Yes, ultrasound can show tendon damage, and it’s one of the most commonly used imaging tools for evaluating tendons throughout the body. It can detect full tears, partial tears, chronic degeneration, calcium deposits, and inflammation. Its accuracy varies depending on the type and severity of damage, with full-thickness tears being much easier to spot than subtle partial tears.
What Ultrasound Can See in a Damaged Tendon
Healthy tendons have a distinctive appearance on ultrasound: a tightly organized, fibrous pattern that shows up as bright, parallel lines. When a tendon is damaged, that pattern breaks down in ways an experienced sonographer can identify.
A degenerated tendon appears thickened and darker than normal on the screen, with a loss of the organized fiber pattern. This is the hallmark of tendinopathy, the chronic wear-and-tear damage that develops over time in tendons like the Achilles or the rotator cuff. Tendon tears are graded by severity: a low-grade tear shows up as tendon thickening, a high-grade tear appears as thinning and weakening of the tendon, and a complete rupture shows a visible gap where the fibers have pulled apart, sometimes with the torn ends retracted away from each other.
Ultrasound is also more sensitive than standard X-rays at detecting calcium deposits inside tendons, a condition called calcific tendinitis. These deposits show up as bright spots, sometimes casting a shadow behind them on the image. The size and sharpness of that shadow help classify the type of deposit.
How Accurate Is It?
Ultrasound performs best when the damage is severe and worst when it’s subtle. For full-thickness rotator cuff tears, one prospective study found ultrasound had 100% specificity (meaning it almost never incorrectly calls a healthy tendon torn) and an overall accuracy of 91.3%. When ultrasound shows a complete tear, you can trust the finding.
Partial tears are a different story. The same study found sensitivity dropped to just 25.8% for partial-thickness rotator cuff tears. That means ultrasound missed roughly three out of four partial tears. Specificity remained high at 91.8%, so a positive finding is still reliable, but a clean ultrasound doesn’t rule out a partial tear. If your doctor suspects a partial tear and the ultrasound looks normal, MRI is typically the next step.
These numbers reflect the rotator cuff specifically, but the general pattern holds across other tendons: ultrasound is excellent at confirming complete ruptures and chronic degeneration, and less reliable for catching small or partial tears.
The Advantage of Real-Time Imaging
One thing ultrasound does that MRI cannot is show your tendon while it moves. During a dynamic ultrasound, the examiner watches the tendon on screen as you flex, extend, or rotate the joint. This is particularly useful for shoulder injuries, where the examiner can observe the rotator cuff tendons sliding under the bone during arm movements to identify impingement, subtle instability, or tears that only become visible under load.
Dynamic imaging also helps evaluate tendons that may sublux, or slip out of their normal groove. The long head of the biceps tendon, for instance, can pop in and out of position in ways that only show up during movement. A static MRI taken with your arm still might miss this entirely.
Detecting Inflammation and Blood Flow
A specialized mode called Power Doppler can detect abnormal blood vessel growth inside and around a damaged tendon. In healthy tendons, blood flow is minimal. When chronic damage triggers a healing response, new tiny blood vessels form within the tendon tissue. A study of 63 symptomatic Achilles tendons found that 63% had detectable new blood vessel growth at the time of diagnosis. At a 12-week follow-up, the degree of blood vessel growth correlated significantly with pain levels and functional scores, making it a useful marker for tracking how the tendon responds to treatment over time.
Ultrasound can also pick up fluid collection around a tendon (a sign of active inflammation) and thickening of the tendon sheath, both of which point toward an acute flare or ongoing irritation.
Where Ultrasound Falls Short
The biggest technical pitfall is something called anisotropy. Tendons are highly sensitive to the angle of the ultrasound beam. If the probe tilts even slightly off-perpendicular, a perfectly healthy tendon can appear abnormally dark, mimicking the look of degeneration or a tear. This artifact is especially pronounced where tendons curve around bones or at their attachment points. An experienced examiner knows to adjust the probe angle to confirm whether a dark area is real damage or just an artifact, but less experienced operators can be fooled.
Ultrasound is also operator-dependent in a way that MRI is not. The quality of the exam depends heavily on the skill and experience of the person holding the probe. A radiologist or sports medicine physician who performs musculoskeletal ultrasound regularly will catch things a less experienced examiner might miss. If your ultrasound results don’t match your symptoms, the quality of the exam itself is worth considering.
Deep structures can also be harder to evaluate. Tendons close to the surface, like the Achilles or patellar tendon, image well. Tendons buried deeper inside the body or obscured by bone may not be as clearly visible, and MRI may provide better detail in those cases.
Monitoring Tendon Repairs After Surgery
Ultrasound plays an important role after tendon surgery, too. It can confirm that a surgical repair is still intact by showing the thickened repair site and the echogenic (bright) suture material holding the tendon ends together. During recovery, the examiner can watch the repaired tendon glide in real time as you move, checking that the repair is functioning mechanically.
Signs of trouble include a fluid-filled gap forming between the repaired tendon ends, suture threads that span across a gap rather than sitting within solid tendon tissue, or dense scar tissue encasing the tendon and preventing it from gliding. When the gap between cut ends exceeds more than a few millimeters, there may be a loss of mechanical advantage, meaning the tendon can no longer effectively transmit force across the joint. Some fluid and sheath thickening are normal in the first few months after surgery, so interpreting post-surgical ultrasound requires clinical context.
What to Expect During the Exam
A musculoskeletal ultrasound typically takes 15 to 30 minutes, though complex cases can run longer. No special preparation is needed. You may be asked to wear loose clothing or change into a gown so the examiner can access the area easily. Leave jewelry at home if it’s near the joint being examined.
During the exam, warm gel is applied to the skin and a handheld probe is pressed against the area. You’ll likely be asked to move the joint in specific directions so the examiner can watch the tendon dynamically. The exam is painless for most people, though pressing on an already-tender area can be uncomfortable. There’s no radiation involved, and results are often available quickly since the examiner is interpreting the images in real time.