Regenerative peripheral nerve interface free muscle graft mass and function.

BACKGROUND: Regenerative peripheral nerve interfaces (RPNIs) transduce neural signals to provide high-fidelity control of neuroprosthetic devices. Traditionally, rat RPNIs are constructed with ~150 mg of free skeletal muscle grafts. It is unknown whether larger free muscle grafts allow RPNIs to transduce greater signal. METHODS: RPNIs were constructed by securing skeletal muscle grafts of various masses (150, 300, 600, or 1200 mg) to the divided peroneal nerve. In the control group, the peroneal nerve was transected without repair. Endpoint assessments were conducted 3 mo postoperatively. RESULTS: Compound muscle action potentials (CMAPs), maximum tetanic isometric force, and specific muscle force were significantly higher for both the 150 and 300 mg RPNI groups compared to the 600 and 1200 mg RPNIs. Larger RPNI muscle groups contained central areas lacking regenerated muscle fibers. CONCLUSIONS: Electrical signaling and tissue viability are optimal in smaller as opposed to larger RPNI constructs in a rat model.

Comparing Prepectoral Versus Subpectoral Tissue Expander Placement Outcomes in Delayed-Immediate Autologous Breast Reconstruction.

BACKGROUND: Delayed-immediate breast reconstruction has traditionally involved placement of tissue expanders (TE) in the subpectoral (SP) position. Development of acellular dermal matrices has renewed interest in the prepectoral (PP) pocket, which avoids extensive muscle manipulation. We compare complication rates between PP and SP TE placement in autologous delayed-immediate breast reconstruction. METHODS: A retrospective chart review of patients undergoing autologous, delayed-immediate breast reconstruction at our institution (June 2009 to December 2018) was performed. Demographics, comorbidities, perioperative information, and complication incidence ≤12 months' follow-up were collected from first- and second-stage surgeries. Complications were modeled using univariable and multivariable binary logistic regressions. RESULTS: A total of 89 patients met the inclusion criteria, and data from 125 breast reconstructions were evaluated. Complication rates following TE placement trended lower in the PP cohort (28.8% vs 37%, P = 0.34). Overall complication rates following autologous reconstruction were significantly lower for PP reconstructions (7.7% vs 23.3%, P = 0.02). Multivariable regression showed TE position (P = 0.01) was a significant predictor of ≥1 complication following autologous reconstruction. Time delay between first- and second-stage surgeries was greater for SP reconstructions (199.7 vs 324.8 days, P < 0.001). Postoperative drains were removed earlier in the PP cohort (8.6 vs 12.0 days, P < 0.001). Mean follow-up time was 331.3 days. CONCLUSIONS: Prepectoral reconstruction in the delayed-immediate autologous reconstruction patient leads to significantly lower complication rates, shorter duration between first- and second-stage surgeries, and shorter times before removal of breast drains compared with SP reconstructions.

An Evaluation of the Choice for Contralateral Prophylactic Mastectomy and Patient Concerns About Recurrence in a Reconstructed Cohort.

BACKGROUND: Rising contralateral prophylactic mastectomy rates are a subject of national concern. This study assessed (1) factors critical to patients when deciding on contralateral prophylactic mastectomy and (2) patients' quality of life related to concerns about recurrence after unilateral or bilateral breast reconstruction. METHODS: Patients with stage 0 to III breast cancer who underwent unilateral mastectomy or contralateral prophylactic mastectomy and breast reconstruction at a single institution between 2000 and 2012 were identified. Demographic and clinical data were extracted by chart review. Women's fears about breast cancer recurrence were assessed using the Concerns About Recurrence Scale, and motivational factors for contralateral prophylactic mastectomy were identified using the Decisions for Contralateral Prophylactic Mastectomy Survey. RESULTS: Survey responses were received from 157 patients (59%) who underwent unilateral reconstruction and 109 (41%) who underwent bilateral reconstruction. The top 3 reasons for choosing contralateral prophylactic mastectomy were (1) decreasing the risk of contralateral breast disease (97%), (2) peace of mind (96%), and (3) improved survival (93%). Women who chose contralateral prophylactic mastectomy reported significantly greater overall fear and worry compared with the unilateral group, specifically, greater fears of dying and worries about adequately fulfilling roles of daily life (P < 0.05). CONCLUSIONS: Despite no proven survival benefit, women chose contralateral prophylactic mastectomy primarily to optimize oncologic outcomes. Among breast reconstruction patients, women who underwent contralateral prophylactic mastectomy had greater anxiety and overall fear of breast cancer recurrence compared with those who chose unilateral mastectomy. These findings are important to consider when counseling women contemplating contralateral prophylactic mastectomy.

