The Fate of the Shoulder Post Rotator Cuff Repair: Biomechanical Properties of the Supraspinatus Tendon and Surrounding Structures.

The study aimed to describe the changes in biomechanical properties of the supraspinatus tendon, deltoid muscle, and humeral head post arthroscopic rotator cuff repair using shear wave elastography. Shear wave velocity of the tendon, deltoid, and humeral head of 48 patients was measured at predetermined sites at 1 week, 6 weeks, 12 weeks, 6 months, and 12 months post repair. One-way ANOVA with Tukey's correction and Spearman's correlation were performed. Mean±SEM healing tendon stiffness, adjacent to tendon footprint, increased from 1 week (6.2±0.2 m/s) to 6 months (7.5±0.3 m/s) and 12 months (7.8±0.3 m/s) (P<0.001). Mean±SEM deltoid muscle stiffness was higher at 12 months (4.1±0.2 m/s) compared to 1 week (3.4±0.1 m/s) and 12 weeks (3.5±0.1 m/s) (P<0.05). Humeral head stiffness did not change. Following arthroscopic rotator cuff repair, supraspinatus tendon stiffness increased in a curvilinear fashion over 6 months. From 6 months, deltoid muscle stiffness increased, corresponding to when patients were instructed to return to normal activities.

C5 Palsy Following Cervical Spine Decompression.

BACKGROUND: Cervical spinal surgery is considered safe and effective. One of the few specific complications of this procedure is C5 nerve root palsy. Expressed primarily by deltoid muscle and biceps brachii weakness, it is rare and has been related to nerve root traction or to ischemic spinal cord damage. OBJECTIVES: To determine the clinical and epidemiological traits of C5 palsy. To determine whether C5 palsy occurs predominantly in one specific surgical approach compared to others. METHODS: A retrospective study of patients who underwent cervical spine surgery at our medical center during a consecutive 8-year period was conducted. The patient data were analyzed for demographics, diagnosis, and surgery type and approach, as well as for complications, with emphasis on the C5 nerve root palsy. RESULTS: The study group was comprised of 124 patients. Seven (5.6%) developed a C5 palsy following surgery. Interventions were either by anterior, by posterior or by a combined approach. Seven patients developed this complication. All of whom had myelopathy and were older males. A combined anteroposterior (5 patients) and posterior access (2 patients) were the only approaches that were associated with the C5 palsy. None of the patients who were operated via an anterior approach did develop this sequel. CONCLUSIONS: The incidence of the C5 root palsy in our cohort reached 5.6%. Interventions performed through a combined anterior-posterior access in older myelopathic males, may carry the highest risk for this complication.

Analysis of the coaptation role of the deltoid in reverse shoulder arthroplasty. A preliminary biomechanical study.

BACKGROUND: Lateralization of the glenoid implant improves functional outcomes in Reverse Shoulder Arthroplasty. Lateralization does not appear to impact the Deltoid's Moment Arm. Therefore, the stabilizing effect described in the literature would not be the result of an increase this moment arm. A static biomechanical model, derived from Magnetic Resonance Imaging, can be used to assess the coaptation effect of the Middle Deltoid. The objective of this study was to analyze the impact of increasing amounts of glenoid lateralization on the moment arm but also on its coaptation effect. METHODS: Eight patients (72.6 ± 6.5 years) operated for Reverse Shoulder Arthroplasty were included in the study. Three-dimensional models of each shoulder were created based on imaging taken at 6 months postoperative. A least square sphere representing the prosthetic implant was added to each 3D models. A static biomechanical model was then applied to different planar portions of the Middle Deltoid (from 3D models), first without lateralization and then with simulated lateralization of 6, 9 and 12mm. This static model enables to compute a Coaptation/Elevation Ratio and to measure the Deltoid's Moment Arm. The inter- and intra-rater agreement of the 3D models was evaluated. RESULTS: One patient was excluded due to motion during imaging. The inter- and intra-rater agreement was over 0.99. The ratio increased starting at 6 mm of lateralization (p<0.05), compared to the initial position. The moment arm was not affected by lateralization (p<0.05), except in two slices starting at 9 mm (S1 p<0.05 and S2 p<0.05). CONCLUSION: Our hypothesis that the Middle Deltoid's coaptation role would be greater with glenosphere lateralization was confirmed. This trend was not found in the moment arm, which showed little sensitivity to lateralization. The stabilizing effect therefore appears to stem from the coaptation role of the Middle Deltoid.

