Injection of the sub-acromial space
Patients complain of pain around the lateral upper arm (around the lateral acromium and down to the deltoid insertion).
Pain exacerbated by any overhead activities, throwing, putting on clothes and sleeping on that side.
- Look for wasting of the shoulder muscles, especially the supraspinatus and infraspinatus muscles behind the shoulder blade
- Active and passive range of movement in forward flexion, abduction, internal and external rotation.
- Look for painful arc = pain from @ 60 – 120 degrees of abduction
- There are hundreds of tests for shoulder pathology. Majority of which most people can’t remember (me included!). The easiest and most useful I think are:-
1. Specific rotator cuff muscle tests:-
- Supraspinatus (abduction) – It may be isolated by having the patient rotate the arm so that the thumbs are away from the floor and resistance is applied with the arms at 30° of forward flexion and 90° of abduction.
- Infraspinatus (external rotation) –Test resisted active external rotation of the shoulder. This is done by asking the patinet to hold their arm at the side, with the elbow bent at 90 degrees. Then ask them to push their hand externally against your hand, keeping the elbow at the side.
- Subscapularis (internal rotation) –Lift off test. Arm behind back. Try and push examiners hand away.
2. Specific impingement tests:-
- Impingement sign = passive forward flexion > 90 degrees causes pain
- Hawkins test = as above but with the thumb pointing down (internal rotation), this brings the greater tuberosity under the acromium and will thus cause increased pain if inflammation present.
- Crossed chest adduction = bring arm across chest, if osteoarthritis of the acromio-clavicular (AC) Jt present, then pain occurs as the joint is compressed.
- Yergason’s test = Resisted supination of forearm. Pain and weakness if biceps pathology.
- Gleno-humeral (shoulder) joint osteoarthritis – usually older patients
- Instability – usually young athletes
- Adhesive capsulitis – Frozen shoulder. More pain and severe restriction in active and passive range of movement, especially external rotation. More common in diabetics and after trauma in other parts of the same upper limb.
• Plain X-Rays – AP and trans-scapular lateral views. Good for general bony anatomy. Look for osteoarthritis of the AC jt, a hooked acromium, sclerosis under the acromium, calcification of the supraspinatus tendon.
• Ultrasound – User dependent. Cheaper and quicker than MRI. My preferred investigation. Good for dynamic views to see impingement during arm abduction. Use if patients have claustrophobia worries about MRI.
• MRI – sensitivity and specificity to cuff tears is @90%. Gives a good picture of both the soft tissues of the shoulder as well as the bones. Does not show dynamic views. Occasionally a dye will also be injected to give a better idea of the size of tears of the cuff (MR arthrography).
- Activity modification. Stop overhead activities.
- Physiotherapy. Including muscle rebalance, ultrasound, acupuncture.
- Steroid injection. See below.
- Surgery. This can be done either as an open procedure or arthroscopically. If a large tear of the cuff is present, I favour an open decompression and repair. If there is only impingement then an arthroscopic subacromial decompression is my preferred option.
When to Refer
Attempt at conservative management is definitely worth trying initially. A majority of mild impingements will settle with activity modification, physio and injection.
Please refer to section on steroid injections.
What’s the Evidence ?
- Cochrane review updated in 2003
- Looked at 26 trials comparing steroids to local anaesthetic and NSAID’s
- Minimal difference in outcome
- I still think it is worth doing however, especially in early disease, as injections do seem to work well.
How to Inject
- Green needle
- 5mls Lignocaine, 20-40 mgs Kenalog
- Hang arm to distract.
- Lateral edge of acromium
- Angle slightly up
It’s my opinion that a maximum of 2 injections in a treatment cycle (i.e 1 year) is indicated.