Foot loading and diabetic ulcer risk
Research type
Research Study
Full title
Factors affecting foot loading and ulcer risk in diabetes patients
IRAS ID
239893
Contact name
Neil Reeves
Contact email
Sponsor organisation
Manchester Metropolitan University
Duration of Study in the UK
2 years, 0 months, 17 days
Research summary
Research Summary
This study aims to determine the effect of biomechanical and neuropathic factors underpinning Diabetic foot ulcer (DFU) development. Up to 85% of amputations associated with diabetes are the result of ulceration. NHS Diabetes report 2012 estimates £650 million is spent (or £1 in every £150 the NHS spends) on foot ulcers and related amputations each year. Diabetic neuropathy causes changes in foot structure, affecting foot function and subsequently leading to increased plantar foot pressure. Stiffening of Achilles tendon limits the range of ankle dorsiflexion (DF), thereby affecting upon nature of foot loading. This study hypothesizes that increased Achilles tendon and plantar flexion muscle-tendon stiffness would be associated with an increased ulcer risk, through the development of elevated forefoot pressures. We will also assess prior ulcer history, foot deformities, neuropathy severity and other clinical factors. Linked to Achilles tendon stiffness, the proposed study will also examine the relationship between DF range of motion, ankle joint passive muscle-tendon unit stiffness, with plantar foot pressure loading and ulceration risk during gait. We will conduct a cross-sectional study with 45 consenting participants with type 2 diabetes placed in three groups on the basis of previous foot ulcer history and severity of diabetic neuropathy. Clinical care teams at The Chorley & South Ribble Hospital and Manchester University NHS Foundation Trust, will support in identification of participants. Sessions with participants will include Neuropathy tests, foot and ankle biomechanics measurements for measuring tendon properties, Gait analysis & Pressure Mapping, Ultrasonography and Magnetic Resonance Imaging of ankle area. Study outcomes will contribute towards the development of algorithms for prediction of foot ulceration risks and inform prevention efforts.Summary of Results
Our findings firstly highlight that Achilles tendon properties are altered in older people with diabetic peripheral neuropathy. Achilles tendon stiffness was higher by ~51% in older people with diabetic peripheral neuropathy compared to controls without diabetes. This means that when force is applied, the tendon is more resistant to elongation and therefore more difficult to ‘stretch’. We found strong associations between measures of diabetic peripheral neuropathy and tendon stiffness, indicating that as diabetic neuropathy severity increases, the tendon becomes stiffer. This increased stiffness with diabetes and peripheral neuropathy is highly likely the result of non-enzymatic glycation of collagen tissues due to diabetes, supported by a strong association found between advanced glycation end products and tendon stiffness. In isolated tests of foot and ankle function on a dynamometer this higher tendon stiffness meant that assisted ankle dorsiflexion range of motion (bringing the foot up towards the lower leg) was reduced by ~42% in older people with diabetic peripheral neuropathy compared to controls.Our gait (walking) analysis data showed that despite older people with diabetic peripheral neuropathy walking more slowly and having longer stance times (where their two feet were in contact with the ground), they lifted their heel significantly earlier in the gait cycle compared to controls. This is important, as it shows the effect of a stiffer tendon on gait, which is to limit the extent to which the ankle can dorsiflex during walking (by ~25%) requiring the heel to come off the ground earlier in the gait cycle. The effect of this is that the pressure is higher for longer on the forefoot region (the ball of the feet and the toes). Indeed, this link between higher Achilles tendon stiffness and earlier heel rise during walking was underlined by an association between these two variables.
In terms of pressure on the bottom of the foot, we found that older people with diabetic peripheral neuropathy develop higher pressure mainly in the forefoot area of the foot, around the ball of the foot (metatarsals) and across the toes compared to controls. The increased Achilles tendon stiffness in people with diabetic neuropathy is a major contributor to this pattern of high foot pressure development on the forefoot area. This is because increased Achilles tendon stiffness restricts elongation of this tendon on the back of the leg and limits the extent to which the ankle can dorsiflex (i.e., limiting how much the tibia can rotate over the foot during the stance phase of gait). This in turn requires the heel to lift off the ground earlier, meaning that higher pressure is developed for longer on the forefoot area (ball of the foot and toes) resulting in an elevated risk of diabetic foot ulcers occurring in this region. In addition to the data above, this process described is further supported by an association between heel rise and tendon stiffness and between peak forefoot pressure and peak ankle dorsiflexion during walking.
In conclusion, increased Achilles tendon stiffness plays a key role in the elevated risk of diabetic foot ulcers in the forefoot region in older people with diabetic peripheral neuropathy. This sets the path for future research to consider the Achilles tendon as an important factor in diabetic foot ulcer development and a target for therapeutic intervention.
REC name
North West - Greater Manchester East Research Ethics Committee
REC reference
18/NW/0274
Date of REC Opinion
10 Jul 2018
REC opinion
Further Information Favourable Opinion