Implanted Pulse Generators in Lower Extremity Neuroprostheses: A 25-Year Review.

OBJECTIVES: Neuroprosthetic devices can improve quality of life by providing an alternative option for motor function lost after spinal cord injury, stroke, and other central nervous system disorders. The objective of this study is to analyze the outcomes of implanted pulse generators that our research group installed in volunteers with paralysis to assist with lower extremity function over a 25-year period, specifically, to determine survival rates and common modes of malfunction, reasons for removal or revision, and precipitating factors or external events that may have adversely influenced device performance. MATERIALS AND METHODS: Our implantable receiver-stimulator (IRS-8) and implantable stimulator-telemeter (IST-12 and IST-16) device histories were retrospectively reviewed through surgical notes, regulatory documentation, and manufacturing records from 1996 to 2021. RESULTS: Most of the 65 devices (64.6%) implanted in 43 volunteers remain implanted and operational. Seven underwent explantation owing to infection; seven had internal failures, and six were physically broken by external events. Of the 22 devices explanted, 15 were successfully replaced to restore recipients' enhanced functionality. There were no instances of sepsis or major health complications. The five infections that followed all 93 IRS and IST lower extremity research surgeries during this period indicate a pooled infection rate of 5.4%. The Kaplan-Meier analysis of technical malfunctions between the implant date and most recent follow-up shows five-, ten-, and 20-year device survival rates of 92%, 84%, and 71%, respectively. CONCLUSIONS: Incidence of malfunction is similar to, whereas infection rates are slightly higher than, other commonly implanted medical devices. Future investigations will focus on infection prevention, modifying techniques on the basis of recipient demographics, lifestyle factors, and education, and integrating similar experience of motor neuroprostheses used in other applications.

Postoperative Elbow Instability: Options for Revision Stabilization.

Persistent and recurrent postoperative elbow instability includes a spectrum of pathologies ranging from joint incongruity and subluxation to dislocation. Restoration of osseous anatomy, particularly the coronoid, is a priority in restoring elbow alignment and maintaining ulnohumeral joint stability. After managing bony deficiencies, soft-tissue and ligamentous structures are typically addressed. When required, both static and dynamic adjunctive stabilization procedures have been described, which aid in maintaining a concentric reduction. In these complex procedures, both complication avoidance and early recognition of postoperative complications assist in obtaining a good result. In this review, we discuss current treatment options for revision stabilization for patients with persistent and recurrent elbow subluxation or dislocation after primary stabilization.

Erratum to "Hand Surgery Patient Perspectives on Medical Cannabis: A Survey of Over 600 Patients" [Journal of Hand Surgery Global Online 5 (2023) 102-107].

[This corrects the article DOI: 10.1016/j.jhsg.2022.02.009.].

Hand Surgery Patient Perspectives on Medical Cannabis: A Survey of Over 600 Patients.

Purpose: Medical cannabis (MC) has been proposed as a potential addition to multimodal pain management regimens in orthopedics. This study evaluates hand and upper-extremity patient perspectives of MC as a treatment for common orthopedic and musculoskeletal pain conditions. This study also aims to identify the proportion of patients already using MC, perceived barriers to MC use, and opinions on insurance coverage and legality of cannabis. Methods: An anonymous cross-sectional survey study was conducted of all patients at least 18 years old presenting from October 2020 to January 2021 to a hand and upper-extremity outpatient clinic. The survey collected information regarding opinion on MC, including use, legality, and willingness to use MC in the future. Medical cannabis was legal in the states where the study was conducted. Results: A total of 679 patients completed the survey (response rate 72.5%). Sixty-eight patients (10.0%) reported currently using MC. Of the 623 patients (90.0%) who reported not currently using MC, 504 (80.9%) would consider using MC for chronic pain, while the remaining 119 (19.1%) would not consider the use of MC for chronic pain. Age was not associated with whether a patient would consider using MC (P = .16) or was already using MC (P = .10). The most identified barrier to MC use was cost, reported as either expensive or not affordable by 477 patients (70.5%). Conclusions: This study found that most patients presenting for hand and upper-extremity complaints would consider using MC (80.9%), and most perceive it as a safe treatment option for common orthopedic conditions. Moreover, 10% of patients reported already using MC. One of the major barriers to MC use is the cost. Most (90.9%) patients support policies for legalization and insurance coverage of MC. Type of study/level of evidence: Therapeutic Level III.

