SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Arm

38

To evaluate the efficacy of remote nonpainful electrical upper arm skin stimulation in reducing migraine attack pain.

Concepts: Migraine, Upper limb, Arm

28

BACKGROUND: Proximal humerus fracture is the third most common fracture type after hip and distal radius fracture in elderly patients. A comprehensive study by Palvanen et al. demonstrated an increase in the annual fracture rate of 13.7% per year over the past 33 years. Should this trend continue, the fracture rate would triple over the next three decades. The increasing incidence of low-energy fractures raises questions about the optimal treatment in terms of functional outcome, pain, and rehabilitation time, as well as the economical impact. Despite the high incidence and costs of proximal humerus fractures, there is currently no valid scientific evidence for the best treatment method. Several publications, including a Cochrane review outline the need for high-quality, well-designed randomized controlled trials. METHODS: The study is a prospective, randomized, national multi-center trial. The hypothesis of the trial is that surgical treatment of displaced proximal humerus fractures achieves better functional outcome, pain relief, and patient satisfaction compared to conservative treatment. The trial is designed to compare conservative and surgical treatment of proximal humerus fractures in patients 60 years and older. The trial includes two strata. Stratum I compares surgical treatment with locking plates to conservative treatment for two-part fractures. Stratum II compares multi-fragmented fractures, including three- and four-part fractures. The aim of Stratum II is to compare conservative treatment, surgical treatment with the Philos locking plate, and hemiarthroplasty with an Epoca prosthesis. The primary outcome measure will be the Disabilities of the Arm, Shoulder and Hand (DASH) score and the secondary outcome measures will be the EuroQol-5D (EQ-5D) value, OSS, Constant-Murley Score, VAS, and 15D.Recruiting time will be 3 years. The results will be analyzed after the 2-year follow-up period. DISCUSSION: This publication presents a prospective, randomized, national multi-center trial. It gives details of patient flow, randomization, aftercare and also ways of analysis of the material and ways to present and publish the results.Trial registrationClinicalTrials.gov identifier: NCT01246167.

Concepts: Osteoporosis, Randomized controlled trial, Humerus, The Trial, Humerus fracture, Distal radius fracture, Bone fractures, Arm

26

The aim of this review was to identify and summarise publications, which have reported clinical applications of upper limb accelerometry for stroke within free-living environments and make recommendations for future studies. Data was searched from MEDLINE®, Scopus, IEEExplore and Compendex databases. The final search was 31st October 2013. Any study was included which reported clinical assessments in parallel with accelerometry in a free-living hospital or home setting. Study quality is reflected by participant numbers, methodological approach, technical details of the equipment used, blinding of clinical measures, whether safety and compliance data was collected. First author screened articles for inclusion and inclusion of full text articles and data extraction was confirmed by the third author. Out of 1375 initial abstracts, 8 articles were included. All participants were stroke patients. Accelerometers were worn for either 24 hours or 3 days. Data were collected as summed acceleration counts over a specified time or as the duration of active/inactive periods. Activity in both arms was reported by all studies and the ratio of impaired to unimpaired arm activity was calculated in six studies. The correlation between clinical assessments and accelerometry was tested in five studies and significant correlations were found. The efficacy of a rehabilitation intervention was assessed using accelerometry by three studies: in two studies both accelerometry and clinical test scores detected a post-treatment difference but in one study accelerometry data did not change despite clinical test scores showing motor and functional improvements. Further research is needed to understand the additional value of accelerometry as a measure of upper limb use and function in a clinical context. A simple and easily interpretable accelerometry approach is required.

Concepts: Clinical trial, Ratio, Upper limb, Accelerometer, Limb, Arm

25

-The study introduced a novel precise method for measurement and calculation of upper arm mass and to assess the difference between masses of upper limbs on the dominant and non-dominant sides of the body of right-handed participants. Forty healthy untrained male (n = 20; M age = 20.8 yr., SD = 1.2) and female (n = 20; M age = 20.7 yr., SD = 1.3) participants without a history of upper-extremity pathology participated. Kinematic and kinetic data were collected during arm motion. The mass of each arm was calculated. Each participant performed 20 movements with each arm. Most often the dominant arm was more massive than the non-dominant in both sex groups; however, mass was more symmetric for female participants than for male participants. Regression equations related to total body mass were calculated for each arm independently.

