Total contact cast wall load in patients with a plantar forefoot ulcer and diabetes

Abstract

BackgroundThe total contact cast (TCC) is an effective intervention to reduce plantar pressure in patients with diabetes and a plantar forefoot ulcer. The walls of the TCC have been indirectly shown to bear approximately 30 % of the plantar load. A new direct method to measure inside the TCC walls with capacitance sensors has shown that the anterodistal and posterolateral-distal regions of the lower leg bear the highest load. The objective of this study was to directly measure these two regions in patients with Diabetes and a plantar forefoot ulcer to further understand the mechanism of pressure reduction in the TCC.MethodsA TCC was applied to 17 patients with Diabetes and a plantar forefoot ulcer. TCC wall load (contact area, peak pressure and max force) at the anterodistal and posterolateral-distal regions of the lower leg were evaluated with two capacitance sensor strips measuring 90 cm2 (pliance®, novel GmbH, Germany). Plantar load (contact area, peak pressure and max force) was measured with a capacitance sensor insole (pedar®, novel GmbH, Germany) placed inside the TCC. Both pedar® and pliance® collected data simultaneously at a sampling rate of 50Hz synchronised to heel strike. The magnitude of TCC wall load as a proportion of plantar load was calculated. The TCC walls were then removed to determine the differences in plantar loading between the TCC and the cut down shoe-cast for the whole foot, rearfoot, midfoot and forefoot (region of interest).ResultsTCC wall load was substantial. The anterodistal lower leg recorded 48 % and the posterolateral-distal lower leg recorded 34 % of plantar contact area. The anterodistal lower leg recorded 28 % and the posterolateral-distal lower leg recorded 12 % of plantar peak pressure. The anterodistal lower leg recorded 12 % and the posterolateral-distal lower leg recorded 4 % of plantar max force. There were significant differences in plantar load between the TCC and the cut down shoe-cast for the whole foot, rearfoot, midfoot and forefoot (region of ulcer). Contact area significantly increased by 5 % beneath the whole foot, 8 % at the midfoot and 6 % at the forefoot in the shoe-cast (p < 0.05). Peak pressure significantly increased by 8 % beneath the midfoot and 13 % at the forefoot in the shoe-cast (p < 0.05). Max force significantly increased 6 % beneath the midfoot in the (shoe-cast p < 0.05).ConclusionIn patients with diabetes and a plantar forefoot ulcer, the walls of the TCC bear considerable load. Reduced plantar contact area in the TCC compared to the shoe-cast suggests that the foot is suspended by the considerable load bearing capacity of the walls of the TCC which contributes mechanically to the pressure reduction and redistribution properties of the TCC.

Effectiveness of offloading interventions to heal foot ulcers in persons with diabetes: a systematic review

“…We identified five controlled trials, and 29 non‐controlled studies, addressing this clinical question for non‐removable offloading devices, removable offloading devices, footwear, other offloading techniques, and surgical offloading.…”

“…A validation set of 30 publications was created, including key studies known to the authors published since our previous search (July 29, 2014) . Using this set, the search strings used were validated; ie, each publication had to be identified before the search strings were used in this systematic review.…”

Guidelines on offloading foot ulcers in persons with diabetes (IWGDF 2019 update)

“…One high‐quality RCT found a removable knee‐high device (bivalved TCC) showed greater plantar pressure reductions from standard footwear baseline levels at the ulcer site than a removable ankle‐high cast shoe or forefoot offloading shoe (67% vs 47% vs 26%, respectively, P = 0.029) . Several cross‐sectional studies also found that removable knee‐high devices show greater forefoot plantar pressure reduction than removable ankle‐high devices . Three RCTs investigated weight‐bearing activity.…”

“…One found TCCs had slightly greater heel plantar pressure reduction, another found knee‐high walkers reduced more heel pressure, and a third found they were the same in pressure relief . Several others found removable knee‐high devices (walkers and bivalved TCCs) had slightly greater heel plantar pressure reductions than ankle‐high devices (walkers, cast shoes, and postoperative healing shoes) but not always to a statistically significant level . Other studies found that removable ankle‐high devices give greater heel plantar pressure reduction than footwear (therapeutic and standard) .…”

Nursing Interventions For The Prevention Of Foot Ulcers In Patients With Diabetes: An Integrative Review

“…It causes functional and structural impairment of peripheral nerves, leading to lack of peripheral sensitivity, deformities and ulceration [4][5]. In addition, the pathological process of infection, ulceration or destruction of the deep foot tissues associated to neurological abnormalities and various degrees of peripheral vascular disease in the lower extremities of DM patients is known as diabetic foot [6].…”