Posterior Tibial Tendonitis in Runners: Symptoms, Treatment & Return to Running

Posterior tibial tendonitis (irritation of the tendon that runs behind the bony bump on the inside of your ankle and supports your arch) is the likely cause when that bump and your arch are tender and the pain builds with running, and it needs a staged treatment plan, not just waiting it out. If the tenderness is along the inner edge of your shin bone instead, that is shin splints, a different injury. Below: how to tell the two apart, what the tendon actually does, symptoms and two home self-checks, why runners get it, a staged treatment plan, whether you should keep running on it, red flags that mean see a doctor, and common questions.

Inner ankle pain that won't settle gets mislabelled all the time, and treating the wrong injury costs you weeks. I see runners mix these two up more than almost any other overuse injury, because they sit in different places and need different fixes. So before the plan, let's work out which one you've actually got, and what is happening in your foot.

Posterior Tibial Tendonitis vs. Shin Splints: How to Tell Them Apart

Press directly behind the bony bump on the inside of your ankle. Tender there, running up into your arch? That's posterior tibial tendonitis. Run a finger along the inner edge of your shin bone instead, in the lower half of your lower leg — tenderness there, along the bone itself, is shin splints.

The two get confused constantly, and it's easy to see why — both show up in runners who've increased their mileage too quickly, and both start as a dull ache that's easy to shrug off. But the mechanism behind each is different. Posterior tibial tendonitis is tendon overload, tied closely to how much support your arch is or isn't getting. Shin splints is irritation of the tissue covering the bone itself, or the muscles attached to it — a different structure altogether. If you're fairly sure it's the shin bone rather than the inner ankle, shin splints is the page you actually want.

What Posterior Tibial Tendonitis Actually Is

Your posterior tibial tendon runs behind the bony bump on the inside of your ankle and does a lot of quiet, unglamorous work supporting your arch every time your foot lands. Ask more of it than it can currently manage, and it gets irritated and inflamed — that's tendonitis, and on its own it's a manageable, treatable injury.

Left unchecked, though, tendonitis can progress into something more serious: posterior tibial tendon dysfunction, where the tendon itself starts to fail at its job of supporting your arch. Over time, that can lead to adult-acquired flatfoot — your arch genuinely collapsing, not just aching. That's the distinction worth understanding early, because it's the difference between a few weeks of rest and a much longer road back.

Symptoms and a Self-Check

Posterior tibial tendonitis usually presents as: pain and tenderness on the inside of your foot and ankle, swelling in the same area, pain when you put weight on the foot, pain when you try to point your toes inward against resistance, and an unsteady gait as your foot compensates.

Two self-checks worth doing at home. First, the single-leg heel raise: stand on the affected foot alone and rise onto your toes. Weakness or pain doing this is a positive sign. Second, the "too many toes" sign — have someone look at your feet from directly behind while you stand normally. If more toes are visible on the affected side than the other, your arch may already be starting to collapse, which points towards progression rather than straightforward tendonitis.

Why Runners Get It

Three things drive this, and all three are worth checking honestly rather than assuming you already know which is yours. Overpronation and low or fallen arches are the primary structural risk factor — your arch simply asks more of the tendon than a higher, better-supported arch would. A sudden jump in mileage or intensity is the second, giving the tendon less time to adapt than it needs. Worn-out shoes that have lost their arch support are the third, and one of the easiest to fix.

For the broader picture on avoiding overuse injuries generally, it's worth reading up on preventing overuse injuries.

How to Treat It: A Staged Protocol

This isn't a one-size-fits-all injury, and treatment escalates in stages depending on how it responds. Here's the framework I walk runners through, alongside — not instead of — your physician's own assessment:

Stage	What it involves
1. Rest, ice, non-steroidal anti-inflammatory drugs (NSAIDs)	Stop or significantly cut back running; ice and anti-inflammatories (ibuprofen) to settle the initial inflammation.
2. Mechanical offloading	Shoe inserts or foam pads, or a specially fitted walking boot, to limit motion at the tendon and let inflammation properly settle. Move here if rest alone isn't working.
3. Short leg cast	More complete immobilisation when Stage 2 hasn't been enough on its own.
4. Imaging and surgical assessment	A magnetic resonance imaging (MRI) to assess the extent of tendon damage and whether surgery is warranted — ranging from a clean-up of the tendon through to full reconstruction.

Depending on the severity of your case and how it responds through those stages, surgery may eventually be considered — ranging from a straightforward clean-up of the tendon through to a full reconstruction. That's a ceiling worth knowing about, not a scare tactic: the overwhelming majority of cases never get anywhere near it.

This staged framework is exactly what I talk runners through once a physician has confirmed the diagnosis — it's a structure to understand where you sit, not a replacement for your physician's own judgement on imaging or surgery.

Should You Keep Running on It?

Mild or early symptoms — a dull ache that doesn't change how you walk — are usually fine to run through cautiously, provided you reduce your volume and keep a close eye on how the pain responds day to day. But once swelling shows up, weight-bearing hurts, or you get a positive heel-raise or too-many-toes result, stop running and move into Stage 2 of the protocol above rather than pushing on.

Once you're cleared and pain-free, ease back in with a graduated return-to-running protocol rather than jumping straight back to your old mileage.

When to See a Doctor (Red Flags)

Get it looked at properly, rather than self-managing, if: you can't bear weight on the foot at all; you notice visible or progressive flattening of your arch, or any change in the shape of your foot — this is the escalation signal specific to this condition, and it means possible progression to tendon dysfunction, not just tendonitis; or you've had no improvement after two to three weeks of Stage 1-2 self-care. Any one of those warrants imaging and a physician's opinion, not more time waiting it out.

For the full rundown of red-flag symptoms across running injuries, it's worth knowing what applies beyond just this condition too.

Posterior tibial tendonitis is manageable once you know what you're actually dealing with — and knowing that starts with telling it apart from shin splints. Get the differential right, work through the staged protocol properly, and give it the time it needs, and you'll be back to full training without your arch paying the price for it. :)

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