Flat feet are simply a normal anatomic variation of the human foot, as much as ‘normal’ or ‘high’ arches are. It is likely mostly genetic, and passed to our children. This variation is quite common, but does pose a unique challenge to modern humans, who tend to wear shoes most of their lives to protect the foot skin from the dangers of civilized living. In populations where shoes are not worn, the foot’s muscle and support system is usually able to adapt to this flat structure from an early age. By wearing shoes, we take away some of this adaptation. However, the danger to the foot by walking barefoot in public or on concrete, gravel, and other hard surfaces far outweighs the lack of structural adaptation, and the notion that one should walk barefoot to keep this ‘natural’ process active is potentially harmful. Unfortunately, because of the infrastructure we have paved our ground with for thousands of years, we are far better off in shoes. However, those of us with flat feet must now deal with the issues that come with an unadjusted foot structure. Even though flat feet are not a deformity in the same vein as an extra toe or clubfoot, we still refer to it as a deformity because in essence it functions as a foot deformity by being the source of numerous foot problems over time.
The foot problems that develop due to flat feet are generally due to instability that is present in the foot when it is allowed to over flatten. This instability will gradually cause numerous other actual foot deformities by forcing the foot’s muscle and support system to change the way it anatomically is supposed to function. The change in the way certain muscles and tendons pull on the foot, and the change in how ligaments and joints are positioned, will often lead to foot deformities like bunions and hammertoes. These deformities in and of themselves can become painful over time in certain people. However, of more importance to this discussion is the role flat feet play in causing tissue injury, which leads to chronic pain. When flat feet are subjected to lengthy or strenuous activity, the overly flexible nature of this foot type can allow other parts of the foot to become overly stretched and strained. This includes the plantar fascia, a thick cord on the bottom of the foot that is the source of the common heel pain when it is injured, as well as a large tendon under the inner side of the ankle called the posterior tibial tendon. When this tendon is injured and not treated properly, it can lead to a debilitating degenerative process that can actually allow the foot to flatten further. Other injuries directly related to flat feet include nerve inflammation in between the long bones of the foot known as a neuronal, as well as various arthritic conditions.
In basic terms, there are two options for treatment, as there are two basic types of flat feet. The options are supportive shoes and prescription orthotics inserts, and surgical reconstruction. The two basic types of flat feet are flexible and rigid. Flexible flat feet (which are most common), can be pushed and held out of a flat position. Rigid flat feet are stuck in that position, due primarily to inflexibility of a deformity that is mostly bone in nature. Today I will discuss shoes and inserts, which are primarily helpful for most cases of flexible flat feet (but not rigid flat feet).
Over the last fifty to sixty years, our understanding of how the foot functions mechanically has grown exponentially. The mechanics of the foot are complex, and not easily measurable by direct means given the intricacy with which the various joints work together to propel us. Our current understanding of this function is advanced, but not perfect. Regardless, the development of the field of foot biomechanics has led to the development of the prescription functional orthotic, a device that has made it possible for countless people to enjoy their lives foot pain-free, or at least with considerably less pain. This device is not the same as over-the-counter arch supports found in stores and TV commercials nationwide, and it is not the same as pricy off-the-shelf plastic inserts masquerading as ‘orthotics’ in numerous national retail chains. A prescription functional orthotic is a medical device that is made of a mold of the foot (usually in plaster, although digital techniques are improving with time). This mold is created while the foot is being stabilized in a mechanically neutral position, otherwise known as the subtalar joint neutral position. In this position, the foot is neither in a flat orientation, nor a high arch orientation. It is roughly a position that research has determined should be the model resting position of the foot,when the foot has stopped rotating inward or outward during the walking cycle. Many different factors contribute to getting the foot in this position, as the foot has numerous ways of compensating for any variation in structure between one part of the foot and another. A true functional orthotic takes into account these variations, and subtle ways of angling or shaping the insert arise in the prescription process that make the resulting orthotics function even better. Because these inserts are constructed based on the specific foot mold, and slightly altered based on a complete biomechanical exam of the foot and lower leg, they will actually correct abnormal foot structure in a predictable and scientific way. Over-the-counter inserts simply shove wads of padding or plastic into the arch blindly and hope it will be close enough to give proper support to the foot. These kinds of inserts are usually comfortable, and do provide more arch support that a shoe alone can give. However, they do not provide the exact level of foot structure control that a condition like flat feet often requires. Only prescription orthotics can fill this role completely.
The use of prescription orthotics allows for stabilization of the flexible flat foot when worn from shoe to shoe. This device reduces much of the strain the bottom of a flat foot endures with standing and walking, and it can indirectly slow down the progression of flat feet related deformities, like bunions and hammertoes, by correcting the underlying cause. The proper choice of shoe also contributes greatly to this treatment. In general, people with flexible flat feet need a shoe constructed with that foot structure in mind. A better choice of shoe is one that is only flexible at the ball of the foot, and not in the middle of the foot. It should have a stiff sole, a stiff area that cradles the heel, and should be wide enough that the sides are not tight against the foot when it widens out as it flattens. Most importantly, it should fit the orthotic and be comfortable to wear after many hours of activity.
For the vast majority of people with flat feet, a prescription orthotic and supportive shoe will be sufficient treatment, much like eyeglasses or contacts are sufficient for those with vision impairment. However, those that have rigidly flattened feet are not generally helped by orthotics, as the foot must be flexible for the orthotic to change foot structure. There are also times with flexible flat in which orthotics do not provide enough support to control pain symptoms. In these cases, the physical structure of the foot needs to be permanently changed to relieve pain and improve foot function.
Surgery is usually reserved for people who have failed orthotic therapy, or those who have rigidly flat feet that generally will not benefit from orthotic inserts. Each surgeon has their own criteria regarding how early they consider surgically correcting flat feet. Some surgeons wait until all other options are exhausted, and others consider surgery much sooner in the treatment process.
Surgery must correct all components of a deformity that can be quite complex. There are three different lines of motion that are involved in the flat foot deformity. Each individual case has a different arrangement, where some feet are more deformed in one or two lines of motion compared with others. The abnormal motions that dominate the deformity are the ones the surgeon needs to concentrate on, as this will affect their choice of surgical procedure. Different surgical procedures have been developed to deal with the many nuances of the flat foot deformity. A typical flat foot reconstructive surgery involves several different individual procedures to correct each component of the deformity. The flat foot deformity can involve a shifting of the foot outward, a bending of the foot upward, and/or a rolling of the foot inward. By addressing the components that dominate the deformity, a surgeon can effectively reconstruct the foot to obtain better foot structure. These procedures involve various combinations of bone cuts and soft tissue procedures that rotate, flex downward, or lengthen the foot. More flexible deformities can tolerate the use of a blocking cone-like implant that keeps the foot from flattening, especially in younger patients. Given the nature of the bone cuts, the foot and leg is usually immobilized during the recovery period, which can take two to three months before regular shoes can be worn. Patients with the implant recover much faster.
Many people who have flat foot reconstructive surgery do quite well. Such surgery does carry with it potential complications, including over or under correction, non-fusing bones, infection, and scar tissue formation. Depending on general health, some people may not be good candidates for what amounts to be a mildly extensive foot procedure. Proper following of all postoperative instructions is very important, as that alone can sometimes be the difference between a successful surgical outcome and a poor result. These procedures are performed by most podiatrists, and some orthopedic foot specialists, and are usually performed in an outpatient, same-day setting.
As you can see, the flat foot deformity is a very complicated condition that requires very careful consideration of all it’s components for treatment to be successful. While most people do well in orthotics, surgery is needed in more advanced cases.
Scott R. Kilberg DPM 