Therapeutic ultrasound is one of the most commonly used physical therapy tools for tendonitis, but the clinical evidence is disappointing. Multiple meta-analyses across different tendon conditions have found that ultrasound therapy performs no better than placebo for reducing pain or improving function. The theory behind it is sound, and animal studies show promising biological effects, but those benefits have not translated reliably to human outcomes.
How Therapeutic Ultrasound Is Supposed to Work
The idea behind ultrasound therapy is straightforward: a handheld device sends sound waves into your tissue, producing two types of effects. The first is thermal. As sound energy is absorbed by the tendon, it creates mild, localized heating that increases blood flow to the area. In animal models, this has been shown to reduce swelling and boost collagen production, which is the main structural protein in tendons.
The second effect is mechanical. The pressure waves create tiny vibrations in the tissue that may influence how cells communicate, improve the alignment of collagen fibers, and change the chemical environment around cells in ways that could speed repair. Lab studies on animal tendons have shown increases in tensile strength, collagen synthesis, and overall structural integrity compared to untreated tendons. These results make a reasonable case for why ultrasound should help. The problem is what happens when you test it in actual patients.
What the Evidence Shows for Shoulder Tendonitis
Rotator cuff tendonitis is one of the most studied conditions for ultrasound therapy, and the results are consistently underwhelming. A systematic review and meta-analysis found that therapeutic ultrasound provided no greater benefit than placebo or simple advice for either pain reduction or functional improvement. When ultrasound was added to an exercise program, outcomes were essentially identical to exercise alone. The pooled difference in a standard shoulder function score was just -0.26 points, which is statistically and clinically meaningless.
That same analysis also found that laser therapy outperformed ultrasound for pain reduction, suggesting the issue isn’t that nothing works for shoulder tendonitis, just that ultrasound specifically doesn’t add much.
Tennis Elbow Results Are Similar
Lateral epicondylitis, or tennis elbow, tells the same story. A meta-analysis published in Medicine found that while pain scores did decrease after ultrasound treatment, they also decreased by a similar amount in control groups who received sham treatments. There was no statistically significant difference between real ultrasound and placebo at any time point: not in the short term, not in the mid-term, and not in long-term follow-up. Grip strength, a key functional measure for tennis elbow, also showed no meaningful difference between ultrasound and control groups.
A separate randomized clinical trial published in Nature’s Scientific Reports compared shockwave therapy to ultrasound combined with deep friction massage for tennis elbow. Both groups improved, but shockwave therapy produced dramatically better results. At seven weeks, the shockwave group’s disability score dropped to a median of 1.5 out of a possible score, while the ultrasound-plus-massage group’s score was still at 11.5. That’s a substantial gap.
Achilles Tendonitis: A Weaker Option
For Achilles tendonitis, the picture is comparable. A randomized clinical trial comparing shockwave therapy to ultrasound therapy for mid-portion Achilles tendonitis found that both groups showed improved symptom scores by six weeks after treatment. However, the percentage improvement was significantly greater in the shockwave group than in the ultrasound group. The researchers noted that tendon healing from these therapies is gradual rather than immediate, but ultrasound was the less effective of the two approaches tested.
Why It Might Feel Like It’s Working
If you’ve had ultrasound therapy and felt better afterward, that’s not unusual, but it likely isn’t the ultrasound doing the heavy lifting. Several factors explain why people report improvement during a course of treatment:
- Natural healing: Tendonitis often improves over time on its own, and treatment courses of several weeks overlap with the body’s natural repair timeline.
- Placebo effect: The ritual of treatment, the hands-on attention, and the expectation of relief all produce real, measurable reductions in pain perception.
- Concurrent treatments: Ultrasound is rarely given in isolation. It’s typically part of a physical therapy program that includes stretching, strengthening, and manual therapy, all of which have stronger evidence behind them.
- Mild warming: The gentle heat from ultrasound can feel soothing in the moment, much like a warm compress, without necessarily changing the underlying tendon pathology.
What Works Better
The treatments with the strongest evidence for tendonitis center on loading the tendon progressively. Eccentric exercises, where you slowly lower a weight rather than lift it, have decades of evidence behind them for Achilles and patellar tendonitis. For rotator cuff issues, a structured exercise program targeting the shoulder muscles consistently outperforms passive treatments like ultrasound.
Shockwave therapy (sometimes called extracorporeal shockwave therapy) is a related but distinct technology that delivers higher-energy pulses to the tissue. Unlike conventional ultrasound, shockwave therapy has shown meaningful superiority over control treatments in several trials, particularly for tennis elbow and Achilles tendonitis. It’s worth asking about if your current treatment isn’t progressing.
Laser therapy has also shown better results than ultrasound for shoulder tendonitis specifically, though the overall evidence base for laser is still developing.
Is It Safe?
Therapeutic ultrasound is very low risk. It should not be used over areas with active infection, over a known tumor, or directly on ischemic tissue with poor blood supply. People with implanted devices like pacemakers should avoid certain forms of focused ultrasound. But for standard tendonitis treatment, serious side effects are essentially unheard of. The concern with ultrasound isn’t safety. It’s that you may be spending time and money on sessions that aren’t contributing meaningfully to your recovery, when that time could be spent on more effective approaches like progressive exercise or shockwave therapy.