A comparison of the 1-step, 2-step, and 3-step protocols for obtaining barefoot plantar pressure data in the diabetic neuropathic foot.

BACKGROUND: Barefoot plantar pressure measurements are routinely used in the risk evaluation for ulceration in diabetic patients with neuropathy. The aim was to compare three step-protocols commonly used for pressure assessment in these patients.
METHODS: Dynamic barefoot plantar pressures were measured in 14 diabetic neuropathic patients (vibration perception threshold >35 V) contacting a pressure platform on the first, second or third step after gait initiation. Ten repeated trials per step-protocol were collected. The 3-step protocol was regarded the reference protocol. Peak pressure, pressure-time integral and contact time were calculated for each of six anatomical foot regions. Intraclass correlation coefficients (ICC) were calculated to assess reliability in each protocol.
FINDINGS: Regional peak pressures and pressure-time integrals were not significantly different between protocols. Contact time was significantly different in the heel region between the 1-step and 3-step protocol only (P<0.05). Intraclass correlation coefficients for the maximum 10 repeated trials were high (>0.87) and similar between protocols. Reliable estimates (ICC>0.85) of peak pressure were achieved with three repeated trials in the 2-step protocol, and four in the other two; for pressure-time integral these numbers were 7 (1-step), 4 (2-step), and 5 trials (3-step).
INTERPRETATION: Barefoot plantar pressures in the diabetic neuropathic foot can be assessed in a reproducible manner with any of the step-protocols used. For this purpose, the 1-step and 2-step protocols prove to be valid methods. A 2-step protocol requires the least amount of repeated trials for obtaining reliable pressure data and may be recommended for assessment of these patients.