Compensatory Movement Patterns Are Based on Abnormal Activity of the Biceps Brachii and Posterior Deltoid Muscles in Patients with Symptomatic Rotator Cuff Tears.

BACKGROUND: Abnormal movement patterns due to compensatory mechanisms have been reported in patients with rotator cuff tears. The long head of the biceps tendon may especially be overactive and a source of pain and could induce abnormal muscle activation in these patients. It is still unknown why some patients with a rotator cuff tear develop complaints and others do not. QUESTIONS/PURPOSES: (1) Which shoulder muscles show a different activation pattern on electromyography (EMG) while performing the Functional Impairment Test-Hand and Neck/Shoulder/Arm (FIT-HaNSA) in patients with a symptomatic rotator cuff tear compared with age-matched controls with an intact rotator cuff? (2) Which shoulder muscles are coactivated on EMG while performing the FIT-HaNSA? METHODS: This comparative study included two groups of people aged 50 years and older: a group of patients with chronic symptomatic rotator cuff tears (confirmed by MRI or ultrasound with the exclusion of Patte stage 3 and massive rotator cuff tears) and a control group of volunteers without shoulder conditions. Starting January 2019, 12 patients with a chronic rotator cuff tear were consecutively recruited at the outpatient orthopaedic clinic. Eleven age-matched controls (randomly recruited by posters in the hospital) were included after assuring the absence of shoulder complaints and an intact rotator cuff on ultrasound imaging. The upper limb was examined using the FIT-HaNSA (score: 0 [worst] to 300 seconds [best]), shoulder-specific instruments, health-related quality of life, and EMG recordings of 10 shoulder girdle muscles while performing a tailored FIT-HaNSA. RESULTS: EMG (normalized root mean square amplitudes) revealed hyperactivity of the posterior deltoid and biceps brachii muscles during the upward phase in patients with rotator cuff tears compared with controls (posterior deltoid: 111% ± 6% versus 102% ± 10%, mean difference -9 [95% confidence interval -17 to -1]; p = 0.03; biceps brachii: 118% ± 7% versus 111% ± 6%, mean difference -7 [95% CI -13 to 0]; p = 0.04), and there was decreased activity during the downward phase in patients with rotator cuff tears compared with controls (posterior deltoid: 89% ± 6% versus 98% ± 10%, mean difference 9 [95% CI 1 to 17]; p = 0.03; biceps brachii: 82% ± 7% versus 89% ± 6%, mean difference 7 [95% CI 0 to 14]; p = 0.03). The posterior deltoid functioned less in conjunction with the other deltoid muscles, and lower coactivation was seen in the remaining intact rotator cuff muscles in the rotator cuff tear group than in the control group. CONCLUSION: Patients with a symptomatic rotator cuff tear show compensatory movement patterns based on abnormal activity of the biceps brachii and posterior deltoid muscles when compared with age-matched controls. The posterior deltoid functions less in conjunction with the other deltoid muscles, and lower coactivation was seen in the remaining intact rotator cuff muscles in the rotator cuff tear group than the control group. CLINICAL RELEVANCE: This study supports the potential benefit of addressing the long head biceps tendon in the treatment of patients with a symptomatic rotator cuff tear. Moreover, clinicians might use these findings for conservative treatment; the posterior deltoid can be specifically trained to help compensate for the deficient rotator cuff.

Electromyographic analysis of selected shoulder muscles during a series of exercises commonly used in patients with symptomatic degenerative rotator cuff tears.

