Concept: Rotator cuff
This paper tackles the design of a graphical user interface (GUI) based on Matlab (MathWorks Inc., MA), a worldwide standard in the processing of biosignals, which allows the acquisition of muscular force signals and images from a ultrasound scanner simultaneously. Thus, it is possible to unify two key magnitudes for analyzing the evolution of muscular injuries: the force exerted by the muscle and section/length of the muscle when such force is exerted. This paper describes the modules developed to finally show its applicability with a case study to analyze the functioning capacity of the shoulder rotator cuff.
Shoulder pathologies of the rotator cuff of the shoulder are common in clinical practice. The focus of this pictorial essay is to discuss the anatomical details of the rotator interval of the shoulder, correlate the anatomy with normal ultrasound images and present selected pathologies. We focus on the imaging of the rotator interval that is actually the anterosuperior aspect of the glenohumeral joint capsule that is reinforced externally by the coracohumeral ligament, internally by the superior glenohumeral ligament and capsular fibers which blend together and insert medially and laterally to the bicipital groove. In this article we demonstrate the capability of high-resolution musculoskeletal ultrasound to visualize the detailed anatomy of the rotator interval. MSUS has a higher spatial resolution than other imaging techniques and the ability to examine these structures dynamically and to utilize the probe for precise anatomic localization of the patient’s pain by sono-palpation.
Recent investigation of human tissue and cells from positional tendons such as the rotator cuff has clarified the importance of inflammation in the development and progression of tendon disease. These mechanisms remain poorly understood in disease of energy-storing tendons such as the Achilles. Using tissue biopsies from patients, we investigated if inflammation is a feature of Achilles tendinopathy and rupture.
Musculoskeletal disorders of the upper extremity are common reasons for patients to seek care and undergo ambulatory. The objective of our study was to assess the overall and age-adjusted utilization rates of rotator cuff repair, shoulder arthroscopy performed for indications other than rotator cuff repair, carpal tunnel release, and wrist arthroscopy performed for indications other than carpal tunnel release in the United States. We also compared demographics, indications, and operating room time for these procedures.
Arthroscopic subacromial decompression (ASD) is the most commonly performed surgical intervention for shoulder pain, yet evidence on its efficacy is limited. The rationale for the surgery rests on the tenet that symptom relief is achieved through decompression of the rotator cuff tendon passage. The primary objective of this superiority trial is to compare the efficacy of ASD versus diagnostic arthroscopy (DA) in patients with shoulder impingement syndrome (SIS), where DA differs only by the lack of subacromial decompression. A third group of supervised progressive exercise therapy (ET) will allow for pragmatic assessment of the relative benefits of surgical versus non-operative treatment strategies.
We performed a systematic review of the literature to determine whether earlier surgical repair of acute rotator cuff tear (ARCT) leads to superior post-operative clinical outcomes.
PURPOSE: It is commonly stated that supraspinatus initiates abduction; however, there is no direct evidence to support this claim. Therefore, the aims of the present study were to determine whether supraspinatus initiates shoulder abduction by activating prior to movement and significantly earlier than other shoulder muscles and to determine if load or plane of movement influenced the recruitment timing of supraspinatus. METHODS: Electromyographic recordings were taken from seven shoulder muscles of fourteen volunteers during shoulder abduction in the coronal and scapular planes and a plane 30° anterior to the scapular plane, at 25%, 50% and 75% of maximum load. Initial activation timing of a muscle was determined as the time at which the average activation (over a 25ms moving window) was greater than three standard deviations above baseline measures. RESULTS: All muscles tested were activated prior to movement onset. Subscapularis was activated significantly later than supraspinatus, infraspinatus, deltoid and upper trapezius, while supraspinatus, infraspinatus, upper trapezius, lower trapezius, serratus anterior and deltoid all had similar initial activation times. The effects of load or plane of movement were not significant. CONCLUSIONS: Supraspinatus is recruited prior to movement of the humerus into abduction but not earlier than many other shoulder muscles, including infraspinatus, deltoid and axioscapular muscles. The common statement that supraspinatus initiates abduction is therefore, misleading.
