Arch Pain and a Flattening Foot: Why Timing Matters

You are 52. For a few months the inside of your ankle has ached after long days, and there is a soft puffiness just below and behind the bony bump on the inner side. Shoes that used to be fine now feel like they tip you inward. Somebody who walked behind you said your foot looks like it is rolling over.

Most foot pain gives you time. A sore heel in the morning, a cranky forefoot, an irritated tendon at the back of the ankle: those can usually wait a few weeks while you try shoes and rest, and you lose nothing by waiting. The pattern described above is the one that does not work that way.

The tendon involved holds up your arch. When it stops holding, the arch drops, and the foot slowly changes shape around the new position. That change is reversible early and permanent late. This post is about how to tell where you are in that sequence and what to do about it.

What the posterior tibial tendon actually does

Run your finger down the inside of your ankle, behind the round bone that sticks out. A tendon passes through there, hooks around that bone like a rope around a pulley, and attaches under the middle of your foot.

It has two jobs. It holds the arch up when you put weight on the foot. It also turns the heel inward at the moment you push off, which locks the bones of the midfoot together and turns a floppy foot into a rigid lever you can push against.

When that tendon is irritated, stretched, or torn, both jobs suffer. The arch settles. The heel drifts outward instead of inward. The front of the foot swings out to the side. The names given to this have changed over the years, which is why you may meet several: posterior tibial tendon dysfunction, adult acquired flatfoot deformity, and the current preferred term, progressive collapsing foot deformity.

That last name came from a consensus group of foot and ankle surgeons. In Foot and Ankle International in 2020, Myerson and colleagues proposed "progressive collapsing foot deformity" to replace the older labels, on the grounds that the earlier names described a tendon problem when the actual condition involves the whole three-dimensional shape of the foot. The word doing the work in that new name is "progressive".

Who tends to get it, and why middle age

The typical patient is an adult in the second half of life rather than a young athlete. StatPearls describes the classic presentation as a woman with obesity in her sixth decade of life, reports that about 81.5% of patients have a body mass index at or above 25, and puts prevalence between 3.3% and 10% depending on the group studied.

Several things raise the risk. Carrying more weight increases the load the tendon resists with every step. Diabetes, high blood pressure, and vascular disease all appear more often in this group, which matters because the tendon has a region behind the inner ankle bone where blood supply is thinner. A foot that was already flat before symptoms started has less margin. Previous ankle injury and inflammatory arthritis also feature.

The reason it shows up in middle age rather than at 25 is accumulation. The tendon works hard every step of every day for decades. Small failures build up faster than repair keeps pace, and eventually the tendon lengthens under load. Once it lengthens, the arch it was holding sits lower, which lengthens the tendon further. That loop is why this condition tends to move in one direction on its own.

The two tests, explained in plain words

Two examination findings do most of the diagnostic work, and you can understand both without any clinical training.

Too many toes. Stand with your back to a mirror, feet hip width apart, weight even. Have somebody look at your feet from directly behind, or take a photo. On a normally aligned foot you see the little toe and perhaps part of the fourth toe peeking out beside the ankle. When the heel angles outward and the front of the foot swings out to the side, more toes come into view on the outer edge. That is the too many toes sign, and it is one of the quickest ways to compare one foot against the other. Your own two feet are the useful comparison, since what counts is asymmetry.

Single leg heel raise. Hold a wall or a counter with your fingertips for balance, stand on the affected leg, and rise onto your toes. Then repeat on the other side. Three things are being watched. Can you get up at all. Does it hurt. And, viewed from behind, does your heel swing inward as you rise.

That last part is the piece people miss. A healthy posterior tibial tendon turns the heel inward at the top of the raise. If the heel stays straight or drifts outward while you rise, the tendon is not doing its locking job even if you managed the height. StatPearls notes that the single limb heel rise separates early disease, where it can be done though sometimes with pain, from later disease, where it cannot be done at all.

Neither test is a diagnosis. A physiotherapist will also press along the tendon for tenderness and swelling, test its strength by resisting as you turn your foot inward, check whether the deformity can be corrected by hand, and look at your shoes for wear patterns. Imaging, when needed, comes through your physician.

