1. Assessment of FOOT Posture and Mobility: Development of a “Physical Therapy” Model
Thomas McPoil, PT, PhD, ATC, FAPTA
School of Physical Therapy

2. Recognize and Thank Professor Mark Cornwall
Northern Arizona University
The DPT Graduate Students who have assisted me in my research efforts

3. Overview of Presentation
Why are PT’s interested in foot posture & mobility?
Major requirements for clinical measurements
Current measurement methods
Foot Posture
Foot Mobility
Foot Image Platform (FIPs)
Foot Assessment Platform (FAPs)

4. Why are PT’s interested in FOOT Posture & Mobility
The basic premise underlying the understanding of foot mechanics - given structural foot type will display certain functional characteristics
These characteristics are often associated with pathological dysfunction of the LE
Clinical measurement of FOOT posture & mobility are inherent components of foot type classification

5. Major Requirements for Clinical Measurements
Must have an operational definition to guide process
Identifies a specific observable event & tells clinician how to measure the event
The measurement must be reproducible
Must demonstrate inter- & intra-rater reliability
Intraclass Correlation Coefficients (ICCs)
Standard Error of the Measurement (SEMs)
Measurements must be valid
They must yield “true” measurements of the event being measured

6. Current “Objective” Measurement Methods
Foot Posture
Boney Arch Index
Valgus Index
Longitudinal Arch Angle
Arch Height Ratio
Foot Mobility
Navicular Drop
Navicular Drift
Podiatric Model
Attempted to use static foot posture to predict dynamic foot movement

7. Current Measurement Methods
Foot Posture
Longitudinal Arch Angle
McPoil & Cornwall, JAPMA walking
McPoil & Cornwall, JAPMA running

8. LAA is Can be used to statically classify foot structure
Supinated Foot Posture
Pronated Foot Posture
Can be used to statically classify foot structure
HIGHLY predictive of dynamic foot posture during walking
RSP vs. MS (r = .971; r2 = .943)

9. Current Measurement Methods
Foot Posture
Arch Height Ratio (AHR)
Williams & McClay, Phys Ther, 2000
McPoil et al, FOOT, 2008
Arch Height
Ball Length
AHR =
50% of
Foot Length

10. Arch Height Ratio McPoil et al, FOOT, 2008 Norm values (n = 850)
Total Foot Length
Rt =
Lt =
Truncated Length
Rt =
Lt =
50% of
Foot Length
Ball Length
Arch Height

11. Arch Height Ratio
Static AHR appears to be predictive of midstance during walking
Franettovich et al, JAMPA 97:115, 2007
Reported that the AHR obtained in static standing correlated to AHR at midstance in walking
r = 0.85; r2 = 0.72

12. Current Measurement Methods
Foot Posture
Boney Arch Index
Valgus Index
Longitudinal Arch Angle
Arch Height Ratio
Major limitation with Foot Posture categorizations is do not account for Foot Mobility

13. Current Measurement Methods
Foot Posture
Boney Arch Index
Valgus Index
Longitudinal Arch Angle
Arch Height Ratio
Foot Mobility
Navicular Drop
Navicular Drift

14. Current Measurement Methods
Navicular Drop test
Change in navicular tuberosity height b/w resting posture & subtalar jt neutral position
First described Brody in 1982
Stated that normal was a 10 mm change; abnormal > 15 mm
NO data to substantiate!
ISSUES
Fair to Poor levels of inter-rater reliability
Result of palpating subtalar jt neutral position
ONLY assesses motion in sagittal plane
Subtalar Jt Neutral Position
Resting
Posture

15. Dynamic Movement of Navicular Bone during Walking
Cornwall & McPoil, Foot & Ankle Int; 1999
Assessed pattern and magnitude of navicular bone movement during walking in 106 subjects
Reported both sagittal & medial-lateral movement
Medial-Lateral Movement
Mean = 14.7mm
Sagittal Movement

16. Current Measurement Methods
Navicular Drift
Described by Menz, JAPMA, 1998
Vinicombe et al, JAPMA, 2001
Assessed the reliability of both navicular drop & drift in 20 subjects
Inter-rater reliability
Navicular Drop ICCs = 0.33 to 0.76; SEMs; to mm
Navicular Drift ICCs = 0.31 to 0.62; SEMs; to mm
Concluded further research required to improve measurement techniques and reliability
Subtalar Jt Neutral Position
Resting Posture

