Charcot Foot: A Case Study
November 2009 Issue
Neuropathic osteoarthropathy, or Charcot foot, will affect 15 percent of the 18.2 million people currently diagnosed with diabetes mellitus, according to the article, "Neuropathic Arthropathy (Charcot Joint)," (eMedicine from WebMD: www.emedicine.medscape.com/article/391989-overview). It is the foot pathology most often associated with diabetic neuropathy.
While it takes decades for diabetic neuropathy to develop, the acute phase of Charcot foot develops within a timeframe of several weeks to months. Currently, there is no cure, and the disease often results in degeneration, fracture, and the abnormal formation of the foot bones. Subluxation of the joints and ulceration of the foot's soft tissue also occur.
Before delving into the variety of orthotic and pedorthic choices for managing this challenging condition, it may be advantageous to briefly review its symptoms and complications.
|Gary Rothenberg, DPM, CWS; Henry McQuade; Gordon Zernich, CP, BOCP; and Tomas Dowell, CPO, LPO.|
Charcot foot progresses through two phases: the acute phase and the post-acute phase. Treatment during the acute phase includes immobilization and stress reduction. Immobilization is usually achieved through a total-contact casting technique of the lower leg and foot, resulting in a total non-weight-bearing effect of the mid- and forefoot until the acute phase is resolved, which generally takes three to six months. Symptoms of the acute phase of Charcot foot—which may be mistaken for cellulitis, osteomyelitis, or thromobophlebitis—include inflammation, swelling, and a three- to seven-degree temperature increase of the foot from its norm.
Other symptoms include dry, cracked, reddened skin and an increase of synovial fluid within the joint cavity as a result of the disease. Foot stability and balance become challenging because of the loss of joint function and bone vitality. About half of patients incur degenerative structural changes to the affected bones and joints, changes that place undue pressures and stresses on soft tissues that are unequipped and ill-suited for it; thus, the risk of ulceration is great.
Because of the neuropathic nature of Charcot disease, the pain the patient feels is significantly less than what would be felt in an otherwise sensate foot undergoing such pathologic changes.
Oftentimes, fixed foot deformities involving bones and ligaments are present once the active phase of the disease coalesces, yet it may take another one to two years for the foot to completely heal. It is usually after the foot's coalescence that the podiatric and orthotic or pedorthic clinical teams evaluate the extent of the damage, identify any complications, and determine what may be done to exploit weight-bearing areas and relieve and/or correct other problematic areas.
The patient may present with any number of lower-leg and foot problems, such as equinovarus contracture, drop foot, hammer toes, hallux rigidus, hallux valgus, and/or a collapsed mid-tarsal bone structure, which may regress into a collapsed longitudinal arch, a rocker bottom foot, or worse, a club foot. Complications from ulcers include infection, a major area of concern since osteomyelitis may lead to amputation of the extremity.
Chronic plantar ulcers lasting six to 18 months or longer complicate the Charcot foot condition. Complex cases benefit from a multidisciplinary team approach including podiatry and wound specialists working closely with prosthetists to design a device that meets an individual patient's needs.
Ulcers heal much slower when circulatory and neurologic problems, coupled with edema, co-exist with bone and joint deformities. The risk of an infection like osteomyelitis—and therefore the possibility of a lower-extremity amputation—becomes greater.
Traditional Options for Managing Charcot Foot
Optimal management of the Charcot foot condition includes correcting, if applicable, the equinovarus deformity; managing drop foot; inhibiting the forward advancement of the tibia over soft tissue areas beneath displaced bones and joints of the mid- and forefoot; and loading areas of the foot plantar surface that may safely support weight while unloading other areas to inhibit the formation of ulcers.
|Photograph courtesy of Larry Gilstad|
Use of a custom-molded, solid-ankle polypropylene AFO in conjunction with an orthopedic shoe is a poor choice for the insensate Charcot foot because the hard, rigid thermoformable plastic presents an increased risk to an already damaged and insensate foot in the warm, dark, moist, confined environment of the shoe: a breeding ground for bacteria.
