Evidence-Based Approach to Timing of Nerve Surgery: A Review.

ABSTRACT: Events causing acute stress to the health care system, such as the COVID-19 pandemic, place clinical decisions under increased scrutiny. The priority and timing of surgical procedures are critically evaluated under these conditions, yet the optimal timing of procedures is a key consideration in any clinical setting. There is currently no single article consolidating a large body of current evidence on timing of nerve surgery. MEDLINE and EMBASE databases were systematically reviewed for clinical data on nerve repair and reconstruction to define the current understanding of timing and other factors affecting outcomes. Special attention was given to sensory, mixed/motor, nerve compression syndromes, and nerve pain. The data presented in this review may assist surgeons in making sound, evidence-based clinical decisions regarding timing of nerve surgery.

A Multicenter Matched Cohort Study of Processed Nerve Allograft and Conduit in Digital Nerve Reconstruction.

PURPOSE: Biomaterials used to restore digital nerve continuity after injury associated with a defect may influence ultimate outcomes. An evaluation of matched cohorts undergoing digital nerve gap reconstruction was conducted to compare processed nerve allograft (PNA) and conduits. Based on scientific evidence and historical controls, we hypothesized that outcomes of PNA would be better than for conduit reconstruction. METHODS: We identified matched cohorts based on patient characteristics, medical history, mechanism of injury, and time to repair for digital nerve injuries with gaps up to 25 mm. Data were stratified into 2 gap length groups: short gaps of 14 mm or less and long gaps of 15 to 25 mm. Meaningful sensory recovery was defined as a Medical Research Council scale of S3 or greater. Comparisons of meaningful recovery were made by repair method between and across the gap length groups. RESULTS: Eight institutions contributed matched data sets for 110 subjects with 162 injuries. Outcomes data were available in 113 PNA and 49 conduit repairs. Meaningful recovery was reported in 61% of the conduit group, compared with 88% in the PNA group. In the group with a 14-mm or less gap, conduit and PNA outcomes were 67% and 92% meaningful recovery, respectively. In the 15- to 25-mm gap length group, conduit and PNA outcomes were 45% and 85% meaningful recovery, respectively. There were no reported adverse events in either treatment group. CONCLUSIONS: Outcomes of digital nerve reconstruction in this study using PNA were consistent and significantly better than those of conduits across all groups. As gap lengths increased, the proportion of patients in the conduit group with meaningful recovery decreased. This study supports the use of PNA for nerve gap reconstruction in digital nerve reconstructions up to 25 mm. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic III.

Chronic postoperative complications and donor site morbidity after sural nerve autograft harvest or biopsy.

BACKGROUND: The sural nerve is the most frequently harvested nerve autograft and is most often biopsied in the workup of peripheral neuropathy. While the complication types associated with these two procedures are well known, their clinical significance is poorly understood and there is a paucity of data regarding the complication rates. METHODS: Pubmed search identified studies regarding complications after sural nerve harvest and biopsy. The data was grouped into sensory deficits, chronic pain, sensory symptoms, wound infections, wound complications, other postoperative complications, and complications impacting daily life. The incidence of each complication was calculated, and a chi-square analysis was performed to determine if there were any differences between nerve biopsies and graft harvest with respect to each complication. RESULTS: Twelve studies yielded 478 sural nerve procedures. Sensory deficits occurred at a rate of 92.9%, chronic pain at 19.7%, sensory symptoms at 41.1%, wound infections at 5.7%, noninfectious wound complications at 7.8%, and impact on daily life at 5.0%. The differences in wound infections, sensory symptoms, and impact on daily life between biopsies versus graft excisions were found to reach statistical significance (p < .05). CONCLUSIONS: Sural nerve excisions can cause chronic postoperative donor-site complications. Given these complications, alternative available mediums for nerve reconstruction should be explored and utilized wherever appropriate. If an alternative medium is unavailable and nerve autograft must be harvested for nerve reconstruction, then patients should be counseled about risks for developing donor site complications that may negatively affect quality of life.

