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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., (Copyright 2011, SLACK Incorporated.)

We measured the alignment of the nails in the hands of 100 normal adults with the interphalangeal joints extended and the metacarpophalangeal (MCP) joints at 0 degrees and 90 degrees. All fingers were naturally supinated (i.e. rotated towards the thumb), the index and little being the most supinated. When examining individual hands in MCP joint extension, only 17% of hands had all nails parallel. With the MCP joints flexed, this improved to 56%. If the little finger was excluded, this improved to 78%. When comparing matching fingers from the two hands, 76% of little, 83% of ring, 77% of middle and 80% of index fingers matched. Thumbnails were assessed in extension and found to match the other side in 95% of individuals. This study identifies that examination of the injured hand alone with all joints extended is an unreliable method of assessing malrotation following fracture, especially in the little finger. Comparing matching fingers in the two hands is more reliable, but there is still substantial variation in approximately 20% of normal individuals.

Nails enhance pulp sensibility, increase pulp stability and are necessary for fine prehension. A finger without a nail will compromise a musician's career if the finger involved is necessary to play a note (strings, keyboards) or hold a position (winds). Salvage of the nail is then a very important part of any surgical procedure in musicians with distal finger trauma. Surgical techniques will depend on the level and type of nail injury. Replantation is by far the best technique in distal finger amputation but, when not feasible, reposition-flap repair may be used. In isolated nail lesions, sutures, split-thickness nail bed graft, or nail matrix flaps are used according to the level and severity of the lesion.

Extended exposure to mechanical vibration has been related to many vascular, sensorineural and musculoskeletal disorders of the hand-arm system, frequently termed 'hand-arm vibration syndrome' (HAVS). A two-dimensional, nonlinear finite element model of a fingertip is developed to study the stress and strain fields of the soft tissue under dynamic loading, that may be encountered while grasping and operating a hand-held power tool. The model incorporates the most essential anatomical elements of a fingertip, such as soft tissue, bone, and nail. The finger is assumed to be in contact with a steel plate, simulating the interaction between the fingertip and a vibrating machine tool or handle. The soft tissue is assumed to be nonlinearly visco-elastic, while the nail, bone, and steel plate are considered to be linearly elastic. In order to study the time-dependent deformation behavior of the fingertip, the numerical simulations were performed under ramp-like loading with different ramping periods and sinusoidal vibrations of the contacting plate at three different frequencies (1, 10, and 31.5 Hz). Owing to relatively large deformations of the soft tissue under specified static and dynamic loading, Lagrangian large deformation theory was applied in the present analysis. The effects of the loading rate and the frequency of the sinusoidal vibration on the time-dependent strain/stress distributions in the different depth within the soft tissue of the fingertip are investigated numerically. Our simulations suggest that the soft tissue of the fingertip experiences high local stress and strain under dynamic loading and the fingertip may separate from the vibrating contact surface due to the viscous deformation behaviour of the soft tissue. For a given deformation, the high frequency loading produces a higher stress in the tissues compared to that obtained at a low frequency loading. The present model may serve as a useful tool to study the mechanism of tissue degeneration under vibratory loading encountered during operation of hand-held power tools.

The fingernail and toenail are unique to primates. The anatomy and physiology of the nail must be understood for nail care to be effective. The most common cause of deformity of the nail bed is trauma, which requires careful suturing and postoperative care if the desired results are to be achieved. Congenital anomalies, tumors, and infection can also cause nail deformities and can frequently be corrected or improved surgically.

Nail spicules result from incomplete excision of the nail matrix of the finger. We report a histological study to delineate the surface anatomy of the nail matrix. Sections were cut longitudinally and transversely in 19 fingertips. The proximal midline extent of the nail matrix was measured and expressed as a ratio of the distance from the nail fold to the distal interphalangeal joint. In the lateral sections, the angle subtended between the midline vertical and the lateral extent of the nail matrix was measured. The mean ratio of the proximal extent was 0.55 in the midline and the lateral angular extent was 66 degrees. The authors recommend that excision of the nail matrix should be rectangular, extending to the midlateral lines and proximally to a point three-quarters of the distance from the nail fold to the distal interphalangeal joint crease.

The authors report the results of 115 dissections of the base of the distal phalanx of fingers and toes. In 85% of cases including hypoplastic supernumerary digits, there is a connective ligament-like structure. It is a dorsal expansion of the lateral ligament of the distal inter-phalangeal joint arising from the intermediate phalanx and ending in the matrix and the lunula. This ligament may have a role in biomechanical strains on the nail. It can explain some dystrophic nails associated with some malpositioned joints in fingers or toes.