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Acquired Flat Foot – Part Two
As the calf muscles contract and a person rises up on tiptoes to bring the bodyweight over the heads of the metatarsals there is normally an inward deviation of the heel region. This inward deviation will not be present if there is a significant dysfunction of the tendon of the posterior tibial muscle and the patient may not be able to attain the position or can do so in part and with pain. The physio will move on to palpating the tendon insertion with the leg up on a plinth, searching for swelling, pain or tenderness. To test muscle power the physio will resist the inward and downward action of the foot.
The physiotherapist will palpate all along the tendon as its strength is being assessed to check it is not ruptured or deficient and then straighten the knee and measure how much dorsiflexion is achievable, typically twenty degrees or so. If the deformity has been present over time and the foot held in an out and down position then this movement can be lost as a tight contracture develops in the joints. This can also occur in the forefoot joints and the physio will move down to check this after the ankle area. Treatment may be appropriate if the patient is having difficulty with walking, managing shoes, pain and deformity.
If the flat foot is painless and the person can walk well then normal shoes with or without insoles will suffice. Conservative management of posterior tibial tendon dysfunction involves resting, immobilisation, anti-inflammatories, physiotherapy and bracing or orthotics. This might be sufficient especially in elderly people as they do not put large forces through the area and may be less suitable for operative intervention. The initial stage of this condition presents primarily with pain, with acute inflammation of the tendon managed in plaster of Paris cast for a few weeks, which can be a weight bearing cast if walking is comfortable.
After the acute inflammatory stage has settled down then orthotics can be employed to support the foot posture and physiotherapy started to increase the ranges of motion of tight joints and increase muscle strength. An AFO or ankle foot orthosis can be used to control the hindfoot posture more strongly as the condition worsens towards a painful but flexible foot deformity. As the deformity increases in rigidity then braces which reach to the knee or above and are individually casted may be necessary. These methods are useful for less active or older individuals who do not demand so much of their feet, leaving surgical management in case of failure.
The initial surgical management of the more acute phase of this condition is done by a release of pressure from opening up the tendon sheath and cleaning up any irregularities in the tendon (debridement) and repairing tears. Immobilisation in a below knee cast for three weeks is a typical post-operative management, with the operation aimed at preventing further deterioration of the condition. Once the dysfunction proceeds to a more severe phase there are a very large number of surgical options, little agreed surgical process and a difficult job to ensure a good outcome.
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.
Overall, surgery aims to achieve a painless foot which can adapt flat to the ground and which can wear shoes easily. Surgery can result either in an under correction of the deformity or an over correction and great care must be taken in aligning the many components of an appropriate foot posture. Initial surgery is to prevent the progression of the tendon inflammation to eventual rupture.
Jonathan Blood Smyth, editor of the Physiotherapy Site, writes articles about Physiotherapist, back pain, orthopaedic conditions, neck pain, injury management and physiotherapists in Liverpool. Jonathan is a superintendant physiotherapist at an NHS hospital in the South-West of the UK.
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Filed under back pain by on Jan 9th, 2010. 
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