SLR - June 2018 - Jayson N. Atves

Effect of Static Foot Posture on the Dynamic Stiffness of Foot Joints During Walking

Reference: Sanchis-Sales, E, Sancho-Bru, JL, Roda-Sales, A, Pascual-Huerta, J. Effect of Static Foot Posture on the Dynamic Stiffness of Foot Joints During Walking. Gait & Posture. Mar 2018;62:241–246.



Reviewed By: Jayson N. Atves, DPM 
Residency Program: MedStar Washington Hospital Center, Washington, DC

Podiatric Relevance: Given that static weightbearing foot type has previously been implicated in the predisposition to lower-extremity pathology, researchers set out to investigate the dynamic stiffness of three foot types during walking to better understand the role of static foot type in development of lower-extremity pathology.

Methods: Seventy healthy adult males with varying foot types defined by the Foot Posture Index (FPI) were recruited and categorized [30 Normal, 20 Highly Pronated (HP) and 20 Highly Supinated (HS)]. Gait analysis was performed using a motion-tracking system and a pressure platform, and dynamic stiffness was subsequently calculated. The range of motion (ROM), the range of joint moments and angles collectively representing dynamic stiffness were averaged across five trials for each subject who were each recorded walking barefoot along a 7-meter walkway at a self-selected pace, stepping on a pressure platform in the middle of the walkway. The effect of static foot type on dynamic stiffness, ROM and range of moments was analyzed and tested for correlation between dynamic stiffness and FPI.

Results:

  • Highly Pronated (HP) foot type displayed:
    • significantly decreased ROM at ankle and metatarsophalangeal joints (MTPJ)
    • greater range of moments at MTPJ (versus HS feet)
    • significantly greater dynamic stiffness during propulsion at all foot joints with positive significant correlations with the squared FPI
    • greatest decrease in the dorsiflexory moments during propulsion
  • Highly Supinated (HS) foot type displayed:
    • greater dynamic stiffness (versus Normal feet)
  • Normal foot type displayed:
    • the most balanced work generated and absorbed (versus both HP and HS feet)

Conclusions: The authors concluded that the extreme static foot types (HP and HS) showed greater stiffness during propulsion and greater work absorbed, which may ultimately increase the risk of developing lower-extremity injury in these foot types. Personally, I concur with this albeit broad conclusion regarding dynamic stiffness of varying static foot types. Although actual dynamic stiffness values differed from one foot type to the next, the HP foot type displayed the most substantial ranges, indicating that there exists a spectrum of potential for foot and ankle pathology with the HP foot type producing less efficient work relative to the HS and Normal foot type. The HP foot type appears to be the most dynamically stiff and thus most likely to experience injury and/or pathology. This data could be of particular interest in analyzing the relationship between foot and ankle pathology and gross static foot type and the anticipated changes with or without intervention. The effects of surgical intervention on a static foot type may modify joint stiffness in a way that creates more efficient gait and thus lessens predisposition to further injury or pathology. Additionally, this may be useful in considering orthotic and prosthetic design for conservative and/or postoperative management for a variety of pathologies.

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