17. Current Measurement Methods
Potential But
PROBLEMS
Foot Posture
Boney Arch Index
Valgus Index
Longitudinal Arch Angle
Arch Height Ratio
Foot Mobility
Navicular Drop
Sagittal Movement
Navicular Drift
Medial – Lateral Movement

18. FOOT IMAGE PLATFORM (FIPs)
Developed for REEBOK Footwear Company in 2001
System for obtaining measurements that was inexpensive, portable, & durable
Foot measurements that were reproducible & reliable between multiple raters
Require minimal to no skin marking of bony landmarks

19. FOOT IMAGE PLATFORM

20. FOOT IMAGE PLATFORM 3 Digital Images Obtained for Each Foot
Total time required for image capture - 6 minutes
No skin markings required
Back View
WB Arch View
Bottom View

21. FOOT IMAGE PLATFORM
FROM THE 3 DIGITAL IMAGES, 15 different measurements were obtained in bilateral standing (50% body weight)
Back View – 3 measures
WB Arch View – 5 measures
Bottom View – 7 measures

22. FOOT IMAGE PLATFORM Positive Points Negative Points
Reliability of the 15 measurements
Excellent intra-rater & inter-rater reliability using inexperienced evaluators
Reliability of foot placement on the FIP
Excellent
Negative Points
Took approximately 45 to 60 minutes to analyze 8 pictures obtained for each subject
NOT feasible for clinical use!

23. FOOT IMAGE PLATFORM
Did convince REEBOK to capture WB & NWB medial arch image
WB Arch View
Non-WB Arch View

24. SIT–to–STAND TEST Determine amount of rearfoot & midfoot mobility
Sitting
Determine amount of rearfoot & midfoot mobility
Standing

25. Arch Height Change during Sit-to-Stand
McPoil et al: J Foot Ankle Res, 2008
Assessed change in arch height b/w Non-WB and WB in 275 healthy subjects
Reported
Good to high levels of intra- & inter-rater reliability
Validated using x-rays as a criterion measure
Mean difference between Non-WB and WB = 1.0 cm
Need to make clinically feasible!
Account for medial-lateral foot mobility

26. FOOT ASSESSMENT PLATFORM ( FAPs )
Initially developed in 2004
An attempt to create a more clinically applicable device based on the FIPs measurements

27. FOOT ASSESSMENT PLATFORM
Measurements of Foot Mobility
McPoil et al, J Foot Ankle Research 2:6, 2009
Difference in arch height at 50% foot length between Non-WB vs WB
Difference in midfoot width at 50% foot length between Non-WB vs WB
Foot Mobility Magnitude

28. FOOT ASSESSMENT PLATFORM
Difference in dorsal arch height between NonWB vs WB
The WB height of the dorsal aspect of the arch minus the WB dorsal arch height
Dorsal height measured at 50% of the length of the foot

29. FOOT ASSESSMENT PLATFORM
Difference in midfoot width between NonWB vs WB
The width of the midfoot is measured at 50% of the length of the foot

30. FOOT ASSESSMENT PLATFORM
Foot Mobility Magnitude (FMM)
FMM =
Diff Arch Ht2 + Diff MF Width2
Diff in Arch Ht / NonWB - WB
Diff in MF Width / NonWB - WB
FMM

31. FAPs DISTRIBUTIONS (n = 690 feet)
Diff in Arch Hgt
Foot Mob Mag
Diff Midfoot Width

32. FAPs Data
ICCs
Intra-rater = .97 to .99; Inter-rater = .83 to .99
SEMs
Intra-rater = 0.03 to 0.09 cm; Inter-rater = 0.04 to 0.13 cm
n = 345
Mean
SEM
Left
Right
Foot Length
25.31
25.32
0.11
0.10
Diff Arch Hgt
1.21
1.31
0.07
0.08
Diff MF Width
0.96
0.93
0.12
0.14
FM2
1.57
1.63
0.09

33. US Army Baylor – NAU Assessed 1,000 individuals using FAPs
566 Males
434 Females
Utilized 4 entry-level PT students as raters
After 1 hour of training & 1 hour of practice
Inter-rater ICCs = .78 to .99
SEMs = 0.03 to 0.20 cm

