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Assessment of FOOT Posture and Mobility: Development of a “Physical Therapy” Model

Assessment of FOOT Posture and Mobility: Development of a “Physical Therapy” Model. Thomas McPoil, PT, PhD, ATC, FAPTA School of Physical Therapy. Recognize and Thank. Professor Mark Cornwall Northern Arizona University The DPT Graduate Students who have assisted me in my research efforts.

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Assessment of FOOT Posture and Mobility: Development of a “Physical Therapy” Model

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  1. Assessment of FOOTPosture 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 • NavicularDrift • 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 2005 - walking • McPoil & Cornwall, JAPMA 2007 - running

  8. > 150o < 130o RSP vs. MS (r = .971; r2 = .943) Supinated Foot Posture Pronated Foot Posture LAA is • Can be used to statically classify foot structure • HIGHLY predictive of dynamic foot posture during walking

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

  10. Arch Height Ball Length 50% of Foot 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

  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 naviculartuberosity height b/w resting posture & subtalarjt 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 subtalarjt 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 Subtalar Jt Neutral Position • 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; + 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

  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 Bottom View Back View WB Arch 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 • 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 Sitting • Determine amount of rearfoot & midfootmobility Standing

  25. Arch Height Change duringSit-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 FootMobility • 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. Diff Arch Ht2 + Diff MF Width2 FMM = FOOT ASSESSMENT PLATFORM • Foot Mobility Magnitude (FMM) Diff in Arch Ht / NonWB - WB Diff in MF Width / NonWB - WB FMM

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

  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

  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 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. 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

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

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

  43. The Podiatric Model • Orthotic Intervention:

  44. 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, ClinBiomech 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

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