Why the staging concept matters to you

Foot and ankle specialists stage this condition because the stage decides what treatment can realistically achieve.

The distinction that matters most to a patient is flexible against rigid. In a flexible foot the arch drops under load but the bones can still be moved back toward normal alignment by hand. In a rigid foot they cannot, because the joints have stiffened into the collapsed position and arthritis has often set in.

The older Johnson and Strom staging, still widely used, runs roughly like this. The earliest stage has tendon inflammation with a normal foot shape and a heel raise that can still be performed. The middle stage has a visibly flattened but still flexible foot, with the heel raise difficult or impossible. The later stages have a fixed deformity, subtalar arthritis, and eventually tilting of the ankle joint itself. The newer 2020 consensus classification simplifies this to flexible against rigid, then describes which parts of the foot are involved.

Here is the practical translation. A flexible foot can be supported by a brace or orthotic that holds it closer to its old alignment, and the muscles around it can be loaded to take over some of the work. A rigid foot cannot be held anywhere it will not go, so bracing becomes about comfort rather than correction, and restoring the shape means surgical reconstruction that often involves fusing joints.

Nobody can tell you your stage from a description. The point is that the flexible window is the one where conservative treatment has the most to offer, and it closes without announcing itself.

What loading and bracing achieve at each stage

Early, flexible, tendon irritated. This is where the evidence is best. A 2009 randomised controlled trial in Physical Therapy by Kulig and colleagues assigned 36 adults with stage I or II tibialis posterior tendinopathy to 12 weeks of one of three programmes: orthoses with stretching, orthoses with stretching plus concentric resistance exercise, or orthoses with stretching plus eccentric resistance exercise. Foot Functional Index scores improved in all three groups. The eccentric group improved most on each subscale and the orthoses-with-stretching group improved least, and pain immediately after a five-minute walk test was reduced across all groups.

Read that carefully, because it is a small trial and the honest summary is narrow. Thirty-six people split across three groups tells you that early-stage patients improved on these programmes. Proving one programme beats another would take a larger study. What it supports is the combination: support the foot, and load the tendon.

In practice the loading part means resisted inversion, which is turning the sole of the foot inward against a band or a weight, progressed over weeks. Heel raises are built up from double leg to single leg as tolerance allows. Calf flexibility gets attention because a tight calf increases the load the arch has to absorb. Your therapist will set the starting dose based on how irritable the tendon is, since a tendon that hurts for a day after exercise has been given too much.

Flexible but visibly collapsed. Support carries more of the weight here. That can mean a custom orthotic with a deep heel cup and medial posting, or a more substantial ankle-foot orthosis, or a walking boot for a period when symptoms are high. Exercise continues alongside, because a brace holds the position while muscle is what holds it in the long run. StatPearls cites nonoperative success rates between 67% and 90% across studies using orthotic devices, cast-boot walkers, anti-inflammatory medication, and physical therapy. If you are weighing custom against over-the-counter support, we have written separately about what a foot assessment for orthotics actually involves.

Rigid. Bracing here is for comfort and function rather than correction, and it can be worth a great deal on both counts. Exercise keeps the rest of the leg strong and protects the joints above. Restoring the arch means surgery, and that is an orthopaedic conversation.

The loading principles are the same ones that apply to tendon problems elsewhere in the foot and ankle, and if you have read our piece on Achilles tendinopathy and how loading is progressed, the pattern will look familiar: measured starting dose, slow progression, symptom response as the guide.

When orthopaedic referral matters

Physiotherapy is the first line for this condition, and most people do not need a surgeon. Several situations change that.

• Symptoms that have not improved after a genuine trial of orthoses, bracing, and progressive loading. AAOS describes surgery as the consideration when pain has not settled after several months of appropriate treatment, and StatPearls describes a three to four month trial before surgical discussion.
• A deformity your therapist finds cannot be corrected by hand, which suggests the flexible window has closed.
• Pain that has moved to the outside of the ankle. This can mean the heel bone has shifted far enough outward to press against the bone above it.
• A sudden change, such as a pop followed by rapid flattening, which can indicate the tendon has ruptured.
• Progression you can see month over month despite treatment.