BACKGROUND: In the nonoperative treatment of degenerative rotator cuff (RC) tears, exercise therapy is advocated. Exercises focusing on strengthening the anterior deltoid (AD) and the scapular muscles are proposed to compensate for RC dysfunction. However, the amount of electromyographic (EMG) activity in these muscles during these exercises remains unclear. Moreover, it is unknown whether muscle activity levels during these exercises alter with increasing age. Therefore, the purpose of this study was to evaluate EMG activity in the deltoid and scapular muscles during 2 series of commonly used shoulder rehabilitation exercises and assess possible age-related changes in muscle activity. METHODS: Fifty-five healthy participants (aged 18-60 years) participated in this study. Surface EMG activity was measured in 8 shoulder girdle muscles during a progression of a closed chain elevation program (bench and wall slides) and during a progression of previously published AD exercises. In addition, muscle activity was compared between 3 age categories (18-32 years, 33-46 years, and 47-60 years). RESULTS: The proposed progressions exhibited increasing activity from <10% of maximal voluntary isometric contraction to >20% of maximal voluntary isometric contraction for the AD for both exercise programs and for the middle deltoid, upper trapezius, and middle trapezius during the closed chain elevation exercises. Activity levels in the other muscles remained <20% throughout the progression. Age-related analysis revealed increased activity in the AD, infraspinatus, and middle trapezius and decreased lower trapezius activity during the bench and wall slides. No age-related changes were noted for the AD exercises. CONCLUSION: These findings may assist the clinician in prescribing appropriate progressive exercise programs for patients with symptomatic RC tears.

Effect of surgical approaches on deltoid innervation and clinical outcomes in the treatment of proximal humeral fractures.

OBJECTIVES: This study aims to investigate the effects of deltopectoral and anterolateral acromial approaches commonly used in open reduction-internal fixation of proximal humeral fractures on the clinical outcomes, and axillary nerve damage through electrophysiological assessment. PATIENTS AND METHODS: Forty-eight patients (22 males, 26 females; mean age 47.9±13.2 years; range, 22 to 73 years) diagnosed with Arbeitsgemeinschaft für Osteosynthesefragen (AO)/Orthopaedic Trauma Association (OTA) type 11 proximal humeral fractures who underwent osteosynthesis with anatomical locking plates in our hospital between January 2015 and June 2016 were prospectively examined. The patients were divided into two groups according to either the deltopectoral or anterolateral deltoid-split surgical approach used. Clinical outcomes were evaluated using the Disabilities of the Arm, Shoulder, and Hand (DASH) scores and Constant-Murley scores (CMS) obtained at three- and 12-month follow-up visits. Needle electromyography (EMG) was performed for the electrophysiological assessment of the deltoid muscle. RESULTS: There were no significant differences between the groups in terms of demographic data, follow-up times, and complications. DASH scores and CMS obtained postoperatively at three months (p=0.327 and p=0.531, respectively) and 12 months (p=0.324 and p=0.648, respectively) revealed no significant differences. In addition, the two groups did not significantly differ with respect to the presence of EMG abnormalities (p=0.792). Avascular necrosis of the humeral head was detected in only two patients from the deltopectoral group. CONCLUSION: Deltopectoral and anterolateral approaches do not differ regarding the presence of postoperative EMG abnormalities and functional outcomes. Surgeons can thus adopt either approach. However, dissection without damaging the soft tissue should be performed in both approaches.

Influence of implant design and parasagittal acromial morphology on acromial and scapular spine strain after reverse total shoulder arthroplasty: a cadaveric and computer-based biomechanical analysis.

BACKGROUND: The purpose was to analyze the influence of deltoid lengthening due to different implant designs and anatomic variations of the acromion and scapular spine (SS) in the parasagittal plane on strain patterns after reverse shoulder arthroplasty (RSA). METHODS: Ten cadaveric shoulders with strain rosettes placed on the surface of the acromial body (Levy II) and SS (Levy III) were tested using a shoulder simulator. RSA using humeral onlay (+3, +5, +8, +10, +13 mm) and glenosphere lateralization (0, +6 mm) was performed. Arm lengthening and magnitude of strain on acromion/SS were measured. The length of deltoid was assessed using validated computer modeling. Anatomic variance of the SS angle and position of acromion in relation to the scapular plane was examined. For comparison of strain as a function of deltoid lengthening, 25 mm was used as a threshold value for comparison based on previous literature demonstrating a decrease in Constant score and active anterior elevation in patients with arm lengthening >25 mm. RESULTS: At maximal deltoid lengthening (30.8 mm), average strains were 1112 µÎµ (acromion) and 1165 µÎµ (SS) (P < .01). There was an 82.6% increase in acromial strain at maximum lengthening compared with 25 mm (P = .02) and a strain increase of 79 µÎµ/mm deltoid lengthening above a threshold of 25 mm. The strain results delineated 2 anatomic groups: 5 of 10 specimens (group A) showed higher strain on SS (1445 µÎµ) vs. acromion (862 µÎµ, P = .02). Group A had a more posteriorly oriented acromion, whereas group B was anteriorly oriented (P < .001). CONCLUSION: Deltoid lengthening above 25 mm produced large strains on the acromion/SS. Anatomic variation may indicate that as the acromion is more posteriorly oriented, the SS takes more strain from the deltoid vs. the acromion. Our study's data may help surgeons identify a high-risk population for increased strain patterns after RSA.

