Thoracic Outlet Syndrome in the Pediatric and Young Adult Population.

PURPOSE: This study aimed to assess both nonsurgical and operative treatment outcomes of pediatric and young adult patients with thoracic outlet syndrome (TOS) at a tertiary care pediatric hospital. METHODS: A retrospective chart review of patients diagnosed with TOS, who were seen between January 2010 and August 2022 at a tertiary care pediatric hospital, was conducted. Collected pre- and postoperative data included symptoms, provocative testing (ie, Roo's, Wright's, and Adson's tests), participation in sports or upper-extremity activities, additional operations, and surgical complications. Assessment of operative treatment efficacy was based on pre- and post-provocative testing, pain, venogram results, alleviation of symptoms, and return to previous activity level 6 months after surgery. RESULTS: Ninety-six patients, (70 females and 26 males) with an average age at onset of 15 ± 4 (4-25) years, met the inclusion criteria for TOS. Among them, 27 had neurogenic TOS, 29 had neurogenic and vasculogenic TOS, 20 had vasculogenic TOS, 19 had Paget-Schroetter Syndrome, and one was asymptomatic. Twenty-six patients were excluded because of less than 6 months of follow-up. Of the remaining 70, 6 (8.6%) patients (4 bilateral and 2 unilateral) underwent nonoperative management with activity modification and physical therapy only, and one was fully discharged because of complete relief of symptoms. Sixty-four (90.1%) patients (45 bilateral and 19 unilateral) underwent surgery. A total of 102 operations were performed. Substantial improvements were observed in provocative maneuvers after surgery. Before surgery, 79.7% were involved in sports or playing musical instruments with repetitive overhead activity, and after surgery, 86.2% of these patients returned to their previous activity level. CONCLUSIONS: Few patients were successfully managed with nonoperative activity modification and physical therapy. In those requiring surgical intervention, first or cervical rib resection with scalenectomy using a supraclavicular approach provided resolution of symptoms with 86.2% of patients being able to return to presymptom sport or activity level. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Nerve Regeneration with a Scaffold Incorporating an Absorbable Zinc-2% Iron Alloy Filament to Improve Axonal Guidance.

Peripheral nerve damage that results in lost segments requires surgery, but currently available hollow scaffolds have limitations that could be overcome by adding internal guidance support. A novel solution is to use filaments of absorbable metals to supply physical support and guidance for nerve regeneration that then safely disappear from the body. Previously, we showed that thin filaments of magnesium metal (Mg) would support nerve regeneration. Here, we tested another absorbable metal, zinc (Zn), using a proprietary zinc alloy with 2% iron (Zn-2%Fe) that was designed to overcome the limitations of both Mg and pure Zn metal. Non-critical-sized gaps in adult rat sciatic nerves were repaired with silicone conduits plus single filaments of Zn-2%Fe, Mg, or no metal, with autografts as controls. After seventeen weeks, all groups showed equal recovery of function and axonal density at the distal end of the conduit. The Zn alloy group showed some improvements in early rat health and recovery of function. The alloy had a greater local accumulation of degradation products and inflammatory cells than Mg; however, both metals had an equally thin capsule (no difference in tissue irritation) and no toxicity or inflammation in neighboring nerve tissues. Therefore, Zn-2%Fe, like Mg, is biocompatible and has great potential for use in nervous tissue regeneration and repair.

Presentation and Management of the Pediatric Trigger Finger: A Multicenter Retrospective Cohort Study.

PURPOSE: Pediatric trigger finger (PTF) is an acquired condition that is uncommon and anatomically complex. Currently, the literature is characterized by a small number of retrospective case series with limited sample sizes. This investigation sought to evaluate the presentation, management, and treatment outcomes of PTF in a large, multicenter cohort. METHODS: A retrospective review of pediatric patients with a diagnosis of PTF between 2009 and 2020 was performed at three tertiary referral hospitals. Patient demographics, PTF characteristics, treatment strategies, and outcomes were abstracted from the electronic medical records. Patients and families also were contacted by telephone to assess the downstream persistence or recurrence of triggering symptoms. RESULTS: In total, 321 patients with 449 PTFs were included at a mean follow-up of 3.9 ± 4.0 years. There were approximately equal numbers of boys and girls, and the mean age of symptom onset was 5.4 ± 5.1 years. The middle (34.7%) and index (11.6%) fingers were the most and least commonly affected digits, respectively. Overall, PTFs managed operatively achieved significantly higher rates of complete resolution compared with PTFs managed nonsurgically (97.1% vs 30.0%). Seventy-five percent of PTFs that achieved complete resolution with nonsurgical management did so within 6 months, and approximately 90% did so within 12 months. Patients with multidigit involvement, higher Quinnell grade at presentation, or palpable nodularity were significantly more likely to undergo surgery. There was no significant difference in the rate of complete resolution between splinted versus not splinted PTFs or across operative techniques. CONCLUSIONS: Only 30% of the PTFs managed nonsurgically achieved complete resolution. Splinting did not improve resolution rates in children treated nonsurgically. In contrast, surgical intervention has a high likelihood of restoring motion and function of the affected digit. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Predictors for operative treatment in pediatric proximal third both-bone diaphyseal forearm fractures in children include age and translation, but not initial angulation.

