None listed
Conditions
Brief summary
Aims: To investigate the role of the rotator cuff muscles in limiting glenohumeral joint translation. This study will compare the electromyographic (EMG) activity of rotator cuff muscles in response to an external translation force in a healthy and pathological population. Participants: There will be a total of 40 participants in this trial - 20 each in the comparison and experimental groups. The participants will be more than 18 years old. The experimental group participants will have diagnosed rotator cuff pathology – typically a tear. The comparison group participants will be gender- and age-matched (within 5 years) and have normal healthy shoulders with no present history of pain or shoulder dysfunction. Brief Description: The rotator cuff is a musculotendinous unit consisting of four muscles (supraspinatus, subscapularis, infraspinatus and teres minor) whose tendons blend into and reinforce the glenohumeral joint capsule (Moore & Dalley, 2006). The close proximity of the rotator cuff muscles to the shoulder joint means they are ideally located to act concurrently, providing dynamic stability that could potentially limit the amount of unwanted translation and increase stability at the shoulder joint (Hess, 2000; Magarey & Jones, 2003). The high prevalence of rotator cuff pathology in shoulder injuries (Murrell & Walton, 2001) and the poor diagnostic accuracy of the clinical tests currently used to diagnose rotator cuff disease (Hughes, Taylor, & Green, 2008) emphasizes the importance of gaining a more thorough understanding of the rotator cuff’s function in dynamic control of shoulder motion. The ability of all rotator cuff muscles in limiting glenohumeral translation in young healthy shoulders has been measured in our previous study (Rathi et al, 2015). This method of measurement will now be replicated in patients with rotator cuff pathology in the present study. This comparative study will determine whether pathology of rotator cuff muscles affects the shoulder movements, specifically glenohumeral joint translations. Intramuscular bipolar fine wire electrodes will be inserted in the rotator cuff muscles to measure muscle activity. Participants will be seated upright in a chair with their affected upper limb fully supported through the use of straps. Elbow, hand and wrist orthoses will be used to allow the limb to maintain position without the use of muscle activity. A vertical board will be strapped across the chest to stabilize the trunk to the chair, particularly during translation procedures. Participants will be tested in two shoulder positions: in neutral and with the shoulder abducted 90º and externally rotated. A standardised procedure will be used for the setting up of the equipment, for instructions to the participants and for the placement of electrodes. These procedures and electrode placements have been established in previous studies in our laboratory. Methods of Data Analysis: To assess whether significant differences exist between the translation of humeral head with and without rotator cuff muscles’ activation will be analysed using independent ANOVAs for each shoulder position (neutral, abduction+ external rotation). Each ANOVA will have three factors: translation force (none, anterior, posterior), activity (none, isometric internal rotation force, and isometric external rotation) and group (patient vs control) with level of significance set at p<0.05.
Interventions
The participants will be seated in neutral and abducted positions, with their tested arm fully supported by slings and arm rested on table.An external translation force (50-70 N) will be applied to the experimental group (patients with diagnosed Rotator cuff tear) and control group participants (healthy population with no rotator cuff pathology) using hand held dynamometer for upto 10 sec. A the same time, they will be asked to do isometric internal and external rotation movements, demonstrated
The participants will be seated in neutral and abducted positions, with their tested arm fully supported by slings and arm rested on table.An external translation force (50-70 N) will be applied to the experimental group (patients with diagnosed Rotator cuff tear) and control group participants (healthy population with no rotator cuff pathology) using hand held dynamometer for upto 10 sec. A the same time, they will be asked to do isometric internal and external rotation movements, demonstrated to them by the examiners prior to the test. The forces will be applied in both neutral and abducted shoulder positions from anterior and posterior directions. The procedure will be performed by an experienced physiotherapist and clinical anatomist, both of whom are well qualified, trained and experienced in such testing. The testing will only be performed once on each participant. The effect of force on glenohumeral joint translation will be observed and measured at the same time.
Sponsors
La Trobe University
Eligibility
Sex/Gender
All
Age
18 Years to 70 Years
Healthy volunteers
Yes
Inclusion criteria
Inclusion Criteria for experiment group 1. Adults at least 18 years 2. Primary diagnosis of partial or complete tear of at least one rotator cuff muscle confirmed on an ultrasound or MRI scan. 3. To be able to move and hold the arm up to at least 90 degrees abduction and external rotation 4. No ailments that could result in altered sensory or motor function at the shoulder such as peripheral nerve disorders Inclusion Criteria for comparison group 1. Normal apparently healthy adults matched for gender and age (within 5 years of the experimental group participant) 2. Full range of motion for all arm movements with no present history of pain or shoulder disability 3. No rotator cuff muscle tears diagnostically confirmed on an ultrasound 4. No ailments that could result in altered sensory or motor function at the shoulder such as peripheral nerve disorders.
Exclusion criteria
Exclusion Criteria for both groups 1. Fracture, dislocation or shoulder instability 2. Insufficient English language skills to be able to read and understand the participant information sheet, consent form and verbal instructions. 3. Fear of needles or allergy to adhesive tape
Outcome results
None listed