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.

A radiographic review of the subacromial architecture: a South African study

The subacromial space, which is occupied by the subacromial bursa, rotator cuff complex and the long head of the biceps brachii tendon, is a well-known area of study due to its association with subacromial disease. Although it is demarcated by the coraco-acromial arch and the supraglenoid tubercle, degenerative changes in these osteological components often lead to mechanical narrowing and subsequent tendon abrasion. In addition to the morphological characteristics, the morphometry of the subacromial architecture is considered to play an important role in maintaining glenohumeral stability. Accordingly, the present study outlined the morphometry of the subacromial architecture and the acromial morphology from a radiological perspective. A total of 120 true lateral-outlet view radiographs (n = 120), representative of 58 males and 62 females of the Black (12), Coloured (10), Indian (27) and White (71) race groups, were analysed. In addition to calculation of the standard and population-specific means, the acromial classification scheme of Bigliani et al. (1986) was adopted. A trend of ascending values from Type III (16.7%) to Type II (37.5%) to Type I (45.8%) acromia was noted. Various shapes of the subacromial space were observed, viz. rhomboidal (20.0%), trapezoidal (65.8%) and triangular (14.1%). Since a statistically significant P value of 0.030 was recorded for the comparison of acromial type with the shape of the subacromial space, the shape of the subacromial space appeared to be dependent on the acromial type. While the parameters were determined with regard to the demographic representation of South Africa, this study also provided standard mean values which were not previously reported. Furthermore, the correlation of the acromio-glenoidal length with side, gender and shape of the subacromial space reflected levels of significance and highlighted this parameter as a diagnostic determinant of subacromial disease due to its tendency to change in accordance with the demographic and morphological factors

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Quantification of the deltoid muscle height in the region of the coraco-acromial ligament - An ultraso-nographical study

Although the triangular deltoid muscle has three distinct portions originating from the scapula and acromion, the underlying coraco-acromial ligament presents as the stabilizing factor for the anterior deltoid, thus bridging the interval within the coraco-acromial arch. As the deltoid muscle integrity is vulnerable during the resection of the coraco-acromial ligament from the acromion, the purpose of this study was to quantify the height of the deltoid muscle over the region of the coraco-acromial ligament. The superior shoulder region in seventeen nor-mal female individuals (n = 34) were bilaterally examined through an ultrasonographic system (Medelec Synergy: Acertys T2 EDX, 2012). In addition to the length of the coraco-acromial ligament, the height of the deltoid muscle was measured at three selected areas between the posterior aspect of the coracoid process and the anterior acromial tip, just superior to the coraco-acromial ligament. The mean coraco-acromial length was found to be 24.8±7.6mm. The mean deltoid height at regions 1, 2 and 3 were 8.4 ± 2.7 mm, 9.1 ± 2.1 mm and 8.4 ± 3.0 mm, respectively. The height of the deltoid muscle was recorded to be constant across all three regions related to the coraco-acromial ligament. Moreover, the specific height of the deltoid muscle in the region of the coraco-acromial ligament was not reported in the literature reviewed. In addition, this study was done to complement the introduction of the delto-fulcral triangle model by Naidoo et al. (2017). The provision of data regarding the specific deltoid height may assist to preserve the deltoid muscle and the accompanying coraco-acromial ligament during operative procedures

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Fracture of the proximal humerus with disruption of the tendon of the pectoralis major.

Combined pectoralis major disruption and proximal humeral fractures are uncommon. A simple radiologic diagnostic tool which consists of the measurement of the displacement from the humeral shaft to the lateral side of the humeral head (lateral to the outer proximal cortex) can help to diagnose this combined lesion.

Can an extracorporeal glenoid aiming device be used to optimize the position of the glenoid component in total shoulder arthroplasty?

PURPOSE: Successful total shoulder arthroplasty (TSA) requires a correct position of the glenoid component. This study compares the accuracy of the positioning with a new developed glenoid aiming device and virtual three-dimensional computed tomography (3D-CT) scan positioning. MATERIALS AND METHODS: On 39 scapulas from cadavers, a K-wire (KDev) was positioned using the glenoid aiming device. It consists of glenoid components connected to the aiming device, which cover 150° of the inferior glenoid circle, has a fixed version and inclination and is available with several different radii. The aiming device is stabilized at the most medial scapular point. The K-wire is drilled from the center of the glenoid component to this most medial point. All scapulas were also scanned with CT and 3D reconstructed. A virtual K-wire (Kct) was positioned in the center of the glenoid and in the scapular plane. Several parameters were compared. Radius of the chosen glenoid component (rDev) and the virtual radius of the glenoid circle (rCT), spinal scapular length with the device (SSLdev) and virtual (SSLct), version and inclination between KDev and Kct, difference between entry point and exit point ("Matsen"-point). RESULTS: Mean rDev: 14 mm ± 1.7 mm and mean rCT: 13.5 mm ± 1.6 mm. There was no significant difference between SSLdev (110.6 mm ± 7.5 mm) and SSLct (108 mm ± 7.5 mm). The version of KDev and Kct was -2.53° and -2.17° and the inclination 111.29° and 111.66°, respectively. The distance between the "Matsen-point" device and CT was 1.8 mm. CONCLUSION: This glenoid aiming device can position the K-wire on the glenoid with great accuracy and can, therefore, be helpful to position the glenoid component in TSA. The level of evidence: II.

Acromioclavicular joint acceleration-deceleration injury as a cause of persistent shoulder pain: Outcome after arthroscopic resection.

BACKGROUND: Shoulder pain in general and acromioclavicular joint (ACJ) pain specifically is common after acceleration-deceleration injury following road traffic accident (RTA). The outcome of surgical treatment in this condition is not described in the literature. The aim of the present study was to report the outcome of arthroscopic resection of the ACJ in these cases. MATERIALS AND METHODS: Nine patients with localized ACJ pain, resistant to nonoperative treatment were referred on an average 18 months after the injury. There were 3 male and 6 females. The right shoulder was involved in seven patients and the left in two. The average age was 38.9 years (range 29-46 years). All presented with normal X-rays but with torn acromioclavicular joint disc and effusion on magnetic resonance imaging (MRI). Arthroscopic ACJ excision arthroplasty was performed in all patients. RESULTS: At a mean followup of 18 month, all patients had marked improvement. The Constant score improved from 36 to 81, the pain score from 3/15 to 10/15 and the patient satisfaction improved from 3.5/10 to 9.3/10. CONCLUSION: Arthroscopic ACJ excision arthroplasty, gives good outcomes in patients not responding to conservative management in ACJ acceleration-deceleration injury.