Reconstructive revision Charcot surgery is a limb salvage procedure. Loss of correction, hardware failure, re-ulceration or nonhealing ulcerations, infection, painful ambulation, instability, and development of remote Charcot neuroarthropathy processes are frequent indications for reconstructive surgery.
Absolute and relative contraindications for Charcot foot and ankle reconstruction, particularly revision, should be evaluated prior to surgical intervention. Absolute contraindications include overt global osteomyelitis, active infection, unacceptable anesthesia or cardiac risks, and inability to rehabilitate. Relative contraindications include insufficient bone stock for arthrodesis, severe dislocation or deformity, peripheral arterial disease, localized infection, elevated glycosylated hemoglobin, perioperative elevated blood glucose levels, poor skin quality or excessive scarring, ambulatory dysfunction, inability to maintain non–weight bearing during postoperative convalescence, and/or lack of family support.1–3
Preoperative Considerations: The Host
There are several important preoperative considerations in revision reconstruction of the Charcot neuroarthropathy patient. These include previous surgery; sometimes multiple, retained hardware; imaging and vascular studies; medical status; preoperative medical, cardiac, and anesthesiology clearance; and patient/family education. Further considerations germane to surgery include type of anesthesia, operating room positioning, special instrumentation for revision surgery, intraoperative imaging, use of orthobiologics, and bone stimulation.4
Patients being prepared for revision surgery should have a thorough medical clearance performed by their primary care physician and other medical specialists including cardiology, nephrology, infectious disease, pulmonology, and endocrinology prior to surgery. Sometimes working with a nutritionist, bariatric surgeon, or behavioral specialist may also prove useful for the patient. The goal is to optimize the patient prior to surgery in as many areas as proves useful.
Preoperative labs may include complete count, basic metabolic profile, erythrocyte sedimentation rate, and C-reactive protein if needed to rule out infection. Prothrombin time, partial thromboplastin time, and international normalized ratio labs will help with anticoagulation planning perioperatively. Vitamin D levels evaluated as insufficiency (20-30 ng) or deficiency (<20 ng/mL) are considered a contributor to many musculoskeletal and brain functions and are of particular importance as they are intrinsic to bone quality and arthrodesis. A systematic review of spinal fusion patients with hypovitaminosis D levels “achieved lower fusion rates and suffered higher rates of recurrent-persistent low back pain” and did not report significant improvement in patient outcomes compared to patients with normal vitamin D levels.5 Vitamin D can be repleted over several weeks to months while the patient is under preoperative evaluation and optimization.
Diabetic Charcot neuroarthropathy patients experience a higher rate of complications than those with Charcot neuroarthropathy from other sources.6 Re-evaluating patients with diabetes and updated hemoglobin A1c (HbA1c) can guide elective surgery scheduling. Consider reconstruction with HbA1c less than 9, but may be more aggressive if the ankle or foot is unstable or with a wound. These patients are obviously at higher risk for complications and should be educated regarding this possibility during the preoperative consultation. Furthermore, tight glycemic control in the perioperative period can be largely indicative of healing and thus should be regulated as much as possible to decrease postoperative infection rates and mortality.
The skin envelope should be thoroughly evaluated. Glycosylated tissues, scar tissue from previous surgery, chronic edema, and severe deformity can result in very limited tissue mobility. This is especially concerning when correction of a severe deformity can result in significant skin tension.3,7 One should avoid incisions in these areas if at all possible to avoid wound complications. Incisional approaches should always be planned with this in mind. Any patient with Charcot deformity and open wound should have the wound debrided and samples sent to rule out osteomyelitis infection prior to definitive surgical reconstructive efforts.8,9Figures 34.1–34.5 demonstrate the surgical process of evaluating and treating ulceration, potential for bone infection, reconstruction, and follow-up with additional minor surgery to maintain a plantigrade reconstruction.
Radiographs consisting of 3 views of the foot and/or ankle and lower extremity to assess the deformity along with calcaneal axial or hindfoot alignment views are indicated prior to surgical intervention. The need to assess the bone quality on the plain films along radiographic angles in preparation for surgery is important. Particular angles of interest are the Meary’s angle, talocalcaneal angle, talonavicular angle, talar position, cuboid “drop” or cuboid height when subluxed, and heel position with respect to the tibia. Advanced imaging is helpful in Charcot neuroarthropathy patients in preoperative planning to assess the deformity and bone quality, particularly computed tomography or magnetic resonance imaging. Significant cyst formation might result in a change in preoperatively planning, requiring osseous filling and later reconstruction or complete resection causing a large void that requires supplemental bone graft or spanning fixation.
Staged, or aggressive efforts, for hindfoot trauma or pathology of the Charcot neuropathic patient are needed to facilitate limb salvage efforts during the preoperative planning period. This can include multiple staged surgeries to eliminate infection or deformity prior to definitive surgical reconstruction.10,11 Surgical treatment may also include considerations for arthrodesis to span primary or revision traumatic arthropathies as well as for complex ankle fractures in the neuropathic population.12 These neuropathic orthopedic complaints will require rather robust sugical constructs, commonly spanning to incorporate joint fusions of unaffected joints to protect the limb reconstructive efforts.
