Biohybrid Robotic Hand to Investigate Tactile Encoding and Sensorimotor Integration.

For people who have experienced a spinal cord injury or an amputation, the recovery of sensation and motor control could be incomplete despite noteworthy advances with invasive neural interfaces. Our objective is to explore the feasibility of a novel biohybrid robotic hand model to investigate aspects of tactile sensation and sensorimotor integration with a pre-clinical research platform. Our new biohybrid model couples an artificial hand with biological neural networks (BNN) cultured in a multichannel microelectrode array (MEA). We decoded neural activity to control a finger of the artificial hand that was outfitted with a tactile sensor. The fingertip sensations were encoded into rapidly adapting (RA) or slowly adapting (SA) mechanoreceptor firing patterns that were used to electrically stimulate the BNN. We classified the coherence between afferent and efferent electrodes in the MEA with a convolutional neural network (CNN) using a transfer learning approach. The BNN exhibited the capacity for functional specialization with the RA and SA patterns, represented by significantly different robotic behavior of the biohybrid hand with respect to the tactile encoding method. Furthermore, the CNN was able to distinguish between RA and SA encoding methods with 97.84% ± 0.65% accuracy when the BNN was provided tactile feedback, averaged across three days in vitro (DIV). This novel biohybrid research platform demonstrates that BNNs are sensitive to tactile encoding methods and can integrate robotic tactile sensations with the motor control of an artificial hand. This opens the possibility of using biohybrid research platforms in the future to study aspects of neural interfaces with minimal human risk.

The Green Transfer-Long-Term Results.

PURPOSE: The purpose of this study was to determine the long-term results of the Green transfer (flexor carpi ulnaris to extensor carpi radialis brevis) for patient-reported outcomes, wrist position, and range of motion. METHODS: We re-examined 13 patients from a previous prospective study involving surgery for hemiplegia that included a Green transfer. The average follow-up was 8 years with the range from 5 to 11 years. The wrist range of motion and the postoperative position of the wrists were measured. The surgical outcomes were measured via the Pediatric Orthopedic Data Collection Instrument, the Shriner's Hospital Upper Extremity Evaluation, Pediatric Quality of Life, and visual analog score for appearance from the patient and the parent. RESULTS: At this follow-up, only 7 of the 13 patients had a wrist position near neutral with the ability to flex and extend the wrist. Wrist range of motion was improved in four, decreased in four, and stayed the same in five patients. In contrast to these positional wrist results, statistically significant improvements were noted in several aspects of the Pediatric Orthopedic Data Collection Instrument, visual analog scores, and Shriner's Hospital Upper Extremity Evaluation scores. CONCLUSIONS: Long-term follow-up of the flexor carpi ulnaris to extensor carpi radialis brevis tendon transfer in hemiplegic patients reveals the results to be variable but favorable from a patient-reported outcome standpoint. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

A New Source of Mutilating Hand Injuries: The Side-by-Side Utility Terrain Vehicle.

BACKGROUND: Rates of mutilating hand injuries are increasing from accidents caused by all-terrain vehicles (ATVs) and the recently popularized side-by-side utility terrain vehicles (UTVs). Increasing surgeon familiarity with upper extremity (UE) injury patterns, severity, and outcomes following ATV and UTV accidents may improve patient care and advocacy. METHODS: Retrospective comparisons of UE injury patterns, severity, hospital and intensive care unit (ICU) admission lengths, and number of operations were made between ATVs and UTVs. Findings were analyzed with Fisher exact tests, multivariate analysis of variance, analyses of variance with post hoc analyses, and multiple linear regressions. RESULTS: A total of 154 cases were identified for inclusion (ATV, n = 87; UTV, n = 67). Patient ages ranged from 4 to 89 years. The UTV group contained significantly more hand and finger injuries, and more of the fractures were open ( P = 0.005, P < 0.001, and P < 0.001, respectively). Riders of UTVs had nearly three times as many mutilating hand injuries and a nearly ninefold increase in amputations compared with ATV riders ( P < 0.001 and P < 0.001, respectively). On average, the UTV group spent 2.5 additional days in the hospital, 0.91 additional days in an ICU, and had 1.3 additional operations ( P = 0.001, P = 0.007, and P < 0.001, respectively). Vehicle type was the only variable significantly correlated with days in the hospital, ICU, and number of UE operations ( P = 0.002, P = 0.008, and P < 0.001, respectively). CONCLUSIONS: Hand surgeons are in a unique position to serve as forerunners for increasing public awareness of off-road vehicle risks and promoting rider safety. Collaborating with manufacturers and emergency care providers and directing teaching initiatives may improve patient outcomes. CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, II.

