Assessment of mechanical strain in the intact plantar fascia

BackgroundA method of measuring tri-axial plantar fascia strain that is minimally affected by external compressive force has not previously been reported.ObjectiveThe purpose of this study was to assess the use of micro-strain gauges to examine strain in the different axes of the plantar fascia.MethodTwo intact limbs from a thawed, fresh-frozen cadaver were dissected, and a combination of five linear and one three-way rosette gauges were attached to the fascia of the foot and ankle. Strain was assessed during two trials, both consisting of an identical controlled, loaded dorsiflexion.ResultsAn ICC analysis of the results revealed that the majority of gauge placement sites produced reliable measures (ICC > 0.75). Strain mapping of the plantar fascia indicates that the majority of the strain is centrally longitudinal, which provides supportive evidence for finite element model analysis.ConclusionAlthough micro-strain gauges do possess the limitation of calibration difficulty, they provide a repeatable measure of fascial strain and may provide benefits in situations that require tri-axial assessment or external compression.