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.
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.
Settling down of the inflammatory and acute phase permits the use of in shoe orthotics to maintain foot posture and a referral to physiotherapy to increase joint ranges of movement and develop increased strength. The rear foot posture can be controlled more precisely if a flexible and painful dysfunction develops by using an ankle foot orthosis or AFO. The next stage of dysfunction, an increasingly rigid deformity, can be managed by more extensive and customised bracing which can extend to above the knee. Such conservative forms of management are the choice for individuals who demand less physically from their feet.
In the earlier stages of more acute dysfunction of the tendon surgical management entails the tendon sheath being opened to release it, a debridement (cleaning up) of the local area and repairs to the body of the tendon. After operation the patient is typically three weeks or so in a below knee cast, with this operation performed in the hope of stopping progression of the condition. More severe foot dysfunction forces the surgeon to choose from a very large number of operative options. There is no agreed surgical management of this phase and a good outcome is hard to ensure.
A ruptured tendon can be trimmed and an end-to-end repair performed, or if avulsed from its bony attachment this can be re-attached to the navicular bone. In more complex surgical procedures the tendons of other local muscles can be used as reinforcements to the posterior tibial muscle tendon, so restoring some of its function. The bony anatomy can also be reshaped by performing an osteotomy and realigning the joint relationships, such an operation on the calcaneum or heel bone aimed at restoring alignment, reducing forces through the plantar and spring ligaments and permitting the soft tissues to endure less stress.
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.