Ictal quantitative surface electromyography correlates with postictal EEG suppression.

OBJECTIVE: To test the hypothesis that neurophysiologic biomarkers of muscle activation during convulsive seizures reveal seizure severity and to determine whether automatically computed surface EMG parameters during seizures can predict postictal generalized EEG suppression (PGES), indicating increased risk for sudden unexpected death in epilepsy. Wearable EMG devices have been clinically validated for automated detection of generalized tonic-clonic seizures. Our goal was to use quantitative EMG measurements for seizure characterization and risk assessment. METHODS: Quantitative parameters were computed from surface EMGs recorded during convulsive seizures from deltoid and brachial biceps muscles in patients admitted to long-term video-EEG monitoring. Parameters evaluated were the durations of the seizure phases (tonic, clonic), durations of the clonic bursts and silent periods, and the dynamics of their evolution (slope). We compared them with the duration of the PGES. RESULTS: We found significant correlations between quantitative surface EMG parameters and the duration of PGES (p < 0.001). Stepwise multiple regression analysis identified as independent predictors in deltoid muscle the duration of the clonic phase and in biceps muscle the duration of the tonic-clonic phases, the average silent period, and the slopes of the silent period and clonic bursts. The surface EMG-based algorithm identified seizures at increased risk (PGES ≥20 seconds) with an accuracy of 85%. CONCLUSIONS: Ictal quantitative surface EMG parameters correlate with PGES and may identify seizures at high risk. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that during convulsive seizures, surface EMG parameters are associated with prolonged postictal generalized EEG suppression.

Relation between preoperative electromyographic activity of the deltoid and upper trapezius muscle and clinical results in patients treated with reverse shoulder arthroplasty.

BACKGROUND: If patients susceptible to poor clinical outcomes could be predicted before reverse shoulder arthroplasty (RSA), it would help to set reasonable postsurgical patient expectations in the preoperative setting. Our hypothesis was that the preoperative electromyographic (EMG) activity of the deltoid and upper trapezius muscles would be correlated with clinical outcomes of patients undergoing RSA. METHODS: EMG activity of the deltoid and upper trapezius muscles was measured in 25 patients scheduled to undergo RSA during 3 motions: shrugging, forward flexion, and abduction. Their postoperative clinical results were assessed prospectively during regular outpatient visits, including strength, active range of motion (ROM), pain, and functional scores. The correlations between the preoperative EMG activities and clinical results were analyzed. RESULTS: Postoperative shoulder strength after RSA was increased in patients with greater preoperative EMG activity of the middle deltoid and upper trapezius. Preoperative EMG activity of the anterior or middle deltoid muscle was associated with active ROM in flexion or abduction, whereas EMG activity of the posterior deltoid was associated with active ROM in external rotation. CONCLUSIONS: Shoulder strength after RSA was positively correlated with preoperative EMG activity of the deltoid and upper trapezius. Active ROM after RSA was positively correlated with preoperative EMG activity of the deltoid. Therefore, preoperative EMG measurements of the deltoid and upper trapezius may predict clinical outcomes after RSA.

Treatment of cephalotuberosity fractures in elderly patients treated by reverse shoulder prosthesis: a study of functional results in relation to deltoid tension.

INTRODUCTION: The treatment of proximal humerus fractures is a therapeutic challenge in the elderly as the functional demands of these patients are high. We postulated that there may be a relationship between functional results and deltoid tension when these fractures are treated with a reverse prosthesis. This study was performed to determine the optimal tension of the deltoid. The primary outcome was the constant score in relation to humeral length at the final follow-up. MATERIALS AND METHODS: Our retrospective cohort consisted of 45 patients treated with a reverse fracture prosthesis during the period from January 2010 to July 2017. The fractures were all classified as Neer III or IV, 91% of our patients were women and the average age was 82 years. RESULTS: Constant score and antepulsion were improved with humeral elongation between 10 and 25 mm (p < 0.02 and p < 0.05, respectively). External rotation was improved with humeral elongation (p < 0.03). CONCLUSION: Tuberosity reinsertion improves mobility in patients treated surgically for a reverse fracture prosthesis. The recovery of anatomical retroversion seems of fundamental importance, and we confirmed that deltoid tension that must also be taken into account to improve functional results of reverse shoulder prosthesis on fracture. The ideal humeral elongation seems to be between 10 and 25 mm, in relation to the contralateral side, to obtain better functional results.

