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Concept: Elbow

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Unilateral elbow pain results in sensori-motor dysfunction that is frequently bilateral, affects local and remote upper limb muscles and persists beyond resolution of local tendon symptoms. These characteristics suggest supraspinal involvement. Here we investigated i) the excitability and organisation of the M1 representation of the wrist extensor muscles and ii) the relationship between M1 changes and clinical outcomes in lateral epicondylalgia (LE; n=11) and healthy control subjects (n=11).

Concepts: Elbow, Thigh, Extensor digitorum muscle, Extension, Upper limb anatomy, Upper limb

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A 73-year-old man with seropositive rheumatoid arthritis and extraarticular involvement (rheumatoid nodules on the right elbow) presented with persistent, painless swelling of the left elbow. His medical history was unremarkable except for hypertension.

Concepts: Medicine, Immunology, Rheumatoid arthritis, Rheumatology, Elbow, Medical history

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BACKGROUND:Studies have demonstrated the potential of platelet-rich plasma (PRP) to heal damaged tissue. To date, there are no published reports of clinical outcomes of partial ulnar collateral ligament (UCL) tears of the elbow treated with PRP. HYPOTHESIS:Platelet-rich plasma will promote the healing of partial UCL tears and allow a return to play. STUDY DESIGN:Case series; Level of evidence, 4. METHODS:Thirty-four athletes with a partial-thickness UCL tear confirmed on magnetic resonance imaging were prospectively followed. All patients had failed at least 2 months of nonoperative treatment and an attempt to return to play. Baseline questionnaires, including the Kerlan-Jobe Orthopaedic Clinic Shoulder and Elbow (KJOC) and Disabilities of the Arm, Shoulder and Hand (DASH) measures, were completed by each patient before injection. Baseline ultrasound measurement of the humeral-ulnar joint space was assessed with 10 lb of valgus stress on the elbow. Each patient received a single type 1A PRP injection at the UCL under ultrasound guidance. The same treating physician at a single institution performed all injections with the same PRP preparation used. Patients completed a course of guided physical therapy and were allowed to return to play based on their symptoms and physical examination findings. Outcome scores, including KJOC and DASH scores, were collected after return to play and were compared with baseline scores. Ultrasound measurements were collected at final follow-up and compared with preinjection values. RESULTS:At an average follow-up of 70 weeks (range, 11-117 weeks), 30 of 34 athletes (88%) had returned to the same level of play without any complaints. The average time to return to play was 12 weeks (range, 10-15 weeks). The average KJOC score improved from 46 to 93 (P < .0001). The average DASH score improved from 21 to 1 (P < .0001). The sports module of the DASH questionnaire improved from 69 to 3 (P < .0001). Medial elbow joint space opening with valgus stress decreased from 28 to 20 mm at final follow-up (P < .0001). The difference in medial elbow joint space opening (stressed vs nonstressed) decreased from 7 to 2.5 mm at final follow-up (P < .0001). One player had persistent UCL insufficiency and underwent ligament reconstruction at 31 weeks after injection. CONCLUSION:The results of this study indicate that PRP is an effective option to successfully treat partial UCL tears of the elbow in athletes.

Concepts: Patient, Nuclear magnetic resonance, Magnetic resonance imaging, Humerus, Elbow, Joint, Ultrasound, Tears

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It has recently been proposed that the caudal curvature (concave caudal side) observed in the radioulna of terrestrial quadrupeds is an adaptation to the habitual action of the triceps muscle which causes cranial bending strains (compression on cranial side). The caudal curvature is proposed to be adaptive because longitudinal loading induces caudal bending strains (increased compression on the caudal side), and these opposing bending strains counteract each other leaving the radioulna less strained. If this is true for terrestrial quadrupeds, where triceps is required for habitual elbow extension, then we might expect that in arboreal species, where brachialis is habitually required to maintain elbow flexion, the radioulna should instead be cranially curved. This study measures sagittal curvature of the ulna in a range of terrestrial and arboreal primates and marsupials, and finds that their ulnae are curved in opposite directions in these two locomotor categories. This study also examines sagittal curvature in the humerus in the same species, and finds differences that can be attributed to similar adaptations: the bone is curved to counter the habitual muscle action required by the animal’s lifestyle, the difference being mainly in the distal part of the humerus, where arboreal animals tend have a cranial concavity, thought to be in response the carpal and digital muscles that pull cranially on the distal humerus.

