Shoulder X-rays are done for a variety of indications ranging from trauma and falls to chronic pain in the shoulder. We usually take multiple X-rays of the shoulder which gives us the ability to best detect abnormalities.
What are shoulder X-rays?
A shoulder X-rays are a series of X-rays done to identify abnormalities of the bones and joints of the shoulder. Each radiology department may have variations on the types of views obtained.
X-rays are done using radiation which creates pictures of your body in shades of white and black, depending on the amount of radiation absorbed by different tissues. Bone will show up as whiter than tissues like the lung.
Shoulder X-ray anatomy
Shoulder X-rays show us the upper part of the humerus or arm bone. We see the glenoid or socket of the shoulder joint. We see the scapula or shoulder blade. Shoulder X-rays show the clavicle which connects the breast bone to the shoulder. The upper part of the lung and ribs are also seen.
Normal shoulder X-ray
A normal shoulder x ray will demonstrate the bones of the shoulder to have expected normal appearance without breaks, bone lesions, or abnormal bone structure.
The head of the humerus or upper arm will be positioned within the socket of the shoulder. The clavicle will be aligned with the acromion or upper edge of the shoulder blade (scapula).
The tissues around the shoulder will be uniform with masses, calcifications or foreign bodies.
The upper lung will be normal without mass, collapse or fluid.
The visualized ribs will all be intact without a break.
Shoulder X-ray views
These are the types of X-rays we do for the shoulder. They can be different across hospitals. They are the same for the right and left shoulder.
The different views of the shoulder help us best detect abnormalities. For example, three X-ray views will better detect abnormalities than one X-ray. There are many different types of X-ray views of the shoulder and some of the more common ones are listed below.
This is a common standard view taken from the front to back of the shoulder. We can see all the bony structures of the shoulder and the joint alignment. We can see part of the lung, the ribs, and surrounding tissues.
Internally rotated view
This is another standard view in a shoulder X-ray series. The shoulder is rotated internally and we can see the lesser tuberosity of the humerus in profile.
Externally rotated view
This is another standard view with the shoulder rotated externally. We can see the greater tuberosity of the humerus in profile.
Y view or lateral view
This view is taken 90 degrees (orthogonal) to the ap view. In other words, this view is taken from the side of shoulder or a profile view of the shoulder. This view allows us to see the relationship between the humeral head and glenoid and whether they are aligned correctly.
This is a modified view which allows us to see the shoulder joint to the best advantage.
Another X-ray view which allows us to see the shoulder joint and it’s relationship.
What can a shoulder X-ray diagnose?
Shoulder X-rays can diagnose many abnormalities of the bones and joints of the shoulder.
Dislocated shoulder X-ray
A dislocated shoulder is one where the humeral head or upper part of the arm bone is no longer aligned with the glenoid or socket of the shoulder joint. The dislocation can be in front of the shoulder or behind it. We can sometimes see associated breaks in the bone.
The acromioclavicular joint can also undergo a dislocation or separation. This is the joint where the clavicle and upper part of the shoulder blade (scapula) meet.
Broken shoulder X-ray
There are many different types of fractures we can see involving the shoulder. We will usually see a break going through the bone, seen as a dark line. Fragments may be separated and migrate away from the fracture site. Some fractures may be hard to see or hairline in appearance.
Shoulder arthritis and it’s severity can often be visualized on shoulder X-rays. This is where the cartilage or end of the bone gets worn down. This can result in pain, stiffness and disability.
Shoulder bone lesion
This is when we identify a focal abnormality that replaces normal bone. This may be a cyst, growth or tumor. We can not always tell if the lesion is cancerous or not.
Shoulder soft tissue abnormality
The soft tissues are not well evaluated on X-rays but we can sometimes see abnormalities. By soft tissues we mean everything outside the bones and visualized lung. We can sometimes see calcifications, masses or foreign bodies.
What can a shoulder X-ray miss?
A shoulder X-ray does not show everything that can be wrong with the shoulder.
A shoulder X-ray can miss broken bones, particularly when they are not separated or hairline in appearance.
A shoulder X-ray may miss some bone lesions or growths.
A shoulder X-ray does not show us important non bony components of the shoulder like the rotator cuff and glenoid. Abnormalities of these structures can lead to pain and instability. They can be assessed with MRI.
A shoulder X-ray does not evaluate the soft tissues well and can miss abnormalities. MRI is best for the soft tissues around the shoulder.
A shoulder X-ray will not identify fluid in the joint or collections around the shoulder. MRI is best for identifying fluid.
Shoulder X-ray: summary
A shoulder X-ray is done to evaluate the bones and joints of the shoulder. A shoulder X-ray series is done to best detect abnormalities. The series consists of X-rays that can be different across hospitals.
While a shoulder X-ray can detect many abnormalities, a normal shoulder X-ray does not exclude all abnormalities of the shoulder. Significant abnormalities may not be seen on a shoulder X-ray. Further imaging with CT or MRI will detect additional abnormalities.