Conditions / Biomechanics & Pain Referral
Flat Feet (Adult Pes Planus)
Flat feet are common in adults and often painless — but when they contribute to foot, ankle, knee or back pain, a biomechanical assessment can identify why and what to do about it.
Flat feet — clinically known as pes planus — describe a foot where the medial arch is reduced or absent when standing. The foot makes more contact with the ground than usual, and the heel and forefoot bear load differently to a foot with a normal arch profile.
Flat feet are extremely common and not inherently a problem. Many people have flat feet and never experience pain. However, when the arch collapses excessively — particularly under load — it can alter the alignment of the entire lower limb, contributing to pain in the foot, ankle, knee, hip or lower back.
Flexible Flat Foot
The arch is present when non-weight-bearing but collapses on standing. The most common type — usually manageable with orthotics and strengthening.
Rigid Flat Foot
The arch is absent even when non-weight-bearing, often due to tarsal coalition or joint degeneration. May require specialist referral.
Posterior Tibial Tendon Dysfunction
The most common cause of adult-acquired flat foot — progressive failure of the tendon that actively supports the arch during walking.
Hypermobility
Hypermobile joints allow excessive arch collapse under load, particularly in people with generalised ligamentous laxity.
Genetics & Foot Structure
An inherited foot type with reduced arch height is the most common reason for flat feet that have been present since childhood.
Weight & Load
Increased body weight raises the demand on the arch and surrounding structures, potentially accelerating collapse in a predisposed foot.
Footwear
Prolonged use of flat, unsupportive footwear reduces the external support available to the arch and may exacerbate symptoms.
Joint Degeneration
Arthritis or degeneration of the midfoot and rearfoot joints can progressively reduce arch height over time in older adults.
Arch or heel pain after prolonged standing or walking
Foot fatigue that limits daily activity or exercise
Inner ankle swelling or tenderness
Knee pain or hip pain linked to altered leg alignment
Shoes wearing unevenly on the inner edge
Difficulty with certain sports or activities due to instability
Treatment is guided by whether the flat foot is causing symptoms and what structures are involved. The goal is to reduce pain, improve function, and support the arch — not to create an artificially high arch.
01
Wear supportive footwear — avoid flat, unsupportive shoes and prolonged barefoot walking on hard floors
02
Build foot and calf strength consistently — intrinsic foot exercises and single-leg calf raises are particularly effective
03
Avoid sudden spikes in walking or running volume — flat feet fatigue faster under high load
04
Use your orthotics consistently — intermittent use produces much poorer results than wearing them daily
If your flat feet are causing pain, fatigue, or contributing to problems in your knees, hips or back, an assessment is worthwhile. Flat feet that have been symptomatic for years do not resolve on their own — the underlying mechanics need to be addressed.
If your arch has recently collapsed or is progressively worsening, this may indicate posterior tibial tendon dysfunction — a condition that requires prompt assessment as it can progress significantly without treatment.
Do flat feet always need treatment?
No. Many people have flat feet and never experience problems. Treatment is only needed when flat feet are causing pain, contributing to injuries, or limiting activity.
Can flat feet be corrected in adults?
For flexible flat feet, strengthening can improve arch control and reduce symptoms significantly. Orthotics provide external support. A structurally flat foot cannot be permanently "corrected" without surgery, but symptoms can be very effectively managed conservatively.
Will orthotics fix flat feet?
Orthotics support the arch and reduce overload on surrounding structures — they work best combined with strengthening. On their own they manage symptoms well but do not strengthen the foot.
Can flat feet cause knee or back pain?
Yes. Overpronation from flat feet alters the rotation of the leg and pelvis, which can contribute to knee pain, hip pain and lower back pain — particularly in runners and those on their feet for long periods.
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