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.

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.

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.

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.

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.

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.

"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.

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.

Implanted neuroprosthesis for restoring arm and hand function in people with high level tetraplegia.

OBJECTIVE: To develop and apply an implanted neuroprosthesis to restore arm and hand function to individuals with high level tetraplegia. DESIGN: Case study. SETTING: Clinical research laboratory. PARTICIPANTS: Individuals with spinal cord injuries (N=2) at or above the C4 motor level. INTERVENTIONS: The individuals were each implanted with 2 stimulators (24 stimulation channels and 4 myoelectric recording channels total). Stimulating electrodes were placed in the shoulder and arm, being, to our knowledge, the first long-term application of spiral nerve cuff electrodes to activate a human limb. Myoelectric recording electrodes were placed in the head and neck areas. MAIN OUTCOME MEASURES: Successful installation and operation of the neuroprosthesis and electrode performance, range of motion, grasp strength, joint moments, and performance in activities of daily living. RESULTS: The neuroprosthesis system was successfully implanted in both individuals. Spiral nerve cuff electrodes were placed around upper extremity nerves and activated the intended muscles. In both individuals, the neuroprosthesis has functioned properly for at least 2.5 years postimplant. Hand, wrist, forearm, elbow, and shoulder movements were achieved. A mobile arm support was needed to support the mass of the arm during functional activities. One individual was able to perform several activities of daily living with some limitations as a result of spasticity. The second individual was able to partially complete 2 activities of daily living. CONCLUSIONS: Functional electrical stimulation is a feasible intervention for restoring arm and hand functions to individuals with high tetraplegia. Forces and movements were generated at the hand, wrist, elbow, and shoulder that allowed the performance of activities of daily living, with some limitations requiring the use of a mobile arm support to assist the stimulated shoulder forces.

Prevention and treatment of elbow stiffness: a 5-year update.

Elbow stiffness is a challenging and common problem faced by upper extremity surgeons. Although functional improvements can be made with both nonsurgical and surgical management strategies, physicians must remain vigilant with efforts to prevent stiffness before it starts. Recent advancements in the biology and pathology of elbow contracture have led to improved understanding of this difficult problem, and they may lead to future breakthroughs in the prevention and treatment of elbow stiffness. This article serves as an update to our previous review of elbow stiffness, focusing on recent advancements in the past 5 years, as well as updating our current algorithm for treatment.

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.

Surgical restoration of arm and hand function in people with tetraplegia.

Improved hand and arm function is the most sought after function for people living with a cervical spinal cord injury (SCI). Surgical techniques have been established to increase upper extremity function for tetraplegics, focusing on restoring elbow extension, wrist movement, and hand opening and closing. Additionally, more innovative treatments that have been developed (implanted neuroprostheses and nerve transfers) provide more options for improving function and quality of life. One of the most important steps in the process of restoring upper extremity function in people with tetraplegia is identifying appropriate candidates - typically those with American Spinal Injury Association (ASIA) motor level C5 or greater. Secondary complications of SCI can pose barriers to restoring function, particularly upper extremity spasticity. A novel approach to managing spasticity through high-frequency alternating currents designed to block unwanted spasticity is being researched at the Cleveland FES Center and may improve the impact of reconstructive surgery for these individuals. The impact of these surgeries is best measured within the framework of the World Health Organization's International Classification of Function, Disability and Health. Outcome measures should be chosen to reflect changes within the domains of body functions and structures, activity, and participation. There is a need to strengthen the evidence in the area of reconstructive procedures for people with tetraplegia. Research continues to advance, providing more options for improved function in this population than ever before. The contribution of well-designed outcome studies to this evidence base will ultimately help to address the complications surrounding access to the procedures.

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.

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.

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.

Tibialis anterior tendon transfer after clubfoot surgery.