Introduction: Proximal third diaphyseal fractures of the radius and ulna represent an onerous fracture pattern due to difficulty maintaining acceptable alignment with nonoperative management. Our aim was to identify the factors that increase the odds for a surgical treatment of these fractures. Recognizing these factors can raise awareness to patients who are more likely to require additional care and assist clinicians in counseling families, targeting treatment plans, and constructing follow-up protocols. We hypothesized that the age of the patient, the amount of initial fracture displacement, and the angulation of the fracture would predict the need for operative treatment. Methods: We retrospectively reviewed 276 proximal third diaphyseal forearm fractures at a single tertiary care institution. All patients underwent a nonoperative treatment trial, and if failed continued to surgery. Following a univariate analysis, we constructed a binary multivariate logistic regression model that included age, initial translation, and initial angulation to assess the association between the tested variables. Results: A regression model revealed that age (10 years and older, odds ratio: 8.2, 95% confidence interval: 3.9-17.24, p < 0.001) and radius translation of more than 100% (odds ratio: 7.06, 95% confidence interval: 2.69-18.52, p < 0.001) were associated with the need for surgical treatment. Initial fracture angulation lacked an association with a surgical treatment (odds ratio: 0.81 95% confidence interval: 0.38-1.74, p = 0.59). Conclusion: Age above 10 years and 100% initial translation of the radius fracture increased the odds for an ultimate decision to perform a surgery. Initial angulation, although often being the most remarkable radiographic feature, was not associated with a nonoperative treatment failure. We recommend an initial reduction attempt after counseling patients and their families that there is a high rate of conversion to operative treatment when the above features are met. Level of evidence: level III.

Effects of Altering Magnesium Metal Surfaces on Degradation In Vitro and In Vivo during Peripheral Nerve Regeneration.

In vivo use of biodegradable magnesium (Mg) metal can be plagued by too rapid a degradation rate that removes metal support before physiological function is repaired. To advance the use of Mg biomedical implants, the degradation rate may need to be adjusted. We previously demonstrated that pure Mg filaments used in a nerve repair scaffold were compatible with regenerating peripheral nerve tissues, reduced inflammation, and improved axonal numbers across a short-but not long-gap in sciatic nerves in rats. To determine if the repair of longer gaps would be improved by a slower Mg degradation rate, we tested, in vitro and in vivo, the effects of Mg filament polishing followed by anodization using plasma electrolytic oxidation (PEO) with non-toxic electrolytes. Polishing removed oxidation products from the surface of as-received (unpolished) filaments, exposed more Mg on the surface, produced a smoother surface, slowed in vitro Mg degradation over four weeks after immersion in a physiological solution, and improved attachment of cultured epithelial cells. In vivo, treated Mg filaments were used to repair longer (15 mm) injury gaps in adult rat sciatic nerves after placement inside hollow poly (caprolactone) nerve conduits. The addition of single Mg or control titanium filaments was compared to empty conduits (negative control) and isografts (nerves from donor rats, positive control). After six weeks in vivo, live animal imaging with micro computed tomography (micro-CT) showed that Mg metal degradation rates were slowed by polishing vs. as-received Mg, but not by anodization, which introduced greater variability. After 14 weeks in vivo, functional return was seen only with isograft controls. However, within Mg filament groups, the amount of axonal growth across the injury site was improved with slower Mg degradation rates. Thus, anodization slowed degradation in vitro but not in vivo, and degradation rates do affect nerve regeneration.

International Pediatric Multidisciplinary Management Using Telemedicine to Promote Equitable Care.

