Rotator cuff tendinitis is swelling or irritation of the tendons that hold your shoulder joint together, almost always caused by repetitive overhead motions. It’s one of the most common shoulder problems, and it develops when the tendons connecting your rotator cuff muscles to bone get pinched between the bones of your shoulder, a process called impingement. The good news: about 80% of people with partial rotator cuff damage improve with nonsurgical treatment, though full recovery can take up to a year.
How Your Rotator Cuff Works
Your rotator cuff is a group of four muscles and their tendons that wrap around your shoulder joint, keeping your upper arm bone seated in its shallow socket. The supraspinatus sits on top and helps you lift and rotate your arm. The subscapularis runs along the front and lets you hold your arm out away from your body. The infraspinatus and teres minor cover the back, helping you turn and rotate your arm outward. Together, these muscles stabilize every shoulder movement you make, from throwing a ball to reaching for a shelf.
Between these tendons and the bony roof of your shoulder (called the acromion) sits a small, fluid-filled cushion called a bursa. The space the tendons and bursa share is tight, and when anything causes swelling in that area, things start rubbing together in ways they shouldn’t.
What Causes the Tendons to Swell
Rotator cuff tendinitis is almost always an overuse injury. Repetitive arm movements, especially those that bring your arm above shoulder height, gradually irritate the tendons. As they swell, the already-tight space beneath your acromion gets even smaller, and the bone begins to pinch the inflamed tendon each time you raise your arm. That pinching causes more swelling, which causes more pinching, creating a cycle that worsens without rest or treatment.
Several factors make this more likely to happen:
- Repetitive overhead work or sports. Painters, electricians, carpenters, swimmers, baseball players, and tennis players are at higher risk because their activities repeatedly compress the subacromial space.
- Age. Risk increases steadily with age. The tendons lose blood supply and elasticity over time, and bone spurs can develop on the acromion, narrowing the space further.
- Bone shape. Some people have an acromion that curves downward or hooks at the edge rather than lying flat. This structural variation pinches the tendons even during normal movement.
- Bursitis. The bursa cushioning the joint can become inflamed on its own, swelling enough to crowd the tendons and trigger impingement.
A study of 683 workers across multiple industries found supraspinatus tendinitis (the most commonly affected tendon) in about 7 to 9% of workers, with age as a consistent risk factor regardless of occupation.
What It Feels Like
The hallmark symptom is a dull, deep ache in the shoulder that gets worse with specific movements. Reaching overhead, combing your hair, or trying to get your hand behind your back to tuck in a shirt or fasten a bra can all reproduce the pain. Many people also notice the pain disrupts sleep, particularly when lying on the affected side.
Arm weakness often accompanies the pain, not because the muscle itself is damaged at first, but because your body guards against motions that hurt. Over time, if the tendon stays inflamed and you avoid using it, genuine weakness can develop from disuse. The pain typically builds gradually over weeks or months rather than appearing suddenly, which helps distinguish tendinitis from an acute tear.
How It’s Diagnosed
Diagnosis usually starts with a physical exam. Your doctor will move your arm into specific positions designed to reproduce the impingement and pinpoint which structures are involved. One well-studied approach combines three tests: a maneuver that passively flexes your arm to compress the subacromial space, a test that checks for pain through a specific arc of motion, and a strength test of one of the rotator cuff muscles. Research from Johns Hopkins found that this three-test combination yields a 95% probability of correctly identifying impingement syndrome.
If the clinical picture is unclear or a tear is suspected, imaging comes next. X-rays can reveal bone spurs or an abnormally shaped acromion. An MRI provides a detailed view of the soft tissue, showing whether the tendon is merely inflamed or partially torn.
Treatment Without Surgery
Most rotator cuff tendinitis responds to conservative treatment. The first step is modifying or stopping the activity that caused the problem. Ice and over-the-counter anti-inflammatory medications help manage pain and reduce swelling in the early stages.
Physical therapy is the cornerstone of long-term recovery. A therapist will guide you through exercises that strengthen the rotator cuff muscles, improve flexibility, and correct movement patterns that contributed to the impingement. The goal is to restore the balance of forces around the joint so the tendons have room to move freely again.
Corticosteroid injections offer another option, particularly when pain is severe enough to interfere with therapy. A study comparing the two approaches found that injections provided faster relief: 77% of patients treated with injections had successful outcomes at seven weeks, compared to 46% of those doing physical therapy alone. By six months to a year, however, the difference between the two groups had largely disappeared. Injections work well as a short-term bridge to reduce pain enough that you can participate in rehab, but they don’t replace the strengthening work that prevents recurrence.
Recovery timelines vary. Mild cases caught early may improve in a few weeks with rest and targeted exercises. More established cases often take three to six months of consistent rehab. Chronic or partial-thickness tears treated conservatively can take up to a year to fully improve.
When Surgery Becomes an Option
Surgery is typically considered only after several months of conservative treatment have failed to relieve symptoms. The most common procedure is subacromial decompression, where a surgeon shaves away bone spurs or a portion of the acromion to create more room for the tendons. This can be done arthroscopically through small incisions or through a slightly larger open incision, depending on severity and surgeon preference. If imaging reveals a partial or full-thickness tear alongside the tendinitis, the surgeon may repair the torn tendon at the same time.
Preventing Recurrence
Because rotator cuff tendinitis is driven by repetitive overhead stress, prevention focuses on reducing how often and how long your arms work above shoulder height. Research from the University of Waterloo’s Centre for musculoskeletal disorder prevention offers practical guidelines. The subacromial space is smallest when your arm is elevated between 60 and 90 degrees, so keeping your upper arm below 60 degrees of elevation whenever possible significantly reduces compression on the tendons.
For workers who can’t avoid overhead tasks, the evidence suggests keeping tool weight under 1.25 kg during overhead shifts, limiting overhead work to less than 50% of your duty cycle, and breaking continuous overhead time into shorter intervals with rest in between. Overhead endurance improves by up to 25% when the same total work time is divided into smaller chunks rather than done all at once. Fatigued rotator cuff muscles lose their ability to stabilize the arm bone in the socket, so resting frequently lets those muscles recover before they lose effectiveness.
Outside of work, a regular routine of rotator cuff strengthening exercises, particularly external rotation with a resistance band, helps maintain the muscular support the joint needs. Warming up before overhead sports, avoiding sudden increases in training volume, and keeping your shoulder blades engaged during lifting all reduce the cumulative stress on the tendons.