Chronic neck pain and muscle activation characteristics of the shoulder complex.

INTRODUCTION: Neck pain is a very common musculoskeletal complaint in industrialized countries. Theoretically, chronic neck pain is thought to possibly change biomechanics and muscle activation patterns of the shoulder complex, causing its pain and dysfunction in the long term. PURPOSE: The present cross-sectional study was conducted to compare shoulder complex muscle activation characteristics in patients with chronic non-specific neck pain, compared to healthy participants. METHOD: Twenty patients with chronic neck pain and twenty healthy participants were recruited for the present study. Surface Electromyographic (sEMG) activity was recorded from four selected muscles (anterior and middle deltoid, upper and lower trapezius) during shoulder elevation with a predetermined load (25-30% of an individual's maximum voluntary exertion). RESULT: Results revealed only two significant increased onset delays in the anterior and middle deltoid,and a peak delay in the upper trapezius in chronic neck pain patients. Furthermore, increased onset delay for other muscles and decreased peak normalized amplitude (MVE%) for all muscles were found in chronic neck pain patients; however, these findings were not statistically significant. CONCLUSION: There were relationships between chronic non-specific neck pain and the shoulder muscle activation characteristic; hence, the alteration may be considered a predisposing factor for the shoulder dysfunction in future studies.

Transarticular external fixation versus deltoid ligament repair in treating SER IV ankle fractures: a comparative study.

BACKGROUND: The topic that whether the injured deltoid ligament should be repaired when associated with ankle joint fractures is still discussed. The objective of this study was to compare the clinical effect of open reduction and internal fixation (ORIF) with deltoid ligament repair (DLR) or transarticular external fixation (TEF) in treating supination-external rotation type IV (SER IV) ankle fractures. METHODS: Between January 2012 and December 2015, 43 patients were diagnosed as SER IV ankle fractures, 20 underwent ORIF and transarticular external fixation (TEF) without DLR (group 1), 23 were treated with ORIF and DLR (group 2). The pre- and post-operative radiographic examination were performed, the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, the visual analog scale (VAS), the Medical Outcomes Short Form 36-item questionnaire score (SF-36), and the ankle range of motion (ROM) were used for functional evaluation. RESULTS: In both groups, the three scores improved significantly after surgery, but there was no significant difference between the two groups. At 6 weeks after surgery, patients in group 2 had better ankle ROM than group 1 (29.35 ± 2.033 vs. 40.35 ± 3.550, P <  0.001), but there was no difference at 12 months postoperatively. No cases of bone nonunion or post-traumatic arthritic changes were seen during the follow-up. Patients in group 1 required a shorter time to achieve fracture union than patients in group 2. CONCLUSIONS: ORIF with TIF is an optional strategy to manage SER IV ankle fractures as it achieves comparable functional results to ORIF with DLR. It also allows patients to start relatively earlier weight-bearing and may promote fracture union.

Motor Strategies Learned during Pain Are Sustained upon Pain-free Reexposure to Task.

INTRODUCTION: Pain affects movement planning and execution, and may interfere with the ability to learn new motor skills. Variations among previous studies suggest task-specific effects of pain on the initial acquisition and subsequent retention of motor strategies. METHODS: The present study assessed how acute pain in the anterior deltoid muscle affects movement accuracy of fast arm-reaching movements during force field perturbations and upon immediate pain-free repetition of the same task. RESULTS: Despite having slower initial rate of improvement, individuals who experienced pain during training achieved the same final performance as pain-free controls. However, pain altered the strategy of muscle activation adopted to perform the task, which involved less activity of the shoulder and arm muscles. Strikingly, motor strategies developed during the first exposure to the force field were retained upon reexposure to the same perturbation after resolution of pain. CONCLUSIONS: Although reduced muscle activation may be interpreted as metabolically efficient, it reduces joint stability and can have negative consequences for joint integrity. These results demonstrate that alternative motor strategies developed in the presence of pain can be maintained when training is resumed after resolution of pain. This effect could have deleterious consequences if it applies when learning motor skills in sports training and rehabilitation.

