The Effect of Mobilization With Movement in Individuals With Shoulder Impingement Syndrome

Shoulder impingement syndrome causes positional fault of the subacromial and soft tissues below the subacromial space. This condition leads to the wrong biomechanics of precise ball and socket kinematics creating maximum concavity compression for shoulder stability. This wrong biomechanics is resulting in the injury of tissue below the subacromial space, such as rotator cuff tendinitis, tears of rotator cuff tendons, and subacromial bursitis. The space between the acromion and humeral was small varying between nine to 14 mm. However, the subacromial space will be decreased during the arm elevation or in the abduction and external rotation position. Some of the researchers defined the shoulder impingement syndrome as the mechanical entrapment of the rotator cuff or the subacromial bursa in the subacromial space. The highest compression of the structures below the subacromial space occurs when people elevate the arm, especially during the shoulder flexion, abduction, and rotation.

The etiology of shoulder impingement syndrome is multifactorial, although a few common causes of the shoulder impingement syndrome were narrowing of the subacromial space and enlargement of the subacromial bursa or rotator cuff tendons. The mechanical factor is believed as the main cause of shoulder impingement syndrome. The postural misalignment and the movement control that makes the improper muscle activation and cause false movement times between acromion and glenoid were shown to associated with the etiology of shoulder impingement syndrome. Individu with the protracted shoulder is frequently associated with the anteriorly tilted and internally rotated of the scapula. The protracted shoulder or forward displacement of the acromion can be measured by the shoulder angle to the seventh cervical spinous process.

The humeral head position depends on the soft tissues surrounding the subacromial region. During arm elevation, the humeral head position should be at the center and adjust anterior translation along with the acromion movement to anterior and lateral. When the humeral head position is faulty or not in the center, because of the anterior inferior glenohumeral ligament cannot restrain the abnormal humeral head translation. This condition leads to decreased subacromial space and irritation to the soft tissue below the acromion which causes the impingement syndrome.

Study protocol This study will recruit shoulder patients around Jakarta city, the age between 20 and 60 years. The patients with shoulder impingement syndrome will be recruited by online brochures and leaflets.

All eligible participants will receive a clear explanation of the purposes, procedures, advantages, and possible risks of this study. Each participant will be asked to sign an informed consent after they understand and accept to participate in this study.

Based on the assessment form, the participant will be assessed by the examiner and researcher. The participants' age will be used to grouping the participants into the conventional or mobilization with the movement group. The participant will be asked to rate their pain intensity using the visual analog scale during the maximum shoulder abduction. Shoulder range of motion will be assessed using the bubble inclinometer during shoulder abduction in the standing position, internal and external rotation in the supine position with 90° shoulder abduction and 90° elbow flexion. Cervical and shoulder with the instruction to the participants to stand in their relaxed posture will be recorded by photogrammetry. Muscle strength of shoulder abductors, external rotators, and internal rotators will be assessed using the handheld dynamometer. The shoulder function will be recorded by the shoulder pain and disability index.

Conventional physical therapy For the conventional group, PT (E), who has had certified level 1 sports physical therapy from the Australian Physiotherapy Association and has had 5 years of working experience, will treat the participants with the conventional and postural correction exercise. This therapist will be blinded by unknowing the group allocation. The participants will receive the conventional intervention, the postural correction exercise, and 10 minutes rest. Then the outcome measures will be reassessed thereafter. The participants in the conventional group will receive conventional physical therapy including stretching, modality, ice, therapeutic exercise, passive mobilization, and postural correction exercise. The conventional physical therapy is adjustable or tailor-made depending on the patient's specific conditions. Therapeutic exercise has a wide variety of types and modes of exercise. The postural correction exercises consist of rotator cuff muscle strengthening with eccentric-concentric, scapular stabilization exercise, and postural awareness. In addition, these exercises include motor control therapeutic exercise for the relearn process and motor control of the correct posture to change the participant's behavior.

Mobilization with movement For the mobilization with movement group, PT (S) will know the code to treat the participants using the conventional or mobilization with movement protocol. Moreover, this therapist will apply the mobilization with movement technique. The participants will receive the conventional intervention, the postural correction exercise, and the mobilization with movement. Then the outcome measures will be reassessed thereafter. The directions of mobilization with movement are a posterolateral glide when the participants raise their arm to perform shoulder abduction until the overhead movement. The therapist will place one hand on the participant's scapula to stabilize movement while placing the thenar eminence of the other hand on the medial of the humeral head. The treatment belt will be placed on the participant's shoulder on top of the PT (S)'s hand. The therapist will provide sustained posterolateral and inferior glide while the participants will be asked to move the shoulder freely in the pain-free angle. PT (S)'s hands will move along with the movement to sustain the glide along the treatment plane with upward rotation of the scapula. The mobilization with movement dose will be 3 sets of 10 repetitions with rest interval 30 seconds between sets, twice a week for 4 weeks.

Sample size calculation will be performed using the formula for the test of the difference between 2 independent means.

According to the G*power 3.1.9.2 program calculation, the total of this study equals 20 subjects. Based on the previous study using the shoulder pain and disability index to measure the shoulder function, in the study of comparing the immediate effects of mobilization with movement and sham techniques. The mean (standard deviation) between group post-intervention for the mobilization with movement group was 4.6 (5.0) and that for the sham group was 0.4 (1.1). In this proposed study, the investigators need an equal number of participants per group; therefore, the drop out the calculation of 20% of the total participants (n = 1/1-20%). Therefore, after the ethical approval, the researcher will collect data from 24 shoulder impingement syndrome patients (12 subjects on the conventional group and 12 subjects on the mobilization with movement group).

Statistical Analysis Data will be analyzed using SPSS version 23. The statistical significance level is set at a p-value < 0.05.

• Shapiro-Wilk will be used to examine the distribution of the data
• Descriptive statistics for demographic data, mean and standard deviation for continuous, cumulative frequency for categorical, and median for ordinal variables, will be calculated.
• Two-way mixed-design ANOVA (two group x four-time) for parametric data. If the data are significant the post hoc analysis will be performed using Bonferroni.
• Friedman tests if the data are not normally distributed.