The cavus foot, or pes cavus, comes in a variety of forms. Most notably, it is characterized by a high arch. While many may think that having a high arch is a good thing, having too high of an arch can lead to difficulty fitting shoes, pain in the ball of the foot (metatarsalgia), painful hammering of the toes, and increased pressure on the lateral or outside of the foot. This increased pressure may result in pain and even fracture of the bones. Callus development in areas of increased pressure is typical. Advanced cases of pes cavus can often lead to a feeling of instability, particularly in the ankles.
An important aspect in the diagnosis of pes cavus is the etiology of the condition. Many times this foot type is associated with neurological disease and weakness of the peroneal muscles and/or the anterior muscles of the leg. These muscles insert into the foot, and control the motion and function of the foot. Some neurological causes of pes cavus include Charcot-Marie-Tooth, cerebral palsy, muscular dystrophy, spina bifida, poliomyelitis, and tumors of the central nervous system. While these condtions can be rare, it is important to let your doctor know of any progression of the deformity, any numbness or tingling in the feet and/or hands, and any other associated symptoms such as tripping or instability.
When the etiology of the cavus foot is unknown, it is referred to as idiopathic. This diagnosis is one of exclusion, and should not be made until a through evaluation is performed.
The next step in evaluating the cavus foot should be to determine whether the deformity is flexible or rigid. In other words, is the foot stuck in the high-arched position, or is it able to be manipulated into a more normal position? This helps determine treatment methods that your doctor may suggest. It also helps determine surgical procedures that may be required in the future to correct the deformity, should they become necessary.
The apex of the deformity should then be determined. This is done by looking at x-rays of the feet. The deformity may be coming from one of three main regions of the foot; the forefoot, midfoot, or hindfoot. In forefoot deformities, it is often one or more of the metatarsals that are malpositioned, causing the rest of the foot to alter its motion to accommodate the deformity. The apex may also be located in the midfoot, with the lesser tarsal bones such as the cuneiforms, navicular, and cuboid defining the deformity. In rearfoot pes cavus, the position of the talus and the calcaneus determine the position of the rest of the foot. Of course, combinations of several deformities can exist as well.
Along with a thorough history and physical, nerve conduction studies and/or muscle testing may be performed to help determine the cause of the deformity. The treating physician should have a high index of suspicion for a neuromuscular etiology. Family history of neurological disorder or of pes cavus running in the family should be mentioned.
Treatment of pes cavus is initiated with conservative measures in the vast majority of cases. This may include things like physical therapy, custom molded or over-the-counter orthotics, shaving of painful calluses, and bracing for unstable ankles. A large percentage of patients will find great benefit from conservative treatment alone.
In cases of failed conservative treatment, surgical intervention may become an option. Pes cavus has been discussed in the medical literature for over one hundred years. Much of our understanding of surgical correction of the deformity comes from cases of polio, where those affected by the disease were left with non-functional limbs. Research and technology have improved the outcomes of surgical correction for pes cavus drastically over the years.
For those with flexible pes cavus, soft tissue procedures may provide adequate correction of the deformity. This can include a plantar fasciotomy and/or various tendon transfer procedures. For those with a non-progressive form of pes cavus, this may be the only correction needed.
For those with rigid deformity, or those with more advanced pes cavus, bone cuts may be necessary to bring the foot to a normal position. Depending on the apex of the deformity, this may include cuts in the metatarsals, in the calcaneus, and/or cuts in the lesser tarsal bones.
In progressive deformity, fusion of joints is usually required to establish a more normal foot. Arthrodesis, or joint fusion, can help prevent recurrence of severe deformity in those with a progressive cavus foot type.
Of course, a through evaluation is required before any decisions can be made regarding treatment of the cavus foot. It is important to discuss with your doctor and a foot and ankle surgeon the various options for treatment. Be prepared to answer questions regarding the progression of the deformity, any signs of neurological involvement such as numbness, burning, or tingling in the hands and/or feet, and if there is a family history of similar conditions. These are all important aspects of the diagnosis and treatment of the cavus foot.
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