Simplifying Arterial Coupling in Microsurgery-A Preclinical Assessment of an Everter Device to Aid with Arterial Anastomosis.

BACKGROUND: A novel arterial everter device was engineered to simplify microvascular coupling of arteries by reliably securing the stiff, muscular wall of arteries over coupler pins. We compare microvascular coupling with the everter device to manual suturing for arterial anastomoses in a live large animal model. MATERIALS AND METHODS: In this preliminary study, bilateral external femoral arteries of five male swine were exposed and sharply divided. Arteries were anastomosed using either interrupted sutures (n = 5) or the everter device and Synovis Coupler (n = 5). The efficiency in engaging coupler pins, the time taken to perform the anastomosis, and vessel patency immediately post-op and at 1-week postanastomosis were evaluated. Vessel wall injury and luminal stenosis were compared between groups using histomorphometric analyses. RESULTS: On an average, 80% of coupler pins engaged the vessel walls after a single pass of the everter. The average time to perform the anastomosis was significantly less when using the everter/coupler compared with manual suturing (6:35 minutes versus 25:09 minutes, p < 0.001). Immediately post-op, 100% patency was observed in both groups. At 1 week post-op, four of five (80%) of coupled arteries and all five (100%) of hand-sewn arteries were patent. The degree of arterial wall injury, neointimal formation, and luminal stenosis for patent arteries were similar between groups. CONCLUSIONS: Successful arterial anastomoses using the everter device with the Synovis Coupler was easier and significantly more efficient when compared with a standard hand-sewn technique. Both techniques had acceptable patency rates and similar effects on the vessel wall and intima.

The Early Years of Practice: An Assessment of Operative Efficiency and Cost of Free Flap and Implant Breast Reconstruction at an Academic Institution.

Objective The purpose of this study was to evaluate the short-term costs, and financial implications of improvements in operative efficiency of free flap and implant-based breast reconstruction within an academic practice. Methods The billing records of 162 patients who underwent postmastectomy implant-based or free flap breast reconstruction by two newly hired microsurgeons at an academic institution during the 2011, 2012, and 2013 fiscal years were reviewed. Actual data on professional revenue, relative value units (RVUs), and facility costs for the first stage of reconstruction as well as costs of postoperative complications were assessed. Results Free flaps consistently generated more revenue and RVUs than implants (p < 0.001). Rates of major complications and associated costs were greater for free flaps during the first 2 years of practice; however, by the 3rd year rates were similar between free flaps and implants (14.3 vs. 18.2%, p = 0.72). There was a 26% reduction in free flap operative time in 2013 as compared with 2011. Operative efficiency (hourly RVU) of first stage procedures increased each year for both modalities. At the completion of reconstruction, flaps and implants had comparable hourly reimbursement ($1,053 vs. $947, p = 0.72) and hourly RVU (22 vs. 29, p = 0.06). Conclusions Contrary to perceptions that free flap breast reconstructions are financially inefficient for the surgeon, we have found that these complex reconstructive procedures are profitable. Even in the early years of practice, hourly reimbursements from completed flap reconstructions are similar to reimbursements received from similar staged implant reconstructions.

Regenerative Peripheral Nerve Interface for Prostheses Control: Electrode Comparison.

