What is Posterior Tibial Tendon Dysfunction? A Complete Guide

If you’ve been told you have posterior tibial tendon dysfunction—or PTTD—you’re probably wondering what exactly that means and why it matters. You’re not alone. This condition is more common than you might think, yet most people have never heard of it until it affects them or someone they love.

Let’s break it down in plain English.

The Simple Definition

Posterior tibial tendon dysfunction (PTTD) is a condition where the main tendon that supports the arch of your foot becomes damaged, inflamed, or weakened. When this tendon isn’t working properly, your arch slowly collapses, causing flatfoot. That’s why you might also hear it called “acquired flatfoot”—because it develops later in life rather than being something you’re born with.

The medical world has started calling it something else too: progressive collapsing foot deformity, or PCFD. That name actually captures what’s happening better—it is progressive, meaning it tends to get worse over time if left untreated.

The Anatomy: How Your Foot arch Works

To understand PTTD, it helps to know a little about how your foot is supposed to work.

Your posterior tibial tendon connects one of your calf muscles (called the tibialis posterior) to the bones on the inner side of your foot. Think of it as a crucial support cable for your arch. Its main jobs are:

  • Holding up your arch while you stand and walk
  • Helping you push off when walking or running
  • Turning your foot inward when you change direction

This tendon does heavy lifting—literally. Every step you take, it absorbs significant force. Over years of use, it can wear out or become overloaded.

There’s another important structure called the spring ligament that works alongside the posterior tibial tendon to support your arch. When the tendon fails, extra stress lands on this ligament, accelerating the problem.

Why It Matters: What Happens When This Tendon Fails

When the posterior tibial tendon isn’t doing its job, your arch doesn’t have the support it needs. The result? A cascade of changes:

  1. Your arch flattens — This happens gradually, which is why many people don’t notice it at first
  2. Your heel shifts outward — As the arch collapses, your heel bone rotates
  3. Pressure moves to the wrong places — You might start feeling pain on the outside of your ankle because the foot is rolling outward
  4. Walking becomes harder — The “push-off” power from your foot decreases

Here’s the thing: early on, you might just feel some achiness after activity. Many people dismiss this as “just being on your feet too much.” But the underlying problem is getting worse, even when you’re not feeling obvious pain.

Who Gets PTTD?

PTTD doesn’t affect everyone equally. Certain factors increase your risk:

  • Age: Most common in people over 40
  • Sex: Women are affected more often than men
  • Weight: Obesity puts extra stress on the tendon
  • Diabetes: People with diabetes have higher rates
  • High blood pressure: There’s an association with cardiovascular health
  • Previous foot injuries: An acute injury can trigger problems
  • High-impact sports — Basketball, tennis, soccer, and running can all strain the tendon

If any of these apply to you, it’s worth paying attention to early warning signs.

The Stages: How PTTD Progresses

PTTD typically moves through several stages:

Stage 1: The tendon is inflamed but still intact. You might have some pain and swelling along the inside of your ankle, but your arch still looks normal.

Stage 2: The tendon has weakened, and your arch starts to sag. You might notice your feet rolling inward. Conservative treatments still work well at this stage.

Stage 3: Significant flatfoot deformity. The tendon is severely damaged, and pain may shift to the outside of the ankle. Surgery becomes more likely.

Stage 4: Arthritis develops in the joints of the foot and ankle. This is the most advanced stage.

The key insight here is that early intervention makes a huge difference. The earlier you address it, the more treatment options you have.

When to Seek Help

You should talk to a doctor or podiatrist if you notice:

  • Pain along the inside of your ankle or foot, especially after activity
  • Swelling around your ankle that won’t go away
  • A flattening of your arch that seems to be getting worse
  • Difficulty standing on your toes
  • Pain on the outside of your ankle
  • Your feet feeling tired or achy more than usual

Don’t wait until the pain becomes severe. Remember: PTTD is progressive. The sooner you get evaluated, the more treatment options you’ll have.

The Good News

The bottom line: most cases of PTTD don’t require surgery, especially when caught early. Custom orthotics, supportive footwear, physical therapy, and activity modifications can all help manage the condition effectively. Even if surgery becomes necessary, modern techniques have come a long way.

The most important thing is awareness. Now that you understand what PTTD is, you can watch for the signs and take action before it progresses.

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