Ostectomies and/or posterior muscle group lengthening can facilitate outcomes in these patients as minor procedures to offload the plantar foot when heterotopic bone, recurrent deformity, or tendon adhesions occurs.13,14
General anesthesia with popliteal nerve blocks and adductor canal nerve blocks is ideal for most patients. Spinal anesthesia may also be considered in cases not anticipated to be longer than approximately 2 hours. Operating room positioning is typically supine with a large bump under the ipsilateral hip. A larger hip bump may be needed if there is a significant amount of external rotation. The heels should be at the end of the table. Pediatric bone foam may be utilized to elevate the limb above the contralateral limb for appropriate intraoperative C-arm fluoroscopy. Additional measures should be put in place to ensure the patient is secure. The operating room table may be air planed at times for better exposure from medial to lateral, helping avoid soft tissue compromise by avoiding additional retraction.
The patient’s ability to use assistive devices to be non–weight bearing using a walker, crutches, wheelchair, or knee scooter should be assessed preoperatively. The authors recommend an appointment with physical therapy prior to surgery to assess their needs. Identifying family support system following surgery is one of the most contributing factors to success postoperatively and may indicate if the patient would do better with assistance for a short period for their care. Supplemental services that may be required include simple to advanced home health care and antibiotic infusion therapy.15,16 The authors encourage having family members present during the surgical consultation to further understand the patient’s condition and to develop an understanding of the expectations following the surgery.
Patient education is important to provide realistic expectations. These operations are often limb sparing in nature. The primary goal is for these patients to maintain a limb that can be appropriately accommodated by a brace and/or customized footwear. The majority of these patients are community ambulators, and most of them will be unable to return to standard footwear following reconstruction. Most patients will be fitted in a Charcot Restraint Orthotic Walker (CROW) for approximately 6 to 12 months following their reconstruction procedure(s). Patients are often transitioned to a double upright brace with rocker bottom sole or customized footwear. However, some patients may require lifetime use of a CROW boot.
Revision Charcot reconstruction is a limb salvage operation, and patients need to understand the inherent risks of loss of limb or loss of life. Furthermore, there are anticipated complications that will result in setbacks that may be quite frustrating to the patient, especially when dependent as a primary wage earner for the family; the patient may require additional antibiotics should they develop infection, or further surgery should they develop nonunion or nonhealing following these attempted reconstructions. Some patients will require known multiple staged procedures without complication, and the time for rehabilitation and leave from work can put an emotional and financial strain on a patient and their family. These patients require frequent follow-up during the immediate postoperative period and will require lifetime follow-up thereafter. Many of these patients will continue to be at risk for recurrent ulceration, recurrent deformity, hardware complications, and infection (Figure 34.6). Additionally, these patients will require social support during the initial postoperative phases following surgery.
Revision Charcot reconstruction is complicated by a number of factors common to the majority of these cases. These factors include recurrent and fixed deformity, poor quality bone, broken hardware, and inability to maintain non–weight bearing following surgery, and these patients are generally poor hosts. They may have elevated HbA1c levels, low vitamin D, and low total protein and albumin, among other underlying medical factors including vascular insufficiency, cardiac disease, stroke history, renal disease or obesity. These factors need to be addressed during surgical consultation.
Full-thickness surgical incisions are recommended. Protecting the soft tissue envelope is of great importance. Soft tissue handling with meticulous dissection and limited retraction should be observed at all times. Soft tissue properties specific to the patient will guide procedure selection and choice of fixation. Full-thickness flaps should be maintained for adequate soft tissue coverage. Having high-quality intraoperative imaging with appropriate technical support allows for easier confirmation of deformity reduction and realignment. Foot and ankle views, long-leg axial and hindfoot alignment views, as well as methods to assimilate weight bearing are important parts of intraoperative imaging. Additionally, intraoperative imaging aids in delivery of a fixation.
Charcot bone has a propensity to not heal, and nonunion is not uncommon. Nonunion can occur due to any of the aforementioned risk factors, or surgical planning that fails to provide robust structural integrity of the hardware used. Figures 34.7–34.13 demonstrate hardware fracture and nonunion revised to healing by incorporating unaffected joints. Figures 34.14–34.17 further demonstrate cases of midfoot Charcot neuropathy reconstruction with construct enhancement by combining subtalar joint arthrodesis into the fusion sites. Bone growth stimulators, electricity or ultrasound based, can be a useful adjunct for revision cases to promote healing at arthrodesis or osteotomy sites. Use of orthobiologics may also enhance arthrodesis. Figures 34.14–34.19 demonstrate examples of hardware failure and revision with use of orthobiologics. At our institution, we often use a combination of autogenous bone marrow aspirate, frozen cancellous chips that are milled, and commercial products with bone morphogenic proteins or mesenchymal stem cells. Respectively, these materials provide stem cells, scaffolding, and growth factors that promote angiogenic, mitogenic, and osteogenic or osteoinductive proteins. Additionally, autogenous bone can be harvested from various lower extremity sites depending on the need (Figure 34.20). Bone quality from the proximal versus distal tibia varies along and the choice should be utilized based on autogenic properties as well as amount of harvested graft needed to enhance fusion mass without significant donor morbidity. Arthrodesis sites as well as previous implants, for instance total knee prosthesis limits the anatomic choice. These areas of harvest should be back filled with cancellous chips or bone putty. If a wedge of autograft bone is taken for its cortical properties for the fusion site, this may be replaced with allogenic unicortical wedge. Plating over the area can provide structural support as the cortical graft harvest heals. This may be of greater importance with proximal grafting to avoid tibial plafond fracture due to stress riser or should the patient fall. Tissue matrix or allograft use combined with commercial orthobiologics or combined with autograft can provide arthrodesis supplementation, with some level of angiogenesis that may be protective in cases of protecting against infection.17–19