BACKGROUND: This study compared epimysial patch electrodes with intramuscular hook electrodes using monopolar and bipolar recording configurations. The purpose was to determine which strategy transduced muscle signals with better fidelity for control of myoelectric prostheses. METHODS: One of the two electrode styles, patch (n = 4) or hook (n = 6) was applied to the left extensor digitorum longus muscle in rats. Electrodes were evaluated at the time of placement and at monthly intervals for 4 months. Evaluations consisted of evoked electromyography signals from stimulation pulses applied to the peroneal and tibial nerves in both monopolar and bipolar recording configurations. RESULTS: Compared with hook electrodes, patch electrodes recorded larger signals of interest and minimized muscle tissue injury. A bipolar electrode configuration significantly reduced signal noise when compared with a monopolar configuration. CONCLUSION: Epimysial patch electrodes outperform intramuscular hook electrodes during chronic skeletal muscle implantation.

Successfully Integrating Research into Plastic Surgery Training Programs.

Successful integration of research into the educational mission of a plastic surgery residency program requires the support and dedication of the faculty members to create a culture that promotes innovation, discovery, and advancement of the field of plastic surgery. Dedicated research time during plastic surgery training is beneficial to both the resident and training program. Regardless of whether residents plan to pursue an academic career or enter private practice, participating in research provides an opportunity to develop skills to think critically and mature professionally. In this article, we review the benefits of resident research to both the trainee and training program and discuss strategies to overcome barriers to integrating research into the curriculum.

Analysis of publication bias in the literature for distal radius fracture.

PURPOSE: Distal radius fractures are the most commonly treated fracture, and their management remains complex. We aimed to evaluate the presence of publication bias in the literature on distal radius fracture management and to identify specific study variables that may influence the reporting of positive outcomes. METHODS: We conducted a systematic review on all available journal articles to find primary articles reporting on the management of distal radius fractures. Data collected included the direction of study outcome (positive, neutral, and negative) and various study characteristics including sample size, geographic origin of the study, clinical setting, study design, type of treatment, analysis for statistical significance, evaluation of wrist function, presence of subjective outcome measures, mean follow-up time, adequacy of reduction, complications, mean patient age, and the presence of any extramural funding. RESULTS: We reviewed 215 journal articles and found that 70% of articles reported positive outcomes, 25% reported neutral outcomes, and 5% reported negative outcomes. Funnel plot analysis suggested the presence of publication bias depicted by the asymmetric distribution of studies. In addition, we found statistically significant differences between study outcomes with respect to treatment type, presence of external funding, reduction adequacy, hand/wrist functional assessment, and patient questionnaires for subjective assessment. CONCLUSIONS: Publication bias likely exists in the literature for distal radius fracture management. Several study characteristics influence the reporting of positive outcomes, but whether the presence of these characteristics portends a greater chance of publication remains unclear. A standardized approach to measure and track results may improve evidence-based outcomes. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic III.

Dermal Sensory Regenerative Peripheral Nerve Interface for Reestablishing Sensory Nerve Feedback in Peripheral Afferents in the Rat.

BACKGROUND: Without meaningful, intuitive sensory feedback, even the most advanced myoelectric devices require significant cognitive demand to control. The dermal sensory regenerative peripheral nerve interface (DS-RPNI) is a biological interface designed to establish high-fidelity sensory feedback from prosthetic limbs. METHODS: DS-RPNIs were constructed in rats by securing fascicles of residual sensory peripheral nerves into autologous dermal grafts, with the objectives of confirming regeneration of sensory afferents within DS-RPNIs and establishing the reliability of afferent neural response generation with either mechanical or electrical stimulation. RESULTS: Two months after implantation, DS-RPNIs were healthy and displayed well-vascularized dermis with organized axonal collaterals throughout and no evidence of neuroma. Electrophysiologic signals were recorded proximal from DS-RPNI's sural nerve in response to both mechanical and electrical stimuli and compared with (1) full-thickness skin, (2) deepithelialized skin, and (3) transected sural nerves without DS-RPNI. Mechanical indentation of DS-RPNIs evoked compound sensory nerve action potentials (CSNAPs) that were like those evoked during indentation of full-thickness skin. CSNAP firing rates and waveform amplitudes increased in a graded fashion with increased mechanical indentation. Electrical stimuli delivered to DS-RPNIs reliably elicited CSNAPs at low current thresholds, and CSNAPs gradually increased in amplitude with increasing stimulation current. CONCLUSIONS: These findings suggest that afferent nerve fibers successfully reinnervate DS-RPNIs, and that graded stimuli applied to DS-RPNIs produce proximal sensory afferent responses similar to those evoked from normal skin. This confirmation of graded afferent signal transduction through DS-RPNI neural interfaces validate DS-RPNI's potential role of facilitating sensation in human-machine interfacing. CLINICAL RELEVANCE STATEMENT: The DS-RPNI is a novel biotic-abiotic neural interface that allows for transduction of sensory stimuli into neural signals. It is expected to advance the restoration of natural sensation and development of sensorimotor control in prosthetics.

