What Can an X-Ray Show for Shoulder Pain?

Shoulder X-rays are the recommended first-line imaging test for acute shoulder pain, and they reveal more than most people expect from a “just bones” exam. An X-ray can show fractures, joint degeneration, calcium deposits in tendons, bone tumors, and even indirect clues about soft-tissue injuries you cannot see directly on the image. But what an X-ray cannot show is often just as important to understand, because the most common causes of shoulder pain, like rotator cuff tears and labral injuries, live in soft tissue that standard radiographs largely miss.

Fractures and Dislocations

The most straightforward thing a shoulder X-ray reveals is a broken bone. The American College of Radiology lists radiography as the imaging modality of choice for the initial assessment of acute shoulder pain specifically because it catches fractures quickly and cheaply.¹ The standard approach uses two views: an anteroposterior (front-to-back) shot and a trans-scapular Y view, which together allow the clinician to evaluate fracture patterns and classify them for surgical planning.² Proximal humerus fractures, the kind that happen near the top of the upper arm bone, are among the most common fractures in older adults after a fall, and X-rays detect them with roughly 94% accuracy.³

Dislocations are usually obvious on an X-ray: the humeral head sits clearly out of the socket. What’s less obvious are the small bony injuries that often accompany a dislocation. After a first-time anterior shoulder dislocation, tiny fractures can occur along the glenoid rim (the socket’s edge) or on the back of the humeral head, called Hill-Sachs lesions. A study examining how reliably clinicians spot these on X-rays found that every evaluator missed at least one glenoid rim fracture out of ten known cases, and none of them caught all of the Hill-Sachs lesions on the images.⁴ These small bone defects matter because they contribute to recurrent instability, so if your shoulder keeps slipping after a dislocation, a CT scan often follows to catch what the X-ray missed. That said, anteroposterior and axillary views do detect many of these bony lesions in patients with recurrent instability, making the initial X-ray a reasonable starting point.⁵

Arthritis and Joint Degeneration

If your shoulder pain has been building over months or years rather than starting with a specific injury, an X-ray is a solid tool for evaluating arthritis. The classic signs radiologists look for include osteophytes (small bone spurs along the joint margins), narrowing of the joint space between the humeral head and the glenoid, and sclerosis (areas where the bone has become denser and whiter on the image in response to chronic stress).⁶ These features are scored using a standardized grading system that gives clinicians a rough measure of how advanced the degeneration is.

Joint space measurements on X-ray can also track progression. In healthy young shoulders, the central joint space on an anteroposterior view averages about 4.3 mm, but in shoulders with established osteoarthritis, that number drops to around 1.5 mm.⁷ Worth noting: some narrowing occurs naturally with aging even without arthritis, which can make it tricky to interpret a moderately narrowed joint in a 70-year-old. Context always matters.

For rheumatoid arthritis, X-rays pick up bone erosions but miss a lot. In a comparative study, conventional X-rays detected erosions in 26 patients, while MRI found them in 39. MRI also found synovitis (inflamed joint lining) in more than twice as many patients as ultrasound did.⁸ So an X-ray gives a useful baseline picture of how much bone damage has already occurred, but it tends to underestimate early inflammatory disease.

Calcific Tendinopathy

One of the most satisfying X-ray diagnoses in the shoulder is calcific tendinopathy, a condition where calcium deposits form inside the rotator cuff tendons. The deposits show up as bright white patches near the humeral head on a standard shoulder X-ray, and the diagnosis is often immediately apparent.⁹ The supraspinatus tendon, which runs across the top of the shoulder, is the most frequently affected. An X-ray can easily confirm the diagnosis, and ultrasound is sometimes used alongside it for further detail.¹⁰

Beyond simply confirming the presence of calcium, the X-ray appearance helps predict outcomes. The deposits are classified into types based on their radiographic appearance: sharply defined, dense deposits behave differently from fluffy, poorly defined ones. In one study, the average deposit measured about 19 mm across, and a third were the dense, well-defined type.¹¹ The location relative to the acromion (the bony roof of the shoulder) and the deposit type can both influence treatment decisions and help predict whether the problem will resolve on its own or need intervention like needling or shockwave therapy.