34. Clinical Applications of FAPs Measurements
32 yo male with Bilateral Calcaneal Fractures
LT was non-displaced
RT displaced & required ORIF
Courtesy of Stephanie Albin, PT, TOSH, Salt Lake City, Utah

35. Clinical Applications of FAPs Measurements
32 yo male with Bilateral Calcaneal Fractures
LT was non-displaced
RT displaced & required ORIF
NORMS
Patient Values
Left
Right
Diff Arch Hgt
1.21
1.31
0.71
0.57
Diff MF Width
0.96
0.93
0.94
0.39
FM2
1.57
1.63
1.18
0.69
Courtesy of Stephanie Albin, PT, TOSH, Salt Lake City, Utah

36. Clinical Applications of FAPs Measurements
Vicenzino, Collins, Cleland, McPoil: BJSM, 2008
Development of clinical prediction rule to identify patients with PFPS who will benefit from foot orthoses
One of the four predictor variables
Diff Midfoot Width > 11 mm
Remaining Predictors
Age over 25 years
Height less than 165 cm
Worst pain less than 53.3 mm on a 100 mm VAS

37. Clinical Applications of FAPs Measurements
McPoil, Warren, Vicenzino, Cornwall, JAPMA, in press
Assessed 43 individuals with a history of unilateral or bilateral PFPS and 86 controls
Nested-case control design
PFPS 4 times more likely to have a larger than normal difference between NWB & WB arch height compared with the controls.
Mean values for difference in arch height and the foot mobility magnitude were also statistically significant between the patient and control groups.

38. FUTURE DIRECTIONS Have developed a large normative database!
Need for clinical trials to determine if measurements can be predictive of LE or Foot pathology
Further assessment on usefulness of measurements for determining which patient/client would benefit from foot orthoses

39. Thank You!

40. Average left WB midfoot width male 8.98 female 7.93 7.92
US ARMY – BAYLOR
NAU
Gender
Mean
Average left WB midfoot width
male
8.98
female
7.93
7.92
Average right WB midfoot width
9.10
9.03
8.02
7.96
Average left WB arch height
6.98
6.87
6.20
6.18
Average right WB arch height
6.74
6.77
6.00
6.07
Average left NWB midfoot width
8.14
7.97
7.19
6.99
Average right NWB midfoot with
8.25
8.03
7.30
7.08
Average left NWB arch height
8.20
8.12
7.38
7.36
Average right NWB arch height
8.17
8.13
7.32
7.35

41. US ARMY - BAYLOR NAU Gender Mean
Gender
Mean
Left mobility of midfoot at 50% foot length
male
0.84
1.02
female
0.74
0.92
Right mobility of midfoot at 50% foot length
0.85
1.00
0.72
0.88
Left mobility of dorsal arch height at 50% foot length
1.22
1.26
1.18
1.19
Right mobility of dorsal arch height at 50% foot length
1.42
1.35
1.31
1.28

42. The PODIATRIC Model
The most common method used by PT’s for the examination & management of the foot & ankle
First described by Podiatrists Merton Root, Bill Orien, & John Weed in the late 60’s
Provided a criteria for classifying a “NORMAL” foot posture
Defined “ABNORMAL” foot structure
Forefoot & Rearfoot deformities
Provided method for fabricating foot orthoses

43. The Podiatric Model’s Theorized Pattern of Rearfoot Motion During Walking

44. The Podiatric Model
Normal & Abnormal Foot Types:
ABNORMAL
NORMAL

45. The Podiatric Model
Orthotic Intervention:

46. The Podiatric Model Current evidence to support use
Little, if any evidence
Legitimacy of using subtalar joint neutral position as the KEY alignment criteria is questionable
Wright, et al, JBJS, 1964
McPoil & Cornwall; Foot & Ankle, 1994
McPoil & Cornwall; JOSPT, 1996
Cornwall & McPoil: JAPMA, 2000
Unable to predict dynamic foot function based on measurements
Hamill, et al, Clin Biomech 1989
McPoil & Cornwall, JOSPT 1997
Cornwall & McPoil, FOOT, 2004
Cornwall, et al, AJPM, 2004
Poor inter-rater reliability of the measurements
Elveru, et al. Phys Ther 1988
Van Gheluwe, et al: JAPMA 2002
Thus multiple clinicians cannot compare findings