Charcot Foot

Charcot Foot (Osteoarthropathy)

Figure 6 - Charcot foot.

 

The etiology of Charcot foot (see Figure 6) is multifactorial and based on neuropathy and metabolic processes.⁴⁴ Neuropathic arthropathy may be defined as a relatively painless, progressive, and degenerative condition of single and multiple joints caused by underlying neurological deficits.⁴⁵ Additional neurovascular theory postulates that increased peripheral blood flow due to autonomic neuropathy leads to a hyperemic bone resorption.⁴⁶ Other predisposing factors may include renal transplantation, immunosuppressive therapy, impaired cartilage growth, and nonenzymatic glycosolation.⁴⁵ Sadly, these deformities can result in major limb amputation.⁴⁷

Eichenholtz⁴⁸ described the stages of bone and joint destruction followed by fracture healing and remodeling. This temporal classification is based on the characteristic clinical and radiographic changes that occur with neuropathic joint destruction and fracture over time; progression occurs from the acute phase (dissolution) through the healing phase (coalescence) to the resolution phase. The resulting foot deformities cause difficulty with shoe fit and significantly increase the propensity toward ulceration in high-pressure areas.⁴⁹ Almost all patients with these deformities will ultimately require specialized footwear with custom total-contact inserts or custom bracing. Surgery for these conditions is predicated on the goal that restoration of stability and alignment of the foot and ankle will make appropriate shoe wear and bracing possible.⁵⁰ Foot ulcers in association with significant neuropathic deformity are usually treated with many modalities, ranging from total-contact casts, CROW boots, AFOs, PTB devices, and removable prefabricated walking braces to custom molded insoles, bracing, and shoes. The type of appliance used is predicated on the Eichenholtz stage of development.

Eichenholtz stages.

Stage I (Dissolution). Radiologically, regional bone demineralization with periarticular fragmentation and joint disarticulation is present. Clinically, acute inflammation, swelling, erythema, and heat are evident. This early stage is easily mistaken for infection or thrombophlebitis.⁵¹ Treatment is nonweight-bearing and usually consists of a total contact cast, BAFO, CROW boot, or a removable prefabricated walking brace. One study of 34 feet revealed that treatment averaged 8.4 months. However, follow-up could continue for 35 months or more.⁵² As treatment progresses, care must be taken to gradually wean the patient from nonweight-bearing to partial and then full weight-bearing along with the help of assistive devices; these include appropriate and professionally guided use of crutches, walkers, or canes.⁵³

Stage II (Coalescence). Radiologically, absorption of bone debris in the soft tissues is evident, along with organization and early healing of fracture fragments and periosteal new bone formation. Clinically, a decrease in inflammation with less fluctuance can be noted as well as increased stability of fracture segments. A study of 43 feet in this classification³⁰ revealed that immobilization lasted an average of 6.4 months in 34 of the feet and follow-up averaged 16.4 months.

Stage III (Resolution). Radiologically, a smoothing of large bone fragment edges is present, along with sclerosis and bony/fibrous ankylosis. Clinically, permanent enlargement of the foot and ankle, fixed deformity, minimal swelling, and normalization of temperature are evident. A study of 60 feet in this category³⁰ required follow-up for 22.1 months. Treatment consisted of custom-molded shoes and insoles unless ulceration dictated otherwise. No immobilization was required in this group because of the healed nature of the process. Anderson et al²¹ recommends an extra-depth shoe coupled with a cushioned insert attached to a double-upright calf-lacing brace with a fixed ankle joint and rigid rocker sole. The shoe may need a wide shank or a more rigid rocker if the midfoot or hindfoot areas are involved. The patient also should be fitted with knee-high compression hose. An AFO or CROW can be used as an alternative.

Robert J. Snyder DPM, FACFAS, CWS, and is a faculty physician at the Wound Healing Center, University Hospital, Tamarac, FL, and a faculty physician and director of wound management education at the Wound Healing Center, Northwest Medical Center, Margate, FL. Karen K. Lanier, CPed, is CEO of Branier Orthopedic Custom Molded Shoes in Sebring FL.