Complex Foot Deformities (CFDs) are usually long-standing foot and ankle deformities that can have different causes. These can either be congenital anomalies (as in cases of many hereditary syndromes); following neurological conditions (such as meningitis or a sequel of poliomyelitis or cerebral palsy); following traumatic conditions (such as crush injuries to the foot and ankle), or following scar contractures (as in cases of burns). There are many other conditions that can result in foot and ankle deformities.
The deformity here is usually multi-planar, which means there is an abnormal relation between the different parts of the foot and the leg.
Such deformities cause uneven distribution of weight on the joints and can cause early wear and tear in the joints. It also involves abnormal weight distribution in the foot, where more weight is taken in areas which are normally not designed to bear such weight. This results in abnormal hard skin and corn formations and can even cause skin breaks and ulcerations.
The presentation usually involves pain due to the abnormal weight distribution and the wear and tear, and difficulty wearing shoes.
Many patients with such severe and long standing deformities would have had multiple operations in the past as children. The traumatic cases might also have been complicated by skin loss or previous plastic surgery or scarring. This usually adds to the challenge of treating these cases due to the unfavourable skin conditions.
Congenital cases may also be accompanied by other problems in the same limb, such as limb length discrepancy.
Complex foot and ankle deformities (CFDs) have always been very challenging to treat. Classically these cases have been treated by specially made shoes and insoles. Surgical treatment was used as a very last resort, as it involved significantly high risks of complications.
The operations involved extensive soft-tissue procedures (such as lengthening the heel cord), which required the removal of large bone wedges or creating multiple breaks in the foot and ankle bones to realign the foot. Fixing the bones in place following these procedures was very challenging and involved the patient wearing a protective plaster cast for long periods of time, usually for three months. Joint fusions were usually needed and amputation would have been advised at some point in most of the severe cases.
Why are these cases (CFD) challenging?
Due to the nature and cause of complex foot and ankle deformities, most of these deformities are longstanding. The foot is usually stiff and painful. Some congenital cases leave the foot shorter on the involved side. This has always been an issue with traditional surgical techniques, which usually leaves the foot even shorter. Previous scars make planning further surgical incisions difficult and can cause problems with wound healing.
Achieving a perfect correction is also very challenging because the deformity involves multiple planes and affects multiple joints.
The traditional surgical techniques also usually required extensive dissection to achieve correction.
The long stay in plaster was another cause of complications, including clots in the leg, joint stiffness and poor bone quality.
Finally, the patient was not allowed weight bearing for a long time, which usually adds a lot of inconvenience and makes the post-operative period quite difficult.
The concept of gradual correction
The concept of gradual deformity correction is referred to as “distraction histogenesis”. This concept, developed in Russia many years ago, involves applying gradual constant tension to tissues using a circular external fixator. This leads to these tissues lengthening over a period. The technique was used to lengthen limbs and correct deformities, with a vast spectrum of applications in different parts of the body.
In the foot and ankle, this technique is applied by using a circular frame that has three main parts. One part lies on the leg, another on the heel and a third part on the forefoot. In many cases the bone is cut in special sites between these three segments. The rods connecting these three segments together are then lengthened or shortened gradually to move these segments in relation to each other.
This gradual movement leads to gradual correction of the deformity and builds new bone in the area where the bone was cut.