Altered Cocontraction Patterns of Humeral Head Depressors in Patients with Subacromial Pain Syndrome: A Cross-sectional Electromyography Analysis.

BACKGROUND: In approximately 29% to 34% of all patients with subacromial pain syndrome (SAPS) there is no anatomic explanation for symptoms, and behavioral aspects and/or central pain mechanisms may play a more important role than previously assumed. A possible behavioral explanation for pain in patients with SAPS is insufficient active depression of the humerus during abduction by the adductor muscles. Although the adductor muscles, specifically the teres major, have the most important contribution to depression of the humerus during abduction, these muscles have not been well studied in patients with SAPS. QUESTIONS/PURPOSES: Do patients with SAPS have altered contraction patterns of the arm adductors during abduction compared with asymptomatic people? METHODS: SAPS was defined as nonspecific shoulder pain lasting for longer than 3 months that could not be explained by specific conditions such as calcific tendinitis, full-thickness rotator cuff tears, or symptomatic acromioclavicular arthritis, as assessed with clinical examination, radiographs, and magnetic resonance arthrography. Of 85 patients with SAPS who met the prespecified inclusion criteria, 40 were eligible and agreed to participate in this study. Thirty asymptomatic spouses of patients with musculoskeletal complaints, aged 35 to 60 years, were included; the SAPS and control groups were not different with respect to age, sex, and hand dominance. With electromyography, we assessed the contraction patterns of selected muscles that directly act on the position of the humerus relative to the scapula (the latissimus dorsi, teres major, pectoralis major, and deltoid muscles). Cocontraction was quantified through the activation ratio ([AR]; range, -1 to 1). The AR indicates the task-related degree of antagonist activation relative to the same muscle's degree of agonist activation, equaling 1 in case of sole agonist muscle activation and equaling -1 in case of sole antagonistic activation (cocontraction). We compared the AR between patients with SAPS and asymptomatic controls using linear mixed-model analyses. An effect size of 0.10 < AR < 0.20 was subjectively considered to be a modest effect size. RESULTS: Patients with SAPS had a 0.11 higher AR of the teres major (95% CI, 0.01-0.21; p = 0.038), a 0.11 lower AR of the pectoralis major (95% CI, -0.18 to -0.04; p = 0.003), and a 0.12 lower AR of the deltoid muscle (95% CI, -0.17 to -0.06; p < 0.001) than control participants did. These differences were considered to be modest. With the numbers available, we found no difference in the AR of the latissimus dorsi between patients with SAPS and controls (difference = 0.05; 95% CI, -0.01 to 0.12; p = 0.120). CONCLUSIONS: Patients with SAPS showed an altered adductor cocontraction pattern with reduced teres major activation during abduction. The consequent reduction of caudally directed forces on the humerus may lead to repetitive overloading of the subacromial tissues and perpetuate symptoms in patients with SAPS. Physical therapy programs are frequently effective in patients with SAPS, but targeted approaches are lacking. Clinicians and scientists may use the findings of this study to assess if actively training adductor cocontraction in patients with SAPS to unload the subacromial tissues is clinically effective. The efficacy of training protocols may be enhanced by using electromyography monitoring. LEVEL OF EVIDENCE: Level II, prognostic study.

Overflow using proprioceptive neuromuscular facilitation in post-stroke hemiplegics: A preliminary study.

Hemiplegia is the classic condition resulting from a stroke. To assist in recovery, the overflow method can be employed to stimulate the affected limb, using the healthy contralateral lower limb (LL) to activate the plegic upper limb (UL) musculature. The aim of this study was to evaluate the immediate effect of overflow using the PNF method on the plegic upper limb muscles of post-stroke individuals in the acute and chronic stages, as well as on the muscles of healthy individuals. A total of 22 individuals participated in the work, comprising 8 healthy individuals (control group), 6 post-stroke acute stage individuals (acute group), and 8 post-stroke chronic stage individuals (chronic group). The participants were assessed using a questionnaire with sections for personal and disease data and application of the ICF scale and the Fugl-Meyer index. The three groups were submitted to electromyographic evaluation, using the posterior deltoid (PD), anterior deltoid (AD), pectoralis major (PM), and external oblique (EO) muscles in four different positions: P1 (resting the UL, with the LL contralateral to the affected limb positioned in diagonal); P2 (resting the UL, with manual resistance in the contralateral LL); P3 (affected UL positioned in diagonal, with manual resistance in the contralateral LL) e P4 (affected UL positioned in diagonal, with fixed point and manual resistance in the contralateral LL). The electromyography results revealed no significant differences between most of the positions for the four muscles evaluated (p > 0.05). However, high clinical relevance (d > 0.8) was found for muscle activation in positions 2 and 4. It could be concluded that for post-stroke individuals in the acute and chronic stages, overflow using PNF effectively increased activation of the PD, AD, PM, and EO muscles in the P2, as well as position 4.

