Shoulder Pain in Ajax: Rotator Cuff Ultrasound Explained

Why does a shoulder that felt perfectly fine last spring now protest every time you reach for a seatbelt, pull on a jacket or roll onto that side in bed? For many adults, the answer lies in a small group of muscles and tendons that most people never think about until they start to hurt: the rotator cuff.

Shoulder pain is one of the most common reasons people see a family doctor, physiotherapist or sports medicine physician, and an ultrasound of the shoulder is one of the tests those providers often request. This article focuses on that one scan. It explains what the rotator cuff is, why it is prone to trouble, why ultrasound suits it so well, and what the appointment actually involves, including the slightly unusual arm positions that surprise many first-time patients. If you want a broader overview of how ultrasound is used for tendons, muscles and ligaments throughout the body, our earlier article on musculoskeletal ultrasound for sports injuries covers that ground.

As always, this is general information for patients in Ajax and the surrounding area. It is not a diagnosis, and decisions about your shoulder belong with your own health-care provider.

A joint built for range, not for stability

The shoulder is the most mobile joint in the body. You can lift your arm overhead, reach behind your back, throw, swim and scratch between your shoulder blades. That freedom comes at a cost. The ball at the top of the upper arm bone sits against a fairly shallow socket, a bit like a golf ball resting on a tee. Bone alone does very little to keep it in place.

Instead, the joint depends heavily on soft tissue. The most important of these structures is the rotator cuff, a set of four muscles that start on the shoulder blade and wrap around the top of the arm bone. Their tendons blend into a kind of sleeve, or cuff, that holds the ball centred in the socket while larger muscles do the heavy lifting.

The four rotator cuff muscles are often remembered together:

• Supraspinatus, which runs across the top of the shoulder and helps start lifting the arm out to the side
• Infraspinatus, at the back, which helps rotate the arm outward
• Teres minor, a smaller muscle at the back that also helps with outward rotation
• Subscapularis, at the front, which helps rotate the arm inward

Close by sit two other structures that commonly appear on shoulder ultrasound reports: the long head of the biceps tendon, which runs in a groove at the front of the shoulder, and the subacromial bursa, a thin, fluid-lined sac that lets the cuff glide beneath the bony roof of the shoulder.

Why rotator cuff problems are so common

Rotator cuff trouble does not always come from a single dramatic injury. It often builds gradually.

Tendons change with age. From middle age onward, many people develop wear in their rotator cuff tendons, and some of these changes never cause symptoms at all. Repetitive overhead activity adds to the load: painting a ceiling, stacking shelves, swimming laps, serving in tennis, or a job that keeps the arms raised for hours. Sometimes a fall onto an outstretched arm or a sudden heavy lift is the trigger.

People who notice shoulder problems often describe patterns like these:

• An ache over the outer upper arm rather than the top of the shoulder itself
• Pain when lifting the arm out to the side, often worst through a middle arc of movement
• Difficulty sleeping on the affected side
• Discomfort reaching behind the back, for example to tuck in a shirt
• A sense of weakness when lifting objects away from the body

These descriptions overlap with several other shoulder conditions, including a stiff or “frozen” shoulder, arthritis and pain that is referred from the neck. Sorting through those possibilities is exactly what your provider’s examination is for, and imaging may or may not be part of that process.

When shoulder pain should not wait for a scan

A community imaging clinic is the right place for planned tests. It is not the right place for an emergency. Call 911 or go to the nearest emergency department if shoulder or arm pain comes with any of the following:

• Chest pain, pressure or tightness, shortness of breath, sweating or nausea, since pain in the left shoulder or arm can sometimes be related to the heart
• A fall or collision after which the shoulder looks deformed or you cannot move the arm at all
• Numbness, coldness or colour change in the arm or hand
• Fever with a hot, red, very painful joint

If you are unsure, Health811 offers free advice from a registered nurse in Ontario.

Why ultrasound suits the rotator cuff

The rotator cuff tendons sit close to the skin, which makes them well suited to ultrasound. Sound waves can reach them easily, and the sonographer can follow each tendon along its length.

