Shoulder impingement syndrome is a condition where the rotator cuff tendons are repeatedly being entrapped or pinched under the narrow subacromial space during shoulder movement. There are two causes for shoulder impingement: 
- Primary causes (Structural narrowing)
- Some people are in-born with narrow subacromial space
- Hence, they are more susceptible to impingement of the soft tissues underneath the subacromial space – bursa or the rotator cuff tendon
- A repetitive impingement on the soft tissues may lead to inflammation of the structures – shoulder bursitis or rotator cuff tendonitis
- However, with aging process, osteoarthritis may set in. Growth of subacromial bone spurs may further reduce the subacromial space
- Secondary causes (Dynamic instability)
- It usually happens after a period of time of repeated overhead activities, trauma, injury, poor posture or inactivity
- For instance: After an injury, due to pain the person develops a compensatory movement that might alter the shoulder alignment. In the long run, muscles imbalance may occur
- Rotator cuff muscles may have to work very hard to maintain the shoulder stability and eventually become fatigue, and weakens
- If the rotator cuffs are not working or function normally, the humeral head is not properly set in the small glenoid fossa. Thus, the humeral head will have the tendency to slide upwards and impinge on the tendons or bursa causing rotator cuff tendonitis or shoulder bursitis
- A constant frictional force may lead to rotator cuff tear
There are 3 stages of impingement syndrome: 
- < 25 age
- Pain during exercises; associated with overused injuries
- No loss of strength and ROM
- Involves oedema/haemorrhage
- Syndrome still reversible
- Age 25-40 years
- Pain during ADL; loss of mobility at night
- Shows fibrosis
- Irreversible tendon changes
- > 50 year
- Limited ROM due to calcification and loss of muscle strength
- Involves tendon rupture/ tear
There are some tests for us to confirm or rule out subacromial impingement: 
- Neer impingement test (useful screening test to rule out SAI)
- Painful Arc(between 60° and 120°) (useful screening and helpful confirming test to rule out SAI)
- Empty can (Jobe): integrity Supraspinatus  (helpful test to confirm SAI)
- External rotation resistance tests (useful screening and helpful confriming test to rule out SAI)
- Drop arm sign: to test the integrity of the Infraspinatus.
Patient elevates the arm and returns slowly. The test is positive when the patient has suddenly severe pain or the arm drops all of the suddenly.
- Lift-off test(or gerber lift test): Integrity Subscapulary muscle. Patient performs an internal rotation by putting his hand on the ipsilateral buttock. Next the patient needs to lift the hand from the buttock against resistance.
- The horizontal adduction test: arm is in adduction directed to the other shoulder and the elbow is flexed. If pain occurs, then the test is positive.
- Yergason test: the elbow is flexed at 90 degrees and the forearm pronated. The patient brings actively the forearm in supination against resistance. If there is pain in the bicipital groove area, then there is a disorder of the biceps tendon.
- Speed test: the elbow is extended and the forearm is supinates. The patient brings his arm in a forward elevation of the humerus (60degrees is resisted). When there is pain in the bicipital groove area, then is the test positive.
* The most sensitive diagnostic test : Hawkins test, Neer test, horizontal adduction test.
* The most specificity test: drop arm test, Yergason test and the speed test.
In terms of management, we will first reduce pain by reducing the inflammation using modalities such as ultrasound therapy or laser therapy. In addition, patient education about prevention on any repetitive overhead activities which is within the painful arc (600-1200) of shoulder abduction. Patient with severe pain can consider going for corticosteroid injection.
Once the pain has subsided, we will work together to regain shoulder full ROM, restore scapula control and normal scapulohumeral rhythm, restore rotator cuff strength, training for high speed, proprioception and agility performance. Finally, prepare patient to return to work pain free.
Loss of motion in glenohumeral joint can be due to muscular tissue or capsular tissue restrictions. Thus, stretching or joint mobilization techniques can be useful in gaining the mobility. A study showed glenohumeral mobilizations and mobilization with movement (MWM) in combination with supervised exercise program is effective in reducing pain and improved shoulder function. 
According to Manske, Grant-Niermann and Lucas (2013), in order to improve shoulder strength, endurance and motor control, exercises to recruit both the scapular and rotator cuff muscles patterns are utmost important.  Besides that, kinesiology taping is found to be more effective than local modalities during the first week, as it can produce an immediate effect in treating shoulder impingement syndrome. 
- Miller J. (2017) Shoulder impingement. [Online] Available at: http://physioworks.com.au/injuries-conditions-1/rotator-cuff-impingement [Accessed on 15th March 2017]
- Drinker D. and Strijker DD. (n.d) Subacromial impingement. Physiopedia. [Online] Available at: http://www.physio-pedia.com/Subacromial_Impingement [Accessed on15th March 2017]
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- Kaya E. Zinnuroglu M. and Tugcu I. (2011) Kinesio taping compared to physical therapy modalities for the treatment of shoulder impingement syndrome. Clin Rheumatol. 2011(30). 201-207.