Recognising features (weakness)

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Recognising features (weakness)

  1. 1. Recognising features due to neuromuscular impairments – weakness Richard Baker Professor of Clinical Gait Analysis 1
  2. 2. What is muscle “weakness”? 2
  3. 3. Strength the ability to generate a normal voluntary force in a muscle or normal voluntary torque (moment) about a joint. This is different to engineering definitions of strength which focus on how difficult it is to break something 3 NIH Task force on Childhood Motor Disorders Sanger, T. D., Chen, D., Delgado, M. R., Gaebler-Spira, D., Hallett, M., & Mink, J. W. (2006). Definition and classification of negative motor signs in childhood. Pediatrics, 118(5), 2159-2167
  4. 4. Weakness 4 muscle fibre length Pennation angle (q) muscle volume Physiological cross sectional area = muscle volume Fibre length x cos(q) Strength is determined primarily by physiological cross sectional area
  5. 5. Muscle belly length 5 Shortland AP, Fry NR, McNee AE, Gough M. (2009) Muscle structure and function. In Gage JR, Schwartz MH, Koop SE, Novacheck TF. The identification and treatment of gait problems in cerebral palsy. London: Mac Keith Press half fibre width/ half muscle belly length
  6. 6. Muscle belly volume 6 Shortland AP, Fry NR, McNee AE, Gough M. (2009) Muscle structure and function. In Gage JR, Schwartz MH, Koop SE, Novacheck TF. The identification and treatment of gait problems in cerebral palsy. London: Mac Keith Press half fibre width/ half muscle belly length
  7. 7. Muscle belly volume 7 Barber, L., Hastings-Ison, T., Baker, R., Barrett, R., & Lichtwark, G. (2011). Medial gastrocnemius muscle volume and fascicle length in children aged 2 to 5 years with cerebral palsy. Dev Med Child Neurol, 53(6), 543-548. half fibre width/ half muscle belly length 2-5 years olds. Mean Dorsiflexion with knee extended = 8°
  8. 8. Activation 8 Stackhouse, S. K., Binder-Macleod, S. A., & Lee, S. C. (2005). Voluntary muscle activation, contractile properties, and fatigability in children with and without cerebral palsy. Muscle Nerve, 31(5), 594-601. Weakness is both neurological and muscular
  9. 9. Muscle weakness 9 Wiley, M. E., & Damiano, D. L. (1998). Lower-extremity strength profiles in spastic cerebral palsy. Developmental Medicine and Child Neurology, 40(2), 100-107.
  10. 10. Measuring muscle strength 10
  11. 11. Manual muscle testing • MRC • Oxford • Kendall 11 Medical Research Council (1943) Aids to the examination of the peripheral nervous system Kendall, HO, & Kendall, FP. (1949). Muscles Testing and Function. Baltimore: Williams and Wilkins.
  12. 12. Manual muscle testing 12 O'Brien, M. D. (2010). Aids to the examination of the peripheral nervous system: W.B. Saunders.
  13. 13. Manual Muscle Testing • Essentially subjective • “Through range • Gravity on distal segment 13
  14. 14. Other techniques • Hand held dynamometry • Biodex/Kincom 14 Taylor, N. F., Dodd, K. J., & Graham, H. K. (2004). Test-retest reliability of hand-held dynamometric strength testing in young people with cerebral palsy. Arch Phys Med Rehabil, 85(1), 77-80.
  15. 15. Recognising weakness from the graphs 15
  16. 16. Kinetics 16 Fosang, A., & Baker, R. (2006). A method for comparing manual muscle strength measurements with joint moments during walking. Gait Posture, 24(4), 406-411.
  17. 17. Kinetics 17 Dallmeijer, A. J., Baker, R., Dodd, K. J., & Taylor, N. F. (2011). Association between isometric muscle strength and gait joint kinetics in adolescents and young adults with cerebral palsy. Gait Posture, 33(3), 326-332.

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