Body weight supported treadmill training improves the regularity of the stepping kinematics in children with cerebral palsy.

Developmental Neurorehabilitation 14(2):87-93.
Kurz MJ, Stuberg W, Dejong SL (2011).

Summary by Nechama Karman, PT, MS, PCS

Summary:
Twelve children ages 8.7 + 4 years) with CP GMFCS level II-IV participated in 2 sessions/week of BWSTT for 12 weeks (24 sessions). Four of the children has spastic diplegia, 8 has spastic quadriplegia. Four were GMFCS level II (did not use assistive device to walk), and 8 used wheeled walker for community ambulation (GMFCS level III). All but 2 used articulating AFOs. BWSTT sessions were held twice a week for 12 weeks, using a Biodex BWS system suspended over a TM, beginning with 40% BWS in week 1, decreasing by 5% on alternate weeks, ending at 15% BWS. Intensity of training was based on HR during training, increasing walking speed each minute of training until 75% of age-adjusted heart rate was achieved; ending speed from each session became the starting speed at the subsequent session. Sessions included 20 minutes of treadmill walking time. Physical assistance was limited to a single person, and only for producing continuous alternating steps, via WS/upright posture at pelvis or at foot for transition to swing, clearance, foot placement.

Outcome measures:
were completed before and after a 12 week BWSTT program. 3-dimensional computerized gait analysis was performed walking over-ground using assistive mobility devices (walkers and AFOs). Reflective marker placement was on the dorsum of the base of the second toe, lateral malleolus and sacrum (midway between PSIS). They included:

  • Regularity of stepping kinematics assessed with Fourier analysis methods. (lower harmonics indicates greater regularity; a sharp power spectrum composed of lower harmonics indicates a controlled, rhythmical stepping pattern).
  • Preferred walking speed measured with instrumented (computerized) 3D gait analysis
  • Step length measured with instrumented (computerized) 3D gait analysis
  • Lower extremity anti-gravity muscle strength measured statically with handheld dynamometer, composite score: sum of strength measured in each leg/body weight.
    • Hip extension: measured supine in 90į flexion
    • Knee extension: measured in sitting, hip and knee each flexed 90į
    • Ankle plantar flexion: measured in supine with hip and knee extended, ankle in neutral.
  • GMFM section E score (walking, running and jumping) includes walking forward, backward, kicking ball, navigating stairs; reported as percentage of possible (72) points

Outcomes:
Student t-tests were used to determine differences (significance p <.05) between pre and post-treatment measures. Percent change between pre and post measures were calculated. Relationship between changes in step length, walking velocity, LE strength and largest harmonic of stepping kinematics was determined using Pearson product moment correlation coefficients. Stepping kinematic harmonics decreased with training, indicating more regular (consistent) stepping kinematics. Power spectrum yielded a dominant peak post-treatment, indicating more control of the stepping kinematics. The effect size of the difference in regularity was large (Cohenís d=.84) , indicating clinical significance. The improved regularity of stepping kinematics was associated with significantly (44%) faster walking speed (Pre: .51 + .09 m/s Post: .60 + .09 m/s Cohenís d= .86) and longer step length (Pre: .29 + .03m Post: .34 + .02m, Cohenís d= .96). GMFM scores significantly improved post-treatment (Pre: 17.7 + 4% Post: 19.5 + 4% Cohenís d= 1.01). There was no significant improvement in overall strength of LE anti-gravity musculature. There were significant correlation between improvements in regularity of stepping (change in highest harmonic) and changes in walking velocity (negative correlation, indicating that more regular stepping kinematics were correlated with faster walking speed and longer step length). Similar (negative) correlation was found between change in highest harmonic and GMFM section E score, indicating that children with more regular stepping kinematics had greater improvement in their ability to perform more skillful movements. The regularity of stepping kinematics explained 75% of variance in walking velocity, 58% of variance in step length and 71% of variance in GMFM section E scores. Strength in the LE anti-gravity musculature was not significantly correlated with any other outcome measures.

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