clinical examination to assess for rotational deformities without the use of specialized instruments. We therefore
sought to assess the reproducibility and degree of overlap and asymmetry in a standard clinical examination.
Materials and Methods
Study patients were healthy volunteers. Any individual with a history of finger or hand trauma, arthritis of the hands, or
any other known deformity of the nails or fingers was excluded. To ensure clinical reproducibility, a digital camera with
a Canon (5.8–17.4mm lens; Lake Success, New York) was mounted on a tripod and set at a distance comparable to the eye level
of a practitioner (45 cm). Photographs of each individual’s hands were taken with the fingers in extension to measure the
nail width of the little finger (Figure ). A second photograph was obtained with the metacarpophalangeal and proximal interphalangeal joints in flexion (Figure ). To observe the fingers in extension, the patients placed their hands in approximately 90° of pronation with their palms
resting on a flat surface. For analysis in flexion, hands were placed in 90° of supination with the dorsal aspect of the hand
resting on the same flat surface. The digital images were uploaded to a computer and analyzed by 2 independent observers (P.J.L.,
M.R.P.) using ImageJ (NIH, Bethesda, Maryland) software to measure both the width of the little fingernail in extension and
the degree of overlap in flexion. The degree of overlap was quantified by the percentage of nail obscured by the adjacent
Figure 1:. Fingers in extension.
Figure 2:. Fingers in flexion.
The mean and standard deviation were calculated for percentage of overlap and chi-square analysis was used to test for significance
between groups. The average difference between left and right hands in each individual was also analyzed. A
P value of <.05 was considered significant. The Kappa coefficient was calculated to measure interobserver reliability between
the 2 authors.
Forty patients met inclusion criteria and had measurements made of both hands. The 23 men and 17 women had an average age
of 35.9 years (range, 22–69 years). Seven patients were left-hand dominant. Seventy of 80 hands had at least partial overlap
of the little finger, and 37 of 40 patients showed asymmetric overlap between left and right hands. The average variation
between hands in individuals was 16%±13%. The average little finger fingernail overlap was 25%±20%, ranging from 0% to 71%.
The average overlap on the left was 20%±18% as compared to 30%±21% for right hands. This difference was statistically significant
P<.01). The Kappa coefficient calculated was 0.82, reflecting substantial agreement between the 2 authors performing measurements.
Malrotation of the little finger is an indication for surgery for metacarpal and phalangeal fractures since it can lead to
overlap and impaired function. A number of different methods have been described to assess malrotation. Scissoring or overlap
at the fingertip with the metacarpophalangeal and proximal interphalangeal joints flexed, particularly when compared to the
contralateral hand, is a well-known technique.
While testing with the distal interphalangeal in flexion may offer additional functional information, it would be impossible
to assess fingernail overlap in this position. As a result, testing was done with the distal interphalangeal joint in extension
to reproduce this common and accepted clinical examination. However, it can be painful for a patient to make a fist with a
Tan et al
showed that end-on examination of the fingernails in extension or flexion is somewhat problematic. Their study showed that
in normal patients, fingernails are neither horizontal nor parallel to each other and the little finger is the most supinated
in both extension and flexion with a range of 30° (-5° to 25°). In addition to substantial variation in the alignment of the
fingernails within a hand, significant asymmetry of nail inclination between the 2 hands also exists. In another study evaluating
nail inclination, 20% of fingernails did not match within 5°, and nearly 5% did not match within 10°.
We challenge the traditional thinking that normal individuals have no overlap when testing for scissoring. In this study,
we found that scissoring is not only common, but actually the norm, with 70 of 80 hands exhibiting some degree of little finger
overlap. The large variability of overlap and the frequent asymmetry in these normal patients demonstrate that scissoring,
even when compared to the contralateral hand, may not reliably demonstrate malrotation. We found the average difference in
overlap of the little finger to vary significantly. This has implications not only in assessing patients for possible surgery,
but also in planning and performing surgical reductions of acute fractures and for correction of malunions.
This study is somewhat limited by the fact that small variations in the position of the hand under the camera could have affected
the amount of overlap recorded. Efforts were made to standardize hand positions while attempting to mimic a clinical examination.
Functional tests were also not performed to determine if any of our normal patients had any functional deficit from their
overlapped little fingers. While it is possible the variation between left and right hands found during data analysis may
be attributed to hand dominance, that analysis goes beyond the scope of our study.
The practitioner must be aware of the variation among the population as well as the individual when determining the treatment
for a patient with little finger pathology.
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