Posterior and inferior glenosphere position in reverse total shoulder arthroplasty supports deltoid efficiency for shoulder flexion and elevation.

BACKGROUND: For humeral flexion and elevation, most relevant for daily activities with reverse total shoulder arthroplasty, the anterior and lateral deltoid muscles are most important. However, how this direction of movement is best supported with the glenosphere position is not fully understood. We hypothesized that both inferior positioning and posterior positioning of the glenosphere may best support this direction of movement. METHODS: A validated, anatomic biomechanical shoulder model was modified to host a reverse shoulder prosthesis. The glenoid baseplate was altered to allow inferior, lateral, and posterior center-of-rotation (COR) offsets. An optical tracking system was used to track the excursion of ropes simulating portions of various shoulder muscles during humeral abduction, elevation, and flexion. RESULTS: The inferior COR offset resulted in a significant increase in the deltoid moment arm in all 3 planes of motion. The lateral COR offset showed a significantly lower posterior deltoid moment arm during humeral abduction and a significantly lower lateral deltoid moment arm during humeral elevation. The posterior offset showed significantly larger anterior and lateral deltoid moment arms during humeral flexion. DISCUSSION AND CONCLUSION: Owing to the oblique direction of the deltoid muscle across the shoulder joint, an inferior offset of the COR in reverse total shoulder arthroplasty increases the deltoid moment arm during abduction, elevation, and flexion, whereas it mainly supports humeral flexion at a posterior offset. For humeral elevation and flexion, favorable positioning of the glenosphere may, therefore, be defined by a more inferior and posterior placement compared with the non-offset position.

Análise da ativação muscular durante o movimento de alcance nas condições ativo, ativo-assistido e autoassistido em pacientes pós-AVE / Análisis de la activación muscular durante el movimiento de alcance en las condiciones activo, activo-asistido y auto-asistido en pacientes post-AVE / Analysis of muscle activation during reaching movement in active, active-assisted and self-assisted conditions in post-stroke patients

RESUMO O Acidente Vascular Encefálico (AVE) é uma patologia que frequentemente causa limitações motoras nos Membros Superiores (MMSS) gerando prejuízos funcionais nos movimentos de alcance. O objetivo do estudo foi analisar o recrutamento muscular do membro superior parético durante três condições de alcance: ativo, ativo-assistido e autoassistido, através de dados eletromiográficos das fibras anteriores do Músculo Deltoide (MD), Bíceps Braquial (BB) e Tríceps Braquial (TB). Estudo do tipo transversal que utilizou como testes clínicos o miniexame do estado mental, escala de equilíbrio de Berg, medida de independência funcional, escala modificada de Ashworth e escala de Fugl-Meyer - seção MMSS. A coleta dos dados eletromiográficos de superfície foi realizada utilizando-se o eletromiógrafo e eletrodos de configuração bipolar da EMG System do Brasil com três canais posicionados nos pontos motores do MD (fibras anteriores), BB e TB de ambos os membros superiores. As variáveis clínicas apresentaram resultados de comprometimento motor, cognitivo e funcional leves. Os dados eletromiográficos mostraram que o MD e TB durante o alcance ativo-assistido contraíram mais que no alcance autoassistido (p<0.05). Os MD e TB apresentaram diferenças significativas durante os movimentos de alcance, enquanto que o músculo BB não mostrou alterações. Entre os diversos tipos de alcance, o ativo-assistido foi o que proporcionou maior ativação muscular. Sugere-se que sejam feitos ensaios clínicos para verificar a eficácia dos treinamentos.