UNLABELLED: Recurrent dynamic and structural deformities following clubfoot surgery are commonly due to residual muscle imbalance from a strong tibialis anterior muscle and weak antagonists. We asked whether subcutaneous tibialis anterior tendon transfer effectively treated recurrent deformities following clubfoot surgery and whether the presence of structural deformities influenced the outcome. The patients were divided into two groups: Group I, dynamic supination deformity only (51 patients, 76 feet); and Group II, dynamic supination with other structural deformities (44 patients, 61 feet). The mean age at surgery was 4.3 years (range, 1.4-10.7 years); the minimum followup was 2 years (mean, 5.2 years; range, 2-12.5 years) for both groups. The results were graded according to our subjective rating system of restoration of muscle balance: good, restoration of muscle balance; fair, partial restoration of muscle balance; and poor, no improvement. The two groups had similar outcomes: in Group I, there were 65 good (87%), 11 fair (13%), and no poor results and in Group II, there were 54 good (88%), seven fair (12%), and no poor results. Our data suggest the tibialis anterior tendon transfer restores muscle balance in recurrent clubfeet; we observed no recurrences. This transfer improves function and may prevent secondary osseous changes. We believe the muscle imbalance supports, at least in part, the neuromuscular etiological aspects of congenital clubfeet. LEVEL OF EVIDENCE: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Prevention and treatment of elbow stiffness.

The elbow is as prone to stiffness as it is essential for upper-extremity function. The elbow is a highly constrained synovial hinge joint that frequently becomes stiff after injury. Elbow contracture is challenging to treat, and therefore prevention is of paramount importance. When this approach fails, nonoperative followed by operative treatment modalities can be pursued. In the future, efforts to prevent and treat elbow stiffness may target the basic science mechanisms involved.

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.

Cadaveric biomechanical analysis of the distal radioulnar joint: influence of wrist isolation on accurate measurement and the effect of ulnar styloid fracture on stability.

PURPOSE: Distal radioulnar joint (DRUJ) instability can be tested using biomechanical cadaveric models, but inadequate isolation of the DRUJ during instability testing may introduce measurement error. The first goal of this investigation was to develop an effective model for isolating the DRUJ during biomechanical cadaveric testing. The second goal was to use this model to measure the effect of ulnar styloid fracture and subsequent repair on DRUJ kinematics in cadaveric specimens. METHODS: Five fresh cadaveric arms were tested using a Biodex System 3 device. The humerus was clamped firmly, the forearm rotated freely, and the hand/carpus was attached to the Biodex device. Three methods of DRUJ isolation were tested. In method 1, the specimen was firmly clamped at the midshaft humerus and the hand/carpus was clamped. In method 2, the distal radius was additionally fixed to the carpal clamp to reduce carpal motion. In method 3, proximal fixation of the olecranon to an elbow rest was added. Testing was done before ulnar styloid osteotomy (group 1), after osteotomy through dorsal capsulotomy (group 2), and after styloid fragment repair with a screw (group 3). Twelve pronation-supination cycles were performed while work of rotation, maximum pronation torque, and maximum supination torque for each method and group were recorded. RESULTS: Analysis of clamping methods showed work of rotation, maximum pronation torque, and maximum supination torque for method 3 were greater than those for methods 1 and 2. Analysis of groups showed the following statistically significant trends for work of rotation: group 1 >>> group 3 > group 2. Maximum supination torque similarly showed statistically significant differences: group 1 >>> group 3 > group 2. Maximum pronation torque showed a similar trend: group 1 >>> group 3 > group 2. However, in contrast with work of rotation and maximum supination torque, group 3 maximum pronation torque was not statistically different from that of group 2. CONCLUSIONS: Increased work of rotation represents decreased joint laxity. Maximum supination torque and maximum pronation torque assess soft tissue restraints at joint end points. Method 3 showed the greatest values in these variables, indicating reduced elbow and carpal motion and better DRUJ isolation. Work of rotation and maximum supination torque in group 3 were increased from those of group 2 but not restored to group 1 values. Styloid fixation restores some soft tissue tension but laxity persists. Maximum pronation torque in group 3 was not increased significantly from that of group 2, perhaps from dorsal capsulotomy causing soft tissue injury and laxity not corrected with fixation. The influence of ulnar styloid fracture on dynamic DRUJ kinematics can be demonstrated in this model.

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.