Forefoot and Rearfoot Plantar Pressures in Diabetic Patients: Correlation to Foot Ulceration

Jeremy Rich, DPM; Aristidis Veves, MD, DSc

Disclosures

Wounds. 2000;12(4) 

In This Article

Abstract and Introduction

In the setting of diabetes mellitus, high plantar foot pressures are an important risk factor and can predict foot ulceration. Most studies have used measurements of peak plantar pressures under the whole foot. The purpose of this study was to evaluate forefoot and rearfoot plantar pressures separately in diabetic patients and examine their validity in predicting foot ulceration. A total of 90 patients were enrolled in a prospective study and were followed up for a mean period of 36 months. All the patients underwent a complete medical history and lower extremity evaluation for neuropathy, vascular status, vibration perception threshold (VPT), joint mobility, and foot pressures. The peak foot pressures under the rearfoot and forefoot were evaluated using the F-scan mat system with patients ambulating without footwear. Significant correlations were found between forefoot peak pressures and age, height, neuropathy disability score (NDS), vibration perception threshold (VPT), and force applied on the ground during walking. In contrast, reverse correlations were found between rearfoot peak pressures and measurements of neuropathic severity. Binary regression analysis showed a higher risk of foot ulceration in patients with high forefoot pressures (OR 1.15, CI 1.04-1.28, p=0.005), while no association was found for rearfoot pressures (OR 0.99, CI 0.96-1.03, p=NS). We conclude that peak foot pressure measurements of the forefoot but not the rearfoot correlate with neuropathy measurements and can also predict foot ulceration over 36 months. Measurement of forefoot peak pressures rather than the whole foot may therefore be more useful in identifying at-risk patients.

Diabetic foot ulceration is a major complication of diabetes mellitus.[1,2,3,4] As such, foot problems represent one of the most common reasons for hospital admission among diabetic patients.4 Despite numerous prevention and treatment protocols in the last two decades, the rate of lower extremity amputation is 15 times greater in diabetic patients than compared with non-diabetic patients.[1] In fact, 50 percent of diabetic amputees may require an amputation of the contralateral limb during the first four years after an amputation of the first limb.[2] However, diabetic foot problems are potentially the most preventable complication of diabetes.

The long-term sequela of the diabetic foot includes motor neuropathy that leads to the clawing of toes and prominent metatarsal heads.[5,6,7,8,9,10,11] Motor neuropathy is perhaps the most important etiopathogenic factor in the production of high foot pressures.[7,10,11] Motor neuropathy causes intrinsic muscle atrophy that promotes foot deformity and decreased joint mobility.[7,10,11] The final result of these changes is the development of high foot pressures under the metatarsal heads and loss of toe function, especially of the great toe.[12,13,14]

Furthermore, autonomic neuropathy accompanies the development of chronic sensorimotor neuropathy and at the foot level is responsible for denervation and subsequent anhydrosis of the foot. This leads to atrophic skin, fissures, and callous formation. Additionally, increased blood stagnation and swelling in the foot predisposes the foot to ulceration.[15,16,17]

Because of sensory neuropathy, high pressures may lead to tissue breakdown and the development of ulceration. The combination of peripheral vascular disease and neuropathy makes the diabetic patient particularly susceptible to foot ulceration and infection.[18]

Although several studies exist evaluating whole foot pressures in diabetic patients, there is a paucity of research examining forefoot and rearfoot plantar pressures. This study evaluated forefoot and rearfoot plantar pressures in diabetic patients and the role they may play in foot ulceration.

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