Use of the subscapular system by maintaining unilateral decubitus placement without repositioning in microvascular free tissue transplantation.

BACKGROUND: In microvascular free-tissue harvest and transfer, the need for repositioning from lateral decubitus position and the inability to use a two-team approach are major drawbacks of the subscapular system. We present our experience with the subscapular system for upper and lower extremity reconstruction using a two-team approach without need for repositioning. METHODS: We conducted a retrospective chart review for all patients undergoing free flap transplant based on the subscapular system to the upper or lower extremity at our microsurgical facility from January 1, 2007 to December 31, 2011. Only cases not requiring intraoperative repositioning were included. Sixty-four patients underwent the two-team approach (37 upper extremity and 27 lower extremity transplants). Flap types included latissimus dorsi musculocutaneous, partial superior latissimus, dorsal thoracic fascia, serratus, scapular bone, and thoracodorsal artery perforator, either alone or as chimeric flaps. All patients were placed in the lateral decubitus position for the duration of the surgery. RESULTS: The ipsilateral subscapular system was used in 16% of cases for lower extremity defects, where the anterior tibial vessels served as recipient vessels. The contralateral subscapular system was used in all remaining cases for upper extremity or the vast majority for lower extremity (84%) defects, where either the superficial femoral, genicular, popliteal, sural, or posterior tibial vessels served as recipient vessels. With the exception of one partial flap loss secondary to infection, all flaps survived. CONCLUSIONS: Proper lateral decubitus positioning allows for a two-team approach without compromising safety or outcomes.

Peripheral nerve repair throughout the body with processed nerve allografts: Results from a large multicenter study.

BACKGROUND: Peripheral nerve damage resulting in pain, loss of sensation, or motor function may necessitate a reconstruction with a bridging material. The RANGER® Registry was designed to evaluate outcomes following nerve repair with processed nerve allograft (Avance® Nerve Graft; Axogen; Alachua, FL). Here we report on the results from the largest peripheral nerve registry to-date. METHODS: This multicenter IRB-approved registry study collected data from patients repaired with processed nerve allograft (PNA). Sites followed their own standard of care for patient treatment and follow-up. Data were assessed for meaningful recovery, defined as ≥S3/M3 to remain consistent with previously published results, and comparisons were made to reference literature. RESULTS: The study included 385 subjects and 624 nerve repairs. Overall, 82% meaningful recovery (MR) was achieved across sensory, mixed, and motor nerve repairs up to gaps of 70 mm. No related adverse events were reported. There were no significant differences in MR across the nerve type, age, time-to-repair, and smoking status subgroups in the upper extremity (p > .05). Significant differences were noted by the mechanism of injury subgroups between complex injures (74%) as compared to lacerations (85%) or neuroma resections (94%) (p = .03) and by gap length between the <15 mm and 50-70 mm gap subgroups, 91 and 69% MR, respectively (p = .01). Results were comparable to historical literature for nerve autograft and exceed that of conduit. CONCLUSIONS: These findings provide clinical evidence to support the continued use of PNA up to 70 mm in sensory, mixed and motor nerve repair throughout the body and across a broad patient population.

Initial Management of Traumatic Digit Amputations: A Retrospective Study of Functional Outcomes.

