Flat foot What happens if I leave my flat foot untreated ?
This will be somewhat dependent upon the cause
With Tibialis posterior dysfunction a progressive deterioration of the rest of the hindfoot and ankle is described. Over what time period this occurs and whether it is inevitable is not definitively known. The stakes are however potentially high as the progression may be to a rigid, painful and arthritic deformity. If an Orthotic controls both the deformity and the pain however this may be all that is required to manage the condition.
The fixed and arthritic flat foot may require at least a triple fusion(see below) and at worst a triple and ankle fusion (or replacement) combined (If the ankle has become involved). This is more extensive and "higher risk" type of surgery than treating early with a tendon reconstruction. Tibialis posterior reconstructionHow does an unhealthy "Tib Post" lead to a flat foot?
The tendon has unhealthy tissue usually over a portion of its length. In this degenerate and inflammed state it stretches. It is effectively unable to support the arch or resist the pull of the peroneal muscles on the outer aspect of the heel and foot which acting unopposed also flatten the arch and move the heel away from the midline. What is involved in reconstructing the tendon?
The diseased tendon is excised and a neighbouring tendon moved into its place (the FDL, Flexor Digitorum Longus) to perform its function. THE INNER(MEDIAL) BORDER OF THE FOOT
Interactive Foot and Ankle 2 2000 Primal Pictures Ltd We anchor the FDL tendon into its new location by using a specially designed "anchor" from Arthrex
(Naples , USA).
The Bio-Tenodesis screw is absorbed by the body once it has served its purpose and the tendon is healed into its new position. 
It is usual to help the tendon mechanically by moving the weight bearing part of the heel back towards the midline, with an osteotomy of the calcaneum (see operative stills). Why can't the tendon simply be repaired?
Once the tendon is no longer able to perform its mechanical function, and lets the arch collapse, experience has shown that it is not amenable/its tissues are too poor to repair.
Once the tendon is no longer able to perform its mechanical function, and lets the arch collapse, experience has shown that it is not amenable/its tissues are too poor to repair. | 