Concepts: Male, Female, Mass, Sex, Classical mechanics, Gamete, Upper limb, Arm

15

Global brachial plexopathies cause major sensory and motor deficits in the affected arm and hand. Many patients report of psychosocial consequences including chronic pain, decreased self-sufficiency, and poor body image. Bionic reconstruction, which includes the amputation and prosthetic replacement of the functionless limb, has been shown to restore hand function in patients where classic reconstructions have failed. Patient selection and psychological evaluation before such a life-changing procedure are crucial for optimal functional outcomes. In this paper we describe a psychosocial assessment procedure for bionic reconstruction in patients with complete brachial plexopathies and present psychosocial outcome variables associated with bionic reconstruction.

Concepts: Pain, Amputation, Ulnar nerve, Median nerve, Arm, Brachial plexus, Axillary artery, Plexus

13

The transition from fish to tetrapod was arguably the most radical series of adaptive shifts in vertebrate evolutionary history. Data are accumulating rapidly for most aspects of these events, but the life histories of the earliest tetrapods remain completely unknown, leaving a major gap in our understanding of these organisms as living animals. Symptomatic of this problem is the unspoken assumption that the largest known Devonian tetrapod fossils represent adult individuals. Here we present the first, to our knowledge, life history data for a Devonian tetrapod, from the Acanthostega mass-death deposit of Stensiö Bjerg, East Greenland. Using propagation phase-contrast synchrotron microtomography (PPC-SRμCT) to visualize the histology of humeri (upper arm bones) and infer their growth histories, we show that even the largest individuals from this deposit are juveniles. A long early juvenile stage with unossified limb bones, during which individuals grew to almost final size, was followed by a slow-growing late juvenile stage with ossified limbs that lasted for at least six years in some individuals. The late onset of limb ossification suggests that the juveniles were exclusively aquatic, and the predominance of juveniles in the sample suggests segregated distributions of juveniles and adults at least at certain times. The absolute size at which limb ossification began differs greatly between individuals, suggesting the possibility of sexual dimorphism, adaptive strategies or competition-related size variation.

Concepts: Evolution, Vertebrate, Upper limb, Sarcopterygii, Tetrapod, Arm, Paleontology, Ichthyostega

3

Embedding computational models in the physical world is a critical step towards constraining their behavior and building practical applications. Here we aim to drive a realistic musculoskeletal arm model using a biomimetic cortical spiking model, and make a robot arm reproduce the same trajectories in real time. Our cortical model consisted of a 3-layered cortex, composed of several hundred spiking model-neurons, which display physiologically realistic dynamics. We interconnected the cortical model to a two-joint musculoskeletal model of a human arm, with realistic anatomical and biomechanical properties. The virtual arm received muscle excitations from the neuronal model, and fed back proprioceptive information, forming a closed-loop system. The cortical model was trained using spike timing-dependent reinforcement learning to drive the virtual arm in a 2D reaching task. Limb position was used to simultaneously control a robot arm using an improved network interface. Virtual arm muscle activations responded to motoneuron firing rates, with virtual arm muscles lengths encoded via population coding in the proprioceptive population. After training, the virtual arm performed reaching movements which were smoother and more realistic than those obtained using a simplistic arm model. This system provided access to both spiking network properties and to arm biophysical properties, including muscle forces. The use of a musculoskeletal virtual arm and the improved control system allowed the robot arm to perform movements which were smoother than those reported in our previous paper using a simplistic arm. This work provides a novel approach consisting of bidirectionally connecting a cortical model to a realistic virtual arm, and using the system output to drive a robotic arm in real time. Our techniques are applicable to the future development of brain neuroprosthetic control systems, and may enable enhanced brain-machine interfaces with the possibility for finer control of limb prosthetics.

