Treadmill Based Gait Assessment CMAS Standards Damien Kiernan

Treadmill Based Gait Assessment & CMAS Standards Damien Kiernan CMAS meeting 30 th Oct. 2015

Treadmill gait • How does treadmill based gait fit with CMAS standards? • Differences in normal walking • Do standards need to be adjusted to incorporate this type of system? • Experience of one lab using treadmill based system – Stanmore • Discussion / Consensus

Many advantages to treadmill gait • Multiple gait cycles • Fix speed for comparison of data over time • Harness support system • Treadmills with integrated force platforms • Size requirements – smaller labs

Treadmill gait vs. over ground walking • Are they equivalent? • How do they fit with CMAS standards? CMAS designed around labs assessing over ground walking e. g. mandatory 7 m walkway Do standards need to be adjusted to incorporate the finer points of treadmill systems? ? e. g. the use of handrails, familiarisation periods, requirements for equipment testing? ? • What does the literature say? ? ?

Treadmill gait vs. over ground walking Kinematics - Young healthy adult subjects - Similar – some statistically significantly differences - Mechanics of gait similar - Magnitude of differences generally less than 2 o Kinetics “- GRF data statistically significantly smaller for TM - Majority of moments measured smaller - Magnitude of differences comparable to normal gait variability - Sagittal plane moments not different - TM gait “essentially” equivalent to OG gait” Riley et al, 2006

Treadmill gait vs. over ground walking Kinematics - Study assessing younger vs. older adults - Subjects displayed “large deviations” from OG initially - More pronounced in older adults (increased step width) - Suggested 20 mins needed before fully familiar with TM - Older adults did not “fully abandon” more careful walking - However differences remained for: step length, cadence & double support Kinetics - Not examined Schellenbach et al, 2010

Treadmill gait vs. over ground walking Kinematics - Young unimpaired subjects - “Familiarisation time is required” before TM gait is equivalent to OG gait - Initially an “unfamiliar” experience - Reliable knee measures after ~ 4 mins - Absolute differences score < 2 o - Highly reliable knee kinematics & TS parameters ~ 6 mins - Tested on Young healthy subjects Kinetics - Not examined Matsas et al, 2000

Treadmill gait vs. over ground walking Kinematics - Young healthy adults - Agreement between temporal-spatial parameters - Small sig. differences cadence/step length/stance phase - Suggested differences “not clinically meaningful” - However, care needed when interpreting w. r. t literature Kinetics - Not examined Wearing et al, 2013

Treadmill gait vs. over ground walking Kinematics - Study assessing young adults - Aim to assess habituation to TM walking - Five 10 min practice sessions (spaced with 1 hr) - Resulted in “more rapid” habituation - Suggested distributed practice sessions for ~1 hr - Do not measure within first 2 mins of performance Kinetics - Not examined Wall & Charteris, 1981

Treadmill gait vs. over ground walking Kinematics - Study assessing young adults - Aim to assess habituation to TM walking - Knee kinematics & spatio-temporal parameters assessed - A “steady state” attained reasonably quickly (~ 30 s) - However ~10 mins before data were reproducible Kinetics - Not examined Van de Putte, 2006

Treadmill gait vs. over ground walking Kinematics - Study assessing CP children - OG vs. self paced TM walking (in virtual environment) - Natural walking (outside lab) also considered - Wider stride width on TM - 2 o more pelvic tilt & 7 o more knee flexion @IC - CP kids walked slower (~6%) on TM - Slightly higher GPS (0. 81 o) for CP on TM - May be as a result of increased fatigue - Concluded differences generally small & non-significant - Found for some individual patients – clinically meaningful Kinetics - Not examined Van der Krogt et al , 2014

Treadmill gait vs. over ground walking Kinematics - Not examined Kinetics - Presented @ ESMAC 2015 - Dual-belt instrumented TM / self-paced mode - Kinetics differed significantly increased peak hip ext by 35% increased peak ankle ext mom CP (9%) decreased peak ankle ext mom TD (7%) hip & knee abduction mom’s increased (~35%) net hip work increased / net ankle work decreased - TM kinetic data “cannot” be compared to OG Van der Krogt et al , 2015