Calcific tendinopathy isn’t the only reason you might see white deposits on a shoulder X-ray. Soft-tissue calcifications can also result from chronic conditions like connective tissue disease, vascular calcifications, or even post-traumatic myositis ossificans, where bone forms in damaged muscle tissue.¹² The pattern and location of calcification on the X-ray help distinguish these from ordinary calcific tendinopathy.

Indirect Signs of Rotator Cuff Tears

Here’s the part that surprises many patients: an X-ray cannot directly visualize the rotator cuff tendons. Tendons are soft tissue, and they don’t show up on standard radiographs the way bones do. So if you have a partial rotator cuff tear, your X-ray will probably look completely normal. That’s frustrating but important to understand.

However, X-rays can reveal indirect evidence of a rotator cuff problem, especially when the tear is large or long-standing. The key measurement is the acromiohumeral distance, the gap between the top of the humeral head and the underside of the acromion. In a healthy shoulder, the rotator cuff tendons hold the humeral head centered in the socket, maintaining this gap. When those tendons are severely torn, the humeral head migrates upward, and the gap shrinks. A distance of 7 mm or less strongly suggests a full-thickness rotator cuff tear. One study found that when this gap was 7 mm or less, 90% of patients had a full-thickness supraspinatus tear, and about two-thirds also had an infraspinatus tear.¹³

A separate cross-sectional study found that an acromiohumeral interval below 7 mm had high specificity (around 95%) and a positive predictive value near 90% for full-thickness tears, meaning that when the gap is narrow, you can be quite confident there’s a significant tear. But the sensitivity was limited to about 50%, meaning plenty of full-thickness tears won’t produce a narrowed gap at all.¹⁴ In chronic cases, X-rays may also show decreased muscle opacity from atrophy or secondary arthritis developing where the humeral head grinds against the acromion.¹⁵

So think of the X-ray as a screening tool for rotator cuff problems rather than a diagnostic one. A narrowed gap is a strong signal; a normal gap doesn’t rule anything out. If your doctor suspects a rotator cuff tear based on your symptoms and physical exam, an MRI or ultrasound is the next step regardless of what the X-ray shows.

Bone Tumors and Osteonecrosis

This is the finding nobody wants, but it’s one reason X-rays are ordered even when a fracture or arthritis seems unlikely. An X-ray can reveal bone lesions, whether benign cysts, tumors, or signs of osteonecrosis (where bone tissue dies from reduced blood supply). When a bone lesion is spotted, radiographic features like the sharpness of its borders, the pattern of any periosteal reaction, and whether it has broken through the outer bone surface help the radiologist assess how likely it is to be aggressive or malignant.¹⁶

The shoulder is not the most common site for bone tumors, but it does happen. A retrospective analysis found 15 malignant tumors in patients who had initially been treated for a “frozen shoulder,” including 10 bone tumors and 5 soft-tissue sarcomas. Seven were inside the humerus, and four were in the scapula, where patients hadn’t noticed a mass on their own.¹⁷ That’s a small but sobering reminder that persistent, unexplained shoulder pain that doesn’t respond to conservative treatment warrants imaging.

For osteonecrosis of the humeral head, which can result from steroid use, sickle cell disease, or heavy alcohol consumption, X-rays form the basis for staging the condition, though MRI is typically more sensitive for catching it in the earliest stages before visible bone collapse occurs.¹⁸

Acromioclavicular Joint Separations

The acromioclavicular (AC) joint, the small joint at the top of the shoulder where the collarbone meets the acromion, is a common source of pain after falls onto the point of the shoulder. Standard X-rays can show whether the joint has widened or the clavicle has shifted upward, indicating a separation. In some cases, weighted stress views are used: the patient holds a weight while the X-ray is taken to see if the joint gap increases under load. Normal AC joint laxity under stress is about 3 mm; anything beyond that suggests ligament damage.¹⁹

That said, stress views have fallen somewhat out of favor in routine practice. A survey of surgeons found that about half relied on plain X-rays alone for treatment decisions regarding AC separations, and only 13% routinely used weighted stress views. Only 10% said the stress view would actually change their treatment plan.²⁰ The clinical exam and standard X-rays are often enough to determine severity.

