When are flat feet normal?
- Normal in babies and toddlers, usually resolving by 6 years of age as the longitudinal arch develops.
- They persist in at least 10% of children, are commonly associated with other features of hypermobility, and are often familial (check parents' feet !).
- Management involves explanation, reassurance and advice regarding appropriate supportive footwear (i.e., supportive heel cup and midfoot support with fastened laces).
- Physiotherapists, orthotists and podiatrists may provide exercises and insoles if problems persist.
Photo: Flat feet in a healthy 4 year old - which normalize and demonstrate an appropriate arch when standing on tip-toe. This normal variant is called mobile flat feet (or flexible flat feet).
When are flat feet not normal?
- Absent arch when child stands on tip toes (non-mobile flat feet).
- Asymmetrical changes (i.e., one foot fixed and flat).
- Evidence of pressure on the foot such as blistering / callosities.
- Swelling or stiffness of joints.
- Limping or persistent pain.
- Abnormal neurologic exam (hyperreflexia, hypertonia, weakness).
- Resulting in pain, or interfering with function (sports or play).
In teenagers with a fixed/painful flat foot, think of tarsal coalition (a congenital condition where bones in the foot are joined together).
Inflammatory arthritis can also cause a painful stiff flat foot. Radiographs can be normal. Referral is required for further investigation.
The indications for referral (to rheumatology or orthopaedics pending your concerns and available referral pathways)
- Joint stiffness or swelling.
- Absence of arch on tiptoe.
- Signs of skin changes from pressure (e.g., blistering).
- Persistent pain.
- Limp or symptoms interfering with function (sport/play).
- Systemic features.
Key conditions to consider include:
- Inflammatory arthritis – joints are stiff, warm or swollen (often the midfoot).
- Tarsal coalition – joints fixed and painful on walking and weightbearing.
Photo below : Stiff Flat Foot due to Inflammatory Arthritis (Juvenile Idiopathic Arthritis).
Photo below : Radiograph showing tarsal coalition with fusion of the calcaneum and navicular bones (arrowed)