Flat Feet - Part Two
Observing the patient rising up on their toes as the calf muscle performs the tiptoe action to bring the weight over the metatarsal heads, we should see an inward deviation of the heel area. This will often be absent if the tendon of the posterior tibial muscle is not working well and the patient may not be able to achieve tiptoes, or can do so partially with pain. Palpation around the tendon insertion is the next action for the physiotherapist, searching for tenderness, swelling and pain in the areas. The muscle power will now be tested as the patient is asked to push the foot inwards against resistance.
During the strength test the tendon can be felt to check that it is present all along its route, then the ability of the patient to pull their foot up with the knee straight is measured, typically at least 20 degrees. In flat foot which has been present for some time this movement may be limited with the inward movement, the foot having been in an outward and downward position for long enough to develop tightness, known as a contracture. The forefoot will also be checked for the maintenance of an abnormal position. Treatment will be pursued if the patient has pain and deformity which is disabling, problems with walking or problems managing shoes.
If the patient has painless flat feet and can walk relatively normally then continuing with normal footwear and perhaps insoles will be appropriate. In more acute cases of inflammation of the posterior tibial tendon immobilisation in a plaster of Paris cast, physiotherapy, anti-inflammatory drugs, braces and orthotics are mainstays of treatment. If large stresses are not applied through this area, such as with older people, then conservative treatment in this way can be useful and avoid operation. Pain is the major presenting factor in the early acute stage of this condition and if there is little then weight bearing through the cast may be permitted.
Orthotics can then be used to support the foot once the acute stage has settled and physiotherapy employed to stretch out any tight joint movements and strengthen the muscle groups. As the dysfunction proceeds and the foot deformity is flexible but painful it may be necessary to control the motion of the hindfoot more closely using a ankle-foot orthosis (AFO) of some kind. Later if the deformity becomes more rigid then individually moulded braces, perhaps extending to the knee or beyond, can be employed. This kind of treatment is for patients who are not physically very active, with operative treatment held in reserve.
Surgical treatment of the early acute stage of tendon dysfunction involves opening up the sheath of the tendon to release pressure, a cleaning up of any irregularities in the tendon (debridement) and repairs of tears in the tendon. A below knee cast is used for three weeks after operation and this sort of intervention is thought to prevent the condition from worsening with time. Once the dysfunction becomes more severe the surgical options are many and the choice of which to employ not universally agreed upon and it is difficult to get a very good surgical result.
If the tendon is ruptured then the ends may be cleaned up and a repair done end to end, or if the tendon has detached from its insertion it can be reattached to the navicular bone. In more complex repairs the tendons of other nearby muscles can be detached and used to reinforce the function of the tibialis posterior muscle. An osteotomy, a corrective bony operation designed to realign the bony anatomy, can be performed on the heel bone or calcaneum to restore more normal alignment, decrease the stresses on the spring and plantar ligaments and allows any soft tissue operative changes to suffer decreased stresses.
The main aim of surgery is to produce a foot which can adapt flat to the ground, take normal footwear and be without pain. It is possible for surgery to cause an over correction or an under correction in foot posture and surgeons must take great care in aligning the various aspects of a more normal foot posture. The aim of surgery in the beginning is to halt progress towards potential tendon rupture.