Objective: To evaluate the use of telemedicine as a collaboration tool between a pediatrician and subspecialists looking to address challenges, such as the lack of health care specialists, which are present in the Dominican Republic. Study design: During this 6-year study, 65 patients were evaluated by a medical team consisting of a local pediatrician and 17 subspecialists from a leading academic medical center in the Unites States. Patient's age ranged from 2 months to 16 years of age (mean 8 years old). The most common reasons for referral were masses or malignancies, vascular malformations, urogenital anomalies, stuttering, and cochlear implant programming. Results: A total of 39 out of 65 cases (60%) carried an initial diagnosis. Of the 65 cases, a change in medical management occurred in 92.31% of cases (60 cases). There was no change in medical diagnosis or treatment in 5 of 65 cases (8%). Conclusion: This protocol exhibited high patient satisfaction with the technology and platform and direct patient savings from transportation costs. It also demonstrated the importance of thorough diagnosis in providing appropriate treatment and solutions. Telemedicine use in comparable practices should be studied further to aid in the development of policies for the diagnosis and management of chronic illnesses that require referrals to subspecialists.

Nonunion of the Clavicle Among Children: A Review of the Literature and a Report of Three New Cases.

Nonunion of the clavicle among children and adolescents is rare. A systematic review was conducted to identify published reports of nonunion of the clavicle among children after conservative treatment. A retrospective study was performed of 2096 children who were treated for clavicle fractures at our institution to identify cases of nonunion. Fourteen studies (27 children) from the literature met the inclusion criteria, and 3 new cases from our institution were identified. The mean age at injury was 11 years. Male sex, age younger than 12 years at the time of injury, and refracture of the clavicle are possible predisposing factors for nonunion. [Orthopedics. 2022;45(4):e190-e195.].

Multiple Continuous Y-to-V-Plasties for Excision and Reconstruction of Constriction Band Syndrome: Case Series and Description of Surgical Technique.

BACKGROUND: Many patients with constriction band syndrome will seek treatment to improve limb function and cosmesis. Although several techniques for excision are reported, cosmetic and functional deficits can persist, including hourglass deformity, lymphedema, and inadequate band excision with resultant neurovascular compromise, which may lead to revision surgery, including amputation. The authors present a novel technique that uses multiple continuous opposing Y-to-V-plasties in a single or staged manner to correct extremity constriction bands. METHODS: Seven patients with 10 involved extremities were included in this retrospective case series. Patient demographics, associated abnormalities, and operative indications were collected from medical records. The primary outcome measures were primary wound healing and release of the constriction band. Secondary outcomes measures were perioperative complications and the need for revision surgery. RESULTS: All patients achieved primary closure with excellent healing in one or two stages. No infections or scar complications occurred, and no revision surgery of the band was required. One patient had mild indentation of scar tissue after their second stage, which improved with scar massage. One patient who had preoperative sciatic compression neuropathy and an insensate foot secondary to band constriction developed chronic calcaneal osteomyelitis requiring a subsequent Syme amputation. Postoperative lymphedema occurred in two patients, which resolved with the use of compression bandages over several weeks. CONCLUSION: Use of multiple continuous opposing Y-to-V-plasties is a safe and effective technique for adequate constriction band excision without residual hourglass deformity and good functional outcomes for patients with partial or circumferential constriction bands. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

The prevalence of Vickers' ligament in Madelung's deformity: a retrospective multicentre study of 75 surgical cases.

In a retrospective multicentre study, we aimed to correlate clinical factors and findings on plain radiographs and MRI with the intraoperative presence of Vickers' ligament in Madelung's deformity. We screened the records, in which the absence or presence of Vickers' ligament was affirmatively indicated, of 75 consecutive operated extremities in 58 patients. In 83% a Vickers' ligament was observed intraoperatively. The whole bone Madelung type (as opposed to the distal type) and a distal radial notch were independent, significant predictors for the presence of the ligament. The correct Vickers detection rate using MRI was 85% of the 27 cases for which MRI was available. Thus, the MRI was a good but not perfectly reliable modality. We conclude that Vickers' ligament is present in the majority but not all cases with Madelung deformity. We advise that patients with a more severe type of Madelung's deformity and a distal radial notch should be monitored closely.Level of evidence: IV.

Bizarre Parosteal Osteochondromatous Proliferation (Nora Lesion) in Pediatric Phalanges.

