PTTD imaging tests: what to expect from diagnosis

Getting diagnosed with posterior tibial tendon dysfunction involves more than just a visual examination. Your doctor will likely order imaging tests to confirm the diagnosis, assess the severity of your condition, and plan appropriate treatment. Understanding what each test shows helps you feel more prepared for your appointment.

Starting with a physical exam

Before any imaging, your doctor performs a physical examination to assess your foot and ankle. This exam often includes:

Too many toes sign. When you stand, your doctor looks at your feet from behind. In PTTD, the arch collapses and toes rotate outward, making more toes visible than normal on the affected side.

Single limb heel rise. You’ll be asked to rise up on one foot. People with PTTD often cannot do this or have significant difficulty due to tendon weakness.

Range of motion testing. Your doctor checks how far your ankle moves and whether movement causes pain.

These tests provide important clues, but imaging gives a clearer picture of what’s happening inside your foot.

X-rays: the first step

X-rays are usually the first imaging test ordered. They show bones and joint positioning but not soft tissues like tendons.

What X-rays reveal

  • Whether your arch has collapsed
  • Joint spacing (narrowing suggests arthritis)
  • Bone spurs or abnormalities
  • Position of your heel bone and forefoot

X-rays help determine the stage of your PTTD and whether arthritis has developed. They’re quick, inexpensive, and available at most medical facilities.

What they don’t show

X-rays cannot visualize the posterior tibial tendon itself. They won’t show tendon tears, inflammation, or degeneration. That’s where other tests come in.

MRI: detailed tendon visualization

Magnetic resonance imaging provides highly detailed images of soft tissues, including the posterior tibial tendon itself.

When MRI is used

  • To confirm tendon tears or degeneration
  • When surgery is being considered
  • If symptoms don’t match what X-rays show
  • To evaluate the quality of tendon tissue

What MRI reveals

  • Tendon tears (partial or complete)
  • Inflammation around the tendon
  • Tendon degeneration or thickening
  • Condition of nearby soft tissues
  • Any associated pathology

MRI is excellent for surgical planning because it shows exactly what the surgeon will encounter.

Considerations

MRI takes 30-45 minutes and requires lying still in a confined space. Some people with claustrophobia find this challenging. The magnet means you cannot have certain metal implants.

Ultrasound: real-time assessment

Ultrasound uses sound waves to create images of soft tissues. It’s less common than X-ray or MRI but offers unique advantages.

Benefits of ultrasound

  • Shows the tendon moving in real-time
  • Faster and less expensive than MRI
  • No radiation or magnet concerns
  • Can compare both feet side-by-side during the same exam

What ultrasound reveals

  • Tendon tears and inflammation
  • Tendon movement and function
  • Fluid around the tendon
  • Changes with different foot positions

Some podiatrists and orthopedists have ultrasound in their offices, making it convenient for follow-up exams.

CT scans: complex cases

Computed tomography is used less frequently for PTTD but has specific applications.

When CT is used

  • For complex deformities
  • When detailed bone imaging is needed
  • As part of surgical planning for severe cases

What CT reveals

  • Detailed bone structure
  • Complex fracture patterns
  • Joint positioning in three dimensions

CT involves radiation exposure, so it’s reserved for situations where the information cannot be obtained another way.

Which test do you need?

The test your doctor orders depends on your specific situation:

Early-stage PTTD. X-rays are usually sufficient to confirm diagnosis and assess foot structure.

Advanced PTTD. X-rays plus MRI help evaluate tendon damage and plan surgery.

Unclear diagnosis. MRI provides the most complete picture of soft tissue involvement.

Surgical planning. MRI or sometimes CT gives surgeons the detailed information they need.

Not everyone needs every test. Your doctor chooses based on your symptoms, examination findings, and treatment plans.

What to expect

Here’s a quick rundown of what each test involves:

X-ray. Takes a few minutes. You stand or sit with your foot positioned. No preparation needed.

MRI. Takes 30-45 minutes. You lie on a table that slides into the magnet. Some clinics offer “open MRI” for claustrophobic patients.

Ultrasound. Takes 15-20 minutes. A technician moves a probe over your ankle. No special preparation.

CT. Takes 10-15 minutes. You lie on a table that rotates through the scanner. May require contrast dye in some cases.

After imaging

Once your doctor has imaging results, you’ll discuss what they show and what that means for your treatment. Imaging helps determine whether conservative treatment is appropriate or if surgery becomes more likely.

Ask your doctor to explain what they see in your images. Understanding your condition helps you make informed decisions about your care.

Sources

  • American College of Radiology: Appropriateness criteria for foot and ankle imaging
  • Journal of Foot and Ankle Surgery: Imaging in adult acquired flatfoot deformity
  • Radiopaedia: MRI of posterior tibial tendon dysfunction