A few features make shoulder ultrasound particularly useful:

1. It shows soft tissue that plain X-ray does not. A standard X-ray shows the bones of the shoulder clearly but not the tendons themselves. Your provider may order an X-ray as well, for example to look at the bony roof of the shoulder or at arthritis in the joint.
2. It can watch the shoulder move. As you lift or rotate your arm, the sonographer can see how the tendons and bursa slide beneath the bone.
3. It allows easy comparison. If it would help, the other shoulder can be scanned during the same visit.
4. It does not use ionizing radiation.

Ultrasound does have limits around the shoulder. Sound waves do not pass through bone, so structures deep inside the joint, such as the cartilage rim of the socket, are generally not well assessed this way. If your provider needs to look there, they may choose a different type of imaging. Our article comparing ultrasound and X-ray explains the broader trade-offs between the two tests.

Inside a shoulder ultrasound, step by step

Most of what happens in a shoulder scan is a series of positions. Knowing them in advance makes the appointment feel much more predictable.

Seating and clothing

Shoulder ultrasounds are usually done with you sitting upright on a stool or the edge of the exam table, often on a chair without arms so the sonographer can move around you. You will need to uncover the whole shoulder, so a sleeveless top or tank top is ideal. Otherwise, you may be offered a gown that opens at the back or side.

The front of the shoulder

The sonographer usually starts at the front, where the biceps tendon runs in its groove. You may be asked to rest your forearm on your thigh with the palm facing up. Rotating the arm outward while keeping your elbow tucked against your side then brings the subscapularis tendon into view.

Hand behind the back

To see the supraspinatus, the tendon most often involved in rotator cuff problems, the sonographer needs it to slide out from under the bony roof of the shoulder. The usual way to do this is to place the hand of the affected arm behind your back, either with the back of the hand against your lower back or with the palm resting on your back pocket. This position can be uncomfortable when a shoulder is sore. Move only as far as you can, and tell the sonographer if it is too much; there are alternative positions.

The back of the shoulder

Next, you may be asked to rest your hand on your opposite shoulder so the sonographer can view the infraspinatus and teres minor from behind.

A lifting movement

In some exams, the sonographer will ask you to slowly raise your arm out to the side while they watch the space beneath the bony roof. This shows whether the tendon and bursa glide smoothly or appear to bunch up. It is a brief part of the scan, and you only need to lift as far as is comfortable.

The whole exam generally involves gentle, steady pressure from the transducer and a cool layer of gel. Many patients find the positioning more noticeable than the probe itself.

Words you may see on the report

The report is written for your health-care provider, but patients often read it too. A few terms appear frequently on shoulder reports:

• Tendinosis or tendinopathy: changes in the structure of a tendon, often related to wear or overuse
• Partial-thickness tear: a tear that goes part of the way through a tendon
• Full-thickness tear: a tear that goes all the way through a tendon, from one surface to the other
• Bursitis or bursal thickening: the bursa appears thicker or contains more fluid than usual
• Calcific deposits: small areas of calcium within a tendon
• Effusion: extra fluid in or around a joint or tendon sheath

Seeing one of these words can be unsettling, but they describe what the images show, not how you will feel or what you should do. Many people with tendon changes on imaging manage well with conservative care, and the significance of any finding depends on your symptoms and examination. Your provider is the right person to put the report into context and discuss options with you.

Small things that help on the day

• Bring your health card and the requisition from your provider.
• Wear a sleeveless or loose top that you can slip off one shoulder easily.
• Leave necklaces and long earrings at home, since they can get in the way of the scan near the neck and upper shoulder.
• If certain movements are very painful, mention this at the start, so the sonographer can plan positions around it.
• Shoulder ultrasound usually needs no fasting or bladder preparation, but follow any instructions you are given when you book.

The clinic offers free parking and ground-floor access, which helps if a painful arm makes carrying bags or opening heavy doors difficult.

Bringing your shoulder in for a look

Shoulder pain can take the joy out of everything from yard work to a good night’s sleep, and getting clearer information is often a useful step. Patients from across Ajax, Pickering and Whitby come to Rossland Diagnostic Clinic at Unit 102, 300 Rossland Road East, for ultrasound ordered by their health-care providers.

If you have a requisition for a shoulder ultrasound, call 905-426-3111 or request an appointment online, and our team will help you find a time that suits you, including Saturday mornings.