Treadmill gait vs. over ground walking Running Kinematics - Study assessing running on TM in paediatric gp. - Differences did exist to OG running - Decreased dorsiflexion (swing) Running Kinetics - Completely different to OG running - More anterior GRF during TM running “Use of TM “not a surrogate” to study of OG running” Rozumalski et al, 2015

Treadmill gait vs. over ground walking VO 2 - Study assessing healthy children (6 yr old) - Acceptable & reproducible VO 2 can be achieved ~10 mins - Must be preceded by brief period TM practice (5 min) (children had attended at a previous session) Tseh et al, 2000 - Study assessing CP hemiplegia (children) - Within and between day stability of VO 2 examined - Stable measures achieved both within & between - Must be preceded by short period TM practice - more involved CP may need longer exposure to TM before stable results achieved Keefer et al, 2005

Treadmill gait vs. over ground walking EMG - Tib Ant – lower activity throughout stance - Gastroc – lower in stance, higher in terminal swing - Hamstrings – lower throughout except at TS - Rectus – higher during transition stance to swing & TS Lee et al, 2008 - EMG activity usually greater on TM ( sig only for quads) Murray et al, 1985 - Similar profiles of EMG activity between TM & OG - Tendency for TM data to indicate larger EMG amplitudes - Concluded could be used interchangably Arsenault et al, 1986

Self paced vs. fixed speed Treadmill gait Kinematics - Self paced vs. fixed speed TM walking - Subjects walk at preferred speed (feedback control) - Assessed on young adults - Differences were small (well within normal variability) - Self paced mode a “suitable alternative” to fixed speed Kinetics - Differences small (~0. 2 Nm) Sloot et al, 2014

Self paced vs. fixed speed Treadmill gait Kinematics - Self paced vs. fixed speed TM (VR) walking - CP kids - No effect of VR - Increased walking speed during SP (7. 3%) - Possibly related to the habituation to TM - Small differences for SP walking for CP - Suggested that CP kids need more time to adjust to SP - Overall differences “too small” to be clinically meaningful Kinetics - Not examined Sloot et al, 2015

Summary: Kinematics - Small kinematic differences (<2 o) - e. g. knee flexion @ IC - TM has a decrease in preferred walking speed - Shorter wider strides - Not clinically different? - Running was different - Familiarisation time important (but how much? ) - don’t measure within first 2 mins - 4 mins reasonably reliable - 6 to 10 mins seems preferred time - some say more… - few studies looked at mod to severe subjects

Summary (contd. ): Kinematics - Local databases - Should interpret to local rather than published - Use a good TM specific reference set - current CMAS recommendation - Fatigue plays an important role - suitable period of familiarisation - BUT…. . need to balance fatigue - Split belt vs. single belt - 3 to 4 cm wider stride width on split - VR – differences but not clinically meaningful

Summary (contd. ): Kinetics - Large differences (esp. in running) - Large differences ( in CP) - Shift from ankle to hip work (CP) - Rely more heavily on hip strategy - More anterior GRF during TM running - Very few studies assessing kinetics (esp. CP)

Summary (contd. ): EMG - Differences but not clinically meaningful…. . .

Equipment testing – additional to TMs? • Warming and drift • Time to warm up ( manufactures guidelines) • Are TM more prone to drift? • Belt speed test • Regular assessment of belt condition • Assessment of kinetic cross talk between split belts • Impact testing? • Spot checks vs. in-depth tests – how often? ? • CMAS say 6 monthly in-depth testing – enough?

Stanmore Lab Experience of one lab using TM system and incorporating CMAS standards Matt Thornton

Adjustments to CMAS standards discussion? • Notable differences in kinetic data • Stressing need for specific local databases • Guidance / requirements on familiarisation time (more for CP? ? ) • Avoiding comparison to published OG databases • Guidance / requirements on QA testing of TM systems • Assistance on. TM – e. g. 2 hands held? ? • More? ?

Equipment testing – what does CMAS require? Mandatory • Daily system checks to verify orientation & synch of 3 D system with other systems ( e. g. force plates) – a poletest • A test of static load on plates to verify vertical force measurement • A check of the orientation of the GRF vector ( in all 3 planes) Recommended • Calibration to verify absolute magnitude in all 3 directions • Verification of the Co. P • Assessment of the magnitude of drift