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Nonoperative treatment with use of a total-contact cast followed by appropriate bracing and footwear is the so-called gold standard for the treatment of most neuropathic (Charcot) fractures and dislocations of the foot and ankle. However, operative treatment is indicated for chronic recurrent ulceration, joint instability, or, in some instances, pain that has not responded to nonoperative treatment. Acute fractures may also be treated operatively if the patient is seen before demineralization of bone and inflammation of soft tissue have occurred. The goals of operative treatment are to preserve function with the aid of appropriate footwear or bracing and to avoid the need for amputation. These goals are achieved through restoration of the contour or alignment of the affected segment of the foot and ankle. Despite the potential for major operative complications, successful limb salvage and reconstruction was achieved in 124 (87 percent) of 143 patients in eight clinical series1,3,8,13,19,22,26,27.
Neuropathic (Charcot) osteoarthropathy is a non-infective, destructive lesion of a bone and joint resulting from a fracture or dislocation, or both, in a patient who has peripheral neuropathy. Diabetes is the most common cause of these deformity-causing fractures in the United States, and they were reported in 101 (0.1 percent) of 68,000 patients who had diabetes mellitus25. There are an estimated sixteen million diabetic individuals in the United States2. Because of improvements in the treatment of diabetes, diabetic patients are living longer. Therefore, neuropathic arthropathy, a late effect of peripheral neuropathy of the foot and ankle, continues to be a problem that is seen in orthopaedic practices. Frequently, a Charcot fracture or dislocation is caused by a minor acute injury, such as a sprain of the ankle or foot, or by an overuse syndrome resulting from repetitive minor injuries. However, it may also be the result of an acute traumatic event, such as a fall from a height or a motor-vehicle accident. The etiology and pathophysiology of neuropathic destruction of bones and joints are poorly understood. However, the stages of bone and joint destruction, followed by fracture-healing and remodeling, were described by Eichenholtz9. The Eichenholtz classification is based on the characteristic clinical and radiographic changes that occur with neuropathic destruction or fracture of a joint over time and is therefore a temporarily based classification. These changes progress from the acute phase (dissolution), through the healing phase (coalescence), to the resolution phase (Table I). The timing and selection of a reconstructive procedure for a patient who has a neuropathic joint should be made with a clear understanding of the natural history of a Charcot joint and the temporal stage of the neuropathic process. Different classifications for the characteristic patterns of neuropathic destruction of bones and joints have been described by other investigators5,7,10. An understanding of these patterns is helpful when making the diagnosis and planning treatment for patients who have occult neuropathy.
Deformities of the foot and ankle resulting from a neuropathic fracture or dislocation cause difficulty with shoe-fitting and marked alteration in the load applied to various parts of the plantar surface of the foot during weight-bearing. These changes lead to an increased propensity for ulceration in high-pressure areas (Fig. 1). These ulcers may become a portal of entry for bacteria and thus may result in superficial or deep infection. A deformity may also be associated with joint instability, which is accentuated by weight-bearing, especially with involvement of the hindfoot or ankle. These changes result in loss of the plantigrade position of the foot and the development of progressive varus, valgus, equinus, or calcaneus deformity.
Nonoperative treatment is indicated for most Charcot deformities of the foot and ankle. Most deformities are treated with immobilization in a total-contact cast to allow healing and stabilization of the fracture. If the ankle or hindfoot joints are involved, prolonged immobilization in an ankle-foot orthosis for twelve to eighteen months, or indefinitely, is often indicated. Involvement of the midfoot and forefoot is typically treated with appropriate extra-depth footwear and custom total-contact inserts.
Operative treatment is indicated when a patient has a severe deformity of the foot and ankle that is not amenable to management with a custom brace or custom footwear, marked instability (usually involving the hindfoot and ankle), or recurrent ulceration. A markedly unstable Charcot joint may be associated with pain; however, unlike painful osteoarthrosis, a painful Charcot joint is rarely the sole reason for operative treatment.
The Goals of Operative Treatment Patients who have a moderate-to-severe deformity resulting from neuropathic arthropathy need special footwear with custom total-contact inserts and, sometimes, a custom brace to prevent recurrent ulceration and progressive deformity. Therefore, the decision is not between operative treatment or the use of prescription footwear and bracing but rather between operative treatment followed by prescription footwear and bracing or prescription footwear and bracing alone. Therefore, operative treatment is indicated primarily to make these patients better candidates for prescription footwear and bracing. Although some patients who have a solid fusion after a realignment arthrodesis may eventually be weaned from the ankle-foot orthosis, weaning is an unrealistic goal for many patients and may lead to recurrent ulceration or stress fractures of the tibia13,15.