BACKGROUND: Traumatic amputation of one or more digits can have a serious detrimental effect on social and economic standings which can be mitigated by successful replantation. Little has been recorded on preoperative management before replantation and how this affects the outcomes of the replanted digit. METHODS: A retrospective cohort study was conducted and data collected over an 18-month period. Three protocols for preoperative management were examined: minimal (basic wound management), complete Buncke (anticoagulation, dry dressing on amputate placed on indirect ice and absence of a digital block), and incomplete (any two or three criteria from complete Buncke in addition to the minimal) protocols. Data was collected on survival rate, secondary operations, and complication rate. Function was defined by sensation, range of movement, and strength. RESULTS: Seventy four of 177 digits were replanted with an overall survival rate of 86.5%. The rates for minimal, incomplete, and complete protocols were 95%, 87%, and 91%, respectively, and not significantly different. The complication rate was significantly different between the complete (20%) and minimal (60%) protocols (p = 0.0484). Differences in sensation and grip strength were statistically significant between protocols (p = 0.0465 and p = 0.0430, respectively). Anticoagulation, no digital block and dry gauze all showed reduced complication rates in comparison to their counterparts. CONCLUSIONS: The Buncke protocol, which includes anticoagulation, no digital block, and dry gauze, was found to significantly reduce the complication rate which suggests that it prevents compromise of tissue integrity. Significant differences were found between protocols for sensation and grip strength. A higher-powered study is needed to investigate the effects of preoperative management on complication rates and functional outcomes.

Use of Processed Nerve Allografts to Repair Nerve Injuries Greater Than 25 mm in the Hand.

Processed nerve allografts (PNAs) have been demonstrated to have improved clinical results compared with hollow conduits for reconstruction of digital nerve gaps less than 25 mm; however, the use of PNAs for longer gaps warrants further clinical investigation. Long nerve gaps have been traditionally hard to study because of low incidence. The advent of the RANGER registry, a large, institutional review board-approved, active database for PNA (Avance Nerve Graft; AxoGen, Inc, Alachua, FL) has allowed evaluation of lower incidence subsets. The RANGER database was queried for digital nerve repairs of 25 mm or greater. Demographics, injury, treatment, and functional outcomes were recorded on standardized forms. Patients younger than 18 and those lacking quantitative follow-up data were excluded. Recovery was graded according to the Medical Research Council Classification for sensory function, with meaningful recovery defined as S3 or greater level. Fifty digital nerve injuries in 28 subjects were included. There were 22 male and 6 female subjects, and the mean age was 45. Three patients gave a previous history of diabetes, and there were 6 active smokers. The most commonly reported mechanisms of injury were saw injuries (n = 13), crushing injuries (n = 9), resection of neuroma (n = 9), amputation/avulsions (n = 8), sharp lacerations (n = 7), and blast/gunshots (n = 4). The average gap length was 35 ± 8 mm (range, 25-50 mm). Recovery to the S3 or greater level was reported in 86% of repairs. Static 2-point discrimination (s2PD) and Semmes-Weinstein monofilament (SWF) were the most common completed assessments. Mean s2PD in 24 repairs reporting 2PD data was 9 ± 4 mm. For the 38 repairs with SWF data, protective sensation was reported in 33 repairs, deep pressure in 2, and no recovery in 3. These data compared favorably with historical data for nerve autograft repairs, with reported levels of meaningful recovery of 60% to 88%. There were no reported adverse effects. Processed nerve allograft can be used to reconstruct long gap nerve defects in the hand with consistently high rates of meaningful recovery. Results for PNA repairs of digital nerve injuries with gaps longer than 25 mm compare favorably with historical reports for nerve autograft repair but without donor site morbidity.

Microsurgical ear replantation-is venous repair necessary?-A systematic review.

BACKGROUND: A common postoperative observation after microsurgical ear replantation has been venous congestion necessitating alternate modes of decongestion, frequently in conjunction with blood transfusion. A comprehensive literature search was performed to assess the relationship between mode of vascular reconstruction and postoperative outcome as well as postoperative transfusion requirement after microsurgical ear replantation. METHODS: The search was limited to cases of microsurgical ear replantation following complete amputation. Only articles published in English and indexed in PubMed were included. RESULTS: The initial search retrieved 285 articles, which was narrowed down to 40 articles reporting on 60 cases that matched the aforementioned criteria. Reconstruction of the arterial and venous limb (Group 1) was performed in 63.3% of patients and artery-only anastomosis (Group 2) was performed in 31.7%. Among measurable outcomes, only the duration of surgery was significantly different between groups (2.6 hours longer in Group 1 than Group 2; P = 0.0042). CONCLUSION: In light of contemporary data demonstrating successful artery-only ear replantation, replantation should not be abandoned when unable to establish venous outflow microsurgically. © 2015 Wiley Periodicals, Inc. Microsurgery 36:345-350, 2016.