A physiotherapist does not diagnose a tendon rupture or stage a deformity radiographically. What they can do is recognise the pattern, quantify what the foot does under load, and tell you when the picture warrants a physician's assessment and onward referral. In our experience the people who do best are the ones who came in while the foot still corrected by hand.

What a first visit looks like

A first physiotherapy assessment for this problem is mostly a conversation followed by a careful look at what your foot does with weight on it. Expect questions about when the pain started, whether it followed an injury or crept in, what activity brings it on, how your shoes have been wearing, and what you need to be able to do at work and outside it.

Then the physical part. Your therapist will look at both feet from behind while you stand, compare the arches, check the too many toes sign, and ask for a single leg heel raise on each side while watching what the heel does. They will palpate along the tendon, test inversion strength against resistance, check whether the deformity corrects passively, assess calf length, and watch you walk.

The plan that follows usually pairs support with loading. Support might be a temporary insert while a custom device is made, or a change of footwear, or a boot if things are irritable. Loading starts at a dose your tendon tolerates, and it is progressed from there. Expect the first few weeks to be about finding that dose rather than chasing progress.

Physiotherapy is a direct-access profession in British Columbia, regulated by the College of Health and Care Professionals of BC, so no physician referral is needed to book an assessment. Some extended-health plans require one for reimbursement, so check your policy before your first visit. If the foot pain came from a motor vehicle crash, ICBC funds physiotherapy under its care scope. If it arose at work, a claim through WorkSafeBC may apply.

When to see a doctor rather than book physiotherapy

Some presentations need medical assessment first. Go to a physician or emergency department for sudden severe pain with an audible pop and inability to bear weight, for a foot that is hot, red, and swollen with fever, or for numbness, pins and needles, or a foot that feels cold or changes colour, which can point to circulation or nerve involvement.

If you have diabetes, any new foot swelling, redness, or warmth deserves prompt medical review rather than a wait-and-see approach, because a different and more urgent condition affecting the bones of the midfoot can present in a similar way and needs to be ruled out early.

Pain that wakes you at night and does not settle with position change, unexplained weight loss alongside foot symptoms, or a history of cancer also warrant a physician's assessment before rehabilitation begins. Arch pain with a different pattern, worst with the first steps in the morning, is often a separate problem, which we cover in our piece on the first six weeks of plantar fasciitis.

This article is general information, not personal medical advice. A regulated practitioner can confirm whether the patterns described apply to you.

Frequently asked questions

What is posterior tibial tendon dysfunction?

It is a condition where the tendon that holds up the arch of your foot stops doing that job well. The tendon runs behind the bony bump on the inside of your ankle and attaches under the midfoot. When it becomes irritated, stretched, or torn, the arch settles, the heel drifts outward, and the front of the foot swings out to the side. A 2020 consensus group writing in Foot and Ankle International proposed renaming it progressive collapsing foot deformity, because the problem involves the whole shape of the foot rather than the tendon alone.

Why is this more time-sensitive than other foot pain?

Because the foot changes shape as the condition advances, and that change stops being reversible. Early on the arch drops under load but the bones can still be moved back toward normal alignment by hand, which means a brace or orthotic can support the foot in a better position while loading builds the muscle back. Later the joints stiffen into the collapsed position and arthritis sets in, at which point nothing external can hold the foot somewhere it will not go. The flexible window closes without warning.

How do I do the single leg heel raise test at home?

Hold a wall or counter with your fingertips for balance, stand on one leg, and rise onto your toes, then repeat on the other side. Watch three things: whether you can get up at all, whether it hurts, and whether the heel swings inward as you rise when viewed from behind. A working posterior tibial tendon turns the heel inward at the top. If the heel stays straight or drifts outward, or you cannot rise on that side, book an assessment. This is a screening observation rather than a diagnosis.

What is the too many toes sign?

