Posterior tibial tendinopathy typically causes pain behind the medial ankle and along the tendon toward the navicular, while plantar fasciitis more commonly causes plantar heel pain near the medial calcaneal origin. Both may produce arch discomfort, which is why exact symptom location, heel-rise loading, walking behavior and palpation matter.
Two structures, two different paths
The tibialis posterior muscle sits deep in the back of the lower leg. Its tendon curves behind the medial malleolus, the bony bump on the inside of the ankle, and runs forward under the arch to attach mainly at the navicular, with further attachments across the midfoot. It helps invert the foot, point it down and control the medial arch as weight moves over the foot during walking.
The plantar fascia is a thick band of connective tissue on the sole. It starts at the underside of the heel bone, close to its inner side, and fans forward to the base of the toes. It helps support the arch and stiffens the foot as the toes extend at push-off.
Both structures support the arch, so both can produce arch discomfort. Their most typical pain sites are different, and that is the starting point for telling them apart.
Where does posterior tibial tendinopathy hurt?
Pain is usually felt:
- Just behind and below the inside ankle bone
- Along the path of the tendon as it curves forward under the ankle
- Near the navicular, the bony prominence on the inside of the midfoot, where the tendon attaches
It tends to rise with walking, especially longer distances or uneven ground, running, hiking and rising onto the toes. The area may be tender to touch and, in some people, mildly swollen along the tendon. Some notice that one foot looks flatter than the other or that they cannot rise onto the toes of the painful foot as easily.
Where does plantar fasciitis hurt?
Plantar fasciitis usually causes pain under the inner heel, close to where the fascia attaches. Pain with the first steps after sleep or rest is common and relevant, but it is not unique to plantar fasciitis, and not everyone with plantar fasciitis has it. Standing, walking and running can all aggravate it, and the heel is often tender to firm pressure on its underside. Lifting the big toe upward, which tightens the fascia through what is called the windlass mechanism, may reproduce the familiar pain in some people.
More on assessment and treatment is on the plantar fasciitis page.
A side-by-side comparison
| Feature | Posterior tibial tendinopathy | Plantar fasciitis |
|---|---|---|
| Usual pain site | Behind the inside ankle bone, along the tendon, near the navicular | Under the inner heel |
| Common aggravators | Walking, running, uneven ground, heel raises, inversion effort | First steps after rest, prolonged standing, walking |
| Key loading test | Single-leg heel rise, resisted inversion | Tenderness at the heel, toe extension tightening the fascia |
| Alignment findings | May be normal early; arch lowering or heel drifting outward in advanced cases | Usually no progressive change in alignment |
These are tendencies, not rules. Both conditions can occur together, and arch pain can come from either.
How does heel-rise loading help?
Rising onto the toes on one leg demands strong work from the tibialis posterior, which helps lock the heel into a stable, inverted position. Pain during the rise, an inability to complete it, the heel not swinging inward as it should, or fatigue after only a few repetitions all point toward the tendon.
In a clinical study of 52 people with medial foot or ankle pain, two physical therapists assessed four common tests. The single-leg heel raise was the most reliable between examiners, with substantial agreement (kappa 0.74), and it was the test most strongly related to grayscale ultrasound changes in the tendon (odds ratio 5.8, 95% CI 1.7 to 20.4). The wide confidence interval and the authors' finding of a disconnect between clinical and ultrasound findings are reminders that no single test settles the diagnosis.
Plantar fasciitis does not typically cause a weak or incomplete single-leg heel rise, although the heel may be sore during the rise.
A 2018 systematic review comparing people with posterior tibial tendon dysfunction to pain-free controls found large deficits in heel-rise endurance, forefoot adduction-inversion strength and arch height. These are group findings; an individual with early tendon pain may show only some of them.
What can walking and standing tell you?
Watching someone walk and stand helps separate an irritated tendon from a mechanical change in the foot. In early tendinopathy, alignment often looks normal. In more advanced posterior tibial tendon dysfunction, now described as part of progressive collapsing foot deformity, the arch may lower, the heel may drift outward, and the forefoot may angle away from the midline. Comparing both feet matters, because many people have naturally low arches without any tendon problem.