The type of orthotic device used depends on the extent of the Charcot foot injury presented during the clinical evaluation and any other complications present. Orthotic appliances include the custom-molded, rigid-leather, lace-up ankle gauntlet, such as the Arizona brace or total-control AFO; Charcot restraint orthotic walker (CROW boot); a custom-molded shoe modified with an insensate orthotic insert, high toe box, rocker sole, and lateral T-strap coupled with a single or bilateral metal upright AFO attached to it; a patellar-tendon-bearing (PTB) AFO is also an option.
Encouraging the patient to regularly wear shoes and stockings is the first line of defense since that protects the foot against external environmental hazards. The more physically active the person is, the more such protection is needed. However, the warm, dark, moist, confined environment of an orthopedic or custom-molded shoe or a CROW boot worn throughout the day, seven days a week, becomes a breeding ground for bacteria on the already compromised, sometimes ulcerated soft tissues of the foot. If the person is less active or uses an assistive device such as a wheelchair for mobility, the protection afforded by shoes become less essential, thus a suitable alternative may be used—especially when infection becomes a primary concern.
A Hybrid Option
There are also times when a hybrid type of orthosis is called for. This type of orthosis incorporates the optimal features of one type into another for a unique, functional purpose and effect to prevent, for example, the infection of an ulcer. An example of a hybrid orthosis is provided in the following case study.
The orthotic and prosthetic department at the Bruce W. Carter Department of Veterans Affairs (VA) Medical Center in Miami, Florida, under the direction of Tomas G. Dowell, CPO, LPO, incorporated the use of a hybrid orthosis—an open-toe healing sandal attached to a solid ankle AFO—for a 70-year old patient with bilateral Charcot deformities. The patient is obese, has diabetes and venous stasis, and presented with additional challenges including edema, reduced mobility, hammer-toe deformities, and hallux valgus and rigidus. A plantar wound on the deformity at the styloid process (fifth metatarsal base) was open for 14 months before healing. Healing was achieved through biweekly visits to the wound clinic, debridement, and compression dressings with off-loading both in the dressing and through the use of a DH walker boot. Once the wound was healed, the same system was used to allow the healed wound to strengthen while awaiting the custom hybrid orthosis.
|Photograph courtesy of Larry Gilstad.|
The patient used an electric wheelchair as his primary mobility device. Long periods of sitting with his legs in a dependent position increased edema through the day. The challenge was to create a system that would control edema, prevent new wounds on the knuckles of the hammer toes, prevent recurrence of the wound on the styloid process, and afford adequate protection from injury while he walked or rode in his wheelchair. In addition, the system had to be "user friendly" in the face of limited hand strength and flexibility. It was thought best to compromise the protective attributes of a shoe for something less likely to harbor bacteria and risk subsequent infection. A single, medial upright solid-ankle AFO with a lateral T-strap (to correct an equinovarus deformity) was used with a rocker-bottom sandal. A closed cell, low-density/low-durometer polyurethane material with a cork base was used for the sandal's custom-molded insert, loading areas of foot's plantar surface where applicable and relieving the deformity on the lateral, plantar aspect of the mid-foot.
The patient is able to manage the device independently and uses Tubigrip for edema control. Maintenance is required to prospectively replace the custom-molded insert before it becomes too compressed, with visits to the wound clinic every other month for callus reduction. The patient has been educated to monitor his feet daily and return to podiatry or the wound clinic immediately if redness or drainage develops.
This orthosis has allowed the patient to return to his usual routine and activities while it prevents progression of the equinovarus deformity. In addition, the wounds on the hammertoes and styloid process have remained healed for more than six months using this system.
The authors work collaboratively at the Bruce W. Carter Department of Veterans Affairs (VA) Medical Center, Miami, Florida.
Gordon Zernich, CP, BOCP, works in the orthotic and prosthetic lab. He has written numerous articles documenting his O&P experiences for professional and health trade journals.
Karin Zachow, MD, CWS, is the director of the Multidisciplinary Wound Care clinic.
Gary Rothenberg, DPM, CWS, is a certified diabetes educator who currently serves as an attending podiatrist and the director of resident training.
Tomas Dowell, CPO, LPO, started his career in orthotics and prosthetics in the U.S. Army in 1968. He is currently the chief of the orthotic and prosthetic lab.