Medically we refer to flattened longitudinal arch with or without a heel that from behind diverges to the outer side of the foot ( valgus) and has pain with dysfunction/ impaired function . The deformity has evolved without a trauma, but maybe through several minor sprains or over time as a degenerative process.
In the medical field a pronating- flat foot is a common feature and is seen in more than ¾ of all patients. Usually this is not a pathological situation but something that might lead to a pathological painful condition. The flatfoot type of foot is defined by a Tight heelcord or calf muscle which forces the anterior part of the foot to the ground. This puts stress to the joint complex under the ankle joint and the midfoot joints and in either of these or in both a progressive deformity might occur. There can be a progressive stretch and subsequent failure of the ligaments or tendons and this will cause the deformity that usually is progressive to occur. In the early stages the deformity is reversible, but in the later stages will lead to degenerative arthritis, finally with a fixed painful deformity.
The deformity occurs more often in women and in two age- groups 40-60 and the elderly group.
Often the symptoms start at the inside of the foot with pain beneath the medial malleolus and distally, often with swelling. Subjective instability and pain upon stance and walking is experienced. As the deformity progresses lateral symptoms beneath the lateral malleolus are often experienced due to abutment of the bony structures due to the deformity. Increasing difficulty to walk or exercise or to accommodate to any kind of shoe-wear. In the later stages the deformity is rigid and painful and the foot might be everted so that weight-bearing is actually impossible or on the medial malleolus.
The clinical examination and details from the patient are usually diagnostic. Within the clinical examination the feet are examined while standing and trying to stand tip-toe and other tests to examine the stability and function of all tendons and joints in the foot.
Weight-bearing plain X-rays of the foot and ankle helps in defining the point of deformity and to dial the proper treatment. Usually a classification is possible to make together with X-ray and clinical examination that can lead the surgeon in the treatment.
As an adjunctive sometimes further investigations like ultrasound or MRI are made. This is however usually not necessary to make the diagnosis.
In early cases with only slight deformity and mostly medial symptoms it is sometimes possible to reverse the symptoms.
Usually a period with off-loading in an orthotic is recommended followed by physiotherapy and corrective / off-loading shoe modifications like insoles and stable shoe-wear.
If pain is relieved and ambulation accepted in these modifications surgery is not indicated.
Whenever medical treatment is not satisfactory or possible surgery is indicated.
Generally a surgical reconstruction with preserved mobility of the rear foot ( hindfoot) is possible in the earlier stages when the foot is still flexible.
With a combination of realigning bone procedures / osteotomies in the heel bone (calcaneus) and possibly stabilizing procedures ( fusions) in the midfoot combined with tendon transfers and ligament reconstructions medially and lengthening of the calf muscles or heel cord a plantigrade foot is possible to restore.
In these cases a likelihood of success is generally between 85-90 % with the surgery that post operatively usually means about 6 weeks non- weight bearing , followed by protected ambulation in an orthosis together with physiotherapy.
In the later cases when the foot is no longer flexible a plantigrade foot is achieved with realigning stabilizing joint procedures ( fusions) and usually lengthening of the calf muscles or heel-cord.
The postoperative regimen is the same in these cases as well as the results, but some joint are sacrificed ( motion) to secure a correct pain-free position of the foot.
The decision of which procedures are most accurate in each case are best made by the treating surgeon.