PTTD and Pronation: Understanding Foot Biomechanics
If you’ve been diagnosed with PTTD, you’ve probably heard the term “pronation” thrown around. Maybe your doctor mentioned overpronation. Maybe you’ve seen it on shoe websites. But what does it actually mean, and why does it matter for your foot health?
Understanding how your foot moves is key to understanding PTTD—and to treating it effectively.
What is pronation?
Pronation is simply the natural rolling motion of your foot when you walk or run. It happens when your foot lands and your arch slightly collapses to absorb shock. Your ankle rolls inward slightly, and your foot flattens out. This is a normal, healthy movement that helps your body handle the impact of each step.
Think of it like a car’s suspension system. Just as a car needs some give to handle bumps in the road, your feet need to flex to absorb force. That’s pronation.
The problem isn’t pronation itself—it’s when pronation becomes excessive.
Normal vs overpronation
Most people pronate to some degree. The question is how much.
Normal pronation means your foot rolls inward about 15 degrees. Your arch collapses slightly to absorb shock, then your body redistributes that force through your leg. Everything works together smoothly.
Overpronation means your foot rolls inward too far—typically more than 15 degrees. Your arch collapses excessively, and your ankle rolls too far inward (this is sometimes called “rolling your ankle”). Over time, this excessive motion can stress tendons, ligaments, and joints.
Here’s a simple way to think about it: normal pronation is like a well-tuned suspension system. Overpronation is like a car with worn-out shocks—everything gets jarred more, and parts wear out faster.
You can often spot overpronation by looking at the wear pattern on your shoes. If the inside edge of your sole wears down faster than the outside, that’s a telltale sign.
The connection between overpronation and PTTD
This is where PTTD comes in. The posterior tibial tendon is the main restraint against excessive pronation. It’s like a rope that keeps your arch from collapsing too far.
When you overpronate, you’re constantly asking your posterior tibial tendon to do more than it should. Every step puts extra stress on this tendon. Over time—months, years, thousands of steps—this repeated strain can cause the tendon to become inflamed, damaged, and eventually dysfunctional.
In a sense, overpronation is both a cause and a consequence of PTTD. The excessive motion damages the tendon, and as the tendon weakens, it can no longer control the motion, leading to more overpronation. It’s a cycle.
This is why addressing pronation is such an important part of PTTD treatment. Simply treating the inflamed tendon isn’t enough if you’re still putting excessive stress on it with every step.
How biomechanics contribute to PTTD
Your feet are the foundation of your entire body. When your feet move abnormally, that abnormal motion travels upward and affects your ankles, knees, hips, and even your lower back.
With PTTD, the biomechanical chain typically works like this:
- Overpronation puts repetitive stress on the posterior tibial tendon
- The tendon becomes inflamed (tendonitis) and eventually degenerates (tendonosis)
- The weakened tendon can no longer support the arch
- The arch collapses further, making the flatfoot worse
- This change in foot position alters how you walk
- The altered gait puts stress on other joints
This is why PTTD often gets worse over time if left untreated. The biomechanical dysfunction doesn’t fix itself—it typically progresses.
Correcting pronation to treat PTTD
The good news: you can break the cycle. Treating PTTD often means addressing the underlying biomechanics that contributed to it in the first place.
Supportive footwear. Shoes with good arch support help limit excessive pronation. Motion-control shoes are designed specifically for this. Avoid shoes with soft, flexible soles that collapse under your weight.
Custom orthotics. For moderate to severe overpronation, custom orthotics prescribed by a podiatrist can provide the extra support needed to control foot motion. These are molded to your specific foot shape and designed to address your specific biomechanics.
Physical therapy. Exercises to strengthen the muscles that support your arch can help. A physical therapist can also teach you gait modifications.
Bracing. In some cases, a brace or ankle-foot orthosis (AFO) helps control motion while the tendon heals.
The goal isn’t to eliminate pronation entirely—that would be unhealthy. The goal is to bring it back into the normal range so your tendons and joints aren’t under constant excessive stress.
Gait analysis: understanding your specific pattern
If you have PTTD, a gait analysis can be incredibly valuable. This is a systematic evaluation of how you walk, typically done by a podiatrist, physical therapist, or at a specialized foot clinic.
During a gait analysis, a specialist watches you walk (often on a treadmill or walkway) and observes:
- How much your ankles roll inward
- How your arches behave throughout the gait cycle
- Whether one foot pronates more than the other
- Any limping or compensating movements
- The timing of your steps
Some clinics use pressure-sensitive mats or video analysis to get detailed measurements. This information helps guide treatment and ensures your orthotics or other interventions are targeted to your specific pattern.
The bottom line
Pronation is a normal movement that helps your body absorb shock. Problems arise when it becomes excessive—overpronation puts repeated stress on the posterior tibial tendon, which can lead to PTTD.
Understanding your foot biomechanics is a key part of treating PTTD effectively. By controlling excessive pronation, you reduce the stress on your tendon and give it a chance to heal. Supportive footwear, custom orthotics, physical therapy, and sometimes bracing all work toward this goal.
If you’re dealing with PTTD, ask your doctor about your pronation pattern. Understanding the mechanics of your own feet helps you make better decisions about treatment—and gives you a clearer picture of what recovery looks like.
Sources
- American College of Foot and Ankle Surgeons: Posterior Tibial Tendon Dysfunction
- Journal of Foot and Ankle Research: Biomechanics of overpronation and PTTD
- American Podiatric Medical Association: Foot biomechanics and orthotics