Outcomes of short-gap sensory nerve injuries reconstructed with processed nerve allografts from a multicenter registry study.

BACKGROUND: Short-gap digital nerve injuries are a common surgical problem, but the optimal treatment modality is unknown. A multicenter database was queried and analyzed to determine the outcomes of nerve gap reconstructions between 5 and 15 mm with processed nerve allograft. METHODS: The current RANGER registry is designed to continuously monitor and compile injury, repair, safety, and outcomes data. Centers followed their own standard of care for treatment and follow-up. The database was queried for digital nerve injuries with a gap between 5 and 15 mm reporting sufficient follow-up data to complete outcomes analysis. Available quantitative outcome measures were reviewed and reported. Meaningful recovery was defined by the Medical Research Council Classification (MRCC) scale at S3-S4 for sensory function. RESULTS: Sufficient follow-up data were available for 24 subjects (37 repairs) in the prescribed gap range. Mean age was 43 years (range, 23-81). Mean gap was 11 ± 3 (5-15) mm. Time to repair was 13 ± 42 (0-215) days. There were 25 lacerations, 8 avulsion/amputations, 2 gunshots, 1 crush injury, and 1 injury of unknown mechanism. Meaningful recovery, defined as S3-S4 on the MRCC scales, was reported in 92% of repairs. Sensory recovery of S3+ or S4 was observed in 84% of repairs. Static 2PD was 7.1 ± 2.9 mm (n = 19). Return to light touch was observed in 23 out of 32 repairs reporting Semmes-Weinstein monofilament outcomes (SWMF). There were no reported nerve adverse events. CONCLUSION: Sensory outcomes for processed nerve allografts were equivalent to historical controls for nerve autograft and exceed those of conduit. Processed nerve allografts provide an effective solution for short-gap digital nerve reconstructions.

Ultrasound-guided carpal tunnel release using the manos CTR system.

PURPOSE: Ultrasound (US) has been used in the management of carpal tunnel syndrome since the 1980s. The first report of US-guided carpal tunnel release (CTR) was published in 1997, with cadaver and clinical reports confirming the safe navigation of surgical tools with US for division of the transverse carpal ligament. The MANOS CTR device was recently reported as a minimally invasive tool for CTR, and may be well suited for use with US guidance. PATIENTS AND METHODS: The authors report three cases of US-guided CTR using the MANOS CTR device. The MANOS device was inserted in a blunt configuration into the safe zone, and the cutting surface was deployed with a thumb-activated trigger that simultaneously ejected a sharp through the palm. The transverse carpal ligament was divided safely and confirmed with US. RESULTS: US allowed for clear identification of the median nerve, safe zones, transverse carpal ligament, and the MANOS CTR device in relation to all pertinent structures of the carpal tunnel. Complete division of the transverse carpal ligament was confirmed in all three cases. There were no median nerve, vessel, tendon injuries, or chronic regional pain syndrome in any of the three cases. CONCLUSIONS: US-guided CTR with the MANOS CTR device appears to be a safe technique and successful in confirming complete release.

Functional outcome following nerve repair in the upper extremity using processed nerve allograft.