When alignment is changing, the foot needs to be assessed as a mechanical problem rather than as tendon pain alone. That shift is covered in when do orthotics help posterior tibial tendon dysfunction?
What can palpation tell you?
Pressing along the tendon behind the ankle and at the navicular often reproduces tendon pain, while pressing under the heel often reproduces plantar fascia pain. Palpation is useful, but it is not definitive. Several tendons, a nerve and joint structures sit close together around the inner ankle, and tender areas can overlap. Palpation is most useful combined with symptom location and loading tests.
Other causes of medial foot and ankle pain
- Tarsal tunnel and tibial nerve irritation: burning, tingling, numbness or altered sensation, sometimes radiating into the sole. Neural symptoms like these point away from a purely tendon problem.
- Flexor tendons: the flexor digitorum longus and flexor hallucis longus run in the same medial ankle corridor and can cause similar pain.
- Navicular or midfoot bone pain: focal bony tenderness, a history of trauma or rapidly increased training, or an atypical load pattern may suggest a stress injury and change the pathway.
- Ankle or subtalar joint pain: joint-line pain, swelling, restricted joint motion or a previous sprain point toward the joint.
- Progressive collapsing foot deformity: a mechanical deformity involving the hindfoot, arch and supporting ligaments rather than tendon pain alone.
When does imaging help?
Imaging is not routinely needed for early tendon pain that matches the examination. It becomes more useful when a tendon tear is suspected, the diagnosis is unclear, or symptoms are not improving.
MRI is particularly useful when a significant posterior tibial tendon tear is suspected. A 2024 systematic review of 12 studies, which included 645 tendons assessed with MRI, 133 with ultrasound and 97 with radiography, found MRI sensitivity up to 95%, specificity up to 100% and accuracy of 96% for detecting posterior tibial tendon tears. Ultrasound showed 80% sensitivity and 90% specificity for tendinopathy, and 90% sensitivity and 80% specificity for peritendinosis when compared with MRI. Ultrasound remains useful for tendon assessment, especially when a dynamic and lower-cost examination is appropriate.
Imaging helps answer structural questions, but tendon structure alone does not replace the clinical examination. In one small rehabilitation study, symptoms, function and heel-rise performance improved after eccentric exercise even though the ultrasound appearance of the tendon remained abnormal.
Can both problems exist together?
Yes. Changes in how the foot loads can irritate more than one structure, and a person can have tendon pain behind the ankle and heel pain under the foot at the same time. When both are present, treatment addresses each source rather than assuming one explains everything.
How Novo approaches medial foot pain
We localize the pain, test the tendon under load with heel raises and resisted inversion, assess foot posture and walking side to side, screen for nerve and joint sources, and decide whether imaging would answer a specific question. Treatment follows the diagnosis. See how we approach posterior tibial tendinopathy and plantar fasciitis, read what the evidence shows about shockwave for posterior tibial tendinopathy, or book a new patient exam.
References
- Ross MH, Smith MD, Mellor R, et al. Clinical tests of tibialis posterior tendinopathy: are they reliable, and how well are they reflected in structural changes on imaging? Journal of Orthopaedic & Sports Physical Therapy. 2021;51(5):253-260. PMID 33779216. (link)
- Ross MH, Smith M, Plinsinga ML, Vicenzino B. Self-reported social and activity restrictions accompany local impairments in posterior tibial tendon dysfunction: a systematic review. Journal of Foot and Ankle Research. 2018;11:49. PMID 30186369. (link)
- Rehman M, Duarte Silva F, Chhabra A. Diagnostic efficacy of posterior tibialis tendon dysfunction: a systematic review of literature. European Radiology. 2024;34(5):3513-3523. PMID 37889271. (link)
- Kulig K, Lederhaus ES, Reischl S, Arya S, Bashford G. Effect of eccentric exercise program for early tibialis posterior tendinopathy. Foot & Ankle International. 2009;30(9):877-885. PMID 19755073. (link)
- Myerson MS, Thordarson DB, Johnson JE, et al. Classification and nomenclature: progressive collapsing foot deformity. Foot & Ankle International. 2020;41(10):1271-1276. PMID 32856474. (link)