Quantifying osteosynthesis plate prominence - mathematical definitions and case study on a clavicle plate.

Hardware prominence remains a clinical challenge in focus for implant design in subcutaneous plate applications. Existing evaluation of hardware prominence relies on plate-to-bone distance at a single point or on average. A reproducible measure for plate prominence remains undefined. This study mathematically defines the plate prominence linked to the cross-sectional area change due to the plate presence on the bone. Two anatomical plate designs were fitted to 100 clavicles, and afterwards plate prominence parameters were evaluated and compared. This methodology enables the quantification of hardware prominence for different plate designs to inform the development of implants targeting low prominence.

Does Time to Operative Intervention of Distal Radius Fractures Influence Outcomes?

BACKGROUND: No investigation has analyzed the time from injury to operative intervention and its effect on complications and functional outcomes in distal radius fractures. This investigation aimed to establish whether the time to surgical intervention from injury was associated with the observed rate of complications in distal radius fractures. METHODS: A retrospective review of all orthopedic trauma patients who came to our center was conducted from 2008 through 2014. Patients who sustained closed distal radius fractures were included. A postoperative complication following distal radius fracture was defined as reoperation, superficial or deep infection, complex regional pain syndrome, new-onset carpal tunnel syndrome, tendon irritation, and symptomatic hardware. RESULTS: In all, 190 patients were included in the study with a mean age of 48 years (SD ±14.7). According to the AO-Müller/Orthopaedic Trauma Association classification, radiographs revealed 80 A fractures, 15 B fractures, and 95 C fractures. Thirty distal radii were fixed within 0 to 3 days after injury, 91 patients within 4 to 10 days, and 69 patients after 10 days. Overall, 28 complications (14.7%) were identified. There was no statistical difference in the rate of complications between the time interval groups (P = .17). CONCLUSIONS: Despite the increased popularity of surgical intervention for distal radius fractures, the optimal parameters to maximize patient outcomes have yet to be clearly defined. Time to intervention did not affect the rate of postoperative complication and range of motion.

Three-dimensional morphometric analysis of the lateral clavicle and acromion: Implications for surgical treatment using subacromial support.

Objectives: Dislocations and periarticular fractures of the acromioclavicular joint are common injuries of the shoulder girdle. When surgical intervention is indicated, subacromial support is one option to restore the alignment between scapula and the distal/lateral clavicle. Devices used for subacromial support rely on a form of subacromial 'hook'. The shape, inclination and orientation of which is often mismatched to the anatomy of the inferior surface of the acromion, which may lead to painful acromial osteolysis and rotator cuff abrasion causing impingement. The primary goal of this study was to characterize the geometrical parameters of the acromion and distal clavicle, and their orientation at the acromioclavicular joint. Methods: Computed tomography scans of 120 shoulders were converted into digital three-dimensional models. Measurements of the acromion inclination and acromion width relative to the torsional angle as well as the clavicle depth were taken. A numerical optimization of the anatomical parameters (including torsional and inclination angles, height and width) was performed to find the combination of those parameters with the lowest interpatient variability. Results: The mean clavicle depth was found to be 11.1 mm. The mean acromion width was 27 mm. The combination of torsional and inclination angles with lowest interpatient variability was found at 80° and 16°, respectively. Conclusion: There is a high interpatient variability in the morphology of the inferior surface of the acromion. Subacromial support using a 'hook' can be optimized for contact surface area, which should lead to fewer complications after the restoration of acromioclavicular orientation using acromial support strategies.

Complications and functional outcomes after transolecranon distal humerus fracture.

