Jaggi Muscle Patterning IntJShoulderSurg 2012 (original) (raw)
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Muscle activation patterns in patients with recurrent shoulder instability
International Journal of Shoulder Surgery, 2012
} Muscle activation patterns in patients with recurrent shoulder instability } Symptomatic chronic long head of biceps rupture: Surgical results } Does age or gender of the patient influence the outcome of type II superior labrum anterior and posterior repair? } Surgical treatment of lateral clavicle fractures associated with complete coracoclavicular ligament disruption: Clinico-radiological outcomes of acromioclavicular joint sparing and spanning implants } Septic failure is not a septic loosening: A case report of a failed shoulder prosthesis } Locking plates for displaced fractures of the lateral end of clavicle: Potential pitfalls } Improved clinical utility in clavicle fracture decision-making with true orthogonal radiographs C o n t e n t s ABSTRACT Purpose: The aim of this study is to present muscle patterns observed with the direction of instability in a series of patients presenting with recurrent shoulder instability. Materials and Methods: A retrospective review was carried out on shoulder instability cases referred for fine wire dynamic electromyography (DEMG) studies at a specialist upper limb centre between 1981 and 2003. An experienced consultant clinical neurophysiologist performed dual needle insertion into four muscles (pectoralis major (PM), latissimus dorsi (LD), anterior deltoid (AD) and infraspinatus ) in shoulders that were suspected to have increased or suppressed activation of muscles that could be contributing to the instability. Raw EMG signals were obtained while subjects performed simple uniplanar movements of the shoulder. The presence or absence of muscle activation was noted and compared to clinical diagnosis and direction of instability. Results: A total of 140 (26.6%) shoulders were referred for fine wire EMG, and 131 studies were completed. Of the shoulders tested, 122 shoulders (93%) were identified as having abnormal patterns and nine had normal patterns. PM was found to be more active in 60% of shoulders presenting with anterior instability. LD was found to be more active in 81% of shoulders with anterior instability and 80% with posterior instability. AD was found to be more active in 22% of shoulders with anterior instability and 18% with posterior instability. IS was found to be inappropriately inactive in only 3% of shoulders with anterior instability but in 25% with posterior instability. Clinical assessment identified 93% of cases suspected to have muscle patterning, but the specificity of the clinical assessment was only correct in 11% of cases.
Physiotherapy Research International, 2009
Background. This pilot study assesses level of agreement between surface and fi ne-wire electromyography (EMG), in order to establish if surface is as reliable as fi ne wire in the diagnosis and treatment of abnormal muscle patterning in the shoulder. Method. Eighteen participants (11 female) with unstable shoulders were recruited after written consent and ethical approval. Anthropometric information and mean skinfold size for triceps, subscapular, biceps and suprailiac sites were obtained. Triple-stud self-adhesive surface electrodes ('Triode'; Thermo Scientifi c, Physio Med Services, Glossop, Derbyshire, England) were placed over pectoralis major (PM), latissimus dorsi (LD), anterior deltoid (AD) and infraspinatus (IS) at standardized locations. Participants performed fi ve identical uniplanar standard movements (fl exion, abduction, external rotation, extension and cross-body adduction). After a 20-minute rest period, a dual-needle technique for fi ne-wire insertion was performed and the standard movements were repeated. An experienced examiner in each technique reported if muscle activation patterns differed from agreed normal during any movement and were blinded to the other test results. Sensitivity, specifi city and Kappa values for level of agreement between methods were calculated for each muscle according to the method of Altman (1991). Results. Fifteen participants were successfully tested. Sensitivity, specifi city and Kappa values between techniques for each muscle were PM (57%, 50%, 0.07), LD (38%, 85%, 0.22), AD (0%, 76%, −0.19) and IS (85%, 75%, 0.6). Only IS demonstrated high sensitivity and specifi city and a moderate level of agreement between the two techniques. There was no correlation between skinfold size and agreement levels. Conclusion. The use of surface EMG may help to classify types of shoulder instability and recognize abnormal muscle patterns. It may allow physiotherapists to direct specifi c rehabilitation strategies, avoiding strengthening of inappropriate muscles. It has a reasonable degree of confi dence to evaluate IS but may have poor sensitivity in detecting abnormal patterns in PM, LD and AD. Further work is required to see if investigator interpretation may have been a factor for the poor level of agreement.