RESUMEN El Accidente Vascular Encefálico (AVE) es una patología que frecuentemente causa limitaciones motoras en los Miembros Superiores (MMSS) generando perjuicios funcionales en los movimientos de alcance. El objetivo del estudio fue analizar el reclutamiento muscular del miembro superior parético durante tres condiciones de alcance: activo, activo-asistido y auto-asistido, a través de datos electromiográficos de las fibras anteriores del Músculo Deltóide (MD), Bíceps Braquial (BB) y Tríceps Braquial (TB). Estudio del tipo transversal que utilizó como pruebas clínicas el mini-examen del estado mental, escala de equilibrio de Berg, medida de independencia funcional, escala modificada de Ashworth y escala de Fugl-Meyer - sección MMSS. La recolección de los datos electromiográficos de superficie fue realizada utilizando el electromiografo y electrodos de configuración bipolar de la EMG System de Brasil con tres canales colocados en los puntos motores del MD (fibras anteriores), BB y TB de ambos miembros superiores. Las variables clínicas presentaron resultados de compromiso motor, cognitivo y funcional leves. Los datos electromiográficos mostraron que el MD y el TB durante el alcance activo-asistido contrajeron más que en el alcance auto-asistido (p<0.05). Los MD y TB presentaron diferencias significativas durante los movimientos de alcance, mientras que el músculo BB no mostró alteraciones. Entre los diversos tipos de alcance, el activo asistido fue el que proporcionó mayor activación muscular. Se sugiere que se realicen ensayos clínicos para verificar la eficacia de los entrenamientos.

ABSTRACT A cerebrovascular accident (CVA) is a disease that often causes upper limb motor limitations and functional losses in reaching movements. The objective of this study was to analyze the muscle recruitment of the paretic upper limb during three reaching conditions: active, active-assisted and self-assisted, through electromyographic data of anterior fibers of Deltoid Muscle (DM), Biceps Brachii (BB) and Triceps Brachii (TB). Cross-sectional study that used as clinical trials the Mini-Mental State Examination, Berg balance scale, functional independence measure, the modified Ashworth scale, and the Fugl-Meyer assessment - upper limbs section. Surface electromyographic data were collected using the electromyograph and bipolar electrode configuration of the EMG System do Brasil with three channels positioned in the motor points of DM (anterior fibers), BB and TB of both upper limbs. Clinical variables showed mild motor, cognitive, and functional impairment. Electromyographic data showed that DM and TB contracted more during active-assisted than during self-assisted exercise (p<0.05). DM and TB presented significant differences during reaching movements, while the BB muscle showed no changes. Among the different reaching exercises, the active-assisted was the one that provided greater muscle activation. Clinical trials are suggested to verify the effectiveness of the training.

Patterns of muscle coordination during dynamic glenohumeral joint elevation: An EMG study.

The shoulder relies heavily on coordinated muscle activity for normal function owing to its limited osseous constraint. However, previous studies have failed to examine the sophisticated interrelationship between all muscles. It is essential for these normal relationships to be defined as a basis for understanding pathology. Therefore, the primary aim of the study was to investigate shoulder inter-muscular coordination during different planes of shoulder elevation. Twenty healthy subjects were included. Electromyography was recorded from 14 shoulder girdle muscles as subjects performed shoulder flexion, scapula plane elevation, abduction and extension. Cross-correlation was used to examine the coordination between different muscles and muscle groups. Significantly higher coordination existed between the rotator cuff and deltoid muscle groups during the initial (Pearson Correlation Coefficient (PCC) = 0.79) and final (PCC = 0.74) stages of shoulder elevation compared to the mid-range (PCC = 0.34) (p = 0.020-0.035). Coordination between the deltoid and a functional adducting group comprising the latissimus dorsi and teres major was particularly high (PCC = 0.89) during early shoulder elevation. The destabilising force of the deltoid, during the initial stage of shoulder elevation, is balanced by the coordinated activity of the rotator cuff, latissimus dorsi and teres major. Stability requirements are lower during the mid-range of elevation. At the end-range of movement the demand for muscular stability again increases and higher coordination is seen between the deltoid and rotator cuff muscle groups. It is proposed that by appreciating the sophistication of normal shoulder function targeted evidence-based rehabilitation strategies for conditions such as subacromial impingement syndrome or shoulder instability can be developed.