A foot that gradually becomes flatter, less stable and more painful is not simply an issue of ageing or worn-out shoes. Posterior tibial dysfunction can change the shape and mechanics of the foot over time, making walking, exercise and even standing at work increasingly difficult. Early assessment matters because treatment is usually simpler before the tendon and supporting joints have become significantly damaged.
The posterior tibial tendon is one of the key structures supporting the arch on the inside of the foot. When it becomes irritated, weakened or torn, the arch can lower and the heel may drift outwards. This condition is also known as posterior tibial tendon dysfunction or, in more advanced cases, progressive collapsing foot deformity.
What does posterior tibial dysfunction feel like?
Symptoms often begin subtly. Many patients notice an ache, swelling or tenderness behind and below the inside ankle bone. The discomfort may be worse after a long day on your feet, walking on uneven ground, climbing stairs or participating in sport.
As the tendon loses its ability to support the arch, the foot may start to roll inwards. You may see more of your toes when looking at the foot from behind, notice that one shoe wears out faster than the other, or find that previously comfortable shoes now press on the inside of the ankle or outside of the forefoot.
Later-stage symptoms can differ from the early pain. Once the tendon has become severely weakened, the original inside-ankle pain may reduce, while pain develops on the outside of the ankle or foot. This happens because the collapsed foot position can cause impingement and overload in other joints and soft tissues.
A useful functional sign is difficulty performing a single-leg heel rise. Standing on one foot and lifting the heel off the ground requires a functioning posterior tibial tendon. Not everyone with heel-rise weakness has this condition, but it is a finding a foot and ankle specialist will assess carefully.
Why the arch starts to collapse
Posterior tibial dysfunction rarely has one simple cause. Repeated loading over years can contribute, particularly where the tendon is already under strain from flat-foot posture, tight calf muscles, high body weight, inflammatory arthritis or previous injury. A sudden twist, fall or sporting injury can also trigger symptoms in a tendon that was already degenerating.
It is more commonly seen in adults, particularly women over 40, but it can affect men and younger patients as well. Diabetes, high blood pressure and steroid exposure may influence tendon health and healing potential. These factors do not mean that a person will develop the condition, but they are relevant when planning treatment.
The shape of the foot also matters. Some people have flexible flat feet for many years without pain or limitation. That does not automatically require treatment. The concern is a foot shape that is changing, painful, weakening or becoming less flexible, particularly on one side.
Assessment: more than looking at a flat foot
A thorough consultation starts with your symptoms, activity demands, medical history and footwear concerns. Your specialist will examine the way you stand and walk, the alignment of the heel and forefoot, tendon tenderness, calf tightness, joint movement and strength.
Weight-bearing X-rays are commonly used because they show how the bones and joints align while you are standing. Depending on the clinical findings, ultrasound or MRI may be helpful to assess the tendon itself, identify a tear or inflammation, and review nearby ligaments and joints. Imaging supports the diagnosis, but it is interpreted alongside the examination rather than in isolation.
One of the most important parts of assessment is establishing whether the deformity remains flexible. A flexible foot can often be repositioned manually and may respond differently to treatment than a stiff or arthritic deformity. This distinction helps determine whether non-surgical treatment is appropriate and, if surgery is being considered, which reconstructive approach is likely to provide the most reliable outcome.
Non-surgical treatment in earlier stages
For many patients, particularly those with early symptoms and a flexible foot, non-surgical care is the appropriate first step. The aim is to settle tendon irritation, support the arch and reduce the forces that continue to overload the tendon.
This may involve a period of activity modification, supportive footwear, an ankle brace or walking boot where symptoms are acute, and customised foot orthoses. Physiotherapy can address calf tightness, balance and progressive strengthening of the posterior tibial tendon and supporting muscles. Anti-inflammatory medication may be appropriate for some people, although it should be discussed with your GP or treating clinician in the context of your general health.
Conservative care is not a quick fix. Tendons recover slowly, and improvement is usually measured over weeks to months. It also depends on the degree of tendon damage, how much the foot has changed shape, the demands of your work or sport, and whether an orthosis or brace is worn consistently. If pain is settling and function is improving, surgery may not be required.
When surgery may be considered for posterior tibial dysfunction
Surgery is considered when persistent pain, progressive deformity or loss of function continues despite an appropriate course of non-surgical management. It may also be recommended earlier if there is a substantial tendon tear, marked structural collapse or joint damage that is unlikely to improve with bracing alone.
There is no single operation for posterior tibial dysfunction. Reconstructive surgery is tailored to the stage of the condition and the individual foot. In a flexible painful flat foot, surgery may involve repairing or reconstructing the damaged tendon, transferring another functioning tendon to assist arch support, lengthening a tight calf muscle, and carefully realigning the heel or midfoot with bone cuts known as osteotomies.
Where the deformity has become rigid and joints are arthritic, fusion of selected joints may be the more dependable option. A fusion sacrifices movement in a damaged joint to reduce pain and create a stable plantigrade foot. This is a significant trade-off, but when arthritis is advanced, preserving painful movement is not always beneficial.
Your surgical plan should account for your X-rays and scans, overall health, bone quality, work requirements, footwear needs and recovery support at home. The objective is not simply to create a higher arch on an X-ray. It is to achieve a stable, comfortable foot that can tolerate daily life as reliably as possible.
Recovery after flat-foot reconstruction
Recovery varies with the procedure. More involved reconstructions commonly require a period without weight-bearing, followed by protected walking in a boot and gradual rehabilitation. Swelling can persist for many months, and returning to higher-impact activity takes patience.
Before surgery, patients should understand the practical side of recovery: time away from driving or work, help with meals and household tasks, keeping the foot elevated, wound care, follow-up appointments and the role of physiotherapy. Clear planning reduces avoidable stress and allows the foot to heal in the best possible conditions.
As with any operation, risks include infection, wound-healing problems, nerve irritation, blood clots, ongoing swelling, non-union of bone cuts or fusions, and incomplete pain relief. A specialist consultation is the right setting to discuss these risks in relation to your health and the specific procedure proposed.
Do not ignore a changing foot shape
Arrange an assessment if pain along the inside of the ankle persists beyond a few weeks, your arch is visibly lowering, you are struggling to walk or exercise, or one foot is changing shape compared with the other. Sudden severe pain, inability to bear weight, a hot swollen foot, fever, numbness or a wound should be assessed promptly.
At Sydney Foot & Ankle Surgeon, assessment focuses on identifying the stage of the condition and explaining the realistic options clearly, from bracing and rehabilitation through to reconstructive surgery where needed. A changing flat foot deserves a proper diagnosis, because the right support and treatment plan can protect both your mobility and confidence on your feet.