Flat foot or pes planus is the foot shape where the medial arch of foot collapses and the whole sole touches the ground. Flat feet can be either developmental or can develop at adulthood who were normal earlier. Second variants are called adult acquired flat feet.
A Developmentally flat foot is either rigid or flexible. Rigid flat foot can remain asymptomatic for a significant time till they suffer from any foot or ankle injury. Most of the time the flexible flat foot remains asymptomatic.

Rigid flat feet develop due to abnormal bony bars between different hindfoot bones which care called collision. Collisions can happen between talus and calcaneus (talocalcaneal coalition) or between calcaneus and navicular (calcaneonavicular coalition). This bony bridge prevents normal development of the foot arch and it never develops during growth. It becomes obvious during adolescence.

New born children do not have a foot arch, it develops gradually as the child grows and it continues till the child’s age is 7 to 10 years. A flexible developmental flat feet is considered only when a child do not develop any foot arch after the age of 10 years. This happens due to developmental laxity of the ligament.

Adult acquired flat feet develops due to insufficiency of tibialis posterior tendon and mid foot injury like Lisfranc’s fracture dislocation or rupture of spring ligament. Insufficiency of tibialis posterior tendon develops due to its degeneration and tear.

Most of the time developmental flat feet are asymptomatic, especially the flexible one. Many of the flexible developmental flat feet never complains of any symptom till their late age and can perform all their activities like other normal child. Only the severely deformed flexible flat feet are symptomatic. Pain is the main symptom associated with reluctance to participate in sports activity or lagging behind the other child of the same age in different sports activities.

Similar presentation can be seen in rigid type developmental flat feet also. It can present with severe pain due to inflammation adjacent to collision. Less deformed ones can remain unnoticed till they suffer an ankle sprain.

Adult Acquired Flat feet are more prevalent in middle aged fatty female but other also can be affected. Initial presentation is pain and swelling at medial aspect of foot and posteromedial aspect of medial eminence of ankle. Along with difficulty in walking and standing for long as well as difficulty in heel raise. As disease progresses the foot arch collapses and the whole foot and heel deviate outwards. Walking becomes painful and limited due to ineffective foot mechanism as well as secondary degeneration of hindfoot and midfoot joints. Up to a certain period this deformity remains correctable but disease progress and secondary arthritis sets in deformity becomes rigid and painful.

Developmental flexible flat feet if asymptomatic they do not need any treatment. Sometimes anxious parents visit a specialist, they need only counselling. Rigid type flat feet whenever is detected either symptomatic or not should consult a specialist Foot & Ankle surgeon. Adult acquired flat feet suspected patients should visit a specialist Foot & Ankle surgeon at the very beginning of their symptom. Because progression of this condition and severe disability can be prevented with timely intervention.

Your doctor will examine your foot to evaluate the severity of deformity as well as its correctability. He will also check the power of different foot muscles as well as range of motion. Will check the other joints for generalised laxity. May enquire about the presence of similar deformity in other siblings or ancestors. He may ask for a weight bearing x-ray of your foot, foot scan. CT and MRI may be required if rigid type flat foot is suspected. USG or MRI is sought for investigation in the early stage of adult acquired flat foot which is called tibialis posterior tendon dysfunction. Although weight bearing x-ray of both feet in both planes is mandatory in every case. Additional heel alignment view is also being done sometimes.

Self Care and prevention:Stretching exercise of calf muscle, strengthening of foot intrinsic muscle, comfortable footwear with adequate arch support and toe box are helpful in keeping foot pain free and maintain adequate foot function as well as prevent gait related other issues.

Definitive treatment: Asymptomatic flexible flat feet do not need any active treatment. For symptomatic flexible flat foot following are the recommended treatment option

• Conservative: Physical therapy in the form of calf muscle stretching, strengthening of ankle and foot muscle. In mild deformity arch support and moderate to severe deformity UCBL, a heel stabilising orthotic is recommended.
• Surgical: surgical treatment are considered only severely symptomatic established flat foot after the age of 5-7 years
• Arthroresis along with calf muscle release
• Calcaneal osteotomy in combination with spring ligament reconstruction and calf muscle release

Treatment for rigid type flat feet depends on their severity of symptom and age of detection

• Conservative: Physical therapy, accommodative arch support and analgesic in acute symptoms.
• Surgical
• Resection of collision if detected before skeletal maturity and there is no arthritis in other joints.
• Triple arthrodesis with recreation of foot arch in late cases and after skeletal maturity.

Adult acquired flat feet treatment varies from conservative to surgical depends on its stage and progression.

• Conservative: Physiotherapy, UCBL; a heel stabilising foot orthotic and analgesic are recommended.
• Surgical: different surgical treatment is recommended at different stage of the disease
• PRP injection
• Arthroscopic tendon debridement
• Arch recreation by osteotomy and tendon transfer
• Triple arthrodesis