OBJECTIVE: The radial and ulnar thumb digital nerves are critical for tactile sensation and dexterity in the hand. This cadaveric study sought to validate a surface landmark for the bifurcation of the thumb radial digital nerve (RDN) and ulnar digital nerve (UDN).
METHODS: We used 24 fresh-frozen cadaveric specimens for dissections. With the thumb placed in the plane of the palm and fully radially abducted, the index finger metacarpophalangeal joint was flexed to 90°. Then, while keeping the distal interphalangeal joint straight, the proximal interphalangeal joint was flexed until the fingertip contacted the thenar eminence to identify the point of bifurcation. We made a U-shaped incision and identified the bifurcation of the thumb RDN and UDN. The point of bifurcation was measured from the ulnar- and proximal-most aspects of the incision.
RESULTS: The bifurcation of the thumb RDN and UDN was consistently identified within the U in 22 of 24 specimens (92%). In 16 specimens, the index RDN was also identified either trifurcating with the thumb RDN and UDN or branching from a common digital nerve of index RDN and thumb UDN. Most bifurcation points were found directly along the ulnar and proximal edge of the incision. Two specimens contained a bifurcation point 2 mm ulnar to the ulnar limb of the U.
CONCLUSIONS: The bifurcation U is a consistent landmark for the thumb RDN and UDN point of bifurcation. The variable branching patterns in this region confirms the importance of thorough clinical examination with penetrating injuries to the thenar eminence.
CONCLUSIONS: This surface anatomic landmark for the thumb RDN and UDN bifurcation may aid in preventing iatrogenic injuries during elective procedures and identifying at-risk structures during penetrating injuries to the palm.

The purpose of this study was to identify surface anatomy of digital nerves in relation to the pigmented border of digits. Three-hundred and sixty digital nerves in 36 preserved adult cadaveric hands were dissected under magnification. The digital nerves were constantly located anterior to the pigmented border. The median curvilinear distance along the skin from the pigmented border to the digital nerves of the index, middle, ring and little fingers was 1.4 mm. In the thumb, this distance was 2.4 and 3.7 mm on the radial and ulnar sides, respectively. The digital nerve was located 2.4 mm deep to the skin in all fingers. The median angle to the nerve from the skin at the pigmented border was 30°. These dimensions differed in the thumb compared with the rest of the fingers. We conclude that the pigmented border of digits is a reliable anatomical landmark to locate digital nerves.

The aim of this study was to assess the resistance of microsurgically repaired proper palmar digital nerves (PPDN) to mobilization. Thirty-nine PPDN from fresh forearms cadavers were transected and then sutured using 10/0 nylon. After skin closure, each finger was forcefully flexed and extended 10 times. Out of the 39 repaired nerves, two were elongated and four were ruptured; this amounts to a 15.38% complication rate. We recommend immobilization of nerve repairs, although this contradicts most recent studies.

BACKGROUND: Current repair options for peripheral nerve injuries where tension-free gap closure is not possible include allograft, processed nerve allograft, and hollow tube conduit. Here we report on the outcomes from a multicenter prospective, randomized, patient- and evaluator-blinded, pilot study comparing processed nerve allograft and hollow conduit for digital nerve reconstructions in the hand.
METHODS: Across 4 centers, consented participants meeting inclusion criteria while not meeting exclusion criteria were randomized intraoperatively to either processed nerve allograft or hollow conduit. Standard sensory and safety assessments were conducted at baseline, 1, 3, 6, 9, and 12 months after reconstruction. The primary outcome was static 2-point discrimination (s2PD) testing. Participants and assessors were blinded to treatment. The contralateral digit served as the control.
RESULTS: We randomized 23 participants with 31 digital nerve injuries. Sixteen participants with 20 repairs had at least 6 months of follow-up while 12-month follow-up was available for 15 repairs. There were no significant differences in participant and baseline characteristics between treatment groups. The predominant nerve injury was laceration/sharp transection. The mean ± SD length of the nerve gap prior to repair was 12 ± 4 mm (5-20 mm) for both groups. The average s2PD for processed allograft was 5 ± 1 mm (n = 6) compared with 8 ± 5 mm (n = 9) for hollow conduits. The average moving 2PD for processed allograft was 5 ± 1 mm compared with 7 ± 5 mm for hollow conduits. All injuries randomized to processed nerve allograft returned some degree of s2PD as compared with 75% of the repairs in the conduit group. Two hollow conduits and one allograft were lost due to infection during the study.
CONCLUSIONS: In this pilot study, patients whose digital nerve reconstructions were performed with processed nerve allografts had significantly improved and more consistent functional sensory outcomes compared with hollow conduits.

We investigated the cutaneous innervation of the distal palm, an area frequently dissected by the hand surgeon. Ten (five paired) fresh-frozen cadaveric hands were dissected under 3.0× loupe magnification. Volar branches were found on both sides in the majority of digits. They originated alongside, or at the proximal margin of, the A1 pulley in 84% of digits. The mean distance from the palmar digital crease to the origin of volar branches was 21 mm.

BACKGROUND: The rolandic cortex exhibits spontaneous rhythmic activity. This oscillation can be modulated by somatosensory stimulation and voluntary movement. The purpose of this study is to elucidate the influence of sensory input on the rolandic oscillation in comparison with movement-related oscillation.
METHODS: Magnetic brain rhythms were recorded in nine healthy subjects in two sessions: electrical stimulation (STIM) of the digital nerve and self-paced movement (SPM) of the right index finger. Thereafter, 10 and 20 Hz oscillatory activities were compared between the two sessions with temporal spectral evolution analysis.
RESULTS: Sensory input altered the rolandic oscillations even under no movement conditions. As for 10 Hz ERD in the STIM session, three subjects showed a contralateral dominant pattern, whereas the remaining subjects showed a bilateral pattern. In spite of this individual variability, ERD showed comparable amplitude in both sessions. However, ERSs in the SPM session were larger than that in the STIM session. These findings might reflect the activation of neural networks common to sensory and motor systems followed by the inhibition of the other surrounding cortical areas.
CONCLUSIONS: Our results suggest that rolandic oscillations may reflect the coordination of sensory and motor systems in the neural networks including both sensory and motor systems.

This study developed a human acellular nerve graft (hANG) as an alternative to autogenous nerve and reports on its safety and efficacy. There were two groups comprised of 72 patients that received digital nerve repair with hANG (test) and 81 that received conventional direct tension-free suture repair of the nerve defect (control). The efficacy of the treatment was evaluated by static 2-point discrimination (s2PD) and Semmes-Weinstein monofilament testing. Safety was evaluated by local wound response and laboratory testing. Mean age of patients in the test group was 33.0 ± 11.1 years (range 18-61 years) and in the control group 36.9 ± 13.4 years (range 15-77 years) (p = 0.0470). Mean time from injury to repair in the test group was 23.7 ± 52 days (range 0-200 days) and in the control group 1.5 ± 10.4 days (range 0-91 days) (p = 0.0005). Mean length of nerve graft was 1.80 ± 0.82 cm (range 1-5 cm). All surgeries were performed successfully and without complications. The excellent and good rate of s2PD in the test group was 65.28% and 95% CI was 51.98-78.93%. s2PD in the test group improved over time and average distance was 12.81 ± 5.99 mm at 6 months postoperatively. No serious adverse or product-related events were reported. These results indicate that hANG is a safe and effective for the repair of nerve defects of 1-5 cm in size.