PURPOSE: Reconstruction of peripheral nerve discontinuities with processed nerve allograft has become increasingly relevant. The RANGER Study registry was initiated in 2007 to study the use of processed nerve allografts in contemporary clinical practice. We undertook this study to analyze outcomes for upper extremity nerve repairs contained in the registry database. METHODS: We identified an upper extremity-specific population within the RANGER Study registry database consisting of 71 nerves repaired with processed nerve allograft. This group was composed of 56 subjects with a mean age of 40 ± 17 years (range, 18-86 y). We analyzed data to determine the safety and efficacy of processed nerve allograft. Quantitative data were available on 51 subjects with 35 sensory, 13 mixed, and 3 motor nerves. The mean gap length was 23 ± 12 mm (range, 5-50 mm). We performed an analysis to evaluate response-to-treatment and to examine sensory and motor recovery according to the international standards for motor and sensory nerve recovery. RESULTS: There were no reported implant complications, tissue rejections, or adverse experiences related to the use of the processed nerve allografts. Overall recovery, S3 or M4 and above, was achieved in 86% of the procedures. Subgroup analysis demonstrated meaningful levels of recovery in sensory, mixed, and motor nerve repairs with graft lengths between 5 and 50 mm. The study also found meaningful levels of recovery in 89% of digital nerve repairs, 75% of median nerve repairs, and 67% of ulnar nerve repairs. CONCLUSIONS: Our data suggest that processed nerve allografts offer a safe and effective method of reconstructing peripheral nerve gaps from 5 to 50 mm in length. These outcomes compare favorably with those reported in the literature for nerve autograft, and exceed those reported for tube conduits.

Microvascular approach to scalp replantation and reconstruction: a thirty-six year experience.

BACKGROUND: Soft tissue defects of the scalp may result from multiple etiologies and can be challenging to reconstruct. We discuss our experience with scalp replantation and secondary microvascular reconstruction over 36 years, including techniques pioneered at our institution with twin-twin scalp allotransplant and innervated partial superior latissimus dorsi (LD) for scalp/frontalis loss. METHODS: A retrospective review of all patients presenting with scalp loss requiring microvascular reconstruction at a single center was performed from January 1971 to January 2007. Medical records were reviewed for age, gender, defect size/location, etiology, type of reconstruction, recipient vessels used, vein grafts, and complications. RESULTS: Thirty-three patients were identified; mean age was 33 years (range, 7-79). Mean scalp defect size was 442 cm(2) (range, 120-900 cm(2)). Thirty-six microvascular reconstructions were performed; of these, 10 scalp replants and 26 microvascular tissue transfers. Of these 26, 17 were LD based (partial superior LD with and without reinnervation, LD combined with serratus, LD combined with parascapular, LD combined with split rib, LD only) and 2 free scalp allotransplant among others. The superficial temporal artery and vein was used as recipient vessels in 70% of cases. Overall, microvascular success rate was 92%; complications occurred in 14 cases, nine major (tumor recurrence [n = 2], partial flap loss [n = 2], replant loss [n = 3, size <300 cm(2) ], hematoma [n = 2]) and five minor (donor site seroma /hematoma [n = 3], flap congestion [n = 1], superficial wound infection [n = 1]). CONCLUSIONS: Every attempt should be made at scalp replantation when the patient is stable and the parts salvageable. Larger avulsion defects had higher success rates after replantation than smaller defects (<300 cm(2) ), with the superficial temporal artery and vein most commonly used for recipient vessels (P = 0.0083). Microvascular tissue transfer remains a mainstay of treatment for scalp defects, with LD-based flaps, demonstrating excellent versatility for a range of defects.

Processed nerve allografts for peripheral nerve reconstruction: a multicenter study of utilization and outcomes in sensory, mixed, and motor nerve reconstructions.

PURPOSE: As alternatives to autograft become more conventional, clinical outcomes data on their effectiveness in restoring meaningful function is essential. In this study we report on the outcomes from a multicenter study on processed nerve allografts (Avance® Nerve Graft, AxoGen, Inc). PATIENTS AND METHODS: Twelve sites with 25 surgeons contributed data from 132 individual nerve injuries. Data was analyzed to determine the safety and efficacy of the nerve allograft. Sufficient data for efficacy analysis were reported in 76 injuries (49 sensory, 18 mixed, and 9 motor nerves). The mean age was 41 ± 17 (18-86) years. The mean graft length was 22 ± 11 (5-50) mm. Subgroup analysis was performed to determine the relationship to factors known to influence outcomes of nerve repair such as nerve type, gap length, patient age, time to repair, age of injury, and mechanism of injury. RESULTS: Meaningful recovery was reported in 87% of the repairs reporting quantitative data. Subgroup analysis demonstrated consistency, showing no significant differences with regard to recovery outcomes between the groups (P > 0.05 Fisher's Exact Test). No graft related adverse experiences were reported and a 5% revision rate was observed. CONCLUSION: Processed nerve allografts performed well and were found to be safe and effective in sensory, mixed and motor nerve defects between 5 and 50 mm. The outcomes for safety and meaningful recovery observed in this study compare favorably to those reported in the literature for nerve autograft and are higher than those reported for nerve conduits.