The Impact of Isolated Versus Multiple Osteochondromas: Analysis of the CoULD Registry.

PURPOSE: The burden of upper extremity (UE) osteochondromas on function and self-perception among pediatric patients is unclear. The purpose of our study was to study the impact of osteochondromas in comparison to population norms and to evaluate solitary versus multiple osteochondromas on subjective UE function as measured by patient rated outcomes. METHODS: We utilized the CoULD (Congenital Upper Limb Differences) Registry to review all pediatric patients presenting with osteochondromas between January 2014 and February 2021. Demographic information was collected and patients were classified as having either single or multiple osteochondromas. Patient-Reported Outcome Measurement Information System (PROMIS) and Pediatric Outcomes Data Collection Instrument (PODCI) tools were utilized for assessment. Scores for PODCI subscales of UE function, Pain/comfort, and Happiness and PROMIS domains of UE Function, Pain, Depression, Anxiety, and Peer Relations were reviewed. Differences between groups were analyzed using the Student t test. RESULTS: Ninety-nine patients met inclusion criteria for the study with an average age of presentation of 9.3 years and 61 patients (62%) were male. Overall, patients demonstrated worse UE Function as well as greater Anxiety and Depression in comparison to the population normals on PROMIS assessment. Patients also demonstrated worse patient and parent reported PODCI UE, Sports and Physical Functioning, Pain/Comfort and Global Functioning scores compared with population norms but demonstrated better than average happiness scores. Patients with multiple osteochondromas demonstrated greater PROMIS pain interference and more disability in PODCI Sports and Physical Functioning, Pain/Comfort and Global Functioning compared with those with solitary osteochondromas. CONCLUSION: Patients with UE osteochondromas have worse overall function in comparison to population norms, exceeding established minimally clinically important difference values. In addition, patients with multiple osteochondromas reported more pain and poorer physical function than those with solitary osteochondromas. Physicians should be alert to the physical and psychosocial burden of this disease. LEVEL OF EVIDENCE: Level II-prognostic.

How Risky Are Risk Factors? An Analysis of Prenatal Risk Factors in Patients Participating in the Congenital Upper Limb Differences Registry.

Purpose: Risk factors for congenital upper limb differences (CoULDs) are often studied at the general population level. The CoULD registry provides a unique opportunity to study prenatal risk factors within a large patient sample. Methods: All patients enrolled between June 2014 and March 2020 in the prospective CoULD registry, a national multicenter database of patients diagnosed with a CoULD, were included in the analysis. We analyzed self-reported, prenatal risk factors, including maternal smoking, alcohol use, recreational drug use, prescription drug use, gestational diabetes mellitus (GDM), and gestational hypertension. The outcome measures included comorbid medical conditions, proximal involvement of limb difference, bilateral involvement, and additional orthopedic conditions. Multivariable logistic regression was used to analyze the effect of the risk factors, controlling for sex and the presence of a named syndrome. Results: In total, 2,410 patients were analyzed, of whom 72% (1,734) did not have a self-reported risk factor. Among the 29% (676) who did have at least 1 risk factor, prenatal maternal prescription drug use was the most frequent (376/2,410; 16%). Maternal prescription drug use was associated with increased odds of patient medical comorbidities (odds ratio [OR] = 1.43, P = .02). Gestational diabetes mellitus was associated with increased odds of comorbid medical conditions (OR = 1.58, P = .04), additional orthopedic conditions (OR = 1.51, P = .04), and proximal involvement (OR = 1.52, P = .04). Overall, reporting 1 or more risk factors increased the odds of patient comorbid medical conditions (OR = 1.42, P < .001) and additional orthopedic conditions (OR = 1.25, P = .03). Conclusions: Most caregivers (72%) did not report a risk factor during enrollment. However, reporting a risk factor was associated with patient medical and orthopedic comorbidities. Of note, GDM alone significantly increased the odds of both these outcome measures along with proximal limb differences. These findings highlight the ill-defined etiology of CoULDs but suggest that prenatal risk factors, especially GDM, are associated with a higher degree of morbidity. Type of study/level of evidence: Prognostic III.

Multichannel haptic feedback unlocks prosthetic hand dexterity.

