When is surgery required for flat feet?

Most patients with flat feet don’t need surgery. Simple, non-surgical treatment settles the symptoms in about 85 per cent of cases within three to six months.

Surgery is considered when non-surgical treatment hasn’t worked after a fair trial, usually three to six months, and the shape of the foot is still causing ongoing pain or making everyday activities difficult. After reconstructive surgery, full recovery can take up to 12 months.

What are the main signs that indicate you need surgery?

Ongoing pain that hasn’t settled with non-surgical treatment is the main reason to consider surgery for flat feet.

Guidelines suggest surgery when the foot is far enough out of line to cause pain, tiredness or difficulty with normal daily activities. Studies show that only 12 to 15 per cent of adults with painful flat feet go on to need an operation within two years.

Who is a suitable candidate for flat foot surgery?

Surgery is usually suitable for adults who have already tried at least three to six months of structured non-surgical treatment without much improvement.

The Royal National Orthopaedic Hospital points out that accurate treatment gives the best results: a careful assessment decides whether surgery is right for you and which type of surgery to use. You may also have a deformity that is getting worse, a stiff flat foot that can’t be moved back into position by hand, or a problem with the main arch-supporting tendon (the posterior tibial tendon) at Stage II or beyond. Children rarely need surgery, unless the flat foot is stiff or two of the bones in the foot are joined together (a tarsal coalition). The following points suggest surgery may be appropriate:

• Pain lasting beyond six months of consistent non-surgical treatment
• A worsening deformity, with the inner arch flattening further
• Being unable to stand on tiptoes on the affected side
• Arthritis (wear and tear) developing in the ankle
• Difficulty with work, sport or other activities you enjoy
• No improvement with custom insoles, braces or physiotherapy

What does the surgical procedure involve?

The operation chosen depends on how advanced the problem is, how flexible the foot still is and whether there is arthritis in the foot joints. Several reconstructive options are available.

In early disease (Stage I), cleaning out the inflamed lining and damaged tissue around the tendon (tenosynovectomy and debridement) may be enough. At Stage IIa, the foot is usually realigned without fusing any joints. This may involve moving the heel bone into a better position (a medial displacement calcaneal osteotomy) and transferring a nearby tendon (the flexor digitorum tendon) to support the arch. More advanced cases often need a fusion, which stiffens the joint to make it stable and stop the foot collapsing further. The operation is done under a general anaesthetic, along with an injection behind the knee (a popliteal nerve block) that keeps the foot comfortable for 12 to 36 hours afterwards. In a follow-up study of 17 adults with a painful tarsal coalition, 10 of the 12 who had surgery still had lasting pain relief three years later.

How long is the recovery period after surgery?

This depends a little on whether you are having flexible correction or fusion surgery. You will spend a period in a plaster cast — six weeks for realignment surgery and 12 weeks for fusion — followed by three weeks in a boot.

For the first two weeks after the operation you must rest with the leg raised above the level of your groin for 55 minutes in every hour. This limits swelling and reduces the risk of complications. Most people are back in normal shoes at around 12 weeks, although physiotherapy continues for several months. According to Chelsea and Westminster Hospital, full recovery takes seven to 12 months, and some swelling can remain for up to a year. Low-impact sport may be possible by six months, but strenuous sport is unlikely by then.

References

• GOV.UK. Synopsis of Causation Pes Planus. Department for Work and Pensions, 2019.
• AAPM&R. Pes Planus/Adult Acquired Flatfoot Deformity. PM&R KnowledgeNow, 2024.
• National Health Service Chelsea and Westminster Hospital. Treating the Flat Foot. Patient Information Leaflet, 2023.
• ACFAS. Clinical Consensus Statement on Adult-Acquired Flatfoot Deformity. American College of Foot and Ankle Surgeons, 2020.
• Royal National Orthopaedic Hospital. A Patient's Guide to Adult Acquired Flatfoot Deformity. NHS England, 2023.
• StatPearls. Pes Planus. NCBI Bookshelf, 2024.
• For further information on flat feet (pes planus), visit matthewwelck.com/flatfoot-pes-planus