History of Microsurgery: The Legacy of Harry J. Buncke, MD.

A historical review of the history of Microsurgery including the important influence and contributions of Harry J. Buncke MD considered by many to be the "Father of Microsurgery". An chronological list of Historic Replants and "Free Flap" and microvascular transplants is included. Those who lived through the age of the birth of this new surgical specialty were fortunate.

Great Toe Transplantation.

Despite being relatively uncommon in the general population, thumb amputations cause severe disability. More than 3,300 thumb amputations occurred in the United States. The thumb makes up around 40% of the function of the hand. Therefore, losing it would result in significant medical, hospital, and societal costs. Thumb reconstruction surgery's primary goal is to restore grip strength, including the range of motion, fine and tripod pinch, power grasp, strength, and sensibility, while secondary goals include restoring hand aesthetics. In cases of thumb replantation, like-for-like replacement is possible; however, when thumb replantation is not possible, great toe-to-hand transplantation is the best available reconstruction. When compared with other reconstructive options such as osteoplastic thumb reconstruction, pollicization, second toe transplantation, and the use of a thumb prosthesis, great toe transplantation provides superior function and aesthetics. For restoring pinch, sensitivity, strength, and aesthetics of the hand with well-tolerated donor site morbidity, toe to thumb transplantation is regarded as the gold standard.

From simple interrupted to complex spiral: a systematic review of various suture techniques for microvascular anastomoses.

Accomplishing successful microvascular anastomoses is undoubtedly one of the most critical steps in performing free tissue transfer. However, the ideal technique has often been a subject of debate. Therefore, our objective was to review the current literature in an attempt to find objective evidence supporting the superiority of one particular technique. A PubMed and OVID on-line search was performed in November 2007 using the following keywords: microvascular anastomoses, microsurgical anastomosis, continuous suture, interrupted suture, mattress suture, and sleeve anastomosis. Our literature review found no difference in short- and/or long-term patency rates between the six main published techniques, which includes continuous suture, interrupted suture, locking continuous, continuous horizontal, horizontal interrupted with eversion, and sleeve anastomoses. These findings were consistent for each technique as long as the microsurgeon maintained standard microsurgical principles and practice, including suture line eversion, minimized tension, and direct intima-to-intima contact. Current literature supports no overall statistical difference in short- and/or long-term patency rates between any of the various techniques. The choice to perform one suture technique over another ultimately depends on the plastic surgeon's preference and microsurgical experience. To date, there are no human randomized, controlled clinical trials comparing the efficacy and clinical outcomes of each of the various suture techniques, and therefore one's comfort and familiarity should dictate his or her microsurgical technique. However, "exposure to many and mastery of one" simply provides the plastic surgery resident, fellow, or staff the technical flexibility needed for less-complicated surgical planning when performing free tissue transfer.

Narrative review of the history of microsurgery in urological practice.

The clinical need for magnified visualization during surgery spurred the evolution of microscope and microsuture technology. Innovative surgeons across various surgical specialties recognized the importance of utilizing and advancing these technologies. Operative microscopy allows human dexterity to perform beyond direct visual limitations. Microsurgery started in otolaryngology and ophthalmology, became popular in reconstruction and transplantation, and was then adopted in urology. Microsurgery in urology involves renal and penile revascularization, penile transplantation and free flap phalloplasty, testicular autotransplantation, reproductive tract reconstruction of the vas deferens and epididymis, varicocele repair, and sperm retrieval. By examining the peer reviewed and lay literature, this review discusses the history of microsurgery and its subsequent development as a subspecialty in urology.

