Pain on the Inner Side of the Ankle or Foot—Posterior Tibial Tendon, Accessory Navicular or Tarsal Tunnel?

Short answer: Pain along the inner ankle or arch may arise from the posterior tibial tendon, an accessory navicular bone, the tarsal tunnel nerve, the deltoid ligament, a joint, stress injury or another condition. Pain with a gradually flattening arch suggests a different problem from burning or tingling into the sole, while sudden bruising after a twist requires assessment for trauma. The location helps organise the possibilities but does not establish the diagnosis.

When inner-ankle or inner-foot pain needs prompt assessment

Seek prompt medical assessment if:

• you cannot bear weight after trauma, the foot appears deformed or swelling is rapidly increasing;
• the arch has newly changed shape or the foot is becoming rapidly flatter, more abducted or difficult to correct;
• there is marked focal bone tenderness after increased running, marching or walking;
• the foot becomes cold, pale, blue, severely numb or suddenly weak;
• there is progressive numbness, loss of toe control or foot drop;
• the area is hot, red and very painful, particularly with fever, a wound or feeling unwell;
• a person with diabetes or reduced sensation develops unexplained warmth, swelling, colour change, a blister or wound;
• one calf becomes unexpectedly swollen or painful, especially with chest pain or breathlessness.

These features may require assessment for fracture, major tendon or ligament injury, infection, acute Charcot neuroarthropathy, impaired circulation, a neurological condition or a blood clot. For a life-threatening emergency in Singapore, call SCDF 995.^[1]

What does the symptom pattern suggest?

The following patterns are clues rather than diagnoses.

Common causes of pain on the inner side of the ankle or foot

Posterior tibial tendinopathy

The posterior tibial tendon passes behind the inner ankle and attaches to structures supporting the arch. It helps control the foot during walking and supports push-off. Symptoms may include tenderness and swelling behind the inner ankle or along the arch, pain with prolonged walking, and weakness or pain during a single-leg heel raise.

An early load-related tendon problem is not automatically the same as advanced arch collapse. Treatment should reflect tendon irritability, strength, foot alignment, body demands and whether the surrounding ligaments and joints remain functional.

Progressive collapsing foot deformity

This term describes a spectrum historically called adult-acquired flatfoot or posterior tibial tendon dysfunction. The arch may lower, the heel may drift outward and the front of the foot may move outward. Later stages can become stiff and arthritic, and pain may eventually occur on the outer side from impingement.

Not every flat foot is diseased. Many people have longstanding flexible, painless flat feet. More concerning features include a new change in shape, increasing pain, loss of heel-raise ability, progressive asymmetry and a deformity becoming rigid. The American Orthopaedic Foot & Ankle Society describes non-surgical and surgical options according to severity and stage.^[2]

Accessory navicular

An accessory navicular is an extra bone or cartilage near the navicular on the inner midfoot. Many people have one without symptoms. It may become painful after trauma, increased activity or shoe pressure, and its relationship to the posterior tibial tendon can matter.

A visible bump on X-ray does not prove it is the pain source. Local tenderness, swelling, shoe contact and tendon function should match. Footwear changes, arch support or temporary protection may help selected cases; persistent symptoms sometimes lead to a surgical opinion.^[3]

Tarsal tunnel syndrome or nerve irritation

The tibial nerve and its branches pass through a tunnel behind the inner ankle. Irritation may cause burning, tingling, electric pain or numbness into the heel, arch or sole. Symptoms can be influenced by prolonged standing or walking and may be associated with swelling, injury, a cyst, varicose vein or foot position.

Tarsal tunnel is not the only explanation for burning feet. Peripheral neuropathy, nerve problems higher in the leg, lumbar nerve irritation and other medical conditions can create similar symptoms. Bilateral or widespread burning requires a broader assessment.

Deltoid ligament injury

The strong deltoid ligament supports the inner ankle. It can be injured when the ankle rolls outward or as part of a more complex fracture or syndesmosis injury. Significant medial pain after trauma should not automatically be treated like a routine outer-ankle sprain.