BACKGROUND: Transolecranon distal humerus fractures are uncommon injuries. This is the first multipatient case series to describe outcomes and complications following transolecranon distal humerus fractures in the adult population. METHOD: Design: retrospective; setting: single level 1 trauma center; patients/participants: 16 patients; intervention: surgical management of transolecranon distal humerus fracture; main outcome measurement: Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire after a minimum of 12 months. RESULTS: A total of 16 patients with open (n = 12) or closed (n = 4) transolecranon distal humerus fractures were identified. Nine female and 7 male patients with a mean age of 47 years were included. Mechanisms of injury included motor vehicle collisions (n = 3), motorcycle crashes (n = 4), ground-level falls (n = 3), falls from height (n = 4), train collision (n = 1), and an industrial accident (n = 1). Seven patients (44%) presented with nerve injury. Patients underwent open reduction with internal fixation (n = 15), external fixation (n = 6), or both (n = 5). Additional surgeries were ultimately required in 11 patients (69%), with a mean of 3 surgeries to manage each patient's elbow injuries. All patients returned for at least 3 clinical follow-up visits; mean clinical follow-up was 15.8 months and mean radiographic follow-up was 12.3 months. Complications were observed in 15 patients (94%). Eleven patients (69%) had limited range of motion with a flexion arc of less than 100° at their last clinic visit. Seven patients (44%) developed deep wound infections requiring repeat débridement and intravenous antibiotics. Implant removal was performed in 10 patients (62.5%) because of infection (n = 5), symptomatic hardware (n = 4), or device failure (n = 1). Heterotopic ossification was seen in 8 patients (50%) and post-traumatic arthrosis in 4 (25%). Two patients (12.5%) required flap reconstruction for soft tissue defects. Nonunion occurred in 7 patients (44%). DASH scores were obtained for 10 patients (62.5%) at a mean of 3.8 years after injury. The mean DASH score was 40.2, ranging from 4.2 to 76.5. Among respondents, 7 (70%) were able to resume working, with an average DASH work module score of 25. CONCLUSION: Management of transolecranon distal humerus fractures remain a challenge for orthopedic surgeons. Complication rates, including deep infection and nonunion, are high, with frequent long-term functional limitations posed to the patient, as evidenced by DASH scores.

Acute compartment syndrome of the deltoid: a case report and systematic review of the literature.

BACKGROUND: Deltoid compartment syndrome is a rare entity. The purpose of this study was to report a recent case and perform a systematic literature review. METHODS: Patient data were gathered from chart review and clinical encounters. For the review, the MEDLINE, Embase, and Ovid databases were queried for deltoid compartment syndrome cases. Seventeen articles reporting on 18 patients with deltoid compartment syndrome were included. RESULTS: Including our patient, 9 of 19 patients (47.4%) presented with compartment syndrome limited to the deltoid. Most patients presented with additional affected compartments, most commonly in the ipsilateral arm (7 of 19, 37%). Isolated deltoid involvement often resulted from iatrogenic injury; of 10 iatrogenic reports, 8 involved only the deltoid. Of 19 cases, 5 (26%) occurred in powerlifters, climbers, or anabolic steroid or testosterone injectors. In 13 of 19 cases (68%), the patients were men aged 18-36 years, and only 1 female case (5%) was reported. Prolonged recumbence owing to substance abuse was documented in 6 of 19 cases (32%). CONCLUSION: Deltoid compartment syndrome is rare, with only 19 reported cases, including our patient. Men are more commonly affected, and isolated deltoid compartment syndrome occurs in about 50% of reported cases. More than half of cases are iatrogenic, secondary to prolonged lateral decubitus positioning, injections, and surgical interventions about the shoulder. Prolonged recumbence from intoxication is also a common etiology. Providers should be aware of and recognize deltoid compartment syndrome to facilitate urgent surgical management.

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

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

The variance of clavicular surface morphology is predictable: an analysis of dependent and independent metadata variables.

BACKGROUND: The anatomy of the clavicle is specific and varied in reference to its topography and shape. These anatomic characteristics play an important role in the open treatment of clavicle fractures. The complex and variable topography creates challenges for implant placement, contouring, and position. Hardware prominence and irritation does influence the decision for secondary surgical intervention. METHODS: Computerized tomographic scans of 350 adult clavicles with the corresponding patients' metadata were acquired and digitized. Morphologic parameters determining the shape of the clavicle were defined and computed for each digitized bone. The extracted morphologic parameters were correlated with patient metadata to analyze the relationship between morphologic variability and patient characteristics. RESULTS: The morphologic parameters defining the shape, that is, the radius of the medial and lateral curves, the apparent clavicle height and width, and the clavicle bow position, correlate with the clavicle length. The clavicle length correlates with the patients' height. Gender differences in shape and form were dependent and related to individual height distribution and clavicle length. Asian populations showed a similarly predictable, but shifted, correlation between shape and clavicle length. CONCLUSION: This anatomic analysis shows that the clavicle shape can be predicted through the clavicle length and patients' stature. Smaller patients have shorter and more curved clavicles, whereas taller patients have longer and less curved clavicles. This correlation will aid surgeons in fracture reduction, implant curvature selection, and in optimal adaptation of clavicle implants, and represents the basis for anatomically accurate solutions for clavicle osteosynthesis.