Bizarre parosteal osteochondromatous proliferation, or Nora tumor, is an uncommon lesion affecting the tubular bones of the hands and feet. Normally arising from the cortical surface and periosteum of these bones, these lesions histologically consist of a hypercellular cartilaginous cap covering a bony stalk that is surrounded by ossified areas and spindle cell stroma. The differential diagnosis includes conditions involving the periosteum such as chondrosarcoma, parosteal osteosarcoma, osteochondroma, turret exostosis, and florid reactive periostitis. The only effective treatment is wide surgical excision; nevertheless, local recurrence rates are extremely high and may necessitate revision surgery. In the present study, we report 3 cases of Nora lesion located in the hand in pediatric patients. The diagnosis in these cases was challenging owing to their presenting symptoms and radiographic findings. The diagnosis was made based on characteristic findings noted on the radiographic images and was confirmed by histological examination following excision.

Are quantitative features of lung nodules reproducible at different CT acquisition and reconstruction parameters?

Consistency and duplicability in Computed Tomography (CT) output is essential to quantitative imaging for lung cancer detection and monitoring. This study of CT-detected lung nodules investigated the reproducibility of volume-, density-, and texture-based features (outcome variables) over routine ranges of radiation dose, reconstruction kernel, and slice thickness. CT raw data of 23 nodules were reconstructed using 320 acquisition/reconstruction conditions (combinations of 4 doses, 10 kernels, and 8 thicknesses). Scans at 12.5%, 25%, and 50% of protocol dose were simulated; reduced-dose and full-dose data were reconstructed using conventional filtered back-projection and iterative-reconstruction kernels at a range of thicknesses (0.6-5.0 mm). Full-dose/B50f kernel reconstructions underwent expert segmentation for reference Region-Of-Interest (ROI) and nodule volume per thickness; each ROI was applied to 40 corresponding images (combinations of 4 doses and 10 kernels). Typical texture analysis metrics (including 5 histogram features, 13 Gray Level Co-occurrence Matrix, 5 Run Length Matrix, 2 Neighboring Gray-Level Dependence Matrix, and 3 Neighborhood Gray-Tone Difference Matrix) were computed per ROI. Reconstruction conditions resulting in no significant change in volume, density, or texture metrics were identified as "compatible pairs" for a given outcome variable. Our results indicate that as thickness increases, volumetric reproducibility decreases, while reproducibility of histogram- and texture-based features across different acquisition and reconstruction parameters improves. To achieve concomitant reproducibility of volumetric and radiomic results across studies, balanced standardization of the imaging acquisition parameters is required.

Attenuation of Dupuytren's fibrosis via targeting of the STAT1 modulated IL-13Rα1 response.

Fibrotic disorders represent common complex disease pathologies that are therapeutically challenging. Inflammation is associated with numerous fibrotic pathogeneses; however, its role in the multifaceted mechanisms of fibrosis remains unclear. IL-13 is implicated in aberrant responses involved in fibrotic disease, and we aimed to understand its role in the inflammatory processes of a common fibrotic disorder, Dupuytren's disease. We demonstrated T-cells produced IFN-g, which induced IL-13 secretion from mast cells and up-regulated IL-13Ra1 on fibroblasts, rendering them more reactive to IL-13. Consequently, diseased myofibroblasts demonstrated enhanced fibroproliferative effects upon IL-13 stimulation. We established IFN-g and IL-13 responses involved STAT dependent pathways, and STAT targeting (tofacitinib) could inhibit IL-13 production from mast cells, IL-13Ra1 up-regulation in fibroblasts and fibroproliferative effects of IL-13 on diseased myofibroblasts. Accordingly, utilizing Dupuytren's as an accessible human model of fibrosis, we propose targeting STAT pathways may offer previously unidentified therapeutic approaches in the management of fibrotic disease.

Humerus Rotation Has a Negligible Effect on Baumann Angle in a Wide Range of Rotational Positions.