Rotator cuff related shoulder pain (RCRSP) is an over-arching term that encompasses a spectrum of shoulder conditions including; subacromial pain (impingement) syndrome, rotator cuff tendinopathy, and symptomatic partial and full thickness rotator cuff tears. For those diagnosed with RCRSP one aim of treatment is to achieve symptom free shoulder movement and function. Findings from published high quality research investigations suggest that a graduated and well-constructed exercise approach confers at least equivalent benefit as that derived from surgery for; subacromial pain (impingement) syndrome, rotator cuff tendinopathy, partial thickness rotator cuff (RC) tears and atraumatic full thickness rotator cuff tears. However considerable deficits in our understanding of RCRSP persist. These include; (i) cause and source of symptoms, (ii) establishing a definitive diagnosis, (iii) establishing the epidemiology of symptomatic RCRSP, (iv) knowing which tissues or systems to target intervention, and (v) which interventions are most effective.
Effect of hand position on EMG activity of the posterior shoulder musculature during a horizontal abduction exercise
- Journal of strength and conditioning research / National Strength & Conditioning Association
- Published over 6 years ago
The reverse fly machine is a popular exercise for strengthening the horizontal shoulder abductors including the posterior deltoid. . There seems to be little consensus as to which hand position most effectively targets the posterior deltoid despite this option on most machines. This study investigated the impact of varying one’s hand position, and consequently altering shoulder joint rotation, on muscle activity in various glenohumeral muscles during exercise on the reverse fly machine. Nineteen resistance trained men (mean age = 23.2 ± 4.3 years; height =176.9 ± 7.1 centimeters; body mass = 81.3 ± 10.5 kilograms; body mass index = 25.9 ± 2.6) were recruited from a university population to participate in the study. In a repeated measures design, subjects grasped the hand bars on the machine with either a pronated (PRO) or neutral (NEU) grip and performed dynamic horizontal abduction repetitions to muscular failure using a load equating to approximately 75% body weight. The order of performance of the hand positions was counterbalanced between participants so that approximately half of the subjects performed PRO first and the other half performed NEU first. Surface electromyography was used to record both mean and peak muscle activity of the posterior deltoid, middle deltoid, and infraspinatus. Results showed that mean EMG activity for the posterior deltoid was significantly greater in NEU compared to PRO (p = 0.046; 95% CI = 0.1 to 7.4% MVIC). Similarly, mean EMG activity of the infraspinatus also was significantly greater in NEU compared to PRO (p = 0.002; 95% CI = 3.7 to 13.6% MVIC). The results of this study show that performing exercise on the reverse fly machine with a neutral hand position significantly increases activity of the posterior deltoid and infraspinatus muscles compared to a pronated hand position.
The deltoid is a fascinating muscle with a significant role in shoulder function. It is comprised of three distinct portions (anterior or clavicular, middle or acromial, and posterior or spinal) and acts mainly as an abductor of the shoulder and stabilizer of the humeral head. Deltoid tears are not infrequently associated with large or massive rotator cuff tears and may further jeopardize shoulder function. A variety of other pathologies may affect the deltoid muscle including enthesitis, calcific tendinitis, myositis, infection, tumors, and chronic avulsion injury. Contracture of the deltoid following repeated intramuscular injections could present with progressive abduction deformity and winging of the scapula. The deltoid muscle and its innervating axillary nerve may be injured during shoulder surgery, which may have disastrous functional consequences. Axillary neuropathies leading to deltoid muscle dysfunction include traumatic injuries, quadrilateral space and Parsonage-Turner syndromes, and cause denervation of the deltoid muscle. Finally, abnormalities of the deltoid may originate from nearby pathologies of subdeltoid bursa, acromion, and distal clavicle.