Schwannoma of the hand in an infant: case report.

Schwannomas (neurilemmomas) are the most common benign tumors of peripheral nerves and originate from the myelinating cells of the nerve sheath. We present a case of congenital schwannoma of the hand.

Estradiol-treated mesenchymal stem cells improve myocardial recovery after ischemia.

BACKGROUND: Stem cell therapy is a promising treatment modality for injured cardiac tissue. A novel mechanism for this cardioprotection may include paracrine actions. Our lab has recently shown that gender differences exist in mesenchymal stem cell (MSC) paracrine function. Estrogen is implicated in the cardioprotection found in females. It remains unknown whether 17beta-estradiol (E2) affects MSC paracrine function and whether E2-treated MSCs may better protect injured cardiac tissue. We hypothesize that E2-exposed MSCs infused into hearts prior to ischemia may demonstrate increased vascular endothelial growth factor (VEGF) production and greater protection of myocardial function compared to untreated MSCs. MATERIALS AND METHODS: Untreated and E2-treated MSCs were isolated, cultured, and plated and supernatants were harvested for VEGF assay (enzyme-linked immunosorbent assay). Adult male Sprague-Dawley rat hearts (n = 13) were isolated and perfused via Langendorff model and subjected to 15 min equilibration, 25 min warm global ischemia, and 40 min reperfusion. Hearts were randomly assigned to perfusate vehicle, untreated male MSC, or E2-treated male MSC. Transcoronary delivery of 1 million MSCs was performed immediately prior to ischemia in experimental hearts. RESULTS: E2-treated MSCs provoked significantly more VEGF production than untreated MSCs (933.2 +/- 64.9 versus 595.8 +/- 10.7 pg/mL). Postischemic recovery of left ventricular developed pressure was significantly greater in hearts infused with E2-treated MSCs (66.9 +/- 3.3%) than untreated MSCs (48.7 +/- 3.7%) and vehicle (28.9 +/- 4.6%) at end reperfusion. There was also greater recovery of the end diastolic pressure with E2-treated MSCs than untreated MSCs and vehicle. CONCLUSIONS: Preischemic infusion of MSCs protects myocardial function and viability. E2-treated MSCs may enhance this paracrine protection, which suggests that ex vivo modification of MSCs may improve therapeutic outcome.

Females exhibit relative resistance to depressive effects of tumor necrosis factor-alpha on the myocardium.