The Timing of Operative Treatment An ulcer of the foot that is associated with a neuropathic deformity is treated, until it has healed (if possible), with use of a total-contact cast so that the incision for the reconstructive procedure may be made through intact skin to reduce the possibility of postoperative infection. If underlying osteomyelitis is suspected in association with a neuropathic fracture, imaging with a combined technetium-99m bone scan and indium-111-labeled white blood-cell scan with use of the dual-window technique helps to confirm or rule out this suspicion11,12,23. If osteomyelitis is present, it is treated with appropriate débridement and antibiotic therapy until the wound has healed and the infection has resolved. Then, the choice with regard to operative or nonoperative treatment of the remaining deformity can be made.
The most important factor in the successful treatment of an acute fracture in a patient who has neuropathic arthropathy is the recognition of the fact that the patient has a severe peripheral neuropathy. A series of small monofilament nylon rods (Semmes-Weinstein monofilaments) can be used to determine the severity and location of the sensory neuropathy16. If sensory testing with Semmes-Weinstein monofilaments shows loss of protective sensation, it is important to alter the typical treatment regimen to help prevent subsequent Charcot destruction of the joint. It is also important to warn the patient about the potential risk of Charcot involvement of the joint, whether or not operative treatment of the fracture is undertaken. The first step in the treatment of an acute fracture is to determine whether it is associated with neuropathic changes (that is, Eichenholtz stage I) or with peripheral neuropathy but not yet with neuropathic changes. This differentiation often can be made on the basis of the medical history. For example, when a patient has had a relatively minor injury followed by several days or weeks of erythema and swelling and has a displaced fracture on presentation, the fracture is usually treated as an Eichenholtz stage-I injury with use of a total-contact cast. However, a patient with severe diabetic peripheral neuropathy who has sustained an acute displaced fracture may be managed with the same orthopaedic principles as would be followed for a patient who does not have neuropathy (if seen acutely), except that a higher rate of complications would be expected and a prolonged postoperative period of non-weight-bearing and immobilization in a total-contact cast followed by use of a brace would be indicated. If treatment after the fixation of a fracture does not include rigid external immobilization and a prolonged period of non-weight-bearing, the fixation may fail before the fracture has healed (Fig. 2).
Acute fractures of the ankle, talus, or midfoot may be treated with use of the same indications for open reduction and internal fixation, assuming that the patient is medically fit, the vascular status is adequate, there is minimum swelling, and the skin is in good condition. Patients who have an acute fracture that is already Eichenholtz stage I, with early demineralization and soft-tissue inflammation, are poorer candidates for operative treatment. Internal fixation of an ankle fracture is augmented by the addition of one or two Steinmann pins across the ankle and subtalar joints to prevent failure of the hardware and deformity of the joint (Fig. 3). The pins are cut off below the level of the plantar skin and are removed six to eight weeks postoperatively at the time of a cast change.
It is important to extend the duration of immobilization for a fracture in a patient with peripheral neuropathy to approximately double the normal period of time that a patient without neuropathy would be non-weight-bearing. Therefore, a patient with neuropathy who has a typical fracture of the ankle is managed with non-weight-bearing for approximately three months (compared with six weeks for a patient without neuropathy), and a cast is worn until approximately four to five months after the injury, at which time the patient is able to walk while wearing a weight-bearing cast and the fracture has united. A brace is then worn for one year after the injury to prevent late development of a Charcot joint. A patient who is doing well twelve to eighteen months after the injury may be weaned from the brace and subsequently managed with use of extra-depth footwear with custom-molded total-contact inserts. During this period, the patient is carefully monitored for the development of a Charcot joint. The prolonged duration of immobilization in this protocol may be excessive for patients in whom a Charcot joint is not destined to develop. However, there are no known factors that predict which fracture will progress to a Charcot joint in a patient who has a neuropathy. Therefore, in order to prevent severe deformity, it seems prudent to manage every patient who has loss of protective sensation as if a Charcot joint will develop.
Ostectomy
The first step in the operative treatment of any neuropathic deformity is to obtain closure of the overlying ulcer, if possible, so that the incision to remove the osseous prominence can be made through intact skin. An alternative technique is to excise the ulcer through a plantar, longitudinal, elliptical incision made directly over the prominence. However, this technique exposes a large amount of underlying cancellous bone to the open ulcer with a potential for bacterial colonization of the underlying superficial bone. A preferred method is to obtain closure of the ulcer with a series of total-contact casts so that the incision can be made through intact skin on the medial or lateral border of the foot closest to the osseous prominence5,14 (Fig. 4-C). The skin incision is made as a full-thickness flap down to the osseous prominence. A periosteal elevator is used to separate the overlying soft tissue from the protuberant bone. A small power saw or an osteotome is used to resect the bone surface, which is then rasped to provide a smooth broad surface in the weight-bearing area. Major tendon attachments, such as the peroneus brevis, anterior tibial tendon, posterior tibial tendon, and Achilles tendon, should be preserved and reattached to bone if they are detached. Resection of a large prominence in the medial part of the midfoot involving the medial cuneiform should include reattachment of the anterior tibial tendon through drill-holes into the remaining bone. Many patients have a coexistent contracture of the Achilles tendon, and percutaneous lengthening of the Achilles tendon is frequently performed at the time of plantar ostectomy18.