Anatomical Variants That Can Cause Pain

Sometimes a shoulder X-ray reveals an unexpected anatomical variant that helps explain the problem. One of the best-known is the os acromiale, a small separate bone fragment at the tip of the acromion that occurs when the growth plates fail to fuse during adolescence. This unfused piece can become unstable, causing impingement-like symptoms and contributing to rotator cuff problems.

The os acromiale is not always easy to spot on routine anteroposterior views; an axillary view (shot from below the armpit) is often needed to see it properly.²¹ Its prevalence varies across populations. In a Japanese study, os acromiale was found in under 1% of shoulders overall, but the prevalence was significantly higher in patients with shoulder pain compared to those without symptoms (about 1.6% versus 0.2%).²² A study from South Africa found a higher rate of 20% among patients presenting with shoulder pain at a tertiary hospital, with 70% of those cases showing signs of instability and subacromial impingement, and more than a third also having rotator cuff tears.²³ So this is far from a trivial incidental finding if you’re having shoulder pain: it can be the cause or a contributor, depending on whether it is unstable.

Post-Surgical Follow-Up

If you’ve had a shoulder replacement or other hardware placed in your shoulder, X-rays become the primary tool for long-term monitoring. Standard radiography is the first-line follow-up modality for shoulder implants, used to check component position, look for signs of loosening, and track changes over time. Specific complications that X-rays help detect include glenoid component loosening in total shoulder replacements and periprosthetic fractures.²⁴ When the X-ray raises concerns but doesn’t give a clear answer, CT or MRI with metal artifact reduction techniques may follow, but the X-ray remains the workhorse for routine visits after surgery.

Shoulder Pain in Young Throwing Athletes

In children and teenagers, shoulder X-rays look different because the growth plates (physes) are still open. This is actually useful: certain conditions unique to growing athletes can be diagnosed with X-rays. The most well-known is “little league shoulder,” where the growth plate near the top of the humerus becomes irritated and widens from repetitive throwing. The X-ray typically shows widening of the proximal humeral physis compared to the unaffected arm.²⁵ A comparison view of the opposite shoulder is often taken to confirm that the widening is abnormal rather than a normal growth variation. Recent research suggests that little league shoulder may also involve changes at the back of the glenoid, expanding the role the X-ray plays in a thorough evaluation.

Beyond throwing injuries, any pediatric shoulder fracture near a growth plate needs careful X-ray evaluation because the fracture may track through the physis, potentially affecting future growth if not managed properly.

When Shoulder Pain Isn’t Really Coming from the Shoulder

A normal-looking shoulder X-ray is, in a way, a finding in itself. When the bones, joints, and visible soft tissues all appear healthy, it prompts the clinician to broaden the search. Shoulder pain can be referred from the cervical spine, and differentiating neck versus shoulder problems is a genuine clinical challenge because the anatomy overlaps and the painful region reported by the patient can be misleading. The physical examination, with specific provocative tests, becomes essential when the X-ray doesn’t reveal a structural explanation for pain.

There are also visceral causes that can masquerade as shoulder pain. Irritation of the diaphragm, whether from gallbladder disease, a subphrenic abscess, or even cardiac events, can refer pain to the left or right shoulder tip. An X-ray won’t help with those diagnoses, but it serves the important role of ruling out a musculoskeletal cause before the workup moves in a different direction.

Radiation Exposure from a Shoulder X-Ray

If you’re concerned about the radiation dose, shoulder X-rays deliver very little. The effective dose for a standard shoulder view is roughly 0.01 mSv, which is a tiny fraction of the annual background radiation you absorb just from living on Earth (roughly 2 to 3 mSv per year). Using a tighter field of view during the X-ray can reduce the dose by about a quarter compared to standard collimation.²⁶ For perspective, a shoulder X-ray delivers less radiation than a single cross-country flight. The risk is negligible for an individual study, and even repeated X-rays for follow-up after surgery or a fracture pose minimal concern for most adults.