Shoulder Pain: Rotator Cuff Injury, Impingement, or a Muscle That Isn't Working?

Shoulder pain can be frustrating because several very different problems can feel almost identical at first. It hurts to lift the arm. It hurts to reach behind you. Maybe you cannot sleep on that side. Maybe somebody has already told you that you have "impingement" or a rotator cuff problem.

Those are real possibilities. The question is whether the painful tissue is injured, irritated because of the way the shoulder is moving, or both.

The Shoulder Needs Motion and Stability at the Same Time

The shoulder gets its tremendous range of motion by sacrificing some of the bony stability that you have at a joint like the hip. The humeral head, shoulder blade, collarbone, rotator cuff, and surrounding muscles all have to coordinate as the arm moves.

The rotator cuff includes the supraspinatus, infraspinatus, teres minor, and subscapularis. Those muscles do much more than rotate the arm. Together they help keep the humeral head controlled in the socket while larger muscles like the deltoid generate movement. [2]

What "Impingement" Actually Describes

With shoulder impingement, the tissues beneath the acromion can become irritated as the arm is elevated. The bursa and rotator cuff tendons are common pain generators. But saying something is being impinged still leaves another question: why is the space being loaded that way? [1]

Sometimes there is a structural reason, such as a significant tendon tear or bony change. Sometimes inflammation follows repetitive overhead activity. And sometimes the mechanics of the scapula and humeral head are simply not being controlled well.

Scapular Rhythm Matters

Every time you lift your arm, the shoulder blade moves with it. The muscles around the scapula help keep the shoulder aligned, and weakness or altered control can change that motion. [3] In an examination, I pay particular attention to the serratus anterior and different divisions of the trapezius.

The pectoral muscles, latissimus, rhomboids, and even the position of the rib cage can change that movement. This is why I rarely look at a painful shoulder as just a ball-and-socket joint. The shoulder blade and thorax are part of the same system.

A Weak Test Does Not Automatically Mean a Torn Muscle

A weak manual muscle test does not automatically mean a tendon is torn. Pain, effort, nerve function, and the testing position all need to be considered. A suspected tear is assessed through the history and orthopedic examination, with ultrasound or MRI when needed. [2]

That difference changes the plan. A significant tendon tear needs appropriate structural assessment. When pain and movement control are the main limitations, rehabilitation may include exercises for the rotator cuff and shoulder blade muscles. [2] [3] I use the examination to decide what to investigate and which movements to reassess.

Two People, Same Shoulder Pain, Different Pattern

One person may have rotator cuff pain after repetitive overhead work. Another may struggle with shoulder-blade control. Sometimes a nerve problem in the neck produces shoulder or arm symptoms. [1] I discuss that possibility in my article on pinched nerves in the neck and arm pain.

The symptom "shoulder pain" is the starting point. It is not the conclusion.

When Imaging or Further Evaluation Matters

A sudden injury followed by major weakness, inability to lift the arm, deformity, repeated dislocation, significant swelling, or persistent night pain deserves a careful structural evaluation. Progressive numbness or weakness into the arm can also point toward cervical or peripheral nerve involvement. [2]

The goal is not to avoid imaging when it is appropriate. The goal is to use it for the question it actually answers: is there structural damage, and does that damage fit the clinical pattern?

The Takeaway

Shoulder pain may involve a tendon, bursa, joint, nerve, or several structures together. I want to understand both the painful tissue and the movements that bring on symptoms, so the care plan fits the person in front of me.

Before deciding what the shoulder needs, find out what the shoulder is actually doing.

You can read more about how I assess these patterns on my chiropractic and injury-care page, or book a free 15-minute consultation to ask whether an appointment is a good fit.

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About the author: Orie Quinn, D.C., is the founder and lead chiropractor at Ozark Holistic Center in Fayetteville, Arkansas.

Sources

[1] American Academy of Orthopaedic Surgeons. Shoulder Impingement/Rotator Cuff Tendinitis. OrthoInfo.

[2] American Academy of Orthopaedic Surgeons. Rotator Cuff Tears. OrthoInfo.

[3] American Academy of Orthopaedic Surgeons. Scapular (Shoulder Blade) Disorders. OrthoInfo.