BACKGROUND: Rotation of the humerus out of the coronal plane is presumed to alter the Baumann angle (BA) value. Identifying the rotational limits of the humerus at which the BA can be accurately and reliably measured will circumvent repeated radiographs and unnecessary exposure to radiation, may improve patient comfort, and save time and medical resources. METHODS: A retrospective chart review was performed to identify patients under the age of 18 who underwent an elbow computed tomography (CT) scan without any humeral pathology and with an open distal humeral physis. For each patient, a 3-dimensional (3D) computerized model was generated with 30% transparency to mimic a plain radiograph. These models were rotated in 10-degree increments and the BA was measured on each position. In addition, the measurements were taken on an anteroposterior radiograph for each patient. Analysis of variance and the Pearson tests were performed to locate differences and define associations. RESULTS: Fifteen 3D CT reconstructions were generated from 14 patients. The mean BA on the neutral position was found to be 72.2±3 degrees, which correlated with the 70.6±5.91 degrees measurement obtained on radiographs. The most extreme rotational positions on which the BA values were consistent with the neutral position values were +40 external rotation (70.97±7.01 degrees, P=1) and -70 degrees internal rotation (68.4±7.47 degrees, P=0.14). A negative correlation was found between the BA values and the extent at which the humerus was rotated from the neutral position. The variability of the BA between patients, implied by the SD of measurements on each position increased with increasing rotation from the neutral position (r=1, P<0.05). CONCLUSIONS: On the basis of 3D CT images, the BA is the most accurate when the arm is positioned at an exact anteroposterior position. It is reliable to measure the BA when the humerus is rotated no more than +40 degrees external rotation to -70 degrees internal rotation. This range of rotation can act as an "accurate zone" and help avoiding multiple radiographs. LEVEL OF EVIDENCE: Level III.

Fracture obliquity is a predictor for loss of reduction in supracondylar humeral fractures in older children.

Supracondylar humeral fractures in older children have different biomechanical characteristics and surgical outcomes when compared to the same fractures in younger children. We aimed to analyze the fracture's architecture in a large group of older children and investigate the correlation between patients' variables, fracture patterns, fixation techniques and the rate of loss of reduction (LOR). A retrospective review study was conducted. We collected the records of 240 consecutive patients aged 8-14 years that sustained Gartland type 2/3 supracondylar humeral fractures between 2004 and 2014 and were operated at our hospital. We excluded patients with intra-articular or pathological fractures. Following the radiographical analysis and chart review, we conducted a multivariable regression analysis. Fracture obliquity on the sagittal plane ( > 20°) occurred in 33% of the cases and was found to be the only factor related to LOR (P = 0.01). Gartland type 3 fractures and more than two lateral pin configuration did not correlate to fixation failure (P = 0.69 and 0.14, respectively). The incidence of flexion-type fractures (5.8%) was found to be higher than in the total pediatric population. The sagittal oblique supracondylar humeral fracture is common and is related to fixation instability and LOR. This pattern needs to be considered when investigating different pin configurations, complication rates, and biomechanical properties. Subclassifying Gartland type 2/3 supracondylar humeral fractures as 'oblique' or 'transverse' might offer more comprehensive information about the anticipated operative results, lead to applying more stable pin constructs to these fractures and allow improved outcomes following surgical fixation.

Performance of a Deep Neural Network Algorithm Based on a Small Medical Image Dataset: Incremental Impact of 3D-to-2D Reformation Combined with Novel Data Augmentation, Photometric Conversion, or Transfer Learning.

Collecting and curating large medical-image datasets for deep neural network (DNN) algorithm development is typically difficult and resource-intensive. While transfer learning (TL) decreases reliance on large data collections, current TL implementations are tailored to two-dimensional (2D) datasets, limiting applicability to volumetric imaging (e.g., computed tomography). Targeting performance enhancement of a DNN algorithm based on a small image dataset, we assessed incremental impact of 3D-to-2D projection methods, one supporting novel data augmentation (DA); photometric grayscale-to-color conversion (GCC); and/or TL on training of an algorithm from a small coronary computed tomography angiography (CCTA) dataset (200 examinations, 50% with atherosclerosis and 50% atherosclerosis-free) producing 245 diseased and 1127 normal coronary arteries/branches. Volumetric CCTA data was converted to a 2D format creating both an Aggregate Projection View (APV) and a Mosaic Projection View (MPV), supporting DA per vessel; both grayscale and color-mapped versions of each view were also obtained. Training was performed both without and with TL, and algorithm performance of all permutations was compared using area under the receiver operating characteristics curve. Without TL, APV performance was 0.74 and 0.87 on grayscale and color images, respectively, compared to 0.90 and 0.87 for MPV. With TL, APV performance was 0.78 and 0.88 on grayscale and color images, respectively, compared with 0.93 and 0.91 for MPV. In conclusion, TL enhances performance of a DNN algorithm from a small volumetric dataset after proposed 3D-to-2D reformatting, but additive gain is achieved with application of either GCC to APV or the proposed novel MPV technique for DA.