Loss of tactile sensations is a major roadblock preventing upper limb-absent people from multitasking or using the full dexterity of their prosthetic hands. With current myoelectric prosthetic hands, limb-absent people can only control one grasp function at a time even though modern artificial hands are mechanically capable of individual control of all five digits. In this paper, we investigated whether people could precisely control the grip forces applied to two different objects grasped simultaneously with a dexterous artificial hand. Toward that end, we developed a novel multichannel wearable soft robotic armband to convey artificial sensations of touch to the robotic hand users. Multiple channels of haptic feedback enabled subjects to successfully grasp and transport two objects simultaneously with the dexterous artificial hand without breaking or dropping them, even when their vision of both objects was obstructed. Simultaneous transport of the objects provided a significant time savings to perform the deliveries in comparison to a one-at-a-time approach. This paper demonstrated that subjects were able to integrate multiple channels of haptic feedback into their motor control strategies to perform a complex simultaneous object grasp control task with an artificial limb, which could serve as a paradigm shift in the way prosthetic hands are operated.

Safety and efficacy of human juvenile chondrocyte-derived cell sheets for osteochondral defect treatment.

Knee cartilage does not regenerate spontaneously after injury, and a gold standard regenerative treatment algorithm has not been established. This study demonstrates preclinical safety and efficacy of scaffold-free, human juvenile cartilage-derived-chondrocyte (JCC) sheets produced from routine surgical discards using thermo-responsive cultureware. JCCs exhibit stable and high growth potential in vitro over passage 10, supporting possibilities for scale-up to mass production for commercialization. JCC sheets contain highly viable, densely packed cells, show no anchorage-independent cell growth, express mesenchymal surface markers, and lack MHC II expression. In nude rat focal osteochondral defect models, stable neocartilage formation was observed at 4 weeks by JCC sheet transplantation without abnormal tissue growth over 24 weeks in contrast to the nontreatment group showing no spontaneous cartilage repair. Regenerated cartilage was safranin-O positive, contained type II collagen, aggrecan, and human vimentin, and lacked type I collagen, indicating that the hyaline-like neocartilage formed originates from transplanted JCC sheets rather than host-derived cells. This study demonstrates the safety of JCC sheets and stable hyaline cartilage formation with engineered JCC sheets utilizing a sustainable tissue supply. Cost-benefit and scaling issues for sheet fabrication and use support feasibility of this JCC sheet strategy in clinical cartilage repair.

A Comparison of Open Carpal Tunnel Release Outcomes Between Procedure Room and Operating Room Settings.

PURPOSE: Carpal tunnel release (CTR) surgical costs are minimized when performed in the procedure room (PR) setting, compared with the operating room. However, it remains unclear whether outcomes differ between surgical settings. Our purpose was to compare outcomes at 1 year or greater follow-up after open CTR between patients treated in PR versus operating room settings using the Boston Carpal Tunnel Questionnaire (BCTQ). METHODS: A change in clinical care protocols at our institution occurred in 2014. Before this, all CTRs were performed in the operating room; thereafter, these were transitioned to the PR. Adult patients who underwent isolated unilateral or bilateral open CTR in either surgical setting were considered for inclusion, in which procedures were conducted between January 2014 and October 2018 for the PR group and January 2009 and March 2014 for the operating room group. The Functional Status Scale (FSS) and the Symptom Severity Scale (SSS) components of the BCTQ were collected for all eligible patients at a minimum of 1 year after surgery. We used univariate and multivariable linear regression to determine whether postoperative BCTQ scores were equivalent between PR and operating room groups within a threshold of one-fourth of the lowest estimates of the minimal clinically important difference. RESULTS: No differences in demographics, comorbidities, or insurance type were observed between the 104 PR and 112 operating room patients. Survey response rate was 25% and 25% for the PR and operating room patients, respectively. At a mean follow-up of 3 ± 1 years, FSS and SSS scores were equivalent between PR and operating room groups on bivariate analysis. The multivariable equivalence test also demonstrated equivalent FSS and SSS scores between PR and operating room groups within a one-fourth minimal clinically important difference threshold while controlling for age, sex, presence of diabetes or thyroid disease, unilateral versus bilateral CTR, and surgeon. CONCLUSIONS: Clinical outcomes did not differ between PR and operating room settings after open CTR. Type of study/level of evidence: Therapeutic III.