It is what a clinician sees when looking at your feet from directly behind while you stand. Normally the little toe and part of the fourth toe are visible beside the ankle. When the heel angles outward and the forefoot swings to the side, more toes come into view on the outer edge of the affected foot. Comparing your two feet is what makes it useful, since asymmetry is the finding that matters.

Who tends to develop this condition?

Adults in the second half of life rather than young athletes. StatPearls describes the classic presentation as a woman with obesity in her sixth decade, reports that about 81.5% of patients have a body mass index at or above 25, and puts prevalence between 3.3% and 10% depending on the group studied. Diabetes, high blood pressure, vascular disease, a pre-existing flat foot, and previous ankle injury all raise the risk.

Do orthotics actually help?

They are part of a combination that has trial support in early-stage disease. A 2009 randomised controlled trial in Physical Therapy assigned 36 adults with stage I or II tibialis posterior tendinopathy to 12 weeks of orthoses with stretching, with or without added concentric or eccentric resistance exercise. Foot Functional Index scores improved in all groups, with the eccentric exercise group improving most and the orthoses-with-stretching group improving least. That is a small trial, so read it as support for pairing foot support with tendon loading rather than proof that one programme is best.

What exercises are used?

Resisted inversion is the main one, meaning turning the sole of the foot inward against a band or weight, progressed over weeks. Heel raises are built from double leg toward single leg as tolerance allows. Calf flexibility usually gets attention, because a tight calf increases the load the arch absorbs. The starting dose depends on how irritable the tendon is, which is why an individual assessment matters more than a generic list.

Can this be fixed without surgery?

Often, particularly when treatment starts while the foot is still flexible. StatPearls cites nonoperative success rates between 67% and 90% across studies using orthotic devices, cast-boot walkers, anti-inflammatory medication, and physical therapy. Success in those studies means symptoms settled and surgery was avoided, rather than the arch returning to its original height. Outcomes depend on the stage at which treatment begins.

When should I see an orthopaedic surgeon?

When a genuine trial of orthoses, bracing, and progressive loading has not improved symptoms. AAOS describes surgery as the consideration after several months of appropriate treatment, and StatPearls describes a three to four month trial before surgical discussion. Sooner referral is reasonable if the deformity cannot be corrected by hand, if pain has moved to the outside of the ankle, if there was a sudden pop with rapid flattening, or if the foot is visibly changing month over month despite treatment.

Is this the same as plantar fasciitis?

No. Plantar fasciitis typically causes pain under the heel that is worst with the first few steps in the morning and eases as you move. Posterior tibial tendon dysfunction causes pain and often swelling along the inside of the ankle and arch, tends to worsen with activity through the day, and comes with a visible change in foot shape over time. The two can occur together, which is one reason an assessment is more useful than matching your symptoms to a list.

Will I need to wear a brace forever?

It depends on the stage and how the foot responds. Some people use a boot or a substantial brace for a defined period while symptoms are high, then move to a custom orthotic worn in normal shoes. Others keep the orthotic long term because it makes walking distances comfortable. In a rigid deformity, bracing is about comfort and function rather than correction, and it is often worth continuing. Your therapist and physician will review this as things change.

Do I need a referral to see a physiotherapist in BC?

No. Physiotherapy is a direct-access profession in British Columbia, regulated by the College of Health and Care Professionals of BC, so you can book an assessment without a physician's referral and without a confirmed diagnosis. Some extended-health insurance plans require a referral for reimbursement even though the profession does not, so confirm with your insurer before your first visit.

Sources

• Myerson, Thordarson, Johnson, et al., "Classification and Nomenclature: Progressive Collapsing Foot Deformity," Foot and Ankle International, 2020
• Kulig, Reischl, Pomrantz, et al., "Nonsurgical Management of Posterior Tibial Tendon Dysfunction With Orthoses and Resistive Exercise: A Randomized Controlled Trial," Physical Therapy, 2009
• StatPearls, "Posterior Tibial Tendon Dysfunction," NCBI Bookshelf
• American Academy of Orthopaedic Surgeons, "Progressive Collapsing Foot Deformity (Flatfoot)," OrthoInfo
• College of Health and Care Professionals of BC, physiotherapist scope of practice