Shoulder electromyography in multidirectional instability
Journal of Shoulder and Elbow Surgery, 2004
We studied shoulder muscle activity in multidirectional instability (MDI) and multidirectional laxity (MDL) of the shoulder, our hypothesis being that altered muscle activity plays a role in their pathogenesis. Six muscles (supraspinatus, infraspinatus, subscapularis, anterior deltoid, middle deltoid, and posterior deltoid) were investigated by use of intramuscular dual fine-wire electrodes in 7 normal shoulders, 5 MDL shoulders, and 6 MDI shoulders. Each subject performed 5 types of exercise (rotation in neutral, 45°of abduction, 90°o f abduction, flexion/extension, and abduction/adduction) on an isokinetic muscle dynamometer at two rates, 90°/s and 180°/s. After filtering, rectification, and smoothing, the electromyography signal was normalized by using the peak voltage of the movement cycle. In subjects with MDI, compared with normal subjects, activity patterns of the anterior deltoid were different during rotation in neutral and 90°of abduction, whereas those of the middle and posterior deltoid were different during rotation in 90°of abduction. In subjects with MDL, the posterior deltoid showed increased activity compared with normal subjects during adduction. Activity patterns of the supraspinatus, infraspinatus, and subscapularis appeared similar in both groups. Dual fine-wire electromyography offers insight into the complex role of shoulder girdle muscle function in normal movement and in instability. Altered patterns of shoulder girdle muscle activity and imbalances in muscle forces support the theory that impaired coordination of shoulder girdle muscle activity and inefficiency of the dynamic stabilizers of the glenohumeral joint are involved in the etiology of MDI. Interestingly, the abnormalities are in the deltoid rather than the muscles of the rotator cuff. (J Shoulder Elbow Surg 2004;13:24-9.) Increased translation of the humeral head on the glenoid in multiple directions is a normal finding if the subject is asymptomatic 7,8 ; this is termed multidirectional laxity (MDL). However, these shoulders may become symptomatic, causing discomfort and instability. This is termed multidirectional instability (MDI). MDI of the shoulder is a relatively new diagnosis, first described by Neer and Foster 15 in 1980. It is a complex condition, still poorly understood, and little is known about its pathophysiology. It is thought that impaired coordination of shoulder girdle muscle activity may be involved in its etiology. 10,11 Most patients with MDI of the shoulder respond to a physiotherapy rehabilitation program. 3 Some do not, and it may be because the rehabilitation program is concentrating on the wrong muscles or activities in these patients. Our aim was to study the pattern of shoulder muscle activity with intramuscular dual fine-wire electromyography (EMG) in normal, MDI, and MDL shoulders, comparing them by use of a validated methodology to gain insight into the complex function of the shoulder girdle musculature in normal movements and instability. Our hypothesis was that muscle activity would be unequivocally abnormal in MDI and that this might be detectable in an early form in MDL. We showed the reproducibility of the method and discussed its calibration and the interpretation of the data in an earlier technical report. 14 This is the first application of the method to MDL/MDI.
Electromyographical comparison of four common shoulder exercises in unstable and stable shoulders
Rehabilitation research and practice, 2012
This study examines if electromyographic (EMG) amplitude differences exist between patients with shoulder instability and healthy controls performing scaption, prone horizontal abduction, prone external rotation, and push-up plus shoulder rehabilitation exercises. Thirty nine subjects were categorized by a single orthopedic surgeon as having multidirectional instability (n = 10), anterior instability (n = 9), generalized laxity (n = 10), or a healthy shoulder (n = 10). Indwelling and surface electrodes were utilized to measure EMG activity (reported as a % of maximum voluntary isometric contraction (MVIC)) in various shoulder muscles during 4 common shoulder exercises. The exercises studied effectively activated the primary musculature targeted in each exercise equally among all groups. The serratus anterior generated high activity (50-80% MVIC) during a push-up plus, while the infraspinatus and teres major generated moderate-to-high activity (30-80% MVIC) during both the prone hori...
Electromyographic analysis: shoulder muscle activity revisited
Archives of orthopaedic and trauma surgery, 2015
Restoring optimal strength and biomechanics of a pathologic shoulder knowledge of activity patterns of healthy glenohumeral muscles is mandatory. Yet, data on normal shoulder muscle activity are not always conclusive. The study was undertaken (a) to evaluate muscle activity patterns in the healthy shoulder using surface and fine-wire electromyography (EMG), and (b) to assess method's suitability in the clinical setting especially regarding painfulness and practicability. Surface and fine-wire EMG was performed on 11 healthy subjects (2f/9m, Ø age 28 years) to assess 14 muscles including rotator cuff muscles during 8 planar standardised shoulder movements (abduction, forward flexion, internal and external rotation in neutral, 45° and 90° abduction). Pain was assessed using the visual analogue scale before testing, after inserting the fine-wire electrodes, after maximal voluntary contraction, before and after exercises, and after electrode removal. The most important finding regar...
Atypical shoulder muscle activation in multidirectional instability
Clinical …, 2005
Objective: Surface and intramuscular electromyography was used to investigate shoulder muscle activity in subjects with multidirectional instability (MDI). Methods: Subjects (seven MDI, 11 control) performed repetitive shoulder abduction/adduction, flexion/extension and internal/external rotation movements on an isokinetic dynamometer. The activity of the deltoid, infraspinatus, supraspinatus, latissimus dorsi, and pectoralis major muscles were recorded using double-differential surface and intramuscular fine-wire electrodes. A repeated measures analysis of variance evaluated group differences in the amplitude, onset, termination and duration of the muscle activity. Results: Significant activation parameter differences for the supraspinatus, infraspinatus, posterior deltoid and pectoralis major muscles were found in the subjects with MDI. The rotator cuff and posterior deltoid muscles demonstrated abbreviated periods of activity when performing internal/external rotation, despite activation amplitudes that were similar to the controls. In contrast, the activation of the pectoralis major differed from the control group in both the amplitude and time domains when performing shoulder extension. Conclusions: MDI is associated with atypical patterns of muscle activity that occur even when highly constrained movements are used to elicit the activity. Significance: In addition to glenohumeral hyperlaxity, the results suggest that dysfunctional neuromuscular control of the rotator cuff is also a contributing factor to the pathoetiology of MDI.
The 'hand squeeze' test for posterior 'muscle patterning instability' of the shoulder
Acta orthopaedica Belgica
Muscular patterning can be a contributor of positional posterior shoulder instability. Failure to recognize this pattern may lead to unnecessary surgical treatment with high failure rate. We analyzed the results of a new simple clinical test (hand squeeze test). The test is regarded positive, if during squeezing with the contralateral hand and elevation of the involved arm, in pronation, no posterior shoulder dislocation occurs. The test is regarded negative if posterior dislocation does occur regardless of the "hand squeeze". The patients with positive test were treated conservatively. Ten patients (12 shoulders) were treated between July 2006 and July 2010. The 'hand squeeze' test was positive in 8 patients (10 shoulders) and negative in 2 patients (2 shoulders). Both patients with a negative sign had structural lesions in the glenohumeral joint confirmed on arthro-MRI and were treated operatively.