Foot posture versus Footprints – does paediatric foot assessment method matter?

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Footprints have long been used to measure foot morphology, with the concept of foot posture, arriving more recently – initially from Dahle and validated by Redmond as the Foot Posture Index (FPI-6).

A recent report from Drs Gijon-Nogueron, Evans (Malaga, Spain – Melbourne, Australia Research Collaboration) explored footprints and foot posture in 316 school children (153 boys, 163 girls) aged 6-9 years, and found an inverse relationship [ https://www.ncbi.nlm.nih.gov/pubmed/31267610 ]

In essence, the greater the foot posture score, the smaller the footprint angle. Hence, footprints may overestimate and misguide paediatric foot posture assessments

Background: Footprints have long been used to define foot types. Footprints and foot posture are both frequently used to categorise feet. Footprints and foot posture (FPI) disparity has confused ideas of increased body mass index and flat feet in children.

New findings:

This study found that footprints (viz. Clarke’s angle) and FPI measures in children do not agree and should not be regarded as synonymous foot measures. [ https://www.ncbi.nlm.nih.gov/pubmed/31267610 ]
Further, Footprints overestimate both planus and cavus foot types when compared to FPI.
Increased body mass index increases footprint area but is not associated with flatter feet. This previously held premise has now been found to be dependent of the assessment method used for foot posture – ie direct anatomical observations (FPI) versus footprints (incorporating adipose tissue surface area increase with weight bearing).

This new study found that footprints (viz Clarke’s angle) and FPI were found to correlate, with the footprints assessment ‘over-rating’ non-rectus foot types.
Foot type extremes, severe flatfeet and cavus feet, when determined by footprints, were respectively moderated as pronated and rectus, when assessed with the FPI.
There was better concordance for rectus feet, with agreement between footprints and FPI approximating 80%.

So what does this mean for clinicians who see children with foot posture concerns:

– A thorough clinical history, and use of the 3QQ triage method, is helpful to discern overtly abnormal presentations [ https://www.ncbi.nlm.nih.gov/pubmed/29148191 ]

– Clinicians need to appreciate that the method of foot assessment may vary clinical impressions (eg flatfeet or fat feet?)

– Note that FPI now has a large paediatric normative data reference set, with an easy-to-interpret ‘Ready Reckoner’ freely available HERE: https://angelaevanspodiatrists.com.au/evidence-essentials-blog-7-may-2019/

– Follow up re foot posture/time, given that feet are expected to become ‘less flat’ across the first decade of life

– Appreciate that overweight/obese children may have ‘fatter’ rather than ‘flatter’ feet – which could be an important consideration regarding footwear fitting

– Appreciate the importance of physical activity for health, advise children regarding activity recommendations [https://www.health.gov.au/internet/main/publishing.nsf/Content/health-pubhlth-strateg-phys-act-guidelines/$File/FS-Children-5-12-Years.PDF]