Flexor tendon problems

Other tendons behind the inner ankle flex the toes and help control the foot. Pain may be linked to resisted toe movement, repetitive loading or snapping. Exact tenderness and functional testing help distinguish them from the posterior tibial tendon and tarsal tunnel.

Navicular or other stress injury

A stress reaction or fracture may follow increased running, marching, jumping or walking. Navicular stress injury can be important because symptoms may be vague and early X-rays may be normal. Focal bone tenderness and impact-related pain deserve assessment rather than repeated massage or testing runs.

Joint, inflammatory or referred pain

Midfoot or ankle arthritis, gout, inflammatory arthritis, infection and pain referred from the leg or back can overlap with medial foot symptoms. Heat, prolonged morning stiffness, multiple painful joints, numbness or systemic symptoms change the diagnostic direction.

How is inner-foot and ankle pain examined?

The history should clarify:

• the exact path of pain and whether it is aching, burning or electric;
• whether onset was gradual, traumatic or linked to an activity increase;
• changes in arch height, heel position or shoe wear;
• walking and standing tolerance and the effect of uneven ground;
• numbness, weakness, back or leg symptoms;
• previous orthoses, immobilisation, physiotherapy, injections or imaging;
• diabetes, inflammatory disease, bone-health and medicine history;
• the patient’s work, sport, timeline and preference for support, exercise or other care.

Examination may include standing alignment from front and back, arch flexibility, walking, footwear, swelling and tenderness, ankle and foot movement, tendon strength, a single-leg heel raise, balance, nerve sensation and selected provocation tests. Comparison with the other side is helpful, but both feet can be affected.

The “too many toes” appearance from behind, loss of heel inversion during a heel raise and inability to perform the task may support a collapsing-foot pattern. These findings still need interpretation: pain, balance and general weakness can also limit the test.

When are X-rays, ultrasound, MRI or nerve tests considered?

Imaging is not automatic. The test should answer a defined question and be likely to change treatment.

Weight-bearing X-rays

Standing foot and ankle X-rays may show arch alignment, joint arthritis, an accessory navicular, bone prominence or some fractures. Weight-bearing images often provide more useful information about deformity than non-weight-bearing views.

Ultrasound

Ultrasound can assess the posterior tibial and other superficial tendons dynamically, and may identify fluid, tears or a cyst affecting nearby structures. It depends on the clinical question and operator experience.

MRI

MRI may be considered when tendon or ligament damage, a stress injury, tarsal tunnel mass, infection or another soft-tissue or bone condition remains uncertain. It may also assist planning when symptoms persist despite appropriate care. ACR guidance separates imaging choices according to whether chronic foot pain is suspected to arise from bone, soft tissue, joint, nerve or another source.^[4]

Nerve-conduction and electromyography tests

These may be considered for persistent or progressive neurological symptoms, but a normal test does not necessarily exclude every local nerve irritation. Results should be interpreted with the neurological examination and possible causes higher in the leg or spine.

Blood tests

Blood tests may be relevant when inflammatory arthritis, gout, infection, diabetes or another systemic contributor is suspected. They are not routine for a straightforward mechanical tendon presentation.

Treatment options for inner-ankle and inner-foot pain

Treatment depends on the suspected structure, severity, stage and patient priorities. A newly painful flexible tendon problem, rigid arthritic collapse, accessory navicular and nerve condition are not interchangeable.

Activity and workload modification

Temporarily reducing long walks, hills, running or prolonged standing may settle tendon symptoms while capacity is rebuilt. A suspected stress injury, acute ligament injury or major tendon tear may need stronger protection. The plan should identify safe activities and how load will be reintroduced.

Footwear and arch support

Supportive footwear, a suitable insole or an ankle-foot brace may reduce tendon demand and support alignment in selected patients. A soft or wider shoe may reduce pressure over an accessory navicular. More support is not always better: a device that presses directly on the painful prominence or nerve can aggravate symptoms.

