Bulk compressive properties of the heel fat pad during walking: A pilot investigation in plantar heel pain

• Published in: Clinical biomechanics (Bristol) Vol. 24; no. 4; pp. 397 - 402
• Main Authors: Wearing, Scott C., Smeathers, James E., Yates, Bede, Urry, Stephen R., Dubois, Philip
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.05.2009
• Subjects: Adult; Cohort Studies; Compression; Compressive Strength; Elasticity; Female; Fluoroscopy; Fluoroscopy - methods; Foot - physiopathology; Gait; Heel - physiopathology; Heel pad; Humans; Male; Middle Aged; Pain - physiopathology; Physical Medicine and Rehabilitation; Pilot Projects; Plantar fasciitis; Pressure; Soft tissue properties; Walking; Plantar fasciitis; Heel pad; Compression; Fluoroscopy; Gait; Soft tissue properties
• ISSN: 0268-0033; 1879-1271; 1879-1271
• DOI: 10.1016/j.clinbiomech.2009.01.002

Altered mechanical properties of the heel pad have been implicated in the development of plantar heel pain. However, the in vivo properties of the heel pad during gait remain largely unexplored in this cohort. The aim of the current study was to characterise the bulk compressive properties of the heel pad in individuals with and without plantar heel pain while walking. The sagittal thickness and axial compressive strain of the heel pad were estimated in vivo from dynamic lateral foot radiographs acquired from nine subjects with unilateral plantar heel pain and an equivalent number of matched controls, while walking at their preferred speed. Compressive stress was derived from simultaneously acquired plantar pressure data. Principal viscoelastic parameters of the heel pad, including peak strain, secant modulus and energy dissipation (hysteresis), were estimated from subsequent stress–strain curves. There was no significant difference in loaded and unloaded heel pad thickness, peak stress, peak strain, or secant and tangent modulus in subjects with and without heel pain. However, the fat pad of symptomatic feet had a significantly lower energy dissipation ratio (0.55 ± 0.17 vs. 0.69 ± 0.08) when compared to asymptomatic feet ( P < .05). Plantar heel pain is characterised by reduced energy dissipation ratio of the heel pad when measured in vivo and under physiologically relevant strain rates.