Concepts: Control theory, Feedback, PID controller, Control system, Control engineering, Robotics, Arm, Fuzzy logic

3

Introduction: The study of tennis players allows the non-racquet arm to act as an internal control for the exercising racquet arm. In addition, study of the upper limbs removes the influence of gravitational loading allowing examination of the influence of muscular force on bone adaptation.Methods: To examine the role of muscular action on bone, strength parameters of the radius, ulna (both at 4% and 60% distal-proximal ulnar length) and humerus (at 35% distal-proximal humerus length) as well as muscle size in both arms of 50 elite junior tennis players (mean age 13.5±1.9y) were measured with pQCT.Results: Strong relationships were found between muscle size and bone size in both arms (all correlations P < 0.001, R = 0.73-0.86) However, muscle:bone ratio was significantly lower (P < 0.001) in the upper arm on the racquet side (compared to the contralateral arm). In addition, material eccentricity analysis revealed that bone strength in bending and torsion increased more than strength in compression as the moment arms for these actions (bone length and width respectively) increased (in all cases P > 0.001, R = 0.06-0.7) with relationships being stronger in torsion than in bending. Large side differences were found in bone strength parameters and muscle size in all investigated sites, with differences in distal radius total BMC (+37±21%) and humerus cortical CSA (+40±12%) being most pronounced (both P < 0.001).Conclusion: These results support a strong influence of muscular action on bone adaptation - however, inter-arm muscle:bone asymmetries suggest factors other than local muscle size determine bone strength. The results also suggest that torsional loads provide the greatest stress experienced by the bone during a tennis stroke.

Concepts: Muscle, Humerus, Forearm, Upper limb, Height, Arm, Tennis, Junior tennis

2

Stromal Vascular Fraction (SVF) cells freshly isolated from adipose tissue include osteogenic- and vascular-progenitors, yet their relevance in bone fracture healing is currently unknown. Here, we investigated whether human SVF cells directly contribute to the repair of experimental fractures in nude rats, and explored the feasibility/safety of their clinical use for augmentation of upper arm fractures in elderly individuals. Human SVF cells were loaded onto ceramic granules within fibrin gel and implanted in critical nude rat femoral fractures after locking-plate osteosynthesis, with cell-free grafts as control. After 8 weeks, only SVF-treated fractures did not fail mechanically and displayed formation of ossicles at the repair site, with vascular and bone structures formed by human cells. The same materials combined with autologous SVF cells were then used to treat low-energy proximal humeral fractures in 8 patients (64-84 years old) along with standard open reduction and internal fixation. Graft manufacturing and implantation were compatible with intraoperative settings and led to no adverse reactions, thereby verifying feasibility/safety. Biopsies of the repair tissue after up to 12 months, upon plate revision or removal, demonstrated formation of bone ossicles, structurally disconnected and morphologically distinct from osteoconducted bone, suggesting the osteogenic nature of implanted SVF cells. We demonstrate that SVF cells, without expansion or exogenous priming, can spontaneously form bone tissue and vessel structures within a fracture-microenvironment. The gained clinical insights into the biological functionality of the grafts, combined with their facile, intra-operative manufacturing modality, warrant further tests of effectiveness in larger, controlled trials. This article is protected by copyright. All rights reserved.

Concepts: Bone, Bone fracture, Fracture, Tissues, Orthopedic surgery, Arm, Copyright, Periosteum

1

End-effector robots are commonly used in robot-assisted neuro-rehabilitation therapies for upper limbs where the patient’s hand can be easily attached to a splint. Nevertheless, they are not able to estimate and control the kinematic configuration of the upper limb during the therapy. However, the Range of Motion (ROM) together with the clinical assessment scales offers a comprehensive assessment to the therapist. Our aim is to present a robust and stable kinematic reconstruction algorithm to accurately measure the upper limb joints using only an accelerometer placed onto the upper arm.

Concepts: Therapy, Clinical psychology, Human anatomy, Upper limb anatomy, Upper limb, Limb, Arm, Limbs