Plantar pressure distribution in gait is not affected by targeted reduced plantar cutaneous sensation

Plantar ulcers are a common and severe complication of the diabetic neuropathic foot. Increased plantar pressures while walking are associated to incidence of plantar ulcer formation in diabetes. There is a strong correlation between the increase in plantar pressures and the severity of peripheral neuropathy. One consequence of peripheral sensory neuropathy is insensitive skin. The influence of reduced plantar sensitivity on changes in plantar pressure distribution is not well understood. The purpose of this study was to identify possible causal dependences between reduced plantar cutaneous sensation and plantar pressure distribution during gait.

Dynamic pressure distribution in gait and sensory perception threshold for pressure touch and vibration (25Hz/200Hz) of the plantar foot were determined pre and post sensory intervention in ten healthy subjects. Cutaneous sensation in both foot soles was experimentally reduced by means of intradermal injections of an anaesthetic solution. This procedure leaves foot and ankle proprioception as well as intrinsic foot muscles unaffected.

The intervention significantly reduced plantar cutaneous sensation to the level of sensory neuropathy. Plantar pressure and force variables, contact times for the entire foot and for the plantar foot regions were not influenced significantly.

Experimentally reducing plantar cutaneous sensation causes no changes in plantar pressure distribution while walking. Our findings suggest that in the diabetic neuropathic foot insensitive plantar skin due to peripheral sensory neuropathy may be not a decisive factor for altering plantar pressures. This is underpinning the importance of concomitant affection of different systems secondary to diabetic peripheral neuropathy.