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

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

Humeral version and neck-shaft angle correlated with demographic parameters in a study of 1104 cadaveric humeri.

BACKGROUND: Baseline anatomic data of the humerus are limited by difficulties in quantifying humeral version and the neck-shaft angle (NSA). This study used a 3-dimensional digitizer to quantify normative values for these variables and to identify possible correlations with demographic categories of age, sex, race, and lateralization. METHODS: Measurements from 1104 cadaveric humeri were collected with a MicroScribe G2 digitizer, which produced 3-dimensional positional data of the proximal and distal humeral articular surfaces, as well as the humeral shaft. Version was measured based on the angle between the proximal and distal articular surfaces in the axial plane. The NSA was measured based on the angle between the proximal articular surface and the proximal humeral shaft in the oblique coronal plane. Multiple regression analysis was used to analyze relationships between age, sex, race, and lateralization vs. version and the NSA. RESULTS: The average age was 56.0 ± 10.5 years. Of the specimens, 738 were from white cadavers and 366 were from black cadavers, and 948 were from men and 156 were from women. Average humeral retroversion was 25° ± 7°. White race and left humeri correlated with increased retroversion. The average NSA was 137° ± 6°. White race correlated with an increased NSA. CONCLUSIONS: This study provides measurements of humeral retroversion and the NSA in a large data set, providing key normative values. The data suggest that version and the NSA are independent of age and sex. Significant differences exist for retroversion vs. race and laterality, as well as for the NSA vs. race. These demographic guidelines can guide future research and individualize care for patients.

Predicting Discharge Disposition After Shoulder Arthroplasty in the United States.

INTRODUCTION: Postdischarge management for shoulder replacement continues to be performed on a case-by-case basis, with no uniform guidelines dictating management. The goal of this study was to develop a nomogram to preoperatively predict a patient's discharge disposition after elective shoulder arthroplasty. METHODS: Patients who underwent elective shoulder arthroplasty between 2012 and 2015 were identified in the National Surgical Quality Improvement Program database. A multivariable logistic regression model was used to identify risk factors for discharge to a postacute care facility, and these results were used to create a predictive nomogram. RESULTS: From 2012 to 2015, 8,363 procedures were identified. In our cohort, 962 patients (11.5%) were discharged to a postacute care facility, and 7,492 patients (88.5%) were discharged home. Preoperative functional status, followed by American Society of Anesthesiologists Class and age, had the strongest predictive value for discharge disposition after shoulder arthroplasty. DISCUSSION: Discharge disposition can be predicted using a nomogram with commonly identified preoperative and intraoperative variables. LEVEL OF EVIDENCE: Level III, retrospective cohort design, observational study.

Evolution of Neuroprosthetic Approaches to Restoration of Upper Extremity Function in Spinal Cord Injury.

Background: Spinal cord injury (SCI) occurring at the cervical levels can result in significantly impaired arm and hand function. People with cervical-level SCI desire improved use of their arms and hands, anticipating that regained function will result in improved independence and ultimately improved quality of life. Neuroprostheses provide the most promising method for significant gain in hand and arm function for persons with cervical-level SCI. Neuroprostheses utilize small electrical currents to activate peripheral motor nerves, resulting in controlled contraction of paralyzed muscles. Methods: A myoelectrically-controlled neuroprosthesis was evaluated in 15 arms in 13 individuals with cervical-level SCI. All individuals had motor level C5 or C6 tetraplegia. Results: This study demonstrates that an implanted neuroprosthesis utilizing myoelectric signal (MES)-controlled stimulation allows considerable flexibility in the control algorithms that can be utilized for a variety of arm and hand functions. Improved active range of motion, grip strength, and the ability to pick up and release objects were improved in all arms tested. Adverse events were few and were consistent with the experience with similar active implantable devices. Conclusion: For individuals with cervical SCI who are highly motivated, implanted neuroprostheses provide the opportunity to gain arm and hand function that cannot be gained through the use of orthotics or surgical intervention alone. Upper extremity neuroprostheses have been shown to provide increased function and independence for persons with cervical-level SCI.

Fully Implantable Peripheral Nerve Stimulation for Hemiplegic Shoulder Pain: A Multi-Site Case Series With Two-Year Follow-Up.

