Tips For General Practitioners – Shoulder Injection
Subacromial Impingement And Rotator Cuff Tears
Subacromial impingement and rotator cuff tears are polarized ends of a spectrum of disorders characterized by shoulder pain and weakness. They are common in middle-aged persons, and frequently present with night pain and pain with activity, particularly movements requiring elevation and internal rotation of the shoulder.
First-line treatment consists of non-steroidal anti-inflammatory drugs (NSAIDs) and activity modification with physiotherapy. Steroid and local anaesthetic injections are quite useful in recalcitrant cases.
Injection with lignocaine is useful as a diagnostic tool to confirm the diagnosis of subacromial impingement and rotator cuff tendonitis. Referred pain from cervical spondylosis or cardiac ischemia will not improve with this injection. Moreover, by eliminating subacromial pain, the functional strength of the rotator cuff can be evaluated and full-thickness tears of the rotator cuff diagnosed.
- Use a 10 mL syringe and a 21-Gauge needle. A 23-Gauge needle is also acceptable.
- Lignocaine can be used safely in dosages of less than 2 mg/kg bodyweight. Generally, 50 mg (5 mL of a one percent preparation) provides adequate analgesia within safe limits.
- Triamcinolone or other steroid preparations are equally acceptable.
- Aseptic techniques should be strictly adhered to.
The landmarks for subacromial injections are the acromion, the humeral head and the coracoid process.
1. Start off by identifying the postlateral corner of the acromion and the coracoid process (Figure 1).
2. Identify the soft spot approximately 2 cm medial and inferior to the postlateral edge of the acromion. This is the landmark for entering the subacromial joint (Figure 2).
3. Palpate the soft spot and the coracoid process between the thumb and index finger. This will give you the “line” with which to approach the subacromial space (Figure 3)
4. By aligning your syringe and needle with the “soft spot” and coracoid process, you will be able to enter and infiltrate the subacromial joint easily. There should be no resistance to flow and the patient should be comfortable throughout the procedure (Figure 4).
Post Op Advice For Patients
- Effects of the lignocaine usually wear off in a few hours. However, the steroid should slowly take effect over the next few weeks.
- Avoid strenuous activity for the following 24 hours.
- If symptoms worsen within the next 2 days, seek medical attention at the clinic. This may be due to a “steroid flare”, which can be managed with cold compresses, NSAIDs and adequate rest.
- Skin abrasions or infections.
- Known allergy to local anaesthetics.