Walking boot or immobilisation

Short-term immobilisation may be considered for a highly irritable tendon, painful accessory navicular, significant sprain or stress injury. It should have a diagnosis, review point and plan to restore movement and strength. Prolonged use can lead to weakness, stiffness and altered walking.

Medication

Simple analgesics or anti-inflammatory medicines may be considered for selected pain flares when medically appropriate. They do not restore tendon capacity, correct fixed deformity, heal an unstable injury or diagnose burning nerve pain. Risks depend on medical history, other medicines and intended duration.

Physiotherapy and progressive rehabilitation

Rehabilitation may address posterior tibial and calf strength, foot control, ankle movement, balance, walking and graded return to work or sport. Loading should begin at a tolerable level and progress toward the patient’s real demands.

A patient with flexible early-stage symptoms may have different potential for strengthening and control than someone with rigid arthritic deformity. Exercise cannot reshape every fixed structural change, but it may still improve capacity and function when appropriately selected.

Nerve-focused management

When symptoms are neurological, management may include reducing compression, addressing swelling or footwear, treating an underlying medical condition and selected rehabilitation. A cyst, severe weakness or another structural cause may require procedural or surgical assessment. Repeatedly stretching a sensitised nerve is not automatically helpful.

Injections

An injection is not a routine treatment for every inner-ankle pain. It may be discussed for a specifically identified joint, tendon sheath or tarsal-tunnel-related condition. The target, evidence and risks matter. Corticosteroid in or near a load-bearing tendon can carry tissue risks, and an injection does not correct progressive deformity.

Platelet-rich plasma and other biologic or emerging procedures are promoted for some tendon problems, but evidence and protocols vary. Newness does not establish superiority, and availability or permissible use in Singapore is subject to current requirements.

Surgical opinion

Surgery may be considered for progressive painful collapsing-foot deformity, persistent symptomatic accessory navicular, significant tendon rupture, nerve compression with an identifiable cause or another structural problem after appropriate non-surgical care. Procedures differ by stage and may involve tendon, ligament, bone alignment, joint fusion or nerve decompression.

A flat-foot appearance or scan abnormality alone does not determine the need for an operation. Pain, flexibility, progression, arthritis, medical risk and patient goals are central.

Which approach fits the patient’s situation?

“I have always had flat feet, but only one side hurts now”

Longstanding flat arches may be normal for that person, while new one-sided pain can reflect tendon overload, injury, arthritis or another cause. Compare current alignment, strength and activity with the opposite side and previous baseline rather than treating the foot shape alone.

“My arch looks lower and I cannot do a heel raise”

This deserves assessment of the posterior tibial tendon, supporting ligaments and joint flexibility. Earlier clarification may preserve more non-surgical options. An X-ray, ultrasound or MRI is selected according to the question rather than ordered automatically.

“I need to keep standing at work”

The immediate plan may include confirming that weight bearing is safe, supportive footwear or a brace, shorter standing blocks and temporary duty modification. A suspected stress injury or major tendon problem may require protection even when time off is inconvenient. Rapid recovery cannot be promised.

“I prefer an insole and do not want exercises”

An insole or brace may reduce load and can be a reasonable priority. If reduced strength and capacity contribute, support alone may not prepare the foot for prolonged walking or uneven ground. A small targeted programme may be more acceptable than a long generic routine.

“I already tried physiotherapy and orthotics”

Reassessment should ask whether the diagnosis and disease stage were correct, whether the device pressed on the painful area, whether loading was appropriate, and whether a stress injury, nerve problem, rigid deformity or arthritis was missed. Options may include a revised programme or brace, targeted imaging, medical treatment or a surgical opinion.

“It burns into my sole and I want the nerve injected”

First confirm that symptoms fit a local tarsal-tunnel problem rather than neuropathy or a nerve issue higher in the leg or back. If an injection is considered, the suspected compression cause, target, risks, likely duration and alternatives should be discussed.

How should progress be monitored?

