Ultrasound (Orthopedic)

What orthopedic ultrasound is

Ultrasound (also called sonography) uses sound waves to create real-time images of soft tissue. A handheld probe, called a transducer, is placed on the skin and sends sound waves into the body. The waves bounce off tissues and return to create a live image on a screen. Unlike MRI, the image is real-time and dynamic—you can watch tendons and ligaments move as the patient activates the muscle. Unlike CT or X-ray, there is no radiation.

What ultrasound sees well

Orthopedic ultrasound excels at imaging structures near the surface:

• Tendons — rotator cuff (supraspinatus, infraspinatus), Achilles, patellar, hamstring, quadriceps. The sonographer can see if the tendon is intact, has a tear, or is thickened and inflamed.
• Bursas — the fluid sacs around joints. Ultrasound shows if a bursa is swollen (filled with fluid).
• Joints and joint fluid — knee, shoulder, hip, ankle. Fluid inside the joint (effusion) is easy to see.
• Ligaments and cartilage surfaces — though MRI is more detailed for cartilage.
• Nerves — carpal tunnel syndrome, tarsal tunnel, and other nerve compression can be visualized.
• Small muscles and fascia — strain, tear, or inflammation.

Advantages of orthopedic ultrasound

• No radiation — completely safe; no X-rays involved.
• Real-time and dynamic — watch the tendon or ligament move; see if pain reproduces at a certain position.
• High resolution — can see fine anatomic detail in tendons and small structures.
• Cheap — less expensive than MRI.
• Quick — 10–15 minutes; no long wait in a machine.
• In-office guidance — the surgeon can perform the ultrasound and immediately inject medication into the exact spot of pathology (see below).
• Operator-dependent — the skill and experience of the person holding the probe matter. At OSI, our providers are trained in ultrasound and do it themselves.

Ultrasound-guided injection

One of the biggest advantages of in-office ultrasound is injection guidance. Instead of injecting “blind” (based on landmarks and anatomy alone), the surgeon can see the target tissue on the screen in real-time and watch the needle approach and deliver the medication precisely.

This is especially useful for:

• Tendon sheath injections (trigger finger, De Quervain’s) — getting the medicine inside the sheath, not outside.
• Bursa injections (subacromial bursa, trochanteric bursa) — hitting the inflamed bursa without injecting muscle.
• Small joints (wrist, ankle, small hand joints) — visualizing the tiny joint space and the needle within it.
• Nerve blocks — for diagnostic or therapeutic purposes.

Ultrasound guidance dramatically improves accuracy and reduces the risk of missing the target or causing collateral damage.

Limitations of ultrasound

Operator-dependent — quality depends on the skill of the sonographer. Two different operators might see things differently.

Poor for deep structures — the deeper the tissue, the harder ultrasound is to interpret. Deep hip or deep spine structures are hard to image well.

Poor for bone — ultrasound can see the surface of bone, but can’t see inside it or detect hairline fractures. X-rays or MRI are better for bone.

Cannot see through metal — if the patient has metal hardware (plates, screws, implants), ultrasound can’t see beyond it.

When we choose ultrasound

For rotator cuff tendinitis, bursitis, trigger finger, De Quervain’s, Achilles tendinopathy, carpal tunnel, most small-joint problems, and knee effusions, ultrasound is often our first imaging choice. It’s quick, accurate, and immediately allows us to inject if needed. For situations where we need to see cartilage detail, bones, or deep structures, MRI is the better choice.

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