OBJECTIVE: To explore the feasibility and safety of a single-lead, fully implantable peripheral nerve stimulation system for the treatment of chronic shoulder pain in stroke survivors. PARTICIPANTS: Participants with moderate to severe shoulder pain not responsive to conservative therapies for six months. METHODS: During the trial phase, which included a blinded sham introductory period, a percutaneous single-lead peripheral nerve stimulation system was implanted to stimulate the axillary nerve of the affected shoulder. After a three-week successful trial, participants received an implantable pulse generator with an electrode placed to stimulate the axillary nerve of the affected shoulder. Outcomes included pain, pain interference, pain-free external rotation range of motion, quality of life, and safety. Participants were followed for 24 months. RESULTS: Twenty-eight participants underwent trial stimulation and five participants received an implantable pulse generator. The participants who received the implantable generator experienced an improvement in pain severity (p = 0.0002). All five participants experienced a 50% or greater pain reduction at 6 and 12 months, and four experienced at least a 50% reduction at 24 months. There was an improvement in pain interference (p < 0.0001). There was an improvement in pain-free external ROM (p = 0.003). There were no serious adverse events related to the device or to the procedure. CONCLUSIONS: This case series demonstrates the safety and efficacy of a fully implantable axillary PNS system for chronic HSP. Participants experienced reduction in pain, reduction in pain interference, and improved pain-free external rotation ROM. There were no serious adverse events associated with the system or the procedure.

Distal Radius Fractures: AAOS Appropriate Use Criteria Versus Actual Management at a Level I Trauma Center.

BACKGROUND: The aim of this study is to determine whether the American Academy of Orthopaedic Surgeons' (AAOS) Appropriate Use Criteria (AUC) for distal radius fractures correlates with actual treatment by orthopedic hand surgeons at a level I trauma center. METHODS: ICD-9 codes were used to retrospectively identify patients who presented with wrist fractures over 1 year. Patients with isolated distal radius fractures were evaluated using the AAOS AUC application for distal radius fractures. Actual treatment was then compared with treatment recommended by the AUC. RESULTS: Of the 112 patients, 64 (57%) received treatment that matched the AAOS AUC recommendation as an "appropriate treatment." Actual management matched the AUC recommendation 100%, 7%, and 50% of the time, for Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association (AO/OTA) type A, B, and C fractures, respectively. Surgery was performed for type A, B, and C fractures 30%, 7%, and 50% of the time, respectively. For type B fractures, only the 2 cases that were managed operatively were in agreement with the AUC. For type C fractures, increased patient age (57 years and older) was significantly associated with nonoperative treatment decisions. Surgeon decisions for nonoperative treatment were in agreement with the AUC recommendations 40% of the time, whereas surgeon decisions for surgery matched the AUC recommendations 97% of the time. CONCLUSIONS: We found low agreement between actual treatment decisions and the AUC-recommended "appropriate" treatments, especially for the type B and C fractures that were managed nonoperatively. The AUC favors surgery for all intra-articular fractures, while we emphasized age and fracture displacement in our decision-making process.

"Long-term stability of stimulating spiral nerve cuff electrodes on human peripheral nerves".

BACKGROUND: Electrical stimulation of the peripheral nerves has been shown to be effective in restoring sensory and motor functions in the lower and upper extremities. This neural stimulation can be applied via non-penetrating spiral nerve cuff electrodes, though minimal information has been published regarding their long-term performance for multiple years after implantation. METHODS: Since 2005, 14 human volunteers with cervical or thoracic spinal cord injuries, or upper limb amputation, were chronically implanted with a total of 50 spiral nerve cuff electrodes on 10 different nerves (mean time post-implant 6.7 ± 3.1 years). The primary outcome measures utilized in this study were muscle recruitment curves, charge thresholds, and percent overlap of recruited motor unit populations. RESULTS: In the eight recipients still actively involved in research studies, 44/45 of the spiral contacts were still functional. In four participants regularly studied over the course of 1 month to 10.4 years, the charge thresholds of the majority of individual contacts remained stable over time. The four participants with spiral cuffs on their femoral nerves were all able to generate sufficient moment to keep the knees locked during standing after 2-4.5 years. The dorsiflexion moment produced by all four fibular nerve cuffs in the active participants exceeded the value required to prevent foot drop, but no tibial nerve cuffs were able to meet the plantarflexion moment that occurs during push-off at a normal walking speed. The selectivity of two multi-contact spiral cuffs was examined and both were still highly selective for different motor unit populations for up to 6.3 years after implantation. CONCLUSIONS: The spiral nerve cuffs examined remain functional in motor and sensory neuroprostheses for 2-11 years after implantation. They exhibit stable charge thresholds, clinically relevant recruitment properties, and functional muscle selectivity. Non-penetrating spiral nerve cuff electrodes appear to be a suitable option for long-term clinical use on human peripheral nerves in implanted neuroprostheses.