Discriminability of multiple cutaneous and proprioceptive hand percepts evoked by intraneural stimulation with Utah slanted electrode arrays in human amputees.

BACKGROUND: Electrical stimulation of residual afferent nerve fibers can evoke sensations from a missing limb after amputation, and bionic arms endowed with artificial sensory feedback have been shown to confer functional and psychological benefits. Here we explore the extent to which artificial sensations can be discriminated based on location, quality, and intensity. METHODS: We implanted Utah Slanted Electrode Arrays (USEAs) in the arm nerves of three transradial amputees and delivered electrical stimulation via different electrodes and frequencies to produce sensations on the missing hand with various locations, qualities, and intensities. Participants performed blind discrimination trials to discriminate among these artificial sensations. RESULTS: Participants successfully discriminated cutaneous and proprioceptive sensations ranging in location, quality and intensity. Performance was significantly greater than chance for all discrimination tasks, including discrimination among up to ten different cutaneous location-intensity combinations (15/30 successes, p < 0.0001) and seven different proprioceptive location-intensity combinations (21/40 successes, p < 0.0001). Variations in the site of stimulation within the nerve, via electrode selection, enabled discrimination among up to five locations and qualities (35/35 successes, p < 0.0001). Variations in the stimulation frequency enabled discrimination among four different intensities at the same location (13/20 successes, p < 0.0005). One participant also discriminated among individual stimulation of two different USEA electrodes, simultaneous stimulation on both electrodes, and interleaved stimulation on both electrodes (20/24 successes, p < 0.0001). CONCLUSION: Electrode location, stimulation frequency, and stimulation pattern can be modulated to evoke functionally discriminable sensations with a range of locations, qualities, and intensities. This rich source of artificial sensory feedback may enhance functional performance and embodiment of bionic arms endowed with a sense of touch.

The Natural History of Pediatric Trigger Thumb in the United States.

PURPOSE: Surgical release of pediatric trigger thumbs has been recommended as definitive treatment, although controversy exists over the natural history of pediatric trigger thumb. This study sought to evaluate the incidence of spontaneous resolution of pediatric trigger thumb and the factors that may influence resolution. METHODS: Pediatric patients were prospectively enrolled by a single surgeon from August 2009 to July 2015. All patients were initially treated with observation. They were followed annually and we collected pain scores (Parental visual analog scale), subjective dysfunction as perceived by parents, and physical examination information including the presence of flexion contracture of the thumb interphalangeal (IP) joint, thumb metacarpophalangeal joint laxity, and medial-lateral plane IP joint angular deformity. A competing risk framework was used to estimate the cumulative incidence at 5 years from the initial visit, and a subdistribution hazards model was used to compare patient characteristics with spontaneous resolution. Hazard ratios (HRs), 95% confidence intervals (95% CIs), and P values were reported. RESULTS: Seventy-eight patients (93 thumbs) with an average age of 20 months ± 1 year (mean ± SD) were enrolled at the first clinic visit and followed for 4.3 years (interquartile range, 3.1-5.5 years). At 5 years from the initial visit, 32% (95% CI, 20%-43%) of thumbs had resolved spontaneously, and 43% (95% CI, 30%-54%) had elected to proceed to surgery. Among those who had surgery, the median time to surgery was 4.1 years (interquartile range, 2.9-5.3 years). Bilateral thumb involvement increased the risk of surgery (subdistribution HR, 2.38; 95% CI, 1.23--4.6). Each degree increase in initial IP joint flexion decreased the occurrence of spontaneous resolution by 3% (subdistribution HR, 0.97; 95% CI, 0.94-0.99). Initial IP joint flexion 30° or less was associated with spontaneous resolution at 3 years (sensitivity, 0.73, 95% CI, 0.37-1.00; specificity, 0.70, 95% CI, 0.38-0.94; positive predictive value, 0.18, 95% CI, 0.13-0.41; negative predictive value, 0.76, 95% CI, 0.71-0.83; area under the curve, 0.78), whereas only 2.5% (95% CI, 0.4%-17%) of patients with an IP joint flexion greater than 30° resolved. CONCLUSIONS: A third of pediatric trigger thumbs resolved spontaneously, but most parents desired eventual surgical release. Patients with IP joint flexion contractures greater than 30° at baseline often lacked spontaneous resolution at 3 years and may be reasonable early surgical candidates. TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic II.

