Flat Feet (Pes Planus)

Flat feet (pes planus) means the arch on the inner side of the foot is low or absent, so most of the sole touches the ground when standing. Flat feet are common and often cause no problems at all. In adults, a flat foot that becomes painful or is gradually getting flatter should be assessed by a specialist.

Small children do not have a visible arch. According to the NHS, most develop one between the ages of 3 and 10. Some people keep flexible flat feet throughout life without any trouble. A flat foot that develops in adulthood is different. It is often caused by weakening or failure of the tendons that support the arch, and it can slowly get worse.

Are flat feet a problem?

Usually not. The NHS states that most flat feet cause no symptoms and need no treatment. Flat feet should not stop anyone from walking, running or playing sport.

Advice is worth seeking if:

• The feet are painful despite well-fitting shoes
• One or both feet seem to be getting flatter
• Only one foot is flat, or a flat foot has appeared recently
• The feet are stiff, weak or numb
• Shoes wear out very quickly
• There are frequent injuries or problems with walking or balance

What causes flat feet in adults?

• Failure of the arch-supporting tendons, particularly the tibialis posterior tendon
• Injury to the foot or ankle
• Rheumatoid arthritis and other inflammatory or degenerative arthritis
• Genetics and joint hypermobility
• Obesity
• Tight calf muscles

Tibialis posterior tendon dysfunction is the most common cause of flat foot that develops in adult life. The condition is increasingly called progressive collapsing foot deformity (PCFD). An instructional review (Mc Donald and colleagues) describes PCFD as collapse of the medial longitudinal arch with hindfoot valgus and forefoot abduction, predominantly in middle-aged and older patients. It is linked with older age, high blood pressure, diabetes, obesity, steroid use and inflammatory arthritis. Less often, flat feet are present from childhood because two foot bones are joined together, or they occur alongside nerve or muscle conditions such as cerebral palsy, spina bifida or muscular dystrophy.

What are the symptoms?

• Aching in the arch or around the inner ankle
• Pain and swelling along the inner side of the ankle, where the tibialis posterior tendon runs
• Tired, aching feet and legs after standing or walking
• A foot that is gradually becoming flatter, with the heel drifting outwards
• Shoes that wear unevenly or quickly

Non-surgical treatment

Most painful flat feet are treated without surgery at first:

• Physiotherapy and stretching exercises
• Single heel raise and toe curl exercises to strengthen the muscles that support the arch
• Custom orthotics, following gait analysis, to support the arch
• Heel raises to reduce strain on a tight calf
• Weight management
• Bracing in more severe cases

The NHS notes that insoles and exercises can ease symptoms but will not change the shape of the foot. Arch-supporting insoles and physiotherapy are used for a supple foot with mild symptoms. For more severe symptoms, a splint or removable boot may be used to support the foot and ankle. Physiotherapy is particularly helpful in the early stages of tendon dysfunction.

When is surgery recommended?

The NHS states that surgery is rarely needed. It is considered when pain and loss of function continue despite a proper trial of non-surgical treatment. The right operation depends on the cause, how flexible the foot is and whether the joints are arthritic. Flatfoot reconstruction often combines several procedures:

• Calcaneal osteotomy: cutting and resetting the heel bone to realign the hindfoot
• Tendon transfer: using a nearby tendon to replace the function of a failed tibialis posterior tendon and improve arch strength
• Extra-articular implants: used in selected cases to stabilise the foot
• Midfoot joint fusion: to reduce collapse of the arch

Minimally invasive flatfoot surgery uses specialised instruments to cut and reset the hindfoot bones through small incisions, secured with screws.

The outcome of surgery is usually good, but not everyone is completely pain-free afterwards. Complications can occur, and some people are not satisfied with surgery. Smoking, being overweight and inactivity increase the risk.

What is recovery like?

Recovery after significant reconstruction takes time:

• 0–6 weeks: immobilisation, non-weight-bearing or protected weight-bearing
• 6–12 weeks: gradual return to walking with physiotherapy support
• 3–6 months: return to most daily activities; orthotics may be needed long-term
• 6–12 months: return to sport and full activity

A walking aid may be needed for several weeks, and driving is usually deferred until the foot is safe and comfortable enough for the pedals.

How Mr Hester can help

Mr Hester is a dual fellowship-trained foot and ankle surgeon (FRCS Tr&Orth), trained at Guy's and St Thomas' and in Toronto and Calgary, and a member of BOFAS and EFAS. He sees patients privately at The London Clinic, Cromwell Hospital, King Edward VII's Hospital and HCA The Shard. His NHS practice is at King's College Hospital.

Insured patients need a GP referral and an authorisation code from their insurer. Self-pay patients are welcome. To book, call 020 7046 8004.

Frequently Asked Questions

Sources

1. Flat feet. NHS. https://www.nhs.uk/conditions/flat-feet/
2. Mc Donald S, Loveday D, Smith G, Bawa A. Progressive collapsing foot deformity: an instructional review. Eur J Orthop Surg Traumatol. 2026;36(1):224. PMID: 42257901. https://pubmed.ncbi.nlm.nih.gov/42257901/
3. Pasapula CS, et al. Review of Classification Systems for Adult Acquired Flatfoot Deformity/Progressive Collapsing Foot Deformity and the Novel Development of the Triple Classification. J Clin Med. 2024;13(4):942. PMID: 38398256. https://pubmed.ncbi.nlm.nih.gov/38398256/