BACKGROUND: Surgical treatment of finger nerve injury is common for hand trauma. However, there are various surgical options with different functional outcomes. The aims of this study are to compare the outcomes of various finger nerve surgeries and to identify factors associated with the postsurgical outcomes via a systematic review and meta-analysis.
METHODS: The literature related to digital nerve repairs were retrieved comprehensively by searching the online databases of PubMed from January 1, 1965, to August 31, 2021. Data extraction, assessment of bias risk and the quality evaluation were then performed. Meta-analysis was performed using the postoperative static 2-point discrimination (S2PD) value, moving 2-point discrimination (M2PD) value, and Semmes-Weinstein monofilament testing (SWMF) good rate, modified Highet classification of nerve recovery good rate. Statistical analysis was performed using the R (V.3.6.3) software. The random effects model was used for the analysis. A systematic review was also performed on the other influencing factors especially the type of injury and postoperative complications of digital nerve repair.
RESULTS: Sixty-six studies with 2446 cases were included in this study. The polyglycolic acid conduit group has the best S2PD value (6.71 mm), while the neurorrhaphy group has the best M2PD value (4.91 mm). End-to-side coaptation has the highest modified Highet\'s scoring (98%), and autologous nerve graft has the highest SWMF (91%). Age, the size of the gap, and the type of injury were factors that may affect recovery. The type of injury has an impact on the postoperative outcome of neurorrhaphy. Complications reported in the studies were mainly neuroma, cold sensitivity, paresthesia, postoperative infection, and pain.
CONCLUSIONS: Our study demonstrated that the results of surgical treatment of digital nerve injury are generally satisfactory; however, no nerve repair method has absolute advantages. When choosing a surgical approach to repair finger nerve injury, we must comprehensively consider various factors, especially the gap size of the nerve defect, and postoperative complications. Type of study/level of evidence Therapeutic IV.

BACKGROUND: Glomus tumors in the digital nerve are extremely rare. Multiple intraneural glomus tumors in different digital nerve fascicles have not been previously reported.
METHODS: We report the case of a 54-year-old male with a 1-year history of progressive numbness of the middle finger with point tenderness at the level of the middle phalanx. Surgical incision revealed the presence of two glomus tumors within different fascicles of the ulnar digital nerve of the middle finger. One tumor was excised along with surrounding fascicle, the other was removed leaving the fascicle intact. Subsequently, the patient regained function of the finger and no tumors have recurred.
CONCLUSIONS: Patients and physicians should be aware of the properties of intraneural glomus tumors so that early diagnosis and treatment can be sought.

Current standard management of a cut digital nerve is end-to-end microsurgical nerve coaptation where possible. A recent systematic review of adult digital nerve injuries that were either repaired or left unrepaired showed that the evidence for good nerve recovery or improved function following nerve repair is poor. In the 30 studies included, only 24% of repaired nerves regained sensory recovery close to or equivalent to estimated pre-injury levels. Neuroma rates were the same in those nerves repaired (4.6%) and those not repaired (5%). Questions under debate include proper assessment methods of outcomes, decision making for repair or no repair to different fingers or the thumb, levels of injury, age, and hand dominance. This review summarizes the major evidence available and debates the surgical dogma that surrounds this injury.

Human acellular nerve allografts have a wide range of donor origin and can effectively avoid nerve injury in the donor area. Very little is known about one-stage reconstruction of digital nerve defects. The present study observed the feasibility and effectiveness of human acellular nerve allograft in the reconstruction of < 5-cm digital nerve defects within 6 hours after injury. A total of 15 cases of nerve injury, combined with nerve defects in 18 digits from the Department of Emergency were enrolled in this study. After debridement, digital nerves were reconstructed using human acellular nerve allografts. The patients were followed up for 6-24 months after reconstruction. Mackinnon-Dellon static two-point discrimination results showed excellent and good rates of 89%. Semmes-Weinstein monofilament test demonstrated that light touch was normal, with an obvious improvement rate of 78%. These findings confirmed that human acellular nerve allograft for one-stage reconstruction of digital nerve defect after hand injury is feasible, which provides a novel trend for peripheral nerve reconstruction.

A digital nerve defect complicated by an associated soft-tissue loss poses a reconstructive challenge. This article reports reconstruction of a similar complex injury using a bipedicled nerve flap including a nerve graft from the dorsal branch of the digital nerve. From July 2008 to May 2010, a retrospective study was conducted with nine consecutive patients who had a combination of soft tissue and digital nerve defects. The injured fingers requiring reconstruction included three index, four middle and two ring fingers. The mean size of the soft-tissue losses was 2.8×2.1 cm. The flap is supplied by the digital artery and the venous drainage is by means of a dorsal vein. The mean flap size was 3.1×2.3 cm. The nerve gaps were bridged with the nerve graft attached with the flap. The average length of the nerve grafts was 3.0 cm. All flaps survived completely, and the defects were reconstructed successfully. Venous congestion was not observed in our series. At a mean follow-up period of 23 months, the average scores of static two-point discrimination (2PD) and Semmes-Weinstein monofilament on the finger pulp of the injured side were 7.5 mm and 3.93, respectively. The donor site morbidity was acceptable. According to the Michigan Hand Outcomes Questionnaire, four patients were strongly satisfied and five were satisfied with functional recovery of the injured finger. The bipedicled nerve flap is a safe and effective option for reconstruction of complex digital injury involving soft tissue and nerve defects. Our technique has been shown to provide sufficient sensory recovery. ClinicalTrials.gov ID: NCT01707654.
METHODS: Therapeutic IV.

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.