Concepts: Humerus, Elbow, Triceps brachii muscle, Ulna, Mammal, Flexion, Extension, Sagittal plane

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The objective of the study was to compare the efficacy of point-of-care ultrasound (POCUS) and computed tomography (CT) in the diagnosis of the fracture of the bones that form the elbow joint and the determination of treatment method in elbow injuries.

Concepts: Bone, Comparison, Medical imaging, Elbow, Medical ultrasonography, Joints, Comparisons

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Injuries to the elbow joint in baseball pitchers appear common. There appears to be a correlation between shoulder range of motion and elbow injuries.

Concepts: Humerus, Elbow, Injury, Joints, Shoulder, Upper limb anatomy, Baseball

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BACKGROUND:An injury to the ulnar collateral ligament (UCL) of the elbow is potentially career threatening for elite baseball pitchers. Stress ultrasound (US) of the elbow allows for evaluation of both the UCL and the ulnohumeral joint space at rest and with stress. HYPOTHESIS:Stress US can identify morphological and functional UCL changes and may predict the risk of a UCL injury in elite pitchers. STUDY DESIGN:Cross-sectional study; Level of evidence, 3. METHODS:A total of 368 asymptomatic professional baseball pitchers underwent preseason stress US of their dominant and nondominant elbows over a 10-year period (2002-2012). Stress US examinations were performed in 30° of flexion at rest and with 150 N of valgus stress by a single musculoskeletal radiologist. Ligament thickness, ulnohumeral joint space width, and ligament abnormalities (hypoechoic foci and calcifications) were documented. RESULTS:There were 736 stress US studies. The mean UCL thickness in the dominant elbow (6.15 mm) was significantly greater than that in the nondominant elbow (4.82 mm) (P < .0001). The mean stressed ulnohumeral joint space width in the dominant elbow (4.56 mm) was significantly greater than that in the nondominant elbow (3.72 mm) (P < .02). In the dominant arm, hypoechoic foci and calcifications were both significantly more prevalent (28.0% vs 3.5% and 24.9% vs 1.6%, respectively; P < .001). In the 12 players who incurred a UCL injury, there were nonsignificant (P > .05) increases in baseline ligament thickness, ulnohumeral joint space gapping with stress, and incidence of hypoechoic foci and calcifications. More than 1 stress US examination was performed in 131 players, with a mean increase of 0.78 mm in joint space gapping with subsequent evaluations. CONCLUSION:Stress US indicates that the UCL in the dominant elbow of elite pitchers is thicker, is more likely to have hypoechoic foci and/or calcifications, and has increased laxity with valgus stress over time.

Concepts: Incidence, Humerus, Elbow, Baseball

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Lateral epicondylitis, or “tennis elbow,” is a common musculotendinous degenerative disorder of the extensor origin at the lateral humeral epicondyle. Repetitive occupational or athletic activities involving wrist extension and supination are thought to be causative. The typical symptoms include lateral elbow pain, pain with wrist extension, and weakened grip strength. The diagnosis is made clinically through history and physical examination; however, a thorough understanding of the differential diagnosis is imperative to prevent unnecessary testing and therapies. Most patients improve with nonoperative measures, such as activity modification, physical therapy, and injections. A small percentage of patients will require surgical release of the extensor carpi radialis brevis tendon. Common methods of release may be performed via percutaneous, arthroscopic, or open approaches.

Concepts: Medical terms, Medical diagnosis, Elbow, Physical examination, Differential diagnosis, Flexor carpi radialis muscle, Extensor carpi radialis brevis muscle, Extensor carpi radialis longus muscle