Restoration of reaching and grasping movements through brain-controlled muscle stimulation in a person with tetraplegia: a proof-of-concept demonstration.

BACKGROUND: People with chronic tetraplegia, due to high-cervical spinal cord injury, can regain limb movements through coordinated electrical stimulation of peripheral muscles and nerves, known as functional electrical stimulation (FES). Users typically command FES systems through other preserved, but unrelated and limited in number, volitional movements (eg, facial muscle activity, head movements, shoulder shrugs). We report the findings of an individual with traumatic high-cervical spinal cord injury who coordinated reaching and grasping movements using his own paralysed arm and hand, reanimated through implanted FES, and commanded using his own cortical signals through an intracortical brain-computer interface (iBCI). METHODS: We recruited a participant into the BrainGate2 clinical trial, an ongoing study that obtains safety information regarding an intracortical neural interface device, and investigates the feasibility of people with tetraplegia controlling assistive devices using their cortical signals. Surgical procedures were performed at University Hospitals Cleveland Medical Center (Cleveland, OH, USA). Study procedures and data analyses were performed at Case Western Reserve University (Cleveland, OH, USA) and the US Department of Veterans Affairs, Louis Stokes Cleveland Veterans Affairs Medical Center (Cleveland, OH, USA). The study participant was a 53-year-old man with a spinal cord injury (cervical level 4, American Spinal Injury Association Impairment Scale category A). He received two intracortical microelectrode arrays in the hand area of his motor cortex, and 4 months and 9 months later received a total of 36 implanted percutaneous electrodes in his right upper and lower arm to electrically stimulate his hand, elbow, and shoulder muscles. The participant used a motorised mobile arm support for gravitational assistance and to provide humeral abduction and adduction under cortical control. We assessed the participant's ability to cortically command his paralysed arm to perform simple single-joint arm and hand movements and functionally meaningful multi-joint movements. We compared iBCI control of his paralysed arm with that of a virtual three-dimensional arm. This study is registered with ClinicalTrials.gov, number NCT00912041. FINDINGS: The intracortical implant occurred on Dec 1, 2014, and we are continuing to study the participant. The last session included in this report was Nov 7, 2016. The point-to-point target acquisition sessions began on Oct 8, 2015 (311 days after implant). The participant successfully cortically commanded single-joint and coordinated multi-joint arm movements for point-to-point target acquisitions (80-100% accuracy), using first a virtual arm and second his own arm animated by FES. Using his paralysed arm, the participant volitionally performed self-paced reaches to drink a mug of coffee (successfully completing 11 of 12 attempts within a single session 463 days after implant) and feed himself (717 days after implant). INTERPRETATION: To our knowledge, this is the first report of a combined implanted FES+iBCI neuroprosthesis for restoring both reaching and grasping movements to people with chronic tetraplegia due to spinal cord injury, and represents a major advance, with a clear translational path, for clinically viable neuroprostheses for restoration of reaching and grasping after paralysis. FUNDING: National Institutes of Health, Department of Veterans Affairs.

Upper Extremity Assessment in Tetraplegia: The Importance of Differentiating Between Upper and Lower Motor Neuron Paralysis.

Scientific advances are increasing the options for improved upper limb function in people with cervical level spinal cord injury (SCI). Some of these interventions rely on identifying an aspect of paralysis that is not uniformly assessed in SCI: the integrity of the lower motor neuron (LMN). SCI can damage both the upper motor neuron and LMN causing muscle paralysis. Differentiation between these causes of paralysis is not typically believed to be important during SCI rehabilitation because, regardless of the cause, the muscles are no longer under voluntary control by the patient. Emerging treatments designed to restore upper extremity function (eg, rescue microsurgical nerve transfers, motor learning-based interventions, functional electrical stimulation) all require knowledge of LMN status. The LMN is easily evaluated using surface electrical stimulation and does not add significant time to the standard clinical assessment of SCI. This noninvasive evaluation yields information that contributes to the development of a lifetime upper extremity care plan for maximizing function and quality of life. Given the relative simplicity of this assessment and the far-reaching implications for treatment and function, we propose that this assessment should be adopted as standard practice for acute cervical SCI.