The skin is closed over a suction drain, which is left in place for twenty-four hours with a compression splint. The next day, a total-contact cast is applied to stabilize the soft tissues, promote wound-healing, and allow the patient limited weight-bearing. It is especially important to avoid excessive bone resection in the midfoot, where removal of the plantar ligaments may cause progression of the rocker-bottom deformity. An ostectomy of the plantar aspect of the midfoot is more successful when the neuropathic deformity is stable in the sagittal and transverse planes. The sutures are removed when the incision has healed, usually two to three weeks after the procedure. At the time of one of the cast changes, a mold of the foot is made for a total-contact insert so that the appropriate footwear and a custom insert will be ready for use when healing has occurred and the cast is removed (Fig. 4-D).
Realignment and Arthrodesis
The contraindications to arthrodesis include (1) infection of the soft tissue or bone except when the arthrodesis is performed as a staged procedure after the infection has been treated, all osteomyelitic bone has been resected, and the soft tissues have healed; (2) a fracture that is in the acute (dissolution) phase of the neuropathic disease process (Eichenholtz stage I); (3) uncontrolled diabetes or malnutrition; (4) peripheral vascular disease; (5) insufficient bone stock to obtain rigid fixation; and (6) the inability of the patient to comply with the postoperative regimen (because of mental illness). Technique: Preoperatively, a total-contact cast is used until the acute phase of the Charcot fracture process has subsided and the skin is intact (Fig. 5-A). Extensive longitudinal incisions are used with full-thickness skin flaps to bone. If the deformity is mild to moderate and is limited to the ankle and subtalar joints, tibiotalocalcaneal arthrodesis may be performed through a posterior approach21. For correction of a severe deformity, exposure is enhanced by making medial and lateral incisions over the ankle rather than a posterior incision. Bone is resected to allow correction of the deformity and to provide apposition of stable bleeding bone surfaces to promote successful fusion. A contracture of the Achilles tendon is corrected with percutaneous lengthening especially when a midfoot or hindfoot arthrodesis is performed. Autologous bone-grafting is used to fill any defects and to provide both an intra-articular and an extra-articular arthrodesis when possible. Morseled pieces of resected tibial and fibular bone may also be used when bone-grafting is needed primarily for extra-articular application. Large, threaded Steinmann pins, compression blade-plates, or custom intramedullary rods are used in whatever combination provides adequate rigid internal fixation (Figs. 5-D, 5-E, 6 through 7). Use of a plate on the plantar aspect of the medial column of the midfoot has been advocated to enhance the rigidity of an arthrodesis of the midfoot24. External fixation provides adequate stability, but positioning of the foot and ankle is more difficult with an external fixator; such fixation is reserved for patients who have an open wound and need osseous stabilization. Problems at the pin sites may also force early removal of the fixator, leading to nonunion or malunion.
Long-term immobilization is crucial for achieving union. In general, the duration of immobilization after an arthrodesis for patients who have neuropathic arthropathy is twice as long as that for patients who do not have neuropathic arthropathy. The postoperative regimen includes three months of non-weight-bearing in a total-contact cast followed by one to two months in a weight-bearing total-contact cast. The patient then is managed with a bivalved ankle-foot orthosis with a rocker sole added to the foot-plate until the use of footwear and a definitive brace is possible. Bracing is continued for twelve to eighteen months postoperatively, as in the treatment of a neuropathic fracture. After an arthrodesis of the midfoot, an extra-depth shoe with an extended steel shank and a rocker sole may be used if there is little swelling and the fusion is solid. For patients who have involvement of the hind-foot and ankle, this type of shoe is attached either to a double-upright calf-lacer or a patellar-ligament-bearing ankle-foot orthosis (Figs. 8-A, 8-B, and 9). A custom-molded polypropylene ankle-foot orthosis may be used inside a shoe with a rocker sole if the deformity of the foot is not severe.