BACKGROUND: Tumor necrosis factor-alpha (TNF-alpha) plays a critical role in myocardial dysfunction following acute injury. It is unknown, however, if a gender-specific response to TNF infusion exists in isolated rat hearts. Elucidating such mechanisms is important to understanding the myocardial gender differences during acute injury. We hypothesize that females will exhibit a relative resistance to TNF-induced myocardial dysfunction compared to males and that menstrual cycle would influence the degree of female myocardial resistance to TNF-induced myocardial functional depression. MATERIALS AND METHODS: Adult male, proestrus female, and metestrus/diestrus female hearts were subjected to 60 min of TNF infusion at 10,000 pg/mL.min via Langendorff. Myocardial contractile function (left ventricular developed pressure, and the positive/negative first derivative of pressure) was continuously recorded. RESULTS: 10,000 pg/mL.min of TNF markedly depressed myocardial function in males compared with other doses of TNF. Myocardial function was significantly decreased in males compared to females following TNF infusion. Additionally, both the proestrus and the metestrus/diestrus females exhibited equal resistance to TNF-induced myocardial dysfunction. CONCLUSION: Our study shows that females exhibit a significantly greater degree of resistance to TNF-induced myocardial depression. Moreover, data from this study suggest that fluctuations in estrogen during the reproductive cycle may have little to no influence on TNF-induced myocardial depression.

Closed-Loop Continuous Hand Control via Chronic Recording of Regenerative Peripheral Nerve Interfaces.

Loss of the upper limb imposes a devastating interruption to everyday life. Full restoration of natural arm control requires the ability to simultaneously control multiple degrees of freedom of the prosthetic arm and maintain that control over an extended period of time. Current clinically available myoelectric prostheses do not provide simultaneous control or consistency for transradial amputees. To address this issue, we have implemented a standard Kalman filter for continuous hand control using intramuscular electromyography (EMG) from both regenerative peripheral nerve interfaces (RPNI) and an intact muscle within non-human primates. Seven RPNIs and one intact muscle were implanted with indwelling bipolar intramuscular electrodes in two rhesus macaques. Following recuperations, function-specific EMG signals were recorded and then fed through the Kalman filter during a hand-movement behavioral task to continuously predict the monkey's finger position. We were able to reconstruct continuous finger movement offline with an average correlation of and a root mean squared error (RMSE) of 0.12 between actual and predicted position from two macaques. This finger movement prediction was also performed in real time to enable closed-loop neural control of a virtual hand. Compared with physical hand control, neural control performance was slightly slower but maintained an average target hit success rate of 96.70%. Recalibration longevity measurements maintained consistent average correlation over time but had a significant change in RMSE ( ). Additionally, extracted single units varied in amplitude by a factor of +18.65% and -25.85% compared with its mean. This is the first demonstration of chronic indwelling electrodes being used for continuous position control via the Kalman filter. Combining these analyses with our novel peripheral nerve interface, we believe that this demonstrates an important step in providing patients with more naturalistic control of their prosthetic limbs.

The Use of Dermal Skin Substitutes for the Treatment of the Burned Hand.

The hand is commonly affected in burn injuries. Joints and extensor tendons are vulnerable given their superficial location. Durable coverage that permits relative frictionless tendon gliding and minimizes scar contracture is required to optimize functional outcomes. When soft tissue donor sites are limited, the use of dermal skin substitutes provides stable coverage with minimal scarring, good mobility, and acceptable appearance. A comprehensive review of dermal skin substitutes and their use with burn reconstruction of the hand is provided.

Acute Calcific Tendinitis of the Index Finger in a Child.

BACKGROUND: Calcific tendinitis is characterized by calcium hydroxyapatite crystal deposition within tendons and is a common cause of musculoskeletal pain in adults. Its clinical manifestations may be acute, chronic, or asymptomatic. Acute calcific tendinitis is self-resolving condition that is rarely reported in the pediatric population and may be overlooked for more common processes, leading to unnecessary treatment. METHODS: A chart reivew was performed of a single case of acute calcific tendonitis of the index finger in a child. RESULTS: We describe a case of calcific tendinitis of the index finger in a 9-year-old boy who was referred to us for a second opinion after surgical exploration of an acutely inflamed digit was recommended based on his initial presentation. The calcifications and symptoms resolved over time without operative management. CONCLUSIONS: Although rare in children, acute calcific tendinitis can present similar to an infection. However, appropriate managment is non-operative as the symptoms and radiographic findings resolve over time.

Providing a sense of touch to prosthetic hands.

