Transcript The USE of PLANTAR PRESSURE DATA for ASESSING FOOT

Assessment of FOOT
Posture and Mobility:
Development of a “Physical
Therapy” Model
Thomas McPoil, PT, PhD, ATC, FAPTA
School of Physical Therapy
• Professor Mark Cornwall
– Northern Arizona University
• The DPT Graduate Students who have
assisted me in my research efforts
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)
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
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
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
Current Measurement Methods
• Foot Posture
– Longitudinal Arch Angle
• McPoil & Cornwall, JAPMA
2005 - walking
• McPoil & Cornwall, JAPMA
2007 - running
LAA is
• Can be used to
statically classify
foot structure
• HIGHLY predictive
of dynamic foot
posture during
walking
> 150o
< 130o
Supinated Foot Posture
Pronated Foot Posture
RSP vs. MS (r = .971; r2 = .943)
Current Measurement Methods
• Foot Posture
– Arch Height Ratio (AHR)
• Williams & McClay, Phys Ther,
2000
• McPoil et al, FOOT, 2008
Arch Height
AHR =
Ball Length
Arch Height Ratio
• McPoil et al, FOOT, 2008
– Norm values (n = 850)
• Total Foot Length
– Rt = 0.253 + 0.02
– Lt = 0.249 + 0.02
• Truncated Length
– Rt = 0.345 + 0.03
– Lt = 0.341 + 0.03
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
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
Current Measurement Methods
• Foot Posture
– Boney Arch Index
– Valgus Index
– Longitudinal Arch
Angle
– Arch Height Ratio
• Foot Mobility
– Navicular Drop
– Navicular Drift
Current Measurement Methods
• Navicular Drop test
– Change in navicular tuberosity height
b/w resting posture & subtalar jt
neutral position
• First described Brody in 1982
Subtalar Jt
Neutral
Position
• 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
Resting
Posture
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
Sagittal Movement
Mean = 14.7mm
Current Measurement Methods
• Navicular Drift
Subtalar Jt Neutral Position
– 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; + 1.5 to + 3.5 mm
» Navicular Drift ICCs = 0.31 to 0.62;
SEMs; + 3.0 to + 5.0 mm
– Concluded further research required to
improve measurement techniques and
reliability
Resting Posture
Current Measurement Methods
• Foot Posture
– Boney Arch Index
– Valgus Index
– Longitudinal Arch
Angle
– Arch Height Ratio
• Foot Mobility
– Navicular Drop
Potential
But
• Sagittal Movement
–PROBLEMS
Navicular Drift
• Medial – Lateral
Movement
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
FOOT IMAGE PLATFORM
FOOT IMAGE PLATFORM
• 3 Digital Images Obtained for Each Foot
– Total time required for image capture - 6 minutes
– No skin markings required
Bottom View
WB Arch View
Back View
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
FOOT IMAGE PLATFORM
• Positive 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!
FOOT IMAGE PLATFORM
• Did convince REEBOK to capture WB &
NWB medial arch image
WB Arch View
Non-WB Arch View
SIT–to–STAND
TEST
Sitting
– Determine amount of
rearfoot & midfoot
mobility
Standing
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
FOOT ASSESSMENT PLATFORM
( FAPs )
• Initially developed
in 2004
– An attempt to create a
more clinically
applicable device
based on the FIPs
measurements
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 NonWB vs WB
– Foot Mobility Magnitude
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
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
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
FAPs DISTRIBUTIONS
(n = 690 feet)
Diff in Arch Hgt
Foot Mob Mag
Diff Midfoot Width
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
Mean
n = 345
SEM
Left
Right
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
0.08
0.09
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
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
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
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
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
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.
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
Thank You!
Average left WB
midfoot width
Average right WB
midfoot width
Average left WB
arch height
Average right WB
arch height
Average left NWB
midfoot width
Average right NWB
midfoot with
Average left NWB
arch height
Average right NWB
arch height
Gender
male
female
male
female
male
female
male
female
male
female
male
female
male
female
male
female
US ARMY – BAYLOR
NAU
Mean
8.98
7.93
9.10
8.02
6.98
6.20
6.74
6.00
8.14
7.19
8.25
7.30
8.20
7.38
8.17
7.32
Mean
8.98
7.92
9.03
7.96
6.87
6.18
6.77
6.07
7.97
6.99
8.03
7.08
8.12
7.36
8.13
7.35
Left mobility of
midfoot at 50%
foot length
Right mobility of
midfoot at 50%
foot length
Left mobility of
dorsal arch height
at 50% foot length
Right mobility of
dorsal arch height
at 50% foot length
US ARMY - BAYLOR
NAU
Gender
Mean
Mean
male
0.84
1.02
female
0.74
0.92
male
0.85
1.00
female
0.72
0.88
male
1.22
1.26
female
1.18
1.19
male
1.42
1.35
female
1.31
1.28
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
The Podiatric Model’s Theorized Pattern of
Rearfoot Motion During Walking
The Podiatric Model
• Normal & Abnormal Foot Types:
NORMAL
ABNORMAL
The Podiatric Model
• Orthotic Intervention:
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