What is a shoulder X-ray?
A shoulder X-ray (or shoulder radiograph) is a black-and-white image produced by sending an X-ray beam through the area of interest (the shoulder in this case) and getting the images on a film. It is usually the first type of imaging done when a shoulder problem is suspected. The bones absorb the X-ray beam more than the other surrounding soft tissues, and therefore, they are usually well-seen on X-rays.
What will a shoulder X-ray show or diagnose?
Shoulder X-rays are readily available and will provide clinicians with valuable information about the condition of the joint. The main indications for a shoulder X-ray are:
Shoulder arthritis: A shoulder x-ray will assess if there is any arthritis and the degree of changes. It will be useful to assess for arthritis within the main ball and socket shoulder joint (also called the glenohumeral joint), formed by the articulation between the upper end of the arm bone, “the humerus”, and a certain part of the shoulder blade “the glenoid”, as well as the smaller acromioclavicular (AC) joint, located between the collar bone (clavicle) and part of the shoulder blade (called the acromion).
An x-ray will help differentiate the type of arthritis (i.e. shoulder osteoarthritis vs cuff tear arthropathy). Shoulder osteoarthritis refers to the wear and tear changes that can affect the protective layer covering the bone, “the cartilage”. Cuff tear arthropathy (or cuff arthritis) describes a special type of shoulder arthritis secondary to a long-standing rotator cuff tear.
Suspected fractures around the shoulder joint: When there is suspicion of any bony injury, a shoulder x-ray is routinely performed to assess for any fractures. It is also useful to follow up on fractures to assess for bony alignment and fracture healing.
Suspected shoulder dislocation: A shoulder x-ray is very useful in confirming the diagnosis, establishing the type of dislocation and also confirming the restoration of the normal alignment after the shoulder is put back in place.
To assess for the presence of calcification within the rotator cuff tendons (calcific tendonitis)
When there is suspicion of bone problems (like bone infection or mass arising from the bone).
What are the limitations of a shoulder X-ray?
A shoulder X-ray cannot assess the shoulder soft tissues adequately. Therefore, when there is suspicion of shoulder soft tissue problems like rotator cuff tear, subacromial bursitis or frozen shoulder, further imaging like shoulder ultrasound or MRI is usually required.
Shoulder X-ray vs Ultrasound and MRI
Ultrasound is high-frequency sound waves produced by a special machine and can provide useful images of the tissues within the body. It is very useful to assess the various structures within the shoulder joint that cannot be assessed by an X-ray. For example, assess for rotator cuff tendon tear, subacromial bursitis, long head of biceps inflammation but most importantly guides procedures like steroid shoulder injections, hydrodilatation, barbotage treatment for calcific tendonitis and suprascapular nerve block. Ultrasound allows for direct visualisation of the needle to ensure 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. To find out more, please see our article about shoulder ultrasound. Visualisation of the deep structures inside the shoulder joint (like the labrum and the articular cartilage) is difficult with ultrasound.
An MRI examination uses strong magnetic fields and radio waves and produces detailed images of a certain body part. MRI is useful for assessment of the soft tissue structures deep within the joint, for example, when there is suspicion of injury to a certain cartilage type tissue within the shoulder joint called “the labrum” or when there is suspicion of injury to the articular cartilage. This is the thin protective layer covering the bone surface to ensure smooth and frictionless movement. MRI, however, is more expensive and requires you to stay still for 20-30 minutes inside a special machine. To find out more, please see our article about shoulder MRI.
Shoulder conditions and treatments