Evaluating the Safety of the Hand Surgery Procedure Room: A Single-Center Cohort of 1,404 Surgical Encounters.

PURPOSE: Performing hand surgeries in the procedure room (PR) setting instead of the operating room effectively reduces surgical costs. Understanding the safety or complication rates associated with the PR is important in determining the value of its use. Our purpose was to describe the incidence of medical and surgical complications among patients undergoing minor hand surgeries in the PR. METHODS: We retrospectively reviewed all adult patients who underwent an operation in the PR setting between December 2013 and May 2019 at a single tertiary academic medical center by 1 of 5 fellowship-trained orthopedic hand surgeons. Baseline patient characteristics were described. Complication rates were obtained via chart review. RESULTS: For 1,404 PR surgical encounters, 1,796 procedures were performed. Mean patient age was 59 ± 15 years, 809 were female (57.6%), and average follow-up was 104 days. The most common surgeries were carpal tunnel release (39.9%), trigger finger release (35.9%), and finger mass or cyst excision (9.6%). Most surgeries were performed using a nonpneumatic wrist tourniquet (58%), whereas 42% used no tourniquet. No patient experienced a major medical complication. No procedure was aborted owing to intolerance. No patient required admission. No intraoperative surgical or medical complications occurred. Observed complications included delayed capillary refill requiring phentolamine administration after a trigger thumb release performed using epinephrine without a tourniquet (n = 1; 0.1%), complex regional pain syndrome (n = 3; 0.2%), infection requiring surgical debridement (n = 2; 0.2%), and recurrent symptoms requiring reoperation (n = 8; 0.7%). CONCLUSIONS: In this cohort of patients in whom surgery was performed in a PR, there were no major intraoperative surgical or medical complications. There was a low rate of postoperative infection, development of complex regional pain syndrome, and a low need for revision surgery. These observations do not support the concern for safety as a barrier to performing minor hand surgery in the PR setting. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Long-term Reoperation Rate for Cubital Tunnel Syndrome: Subcutaneous Transposition Versus In Situ Decompression.

Background: The purpose of this study was to compare the long-term revision rate of in situ ulnar nerve decompression with anterior subcutaneous transposition surgery for idiopathic cubital tunnel syndrome. Methods: This retrospective, multicenter, cohort study compared patients who underwent ulnar nerve surgery with a minimum 5 years of follow-up. The primary outcome studied was the need for revision cubital tunnel surgery. In total, there were 132 cases corresponding to 119 patients. The cohorts were matched for age and comorbidity. Results: The long-term reoperation rate for in situ decompression was 25% compared with 12% for anterior subcutaneous transposition. Seventy-eight percent of revisions of in situ decompression were performed within the first 3 years. Younger age and female sex were identified as independent predictors of need for revision. Conclusions: In the long-term follow-up, in situ decompression is seen to have a statistically significant higher reoperation rate compared with subcutaneous transposition.

Long-term performance of Utah slanted electrode arrays and intramuscular electromyographic leads implanted chronically in human arm nerves and muscles.

OBJECTIVE: We explore the long-term performance and stability of seven percutaneous Utah Slanted Electrode Arrays (USEAs) and intramuscular recording leads (iEMGs) implanted chronically in the residual arm nerves and muscles of three human participants as a means to permanently restore sensorimotor function after transradial amputations. APPROACH: We quantify the number of functional recording and functional stimulating electrodes over time. We also calculate the signal-to-noise ratio (SNR) of USEA and iEMG recordings and quantify the stimulation current necessary to evoke detectable sensory percepts. Furthermore, we quantify the consistency of the sensory modality, receptive field location, and receptive field size of USEA-evoked percepts. MAIN RESULTS: In the most recent subject, involving USEAs with technical improvements, neural recordings persisted for 502 d (entire implant duration) and the number of functional recording electrodes for one USEA increased over time. However, for six out of seven USEAs across the three participants, the number of functional recording electrodes decreased within the first 2 months after implantation. The SNR of neural recordings and electromyographic recordings stayed relatively consistent over time. Sensory percepts were consistently evoked over the span of 14 months, were not significantly different in size, and highlighted the nerves' fascicular organization. The percentage of percepts with consistent modality or consistent receptive field location between sessions (∼1 month apart) varied between 0%-86.2% and 9.1%-100%, respectively. Stimulation thresholds and electrode impedances increased initially but then remained relatively stable over time. SIGNIFICANCE: This work demonstrates improved performance of USEAs, and provides a basis for comparing the longevity and stability of USEAs to that of other neural interfaces. USEAs provide a rich repertoire of neural recordings and sensory percepts. Although their performance still generally declines over time, functionality can persist long-term. Future work should leverage the results presented here to further improve USEA design or to develop adaptive algorithms that can maintain a high level of performance.