Each year, approximately 185,000 Americans suffer the devastating loss of a limb. The effects of upper limb amputations are profound because a person's hands are tools for everyday functioning, expressive communication, and other uniquely human attributes. Despite the advancements in prosthetic technology, current upper limb prostheses are still limited in terms of complex motor control and sensory feedback. Sensory feedback is critical to restoring full functionality to amputated patients because it would relieve the cognitive burden of relying solely on visual input to monitor motor commands and provide tremendous psychological benefits. This article reviews the latest innovations in sensory feedback and argues in favor of peripheral nerve interfaces. First, the authors examine the structure of the peripheral nerve and its importance in the development of a sensory interface. Second, the authors discuss advancements in targeted muscle reinnervation and direct neural stimulation by means of intraneural electrodes. The authors then explore the future of prosthetic sensory feedback using innovative technologies for neural signaling, specifically, the sensory regenerative peripheral nerve interface and optogenetics. These breakthroughs pave the way for the development of a prosthetic limb with the ability to feel.

Comprehensive breast reconstruction in an academic surgical practice: an evaluation of the financial impact.

BACKGROUND: This study assessed the financial implications of providing all forms of breast reconstruction at a single academic institution with insurance as the primary mode of reimbursement. METHODS: Billing records of 152 patients who underwent postmastectomy breast reconstruction offered at the University of Michigan for the 2012 fiscal year were reviewed. Professional and facility revenue, cost, and earnings for the first stage of reconstruction were calculated by applying actual collections and charges. Similar financial data were compiled for a subset of 49 patients who went on to complete reconstruction. RESULTS: The professional revenue and expenses allocated to breast reconstruction were $647,437 and $591,184, respectively (8.7 percent margin). Health care system facility revenue and costs were $2,762,797 and $2,773,131, respectively (-0.4 percent margin). Physician reimbursement by surgical time was highest for delayed tissue expander placement ($3505 per operating room hour). Abdominal free flap reconstructions resulted in greater professional revenue for the first stage of reconstruction ($7801 versus $2961) and for completed reconstructions ($14,943 versus $7703) relative to implant reconstructions. The facility also did better fiscally after the first stage of abdominally based reconstruction compared with implant reconstructions (10 percent versus -10.4 percent margin). CONCLUSIONS: Postmastectomy breast reconstruction for this academic surgical practice remains fiscally profitable. Implant-based reconstruction compared with abdominal flap reconstruction produces greater revenue per operative hour but ultimately generates less total revenue and results in financial losses for the facility. Abdominally based perforator flap reconstruction reimbursed through standard insurance plans can be financially advantageous for the academic surgical practice and health care system.

Proestrus female rats are more resistant to right ventricular pressure overload.

Multiple studies of left ventricular dysfunction suggest that females may be more resistant to ischemia or endotoxemia. However, sex differences in right ventricular (RV) responses to pressure overload and/or endotoxemia have not been elucidated. We hypothesized that females would maintain better RV function during acute pressure overload (APO), endotoxemia, or a simultaneous insult from both processes. Age-matched male and proestrus female Sprague-Dawley rats were given an intraperitoneal injection of either phosphate buffered saline or LPS. Six hours after injection, hearts were removed by median sternotomy and isolated via Langendorff. End-diastolic pressures were sequentially elevated past physiologic levels by increasing the volume of a latex balloon that was inserted into the RV. Male RV function was depressed to a greater degree after APO injury compared with that in females (developed pressure: male, 44.97 mmHg vs. female, 58.23 mmHg). Interestingly though, at a physiologic end-diastolic pressure of 5 mmHg, endotoxic males and females maintained equivalent RV function. However, with concurrent endotoxic insult and APO, RV function was better maintained in males as compared with that in females (developed pressure: male, 59% of control versus female, 41% of control). Furthermore, tissue levels of IL-1 and IL-6, but not IL-10, were increased after endotoxin exposure but did not differ based on sex. Through this study, we have shown that sex differences exist in RV dysfunction, and that different cardiac insults diversely affect myocardial function. Understanding these differences may allow for the implementation of novel therapeutic treatment options that are designed to attenuate RV cardiovascular collapse.