Charcot Arthropathy: When Mechanical Treatment Can Help
Charcot arthropathy is an extremely challenging disease process to treat for many reasons, according to David Levine, DPM, CPed. He says one of the big problems is not being able to rely upon the patient for feedback. Given the profound peripheral sensory neuropathy present in these patients, Dr. Levine says vigilant monitoring of any changes in the foot is essential for preventing further complications. With this in mind, our expert panelists take a closer look at mechanical management of Charcot arthropathy and when it can help facilitate successful treatment outcomes. Q: In your opinion, what are the most important biomechanical considerations in managing Charcot arthropathy? A: Daryl Phillips, DPM, says the three major goals in treating this condition are: 1) immobilizing the Charcot joint; 2) equalizing pressure across the entire plantar foot surface; and 3) equalizing inversion and eversion moments around the ankle and subtalar joints. Bret Ribotsky, DPM and Dr. Levine agree that you should first determine the stage of Charcot arthropathy before weighing the appropriate treatment course, biomechanical or otherwise. In the acute stage, Dr. Levine says you should emphasize nonweightbearing and immobilization. However, he points out that crutch walking may be impractical and you may have to employ another method to reduce weightbearing forces on the affected foot. Dr. Levine says biomechanical considerations play a larger role when your patient has chronic Charcot arthropathy. Reducing pressure areas and improving propulsion are two key goals, according to Dr. Levine. He also emphasizes assessing the stability of the deformity. Determining the region of the foot that is involved will help you determine the stability. Dr. Levine says treating unstable feet biomechanically can be challenging as they are susceptible to changes. However, he explains that if your patient has stable feet, you can provide biomechanical treatment in order to help him or her offload specific areas and improve propulsion. It’s also important to address any equinus deformity, according to Drs. Levine and Ribotsky. As the bones and joints change positions, Dr. Levine says the muscles and tendons fight over the balance of power. “Often times, the tendoachillis will win out, producing primarily a sagittal deformity that may be difficult to control conservatively,” warns Dr. Levine. Q: Assuming that neither patient is currently ulcerated, how does your strategy differ between patients with and those without a history of ulceration? A: Nicholas Sol, DPM, CPed and Dr. Ribotsky note that patients who have had previous ulcers are obviously prone to reulceration, so offloading pressure from the particular area is essential. For these patients, Dr. Phillips says it is equally important to equalize pressure across the plantar foot surface and immobilize the affected joint. Dr. Ribotsky concurs and also cautions DPMs to avoid transferring the weight to an area that overloads another portion of the foot. Unless there is less soft tissue under the previously ulcerated area than under the surrounding area, Dr. Phillips tries to avoid decreasing the pressure in the previously ulcerated area to an amount less than the surrounding area. In order to meet these goals, Dr. Phillips emphasizes doing an in-shoe dynamic pedobarograph study. In his quest to reduce or eliminate as much direct pressure and shear forces over previously ulcerated areas as possible, Dr. Sol relies on in-shoe pressure analysis. He says it’s his primary tool for fabrication, adjustment and monitoring efficacy. Dr. Levine employs a simple ink mat impression test, whether the patient has had previous ulceration or not. He says this “fast and easy” helps assess regions of increased weighbearing pressures. His goal is to reduce pressures where there is too much and help facilitate a more propulsive gait. Q: What specific clinical criteria do you use to decide between using a custom foot orthosis, custom shoes, an AFO device or a CROW walker? A: Drs. Ribotsky and Sol say it’s important to assess the level of deformity as well as the level of impairment. For example, if you’re treating a patient who has developed a significant Charcot arthropathy with a contracted Achilles tendon and a dysfunctional posterior tibial tendon, Dr. Ribotsky says it’s essential to ensure control above the ankle joint. Therefore, in this situation, he recommends using a device that will give you control of more proximal joints. In providing long-term therapy for Charcot arthropathy, Dr. Phillips says employing a rigid custom foot orthosis works “extremely well” for a Lisfranc’s joint arthrosis. However, he says you must provide a very precise fit to the plantar foot (ensuring that the device fully pronates the midtarsal joint) and an accurate posting prescription. Dr. Phillips says he doesn’t worry about using a rigid orthosis as long as it has appropriate padding on top and that the pedobraograph readings are not registering excessive peak pressures. Dr. Phillips adds that it may be necessary to use a custom-made shoe if your patient has developed a true rocker bottom foot or if the foot has become severely displaced medially or laterally relative to the leg. He says he always makes sure that he uses a rigid orthosis concept inside the shoe. Shoe modifications are a “remarkably underutilized service” that DPMs should be providing to patients, explains Dr. Levine. For example, if you’re looking at a severe Charcot foot with complete collapse, Dr. Levine says a functional leg length discrepancy may occur and a custom orthotic device would be “woefully insufficient” in this situation. You may need a lift on the shoe in addition to the orthoses, according to Dr. Levine. What about a patient who has unilateral collapse of the foot? Even with surgical reconstruction, significant asymmetry may persist, according to Dr. Levine. He says using an off-the-shelf shoe may not provide a proper fit for the affected foot. In this scenario, Dr. Levine notes that relasting the shoe in order to make the midfoot of the shoe wider may be an excellent, cost-effective alternative for the patient. If you’re treating a patient who has minimal localized Charcot arthropathy, Dr. Ribotsky says employing a local weight distribution device would be appropriate. You may also consider using this device to treat patients who are still propulsive during gait, according to Dr. Ribotsky. Dr. Levine strongly emphasizes the value of performing gait analysis. Using video cameras from four different angles and integrating pressure sensing computer software, you can gain a comprehensive understanding of the patient’s gait. Q: In patients with Charcot arthropathy, what are the effects of occupational demands, including cumulative weightbearing time, surface characteristics, climbing and load carrying? A: Generally, the risk of complication is proportionate to the number of repetitive loads applied to the feet and/or cumulative weightbearing time, according to Dr. Sol. He notes that harder or irregular surfaces, climbing and load carrying can create additional stress. Dr. Phillips adds that considering the load the feet have to carry is important in dictating how strong or rigid you should make the device or shoe. While Dr. Phillips notes that every case is different, he is most concerned about irregular surfaces, which distort the foot position from what you’re trying to accomplish. Ideally, Dr. Phillips notes, you want to have the patient walking on a flat surface, so you can plan better how the foot relates to the ground. Occupational shoewear can also pose problems, according to Dr. Levine. For example, he points out that the combination of steel toe safety shoes with insensate feet can be disastrous. Dr. Levine adds that occupational demands, like climbing ladders or standing eight hours a day, can also be problematic. He emphasizes educating these patients to do routine inspections of their feet in order to help facilitate biomechanical control. Q: Do you recommend continued mechanical management following a surgical fusion to correct Charcot arthropathy? A: All the doctors agree that continued mechanical management is vital for ensuring favorable long-term outcomes. As Dr. Ribotsky points out, continued changes, deviations in gait pattern and weight changes will affect the patient’s ability to ambulate in stride length. “Surgery can take care of the gross deformities,” notes Dr. Phillips, “however, there is still much fine-tuning of the ground reaction forces that can only be addressed by the foot gear.” n Dr. Sol (shown on the right) founded the Walking Clinic, PC and practices in Colorado Springs, Colo.. Dr. Levine is the Director of Dr. Levine’s Podiatry and Footwear Center in Frederick, Md. Dr. Phillips is the Director of Podiatric Residency at the Coatesville Veterans Affairs Medical Center in Coatesville, Penn. Dr. Ribotsky is the President of the American College of Foot and Ankle Orthopedics and Medicine.