Shoulder Impingement


The rotator cuff is a group of four muscles: supraspinatus, infraspinatus, subscapularis and teres minor, which together control movement of the upper arm bone (humerus) against the shoulder blade (scapula).

The shoulder joint has a very large range of movement, which is achieved by a ball at the top of the humerus moving against a very shallow socket on the scapula. Unlike other joints, such as the hip, there are no strong ligaments to hold the bones together and control movement. Instead the shoulder relies on the coordinated contraction of the rotator cuff muscles to fine tune movement and keep the head of the humerus sitting against the shallow socket. The rotator cuff muscles attach to the shoulder blade and the top of the humerus and form an enclosing cuff close to the joint. If these muscles are weak, damaged or poorly coordinated the head of humerus will tend to slide upwards or forwards in the socket as the arm is lifted. This excess gliding movement can cause pinching, or impingement, of soft tissues above and in front of the shoulder joint.

Symptoms of impingement include:
  • Pain radiating from the front of the shoulder to the side of the arm that is present both with activity and at rest;
  • Pain and limitation with lifting and reaching movements, including arm behind back, and pain when lying on affected side;
  • local swelling and tenderness in the front of the shoulder.

Impingement symptoms may either occur as the result of specific trauma or can develop gradually, often in association with poor upper trunk posture.

Treatment
The aims of treatment are:
  1. reduction in the inflammation of the affected tendon through massage, manual therapy, ultrasound, and taping;
  2. improvement of strength and coordination of the rotator cuff muscles. This involves specific exercises which are progressed by increasing the resistance and making the coordination task more difficult. There is significant evidence that exercise improves shoulder pain in both short and longer-term.1

Because treatment requires muscle strengthening and postural re-education, it normally takes between 6 weeks and 3 months to resolve shoulder impingement.
If a significant tear in the rotator cuff has been sustained and a high level of function is required as in sporting activities (tennis serve, cricket bowling, competitive swimming), surgical repair may be necessary. An ultrasound or MRI scan can be useful in diagnosing the presence and extent of tearing.


Impingement of the rotator cuff

1. Scapula depression in sitting
Correct your posture by gently straightening your lower back and pelvis. A number of different cues may be used to help you set the shoulder blades in the correct position with optimum use of controlling muscles:
  • draw your head and neck back on your shoulders keeping the back of the neck long
  • let your shoulders drop away from your ears
  • open the front of your chest without lifting the chest bone
  • gently draw the shoulder blades “up and away” from your chest” or “back and down toward the opposite back pocket”
When you can achieve the correct position try to maintain it for 5 mins every hour.
2. Scapula depression in side lying
  • Lie on right side with the hand of your right arm underneath the pillow;
  • Rest your left hand on your right forearm. Roll your left shoulder blade back across your ribs toward the centre of your back.
  • Hold 10 seconds repeat 5 times.
  • Repeat other side.
3. Rotator cuff in side lying
  • Lie on one side, pillow under head, knees bent;
  • Hold a light weight (your physio will advise) in upper hand and rest upper arm on side of body with elbow bent to 90º;
  • Gently squeeze on a small towel roll between elbow and side of body and pinch shoulder blades together using the muscles at the lower corner of your shoulder blades;
  • Keep elbow still and lift hand up towards the ceiling. Very slowly return to start position. You should not feel your neck muscles working, just a feeling that muscles are working deep in your shoulder.
4. Rotator cuff with weight in elevation
  • Sit on ball or on the front of a chair- feet parallel, knees shoulder distance apart and pointing at second toes, gently hold pelvic floor and deep abdominal muscles;
  • Set shoulder blades by gently squeezing the muscles at the lower corner of the blades (without pushing the chest forward) and maintain this position;
  • Holding a _ kg hand weight lift one arm so that the upper arm is 45° from the body and the elbow is held bent at 90°. Gently place the back of your other hand against the elbow to help you control its position;
  • Slowly turn your arm to take your hand across your body and then return it to the upright position. The point of the elbow should remain still. Do not allow the shoulder to hunch up or round forward.
To progress the exercise:
  • remove the supporting hand
  • take the elbow 45° out to the side.
5. Standing – external rotation with exercise band
  • Set shoulder blades by gently squeezing the muscles at the lower corner of the blades (without pushing the chest forward) and maintain this position;
  • Wrap the exercise band around both hands;
  • Keep elbows at sides and bent at 90°
  • Slowly pull on band and take hands out to side, slowly release;
  • Keep elbows into sides throughout movement.
6. Standing – internal rotation with exercise band
  • Set shoulder blades by gently squeezing the muscles at the lower corner of the blades (without pushing the chest forward) and maintain this position;
  • Attach exercise band to something solid at waist height and wrap the other end around your hand;
  • Slowly pull against the band to take your hand across your body;
  • Slowly release, keeping elbow tucked in.

(1) Australian Acute Musculoskeletal Guidelines Group Evidence-based Management of Acute Musculoskeletal Pain Australian Academic Press 2004 p48