Clinical Outcomes of Symptomatic Neuroma Resection and Reconstruction with Processed Nerve Allograft.

BACKGROUND: Neuromas causing sensory disturbance can substantially affect nerve function and quality of life. Historically, passive termination of the nerve end and proximal relocation to muscle or bone has been performed after neuroma resection, but this method does not allow for neurologic recovery or prevent recurrent neuromas. The use of processed nerve allografts (PNAs) for intercalary reconstruction of nerve defects following neuroma resection is reasonable for neuroma management, although reported outcomes are limited. The purpose of this study was to assess the outcomes of pain reduction and functional recovery following neuroma resection and intercalary nerve reconstruction using PNA. METHODS: Data on outcomes of PNA use for peripheral nerve reconstruction were collected from a multicenter registry study. The registry database was queried for upper extremity nerve reconstruction with PNA after resection of symptomatic neuroma. Patients completing both pain and quantitative sensory assessments were included in the analysis. Improvement in pain-related symptoms was determined via patient self-reported outcomes and/or the visual analog scale. Meaningful sensory recovery was defined as a score of at least S3 on the Medical Research Council Classification scale. RESULTS: Twenty-five repairs involving 21 patients were included in this study. The median interval from injury to reconstruction was 386 days, and the average nerve defect length was 31 mm. Pain improved in 80% of repairs. Meaningful sensory recovery was achieved in 88% of repairs. CONCLUSION: Neuroma resection and nerve reconstruction using PNA can reduce or eliminate chronic peripheral nerve pain and provide meaningful sensory recovery.

Digit Tip Injuries: Current Treatment and Future Regenerative Paradigms.

Over the past several decades there has been a profound increase in the understanding of tissue regeneration, driven largely by the observance of the tremendous regenerative capacity in lower order life forms, such as hydra and urodeles. However, it is known that humans and other mammals retain the ability to regenerate the distal phalanges of the digits after amputation. Despite the increased knowledge base on model organisms regarding regenerative paradigms, there is a lack of application of regenerative medicine techniques in clinical practice in regard to digit tip injury. Here, we review the current understanding of digit tip regeneration and discuss gaps that remain in translating regenerative medicine into clinical treatment of digit amputation.

Recovery of Motor Function after Mixed and Motor Nerve Repair with Processed Nerve Allograft.

BACKGROUND: Severe trauma often results in the transection of major peripheral nerves. The RANGER Registry is an ongoing observational study on the use and outcomes of processed nerve allografts (PNAs; Avance Nerve Graft, AxoGen, Inc., Alachua, Fla.). Here, we report on motor recovery outcomes for nerve injuries repaired acutely or in a delayed fashion with PNA and comparisons to historical controls in the literature. METHODS: The RANGER database was queried for mixed and motor nerve injuries in the upper extremities, head, and neck area having completed greater than 1 year of follow-up. All subjects with sufficient assessments to evaluate functional outcomes were included. Meaningful recovery was defined as ≥M3 on the Medical Research Council scale. Demographics, outcomes, and covariate analysis were performed to further characterize this subgroup. RESULTS: The subgroup included 20 subjects with 22 nerve repairs. The mean ± SD (minimum-maximum) age was 38 ± 19 (16-77) years. The median repair time was 9 (0-133) days. The mean graft length was 33 ± 17 (10-70) mm with a mean follow-up of 779 ± 480 (371-2,423) days. Meaningful motor recovery was observed in 73%. Subgroup analysis showed no differences between gap lengths or mechanism of injury. There were no related adverse events. CONCLUSIONS: PNAs were safe and provided functional motor recovery in mixed and motor nerve repairs. Outcomes compare favorably to historical controls for nerve autograft and exceed those for hollow tube conduit. PNA may be considered as an option when reconstructing major peripheral nerve injuries.