BACKGROUND: Diabetes-related medial column foot deformities contribute to high plantar pressure, joint instability, ulceration and amputation. Impaired foot function may be an early indicator of foot structural incompetence and contribute to deformity progression. This study examines the ability of single-limb heel rise multi-segmental kinematics and kinetics to identify midfoot and hindfoot dysfunction in those with diabetes-related medial column foot deformity.
METHODS: Single-limb heel rise foot kinematics and kinetics were examined in adults with diabetes mellitus and peripheral neuropathy with and without medial column foot deformity and age-, weight-matched controls.
FINDINGS: Hindfoot relative to shank plantarflexion, peak and excursion, were reduced in both diabetes groups compared to controls (P<0.017). Controls' initial forefoot relative to hindfoot position was plantarflexed 31° and plantarflexed an additional 13° during heel rise. The initial forefoot relative to hindfoot position for the diabetes group without deformity was similarly plantarflexed as controls (34°) while the diabetes deformity group was less plantarflexed (lower arch position: 23°, P<0.017). During the heel rise task both diabetes groups demonstrated less ability to plantarflex the forefoot relative to the hindfoot compared to controls (2 and 5° respectively, P<0.017). Ankle plantarflexion power was reduced in the diabetes deformity group compared to controls (P<0.017).
INTERPRETATION: The single-limb heel rise task identified movement dysfunction in those with diabetes mellitus and peripheral neuropathy. Failure to plantarflex the forefoot relative to hindfoot may compromise midfoot joint stability and increase the risk of injury and arch collapse.