An In-Shoe Journey to Offload a Patient with Charcot Foot Deformity

David Sutton, Certified Pedorthist & Clinical Advisor

The following case study was shared by David Sutton, a certified pedorthist and clinical advisor who has been instrumental in developing innovative approaches to managing complex foot conditions.

Fig #1: Pressure mat measurement using bilateral loading. Notice the wavering PP; highly unstable.

Managing a Charcot foot deformity alongside a fused ankle presents a significant challenge. Not only does it alter the foot's functionality, but it also changes its shape and increases the risk of recurring ulcers. Patients dealing with these conditions often experience heightened levels of anxiety and depression, coupled with reduced muscle strength. This combination results in a less fluid gait pattern, where the feet tend to drop and swing forward rather than move in a purposeful manner. Addressing these psychological barriers and improving self-esteem, motivation, and reducing the risk of falls can significantly enhance patient compliance and help prevent further ulceration.

Given these complexities, our primary objective is to create footwear that is not only functional but also aesthetically pleasing. If we cannot meet these criteria, patient adherence will likely be poor, and we will ultimately fail in achieving our goals. To ensure optimal outcomes, we employ in-shoe pressure mapping to keep peak pressures (PP) below 200 kPa, as recommended by Schaper et al. (2019) and van Netten et al. (2017). The data generated through this process provides valuable insights into the effectiveness of our interventions, helping patients visualize the tangible benefits of our treatments.

During our initial consultation, we conducted a baseline measurement of pressure distribution using a pressure mat (refer to Fig #1). Typically, we would perform an in-shoe measurement, but due to the patient’s current condition—wearing a CAM boot on one foot and a slipper on the other—we decided against it. Following this, we reviewed the X-rays and performed a clinical assessment of range of motion (ROM), leading us to conclude that custom footwear and orthotics were necessary.

Once we had captured a 3D laser scan of the patient’s feet (refer to Fig #2), we proceeded to create a custom-made last. A clear check fit was then developed to confirm the proper fit and to involve the patient in the process, giving them a visual preview of the final product and how it would suit them.

Fig #2: 3D LASER scan of the feet for Last making in a static moment. Visible deformity in the right foot and the inclined ankle, combined with the PP from the Mat is sufficient evidence to support that this patient will fail in a prefab shoe; client has a history of failure in prefabricated footwear.

Once the ankle boot and orthoses were fabricated, we began the in-shoe pressure mapping journey.

Data was collected from an eight-step average, with the software masking the highest peak pressure (PP) areas bilaterally. After the first in-shoe assessment (refer to Fig #3) with the new custom footwear and orthoses, modifications were made to the right boot based on the collected data. A 5mm-thick addition was made to the sole, while the left boot underwent adjustments such as moving the sole fulcrum more proximally and adding a met dome to the orthosis. These modifications yielded noticeable improvements, as evidenced in the second in-shoe pressure mapping assessment (refer to Fig #4).

Leg length discrepancies (LLDs) are frequently overlooked, particularly when it comes to the contralateral limb. Even a small discrepancy of 5mm can significantly impact both feet. By adding 5mm to the right boot, the peak pressure loading under the base of the 5th metatarsophalangeal joint (MPJ) of the right foot decreased from 335kPa to 149kPa. However, this adjustment also affected the loading on the left heel (refer to Fig #4).

After the second assessment, further modifications were made to the left sole fulcrum, shifting it further proximally, and enhancing the met dome on the left orthosis. No additional changes were required for the right devices, though minor shifts in loading were observed (refer to Fig #5). Post the third assessment, the patient was sent home with detailed wearing instructions. It’s not uncommon for patients to overdo activities once they receive new footwear, so careful moderation is essential to ensure long-term success.

Fig #3: First F-Scan assessment

Fig #4: Second F-Scan assessment.

Fig #5: Third F-Scan assessment, and the final outcome for the patient.

References:

Schaper, N. C., van Netten, J. J., Apelqvist, J., Bus, S. A., Hinchliffe, R. J., Lipsky, B. A., & IWGDF Editorial Board. (2020). Practical Guidelines on the prevention and management of diabetic foot disease (IWGDF 2019 update). Diabetes/Metabolism Research and Reviews, 36, e3266.

van Netten, J. J., Lazzarini, P. A., Fitridge, R., Kinnear, E. M., Griffiths, I., Malone, M., Perrin, B., Prentice, J., Sethi, S., & Wraight, P. R. (2017). Australian diabetes-related foot disease strategy 2018-2022: the first step towards ending avoidable amputations within a generation.

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