Flexible flatfeet

in children


What are flexible flatfeet?

Flexible flatfeet are feet that appear flat when the patient stands but when the patient stands on tip toe the arch reforms. Flexible flat feet appear in children from a young age and may disappear after the age of 7-10 for many children. We know that in individuals who have lifelong flat feet that they are more susceptible to failure of the structures which support the arch. If individuals develop warning signs that the arch of the foot is failing it may be that surgery to protect the structures which support the arch of the foot is advisable.

What is the Tibialis Posterior Tendon?

The Tibialis Posterior is a muscle that runs deep in the calf and its tendon inserts onto the arch of the foot. The tendon is one of the key arch supports along with several ligaments (and also the bones whose shape forms the arch of the foot).

In children the attachment of the tendon to the bone (navicular) can be irritated during rapid growth and the bone can develop injuries seen only on MRI. This is called medial navicular stress syndrome. Alternatively, if the tendon attaches via an extra area of bone the attachment can be inflammed. The extra bone is the accessory navicular (os navicularum) can be or varying sizes and shapes. Some attach via a flat connection with the main navicular whereas some are a separate small round bone within the tendon.

What is the Spring Ligament?

The Spring Ligament supports the arch of the foot. It is deep inside the plantar foot under the tibialis posterior tendon. We know that in some individuals the Spring Ligament tears before the tibialis posterior tendon tears. When is tears it can resemble the rotator cuff tear that shoulder patients suffer from. Repair is possible but it is deep within the foot so healing is slow. The spring ligament is always repaired when a patient has a tibialis posterior tendon reconstruction but a sinus tarsi implant can help to support the arch of the foot and should stop further tearing in the spring ligament.


What are the treatment options when a young patient has a painful flatfoot?

When the tendons and ligaments which support the arch of the foot are inflammed or damaged but still working there are options:

  1. Insoles to elevate the arch and supportive shoes.

  2. Physiotherapy to stretch the tight muscles in the back of the legs.

  3. In adolescents:Release the tight muscle in the back of the legs to allow the arch supports to work better.

  4. In very rare cases: Key hole surgery to insert a sinus tarsi implant which will allow the spring ligament and tibialis posterior tendon a chance to rest and repair. Gastrocnemius lengthening is needed in combination with this surgery.

  5. In extremely rare cases: A Kidner Procedure to repair the attachment of the tibialis posterior tendon










Why do the soft tissues heal so slowly?

In relative terms surgery on bone heals very quickly and keyhole bony surgery heals even faster. By contrast surgery which requires tendons to heal is very slow. (Tendons are very specialised soft tissue made up largely of a specialised protein which is super-organised in order to give the tendon strength. Tendons have a poorer blood supply and only a small amount of cells within them. It is the cells which must make the proteins and because their are few cells, little blood supply of nutrients and a complex structure to heal; the end result is slow healing.) It should be emphasised that in children soft tissue healing is faster compared to adults even though the healing is slow compared to bone.

What is a Sinus tarsi Implant?

Once a specialist has decided that a child has a normal flexible flatfoot, it is really quite rare for a child to need more than insoles and physiotherapy. A sinus tarsi implant might be used in a sporty adolescent who has repeated problems. A sinus tarsi implant is a small metal spacer which sits between the calcaneus and the talus. It holds these bones apart and prevents the arch from collapsing. The implant is also called an arthroereisis screw. The arthroereisis screw sits between the two bones in an area that does not have any cartilage, called the sinus tarsi. This is why the screw is called a sinus tarsi implant.

How Long Should a Sinus Tarsi Implant Stay in For?

There are no clear guidelines about how long the implant should stay in for. If the implant causes no pain there is no need to remove it but if there are any symptoms, it can be removed after 6 months. There are reports that the implant produces some positive changes to how some patients use their arch permanently. If the implant causes no symptoms and allows the patient to resume normal life - it is unlikely that the surgeon and patient will decide to remove it.

Why does the Gastrocnemius Muscle get tight in children?

The gastrocnemius muscle is one of the two muscles which insert onto the Achilles Tendon. The gastrconemius becomes tight because it crosses the knee joint where most of the lower limb growth is occurring.

Why does the Gastrocnemius Muscle tightness cause problems?

The gastrocnemius muscle is one of the two muscles which insert onto the Achilles Tendon. Gastrocnemius tightness stops the ankle from moving normally and leads to equinus.

In a child this can affect a number of foot conditions:

  • Young children can become habitual toe walkers

  • The restricted motion in the ankle joint can be accommodated by the child developing other compensatory abnormalities:

    • The child can stretch out the back of the knee and develop hyper-extension

    • The child can increase the lordosis (curvature) of their spine

    • The child can also accomodate through their hips

  • The child can develop a heavy heel strike and the imbalance on the Achilles tendon can lead to fragmentation of the heel (Sever's Disease)

  • The child can overpronate or flatten the arch of the foot- This is always seen in children with tight gastrocnemius muscles and flexible flat feet

How do I help my child to stretch their tight gastrocnemius?

The knee must be straight in order for anyone to stretch just the gastrocs. Experience has taught me that stretching on a slope or slant board is the most effective. The best regimen is 3 minutes of stretching every three hours.

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  • You can go up and down on tiptoes in sets of 3, slowly and 15 reps in each

  • You can stand on a skipping rope and adjust your foot position

  • You can hold a DHR for 15 seconds

  • It can be difficult to progress to the next award level because the ankle will take double the weight when you move to lifting the good leg to lower only on the operated leg.

  • You are better to stay at the bronze award level but to add in a back pack with increasing weight as you feel ready for more

  • When you have done this for some time you will be ready to progress to the silver award level




  • May need to add weight in backpack on DHR to reach silver level

  • You go up on both feet but lift unoperated leg and lower slowly only on operated leg

  • 3 sets, working up to 15 reps in each

  • You can stand both feet on a wobble board

  • You can hold a solid DHR for 20 seconds




  • 3 sets, working up to 15 reps in each

  • You can stand on one foot on wobble board

  • You can hold a solid DHR for 40+ seconds

  • Many patients decide to finish physiotherapy when they have achieved this level



  • Progress to hopping in all directions

  • Double Hops

  • Gentle jogging to reintroduce running