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BACKGROUND: sEMG signal has been widely used in different applications in kinesiology and rehabilitation as well as in the control of human-machine interfaces. In general, the signals are recorded with bipolar electrodes located in different muscles. However, such configuration may disregard some aspects of the spatial distribution of the potentials like location of innervation zones and the manifestation of inhomogineties in the control of the muscular fibers. On the other hand, the spatial distribution of motor unit action potentials has recently been assessed with activation maps obtained from High Density EMG signals (HD-EMG), these lasts recorded with arrays of closely spaced electrodes. The main objective of this work is to analyze patterns in the activation maps, associating them with four movement directions at the elbow joint and with different strengths of those tasks. Although the activation pattern can be assessed with bipolar electrodes, HD-EMG maps could enable the extraction of features that depend on the spatial distribution of the potentials and on the load-sharing between muscles, in order to have a better differentiation between tasks and effort levels. METHODS: An experimental protocol consisting of isometric contractions at three levels of effort during flexion, extension, supination and pronation at the elbow joint was designed and HD-EMG signals were recorded with 2D electrode arrays on different upper-limb muscles. Techniques for the identification and interpolation of artifacts are explained, as well as a method for the segmentation of the activation areas. In addition, variables related to the intensity and spatial distribution of the maps were obtained, as well as variables associated to signal power of traditional single bipolar recordings. Finally, statistical tests were applied in order to assess differences between information extracted from single bipolar signals or from HD-EMG maps and to analyze differences due to type of task and effort level. RESULTS: Significant differences were observed between EMG signal power obtained from single bipolar configuration and HD-EMG and better results regarding the identification of tasks and effort levels were obtained with the latter. Additionally, average maps for a population of 12 subjects were obtained and differences in the co-activation pattern of muscles were found not only from variables related to the intensity of the maps but also to their spatial distribution. CONCLUSIONS: Intensity and spatial distribution of HD-EMG maps could be useful in applications where the identification of movement intention and its strength is needed, for example in robotic-aided therapies or for devices like powered- prostheses or orthoses. Finally, additional data transformations or other features are necessary in order to improve the performance of tasks identification.

Concepts: Muscle, Elbow, Electromyography, Electrode, Nerve, Extension, Forearm, Brachioradialis

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BACKGROUND: Bradykinin type 2 receptor (B2BRK) genotype was reported to be associated with changes in the left-ventricular mass as a response to aerobic training, as well as in the regulation of the skeletal muscle performance in both athletes and non-athletes. However, there are no reports on the effect of B2BRK 9-bp polymorphism on the response of the skeletal muscle to strength training, and our aim was to determine the relationship between the B2BRK SNP and triceps brachii functional and morphological adaptation to programmed physical activity in young adults. METHODS: In this 6-week pretest-posttest exercise intervention study, twenty nine healthy young men (21.5 +/- 2.7 y, BMI 24.2 +/- 3.5 kg/m2) were put on a 6-week exercise protocol using an isoacceleration dynamometer (5 times a week, 5 daily sets with 10 maximal elbow extensions, 1 minute rest between sets). Triceps brachii muscle volumes were assessed by using magnetic resonance imaging before and after the strength training. Bradykinin type 2 receptor 9 base pair polymorphism was determined for all participants. RESULTS: Following the elbow extensors training, an average increase in the volume of both triceps brachii was 5.4 +/- 3.4% (from 929.5 +/- 146.8 cm3 pre-training to 977.6 +/- 140.9 cm3 after training, p<0.001). Triceps brachii volume increase was significantly larger in individuals homozygous for -9 allele compared to individuals with one or two +9 alleles (-9/-9, 8.5 +/- 3.8%; vs. -9/+9 and +9/+9 combined, 4.7 +/- 4.5%, p < 0.05). Mean increases in endurance strength in response to training were 48.4 +/- 20.2 %, but the increases were not dependent on B2BRK genotype (-9/-9, 50.2 +/- 19.2%; vs. -9/+9 and +9/+9 combined, 46.8 +/- 20.7%, p > 0.05). CONCLUSIONS: We found that muscle morphological response to targeted training – hypertrophy – is related to polymorphisms of B2BRK. However, no significant influence of different B2BRK genotypes on functional muscle properties after strength training in young healthy non athletes was found. This finding could be relevant, not only in predicting individual muscle adaptation capacity to training or sarcopenia related to aging and inactivity, but also in determining new therapeutic strategies targeting genetic control of muscle function, especially for neuromuscular disorders that are characterized by progressive adverse changes in muscle quality, mass, strength and force production (e.g., muscular dystrophy, multiple sclerosis, Parkinson’s disease).

Concepts: Genetics, Allele, Muscle, Physical exercise, Biceps brachii muscle, Elbow, Triceps brachii muscle, Strength training