Useful measures include:

• walking or standing time before symptoms begin;
• pain and swelling along the tendon or inner foot;
• single-leg heel-raise ability and quality;
• arch and heel alignment over time;
• burning, tingling, numbness and night symptoms;
• shoe and brace tolerance and skin pressure;
• ability to complete work, stairs, running or sport tasks.

Rapid shape change, increasing weakness, new numbness, focal bone pain, skin breakdown, heat or redness requires reassessment rather than simply increasing exercise or support.

Integrated doctor and physiotherapy management

The Pain Relief Clinic has in-house physiotherapists who can work with the licensed medical doctor for integrated management. This can help coordinate the working diagnosis, need for imaging or medical tests, footwear and support choices, symptom control, progressive rehabilitation and return-to-work or activity planning.

Integrated care is particularly useful when a tendon, deformity and nerve symptoms overlap, when prior orthotics or physiotherapy have not worked, or when protection must be balanced with rebuilding capacity. Physiotherapists practising in Singapore should be appropriately registered.^[5]

Insurance referrals and supporting paperwork

The clinic can assist with clinically appropriate referrals and supporting paperwork for insurance claims. Coverage, required documents, pre-authorisation and reimbursement depend on the patient’s policy and insurer. A referral, form or medical report does not guarantee approval or payment.

Before imaging or physiotherapy, patients may wish to check whether their policy requires a doctor’s referral, panel provider, pre-authorisation, itemised invoice or medical report.

Frequently asked questions

Does inner-ankle pain mean posterior tibial tendon dysfunction?

Not always. An accessory navicular, deltoid ligament injury, flexor tendon, nerve, joint or stress injury can cause pain in the same region. Examination matters.

Are flat feet always a problem?

No. Many flexible flat feet are longstanding and painless. New pain, progressive shape change, weakness, rigidity or functional loss deserves assessment.

Can posterior tibial tendon pain improve without surgery?

Many early and flexible presentations are managed with load modification, suitable support and progressive rehabilitation. Advanced rigid deformity or persistent structural failure may require a surgical opinion.

Do I need custom orthotics?

Not automatically. Suitable off-the-shelf support may help some patients, while others need a custom device or brace. Fit, pressure, diagnosis, footwear and functional response are more important than the label.

Is an accessory navicular dangerous?

It is a common anatomical variation and is often painless. It becomes clinically relevant when local tenderness, swelling, shoe pressure or tendon-related symptoms match the location.

Do I need an MRI for tarsal tunnel syndrome?

Not in every case. MRI or ultrasound may help when a cyst, mass, tendon problem or other structural cause is suspected. Nerve tests and assessment of the leg or spine may answer different questions.

Arrange an inner-ankle or inner-foot pain assessment in Singapore

If pain behind the inner ankle or along the arch is persistent, associated with arch change, burning or weakness, or has not improved with previous care, an assessment can consider tendon, bone, nerve, ligament and joint causes and whether support, rehabilitation, imaging or referral may be appropriate.

The Pain Relief Clinic
350 Orchard Road, #10-00 Shaw House
Singapore 238868
Telephone: +65 9068 9605

Not every investigation or treatment discussed on this page is required, offered or recommended by the clinic. Availability and permissible use of tests, medicines, devices, injections and emerging treatments in Singapore may change with evolving Ministry of Health, Health Sciences Authority and Singapore Medical Council requirements. Individual decisions require clinical assessment and should follow current Singapore regulations and professional guidance.

References

1. Singapore Civil Defence Force. Emergency Medical Services.
2. American Orthopaedic Foot & Ankle Society. Adult Acquired Flatfoot Deformity.
3. American Orthopaedic Foot & Ankle Society. Accessory Navicular.
4. American College of Radiology. ACR Appropriateness Criteria: Chronic Foot Pain.
5. Allied Health Professions Council Singapore. Search the register.

Disclaimer: This information is provided for general reference only and should be used in consultation with your licensed medical doctor. It is not a diagnosis or a substitute for personalised medical advice. Seek urgent care for severe, rapidly worsening or warning-feature symptoms.

Reviewed by Dr Terence Tan — 13 September 2026