Foot Posture Index (FP1-6)

Objective[edit | edit source]

Archers of the foot

The FPI-6 is a novel method of rating foot posture using set criteria and a simple scale, and is a quick, reliable diagnostic tool. It is used to quantify the degree to which a foot is pronated, neutral, or supinated. It is a measure of standing foot posture and so is not a replacement for gait assessment where time and facilities exist. It is however a more valid approach than many of the static weightbearing and non-weightbearing goniometric measures currently used in the clinic.

Intended Population[edit | edit source]

The FPI has been used in a variety of clinical and research settings. The applications of the FPI include studies of biomechanical risk factors for neuropathic ulceration in diabetes , identifying foot type as a basis for screening subjects as inclusion or exclusion criteria in clinical research, investigating the relationship between foot types and risk factors for sports and training injuries, investigating whether foot posture is associated with falls in older people and as a means of assessing age-related differences in foot structure.[1]

Viewing[edit | edit source]

Below, watch Jodi Young discuss the six observations associated with the Foot Posture Index(4 minute clip).

[2]

Method of Use[edit | edit source]

The patient should stand in their relaxed stance position with double limb support.

The patient should be instructed to stand still, with their arms by the side and looking straight ahead. It may be helpful to ask the patient to take several steps, marching on the spot, prior to settling into a comfortable stance position.

The patient will need to stand still for approximately two minutes in total for the assessment to be conducted. The assessor needs to be able to move around the patient during the assessment and to have uninterrupted access to the posterior aspect of the leg and foot.

If an observation cannot be made (e.g. because of soft tissue swelling) simply miss it out and indicate on the datasheet that the item was not scored.  If there is genuine doubt about how high or low to score an item always use the more conservative score.

There are six criteria for the Foot Posture Index for the physical therapist to observe. They include:

-2 -1 0 +1 +2
Talar head palpation Talar head palpable on lateral side/but not on medial side Talar head palpable on lateral/slightly palpable on medial side Talar head equally palpable on lateral and medial side Talar head slightly palpable on lateral side/palpable on medial side Talar head not palpable on lateral side/but palpable on medial side

Supra and infra lateral malleoli curvature (viewed from behind)

Curve below the malleolus either straight or convex Curve below the malleolus concave, but flatter/more than the curve above the malleolus Both infra and supra malleolar curves roughly equal Curve below the malleolus more concave than curve above malleolus Curve below the malleolus markedly more concave than curve above malleolus
Calcaneal frontal plane position (viewed from behind) More than an estimated 5o inverted (varus) Between vertical and an estimated 5o inverted (varus) Vertical Between vertical and an estimated 5o everted (valgus) More than an estimated 5o everted (valgus)
Prominence in region of TNJ (viewed at an angle from inside Area of TNJ markedly concave Area of TNJ slightly, but definitely concave Area of TNJ flat Area of TNJ bulging slightly Area of TNJ bulging markedly
Congruence of medial longitudinal arch (viewed from inside) Arch high and acutely angled towards the posterior end of the medial arch Arch moderately high and slightly acute posteriorly Arch height normal and concentrically curved Arch lowered with some flattening in the central position Arch very low with severe flattening in the central portion - arch making ground contact
Abduction/adduction of forefoot on rearfoot (view from behind) No lateral toes visible. Medial toes clearly visible Medial toes clearly more visible than lateral Medial and lateral toes equally visible Lateral toes clearly more visible than medial No medial toes visible. Lateral toes clearly visible.
FPI would be positive

Features commensurate with an approximately neutral foot posture are graded as zero, while

  • Pronated postures are given a positive value, the higher the value the more pronated.
  • Supinated features are given a negative value, the more negative the value the more supinated.
  • For a neutral foot, the final FPI aggregate score should lie somewhere around zero[3].

Physiotherapy Relevance[edit | edit source]

The results of the FPI help in deciding the appropriate interventions to use with your patient, eg strengthening, stretching, manual therapy or gait training. The results of the Foot Posture Index also help in deciding the appropriate orthotic for the patient.

Reliability and Validity[edit | edit source]

Reliability and validity of Foot Posture Index (FPI-6) for evaluating foot posture in participants with low back pain” concluded that “ The inter-rater and test-retest reliability and validity of FPI-6 on people with LBP were proved reliable. It might be considered a reliable and valid adjunctive tool to detect possible changes of foot posture after interventions in patients with LBP.”

Morrison & Ferrari studied the inter-rater reliability of the FPI-6 in the assessment of the pediatric foot, and there was an inter-rater agreement when the actual score was compared using a weighted Kappa test (Kw = 0.88). The study concluded that the FPI-6 is a quick, simple, and reliable clinical tool that has demonstrated good inter-rater reliability when used in the assessment of the pediatric foot[4].

Validity[edit | edit source]

The FPI-6 has been subjected to evaluation against the Rasch statistical model. This analysis confirms the construct validity of the six-item instrument and the linearity of the metric output[5]. (PSI=0.88)

Resources[edit | edit source]

References[edit | edit source]

  1. Redmond AC, Crane YZ, Menz HB. Normative values for the foot posture index. Journal of Foot and Ankle research. 2008 Dec;1:1-9.
  2. LBG Medical. Foot Posture Index. Available from: https://m.youtube.com/watch?v=heyYTsG9c7g [last accessed 2/7/2022]
  3. Redmond A. Easy quantification of standing foot posture Six item version User guide and manual.
  4. Morrison SC, Ferrari J. Inter-rater reliability of the Foot Posture Index (FPI-6) in the assessment of the paediatric foot. Journal of foot and ankle research. 2009 Dec;2:1-5.
  5. Keenan AM, Redmond AC, Horton M, Conaghan PG, Tennant A. The Foot Posture Index: Rasch analysis of a novel, foot-specific outcome measure. Archives of physical medicine and rehabilitation. 2007 Jan 1;88(1):88-93.
  6. Redmond AC, Crosbie J, Ouvrier RA. Development and validation of a novel rating system for scoring standing foot posture: the Foot Posture Index. Clinical biomechanics. 2006 Jan 1;21(1):89-98.
  7. Keenan AM, Redmond AC, Horton M, Conaghan PG, Tennant A. The Foot Posture Index: Rasch analysis of a novel, foot-specific outcome measure. Archives of physical medicine and rehabilitation. 2007 Jan 1;88(1):88-93.