When there is a severe deformity of the foot, it is preferable to use whatever shoe-and-foot-orthosis combination accommodates the foot deformity and then to have the shoe attached to a double-upright brace. A custom-molded polypropylene ankle-foot orthosis that extends into the foot region takes up space in the shoe and may not adequately accommodate a severe deformity of the foot, thereby causing a recurrent ulcer. After an arthrodesis of the midfoot, hindfoot, or ankle, use of a brace is necessary for at least the first twelve to eighteen months, to allow complete healing and a return to weight-bearing. An arthrodesis of the ankle, hindfoot, or midfoot at the level of the talonavicular joint is prone to either recurrent Charcot changes at adjacent joints or stress fractures15 and should be protected with use of a brace indefinitely. After an arthrodesis of the midfoot distal to the level of the talonavicular joint, stability of the site is provided with use of an extra-depth shoe with a total-contact insert, an extended steel shank, and a rocker sole. The choice of whether to wean a patient from the ankle-foot orthosis at twelve to eighteen months after an arthrodesis depends on multiple factors, including union and stability at the site of the arthrodesis, the location of the arthrodesis, and the reliability as well as the activity level of the patient. After an arthrodesis of the hindfoot involving the tibiotalocalcaneal joint, active patients may be prone to stress fractures in the distal part of the tibia when a brace is not used for strenuous activities because the foot acts as a long, rigid lever arm that places stresses on the tibia13,15 (Fig. 7).
The rates of union reported after arthrodesis of the foot and ankle for the treatment of neuropathic deformity in 143 patients in eight clinical series averaged 70 percent (ranged, 54 to 100 percent)1,3,8,13,19,22,26,27. However, the goal of achieving a stable foot on which a brace or a shoe, or both, could be worn was attained for 87 percent (124) of the patients after the initial operative procedure, regardless of whether or not a solid union or a stable nonunion had been achieved1,3,8,13,19,22,26,27. Complications that may lead to failure of the procedure and necessitate a repeat procedure include a deep wound infection, an unstable nonunion, and a malunion. Although authors of earlier reports have expressed caution with respect to the performance of an arthrodesis for the treatment of neuropathic arthropathy6,26, modern techniques of internal fixation and prolonged immobilization have substantially increased the rate of union and decreased the rate of complications. The rate of satisfaction with these procedures is high, in large part because pain is not a major factor1,3,13,17,19,22,27. Most patients are grateful if the ability to walk in an appropriate shoe or brace is restored and an amputation is avoided. In a recent study, thirty-two arthrodeses were performed for the treatment of neuropathic deformities of the foot and ankle; the series included twenty-seven feet (twenty-five patients)13. Five of these procedures had been preceded by an initial attempt at realignment arthrodesis; two were repeat arthrodeses, and three were plantar ostectomies. Including the reoperations, twenty-six (96 percent) of the twenty-seven feet were eventually rendered stable and the patient was able to wear a brace. The goals of the operation were not met in one patient, in whom a deep infection developed and led to a transtibial amputation.
Because of the technical difficulty involved in the management of patients who have Charcot arthropathy as well as the potential complications and the prolonged duration of treatment that is required, some practitioners may offer an amputation rather than reconstruction to treat a neuropathic deformity that does not allow use of a brace. Previous studies on energy expenditure according to level of amputation have demonstrated that the more distal the level of the amputation, the less energy is expended during walking20. Therefore, it would be logical that a patient with a Charcot deformity who has been managed with reconstruction would expend less energy during walking and may have a higher level of function than would a patient who has been managed with an amputation, especially a patient who has limited cardiovascular reserves. Perhaps the most compelling reason for limb salvage is the long-term uncertainty about the status of the other foot. Peripheral vascular disease or an ulcer on the contralateral foot may lead to a deep wound infection, necessitating an amputation in the future. Reconstruction instead of amputation for the treatment of a neuropathic deformity in a patient who is a candidate for reconstruction may allow the patient to avoid eventual bilateral amputation.
Reconstruction of the Charcot foot and ankle is a valuable technique for the management of a patient who has a severe deformity that cannot be treated with use of appropriate footwear and a brace. The goals of operative treatment are to allow the patient to wear a shoe and a brace and to prevent amputation. Despite complications, the overall rate of success is more than 80 percent1,3,8,13,19,22,26,27. Stability and appropriate alignment are more important than union for achieving a successful result. Meticulous handling of the soft tissues and rigid internal fixation with use of bone-grafting are important parts of the operative technique. Prolonged immobilization is necessary. Limb salvage with realignment and arthrodesis of a severely deformed foot and ankle allows most patients to avoid amputation and probably provides a more functional limb. Use of these operative indications and techniques results in a high degree of patient satisfaction.
*No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. No funds were received in support of this study.
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