Upper Extremity Function, Peer Relationships, and Pain Interference: Evaluating the Biopsychosocial Model in a Pediatric Hand Surgery Population Using PROMIS.

PURPOSE: The relationship between biopsychosocial factors and patient-reported function is less clear in pediatric than in adult hand surgery patients. Our primary hypothesis was that pain interference (PI) and peer relationships (PR) would demonstrate association with upper extremity function. Secondarily, we hypothesized that the magnitude of this effect would increase with age. METHODS: Patients aged 5 to 17 years presenting to a tertiary academic clinic between October 2017 and January 2019 were included. The parent/guardian was administered the following instruments after indicating they, rather than the patient, were answering the questions on a tablet computer: Patient-Reported Outcomes Measurement Information System (PROMIS) Upper Extremity (UE) Parent Proxy (PP) Computer Adaptive Test (CAT) v2.0, PROMIS PI PP CAT v2.0, and the PROMIS PR PP CAT v2.0. Ceiling/floor effects and Spearman correlations were calculated. Multivariable Tobit modeling was performed to determine whether biopsychosocial factors and upper extremity function were associated. Multivariable regression coefficients were compared between age cohorts using a separate multivariable model to evaluate the interaction between age and other predictors. RESULTS: Of 139 included participants, the mean age was 11.7 ± 3.7 years and 50% were female. For patients 11 years of age or younger, UE was weakly correlated with PI (coefficient, -0.34; 95% confidence interval, -0.56 to -0.08) and was not correlated with PR. For patients older than 11 years, UE had moderate correlation with PI (coefficient, -0.60; 95% confidence interval, -0.72 to -0.45) and was not correlated with PR. Multivariable analysis demonstrated a significant negative association between PI and UE, with a significantly larger magnitude of effect for patients older than 11 years of age. CONCLUSIONS: The biopsychosocial model applies to pediatric hand surgery patients. The association between greater pain interference and worse patient-reported upper extremity function, as assessed using parent proxy instruments, was significantly stronger for patients older than 11 years than those 11 years old or younger. CLINICAL RELEVANCE: This study suggests that the biopsychosocial model applies to pediatric hand patients.

A prospective, randomized clinical trial of transverse versus longitudinal incisions for trigger finger release.

We investigated whether incision type affects scar quality or outcome following trigger finger release. Our primary and secondary hypotheses were that transverse and longitudinal incision types yield similar scar quality and functional improvement. Digits undergoing trigger finger release at the participating hospitals were randomized to receive transverse or longitudinal incisions. The Patient Scar Assessment Scale, Observer Scar Assessment Scale, and the Disabilities of the Arm, Shoulder and Hand score were collected at 8 and 54 weeks postoperatively. Of 86 randomized patients, 67 patients (71%) had followed-up at 54 weeks postoperatively. We found no significant differences in above three assessments between the incisions at either time-point. Among patients receiving both incision types for multiple simultaneous trigger finger release, there were no significant differences in Patient Scar Assessment Scale or Observer Scar Assessment Scale scores. We found no significant difference in the scar quality and improvement in patient-reported disability with transverse or longitudinal incisions for trigger finger release. Level of evidence: II.

Syndactyly release: a comparison of skin graft versus graftless techniques in the same patient.

Syndactyly release may be done by skin graft or graftless techniques. We prospectively examined bilateral syndactyly releases in the same patient at one operation. The grafted side was randomized and the contralateral side was done graftless. Fourteen patients had surgery at a mean age of 27 months (range 7-166). The mean follow-up was 52 months (range 6-111). The mean tourniquet time was 97 minutes (range 66-135) for graft and 84 minutes (55-120) for graftless. The mean finger abduction was 57° (32°-80°) for graft and 54° (38°-80°) for graftless. The mean web creep score was 1.2 (0-3) for graft and 2.1 (0-3) for graftless. The mean scar score was 1.9 (1-3) bilaterally. The mean parents' visual analogue scale for graft cosmesis was 7.1 (5-9) and 6.2 (4.3-8) for graftless. The surgeon's visual analogue scale for graft was 7.9 (6.4-9.5) and 6.2 (4-8.7) for graftless. The therapist's visual analogue scale was 7.9 (6.5-10) and 6.4 (4.7-8) for graftless. Although there is a longer tourniquet time with grafting, there may be advantages in appearance and web creep. Level of evidence: II.

