What is an ultrasound scan?
Ultrasound is high-frequency sound waves produced by a special machine. They can provide very useful images of the tissues within the body, and it is extremely useful in assessing various musculoskeletal conditions involving tendons, muscles, joints and adjacent soft tissues. Unlike X-rays, ultrasound is harmless and involves no radiation or other harmful side effects.
Do I need a shoulder ultrasound scan?
Shoulder ultrasound is very useful in assessing different shoulder conditions. These include:
The sub-acromial bursa is a thin fluid-containing sac located within the shoulder joint. It ensures smooth movement as we lift our arms. Sub-acromial bursitis refers to inflammation of this bursa and usually results in shoulder pain, particularly when trying to lift up your arm above the head level.
Rotator cuff pain is a spectrum of conditions that includes tendon inflammation (tendinosis), partial thickness and full-thickness tears to the rotator cuff tendons. Ultrasound is an excellent tool for assessing rotator cuff tendon problems and subacromial bursitis, as the two can be seen together.
Shoulder impingement is a term used to describe a certain type of shoulder pain which can be the result of a number of conditions (Rotator cuff pain, Subacromial bursitis, and Acromioclavicular joint arthritis). Other conditions included are the Long head of biceps tendon pain and sometimes Shoulder calcific tendonitis. Dynamic assessment can be performed using ultrasound to look at the movement of the tendons and bursa while lifting the arm. Often, the bursa can be seen pinched during shoulder movement, confirming the diagnosis of shoulder impingement.
Calcific tendonitis (calcific tendinopathy) is the deposition of calcium material within the rotator cuff tendons. The patients usually have significant shoulder pain and do not recall a specific reason. The shoulder movements can be significantly restricted. Ultrasound is an excellent modality to assess for the presence of calcification and inflammation and to rule out other causes of shoulder pain like rotator cuff tear.
Ultrasound can guide the treatment, including ultrasound-guided shoulder joint cortisone injection and hydro dilation. Please see our article to find out how shoulder hydrodilatation is performed.
Ultrasound-guided steroid injections can be used to manage AC joint pain.
Biceps tendinitis refers to inflammation of the biceps tendon. The tendon runs at the front of the shoulder/upper arm, and inflammation typically results in pain at the front of the shoulder. Ultrasound is excellent for the assessment here.
Assessing soft tissue lumps around the shoulder joint. Ultrasound is usually the first choice of imaging to assess for swelling around the shoulder.
Shoulder ultrasound is extremely useful in guiding injections and procedures. Ultrasound allows for direct visualisation of the needle to ensure that the medicines are injected into the exact targeted site. There is significant evidence that ultrasound-guided injections provide better levels of pain relief and longer effects compared with injections done without imaging guidance. Injecting under ultrasound guidance allows for visualising the adjacent structures and reduces the risk of tissue injury at the injection site.
Shoulder ultrasound-guided procedures include:
What are the limitations of a shoulder ultrasound scan?
Visualisation of the deep structures inside the shoulder joint (like the labrum and the articular cartilage) is difficult with ultrasound. MRI would be more suitable to assess this. While ultrasound is excellent in assessing soft tissue lumps, an assessment with a shoulder X-ray or MRI would be more useful if there is a possible bone lesion.
Shoulder ultrasound vs X-ray and MRI
A shoulder X-ray (or shoulder radiograph) is a black-and-white image produced by sending an X-ray beam through the shoulder and getting the images on a film. It is usually the first type of imaging done when there is a shoulder problem, particularly if there is suspicion of shoulder arthritis or fracture. However, they cannot assess the soft tissues like ultrasound and involve a small dose of radiation. To find out more, please see our article about shoulder X-rays.
An MRI examination uses strong magnetic fields and radio waves to produce detailed images of the shoulder. MRI is an excellent modality to assess the shoulder ligaments, tendons and bones. It is particularly useful when there is a significant shoulder injury (like shoulder dislocation). MRI, however, is more expensive and requires you to stay still for 20-30 minutes inside a special machine. Also, it is very difficult to use MRI guidance when performing procedures, unlike ultrasound. To find out more, please see our article about shoulder MRI.