Increasing Brace Treatment for Pediatric Distal Radius Buckle Fractures: Using Quality Improvement Methodology to Implement Evidence-based Medicine.

BACKGROUND: Multiple randomized trials have showed equivalent outcomes and improved patient/family satisfaction using a removable brace to treat pediatric distal radius buckle fractures (DRBF). We tested the hypothesis that we could use quality improvement (QI) methodology to increase the proportion of patients with DRBF treated with removable braces at 2 tertiary care orthopaedic clinics from a baseline of 34.8% to 80%. METHODS: Clinic billing records were reviewed monthly to determine treatment (brace vs. cast) of DRBF and tracked using control charts (p-chart). Balance measures including correct application of the diagnostic criteria and algorithm were monitored. Process measures including the number of follow-up visits, radiographs obtained, and total cost of treatment were collected. Baseline data were obtained over a 3-month period, followed by a 12-month period of interventions using Plan-Do-Study-Act cycles targeting both individuals and groups of providers. RESULTS: The proportion of DRBF treated in a brace increased from a combined baseline of 34.8% to a combined 84% at the end of the study period. Following intervention, 83% (15/18) of providers began using braces for a majority of patients (defined as >67%), with only 1 provider continuing to use casts 100% of the time. Patient preference was cited as the most common reason for use of cast treatment. There was a significant decrease in the number of radiographs obtained at 1 of 2 institutions. The charges for brace treatment averaged $630 less per patient than for cast treatment, leading to an estimated medical-cost savings of $205,000 following intervention. CONCLUSIONS: Implementation of brace treatment for pediatric DRBF using QI methodology resulted in a shift toward brace treatment in the majority of patients, leading to substantial medical and nonmedical cost savings. Although patient preference was cited as the most common reason for persistent cast treatment, the data show the use of cast treatment to be more dependent upon individual provider preference. LEVEL OF EVIDENCE: Level II-therapeutic.

Embedding magnesium metallic particles in polycaprolactone nanofiber mesh improves applicability for biomedical applications.

Magnesium (Mg) metal is of great interest in biomedical applications, especially in tissue engineering. Mg exhibits excellent in vivo biocompatibility, biodegradability and, during degradation, releases Mg ions (Mg2+) with the potential to improve tissue repair. We used electrospinning technology to incorporate Mg particles into nanofibers. Various ratios of Mg metal microparticles (<44 µm diameter) were incorporated into nanofiber polycaprolactone (PCL) meshes. Physicochemical properties of the meshes were analyzed by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), mechanical tensile testing, X-ray diffractometry and UV-VIS spectrophotometry. Biological properties of meshes were evaluated in vitro and in vivo. Under mammalian cell culture conditions, Mg-containing meshes released hydrogen gas and relative amounts of free Mg2+ that reflected the Mg/PCL ratios. All meshes were non-cytotoxic for 3T3 fibroblasts and PC-12 pheochromocytoma cells. In vivo implantation under the skin of mice for 3, 8 and 28 days showed that Mg-containing meshes were well vascularized, with improved measures of inflammation and healing compared to meshes without Mg. Evidence included an earlier appearance and infiltration of tissue repairing macrophages and, after 28 days, evidence of more mature tissue remodeling. Thus, these new composite nanofiber meshes have promising material properties that mitigated inflammatory tissue responses to PCL alone and improved tissue healing, thus providing a suitable matrix for use in clinically relevant tissue engineering applications. STATEMENT OF SIGNIFICANCE: The biodegradable metal, magnesium, safely biodegrades in the body, releasing beneficial byproducts. To improve tissue delivery, magnesium metal particles were incorporated into electrospun nanofiber meshes composed of a biodegradable, biocompatible polymer, polycaprolactone (PCL). Magnesium addition, at several concentrations, did not alter PCL chemistry, but did alter physical properties. Under cell culture conditions, meshes released magnesium ions and hydrogen gas and were not cytotoxic for two cell types. After implantation in mice, the mesh with magnesium resulted in earlier appearance of M2-like, reparative macrophages and improved tissue healing versus mesh alone. This is in agreement with other studies showing beneficial effects of magnesium metal and provides a new type of scaffold material that will be useful in clinically relevant tissue engineering applications.