Virtual Reality Provides an Effective Platform for Functional Evaluations of Closed-Loop Neuromyoelectric Control.

Although recent advances in neuroprostheses offer opportunities for improved and intuitive control of advanced motorized and sensorized robotic arms, practical complications associated with such hardware can impede the research necessary for clinical translation. These hurdles potentially can be reduced with virtual reality environments (VREs) with embedded physics engines using virtual models of physical robotic hands. These software suites offer several advantages over physical prototypes, including high repeatability, reduced human error, elimination of many secondary sensory cues, and others. There are limited demonstrations of closed-loop prostheses in the VRE, and it is unclear whether VRE performance translates to the physical world. Here we describe how two trans-radial amputees with neural and intramuscular implants identified objects and performed activities of daily living with closed-loop control of prostheses in the VRE. Our initial evidence further suggests that capabilities with virtual prostheses may be predictors of physical prosthesis performance, demonstrating the utility of VREs for neuroprosthetic research.

Selective Decrease in Allodynia With High-Frequency Neuromodulation via High-Electrode-Count Intrafascicular Peripheral Nerve Interface After Brachial Plexus Injury.

OBJECTIVES: Kilohertz high-frequency alternating current (KHFAC) electrical nerve stimulation produces a reversible nerve block in peripheral nerves in human patients with chronic pain pathologies. Although this stimulation methodology has been verified with nonselective extrafascicular electrodes, the effectiveness of producing a selective nerve block with more-selective intrafascicular electrodes has not been well documented. The objective of this study was to examine whether intrafascicular electrodes can block painful stimuli while preserving conduction of other neural activity within the implanted nerve. MATERIALS AND METHODS: We analyzed the effects of various stimulation waveforms delivered through Utah Slanted Electrode Arrays (USEAs) implanted in the median nerve of a male human subject with a left brachial plexus injury. We compared KHFAC stimulation with a sham control. RESULTS: KHFAC stimulation through USEA electrodes produced a reduction in pain sensitivity in the palmar aspect of the left middle finger. KHFAC had limited effects on the patient's ability to feel tactile probing in the same area or move the digits of his left hand. Other tested stimulation parameters either increased or showed no reduction in pain. CONCLUSIONS: KHFAC stimulation in peripheral nerves through intrafascicular electrodes demonstrated a selective reduction in pain sensitivity while preserving other nerve functions. This treatment may benefit patient populations who have chronic pain originating from peripheral nerves, but who do not want to block whole-nerve function in order to preserve sensory and motor function reliant on the implanted nerve. Furthermore, KHFAC may benefit patients who respond negatively to other forms of peripheral nerve stimulation therapy.

Improved Training Paradigms and Motor-decode Algorithms: Results from Intact Individuals and a Recent Transradial Amputee with Prior Complex Regional Pain Syndrome.

Working towards improved neuromyoelectric control of dexterous prosthetic hands, we explored how differences in training paradigms affect the subsequent online performance of two different motor-decode algorithms. Participants included two intact subjects and one participant who had undergone a recent transradial amputation after complex regional pain syndrome (CRPS) and multi-year disuse of the affected hand. During algorithm training sessions, participants actively mimicked hand movements appearing on a computer monitor. We varied both the duration of the hold-time (0.1 s or 5 s) at the end-point of each of six different digit and wrist movements, and the order in which the training movements were presented (random or sequential). We quantified the impact of these variations on two different motordecode algorithms, both having proportional, six-degree-offreedom (DOF) control: a modified Kalman filter (MKF) previously reported by this group, and a new approach - a convolutional neural network (CNN). Results showed that increasing the hold-time in the training set improved run-time performance. By contrast, presenting training movements in either random or sequential order had a variable and relatively modest effect on performance. The relative performance of the two decode algorithms varied according to the performance metric. This work represents the first-ever amputee use of a CNN for real-time, proportional six-DOF control of a prosthetic hand. Also novel was the testing of implanted high-channelcount devices for neuromyoelectric control shortly after amputation, following CRPS and long-term hand disuse. This work identifies key factors in the training of decode algorithms that improve their subsequent run-time performance.