Proximal compensation for distal weakness: comparison of subjects with CMT and h

[Guest guest]

(Oral presentation at Antwerp Consortium July 2009)

Proximal compensation for distal weakness: comparison of subjects with Charcot

Marie Tooth Disease and healthy subjects with exercise induced weakness.

G. Ramdharry1, B.Da~,M. Reilly3 and J. Marsden4

ISchool of Physiotherapy, St 's University of London and Kingston

University, London, UK; 'Sobell department of Motor Neuroscience and Movement

Disorders, University College London, London, UK; 3MRC Centre for Neuromuscular

Diseases, Department of Molecular Pathogenesis, University College London,

London, UK; ·School of Health Professions, University of Plymouth, Plymouth, UK

To maintain walking ability people with CMT may employ proximal strategies to

compensate for distal weakness. This is a presentation of two separate studies

of proximal compensatory strategies, the first in people with CMT and the second

in healthy subjects who have been weakened with fatiguing exercise

Study I:

Methods· We recruited 14 people CMT and 12 healthy subjects matched for height,

weight, age and gender Hip and ankle strength and sensation measures were

recorded Gait was characterised using a 3D motion analysis system (CODAmotion)

combined with force plates

recordings (Kistler) Moments and power during walking were calculated using

inverse dynamics with additional markers to record trunk kinematics. Kinematic

and kinetic data were compared using an ANCOVA with gait speed as a covariant.

Results .. PwCMT were weaker distally than controls with greater sensory

impairment The ankle plantaflexor moment and power generation at push off was

lower in pwCMT (moment p=O..01; power p=O.OOI) An increase in hip flexor range

and was observed that was related to

peak dorsiflexion angle (p=O 009; r=-0..6, p=004) and increases in knee power

generation were observed in pwCMT (p=O.Ol). PF strength was associated with an

increase in the range of trunk rotation (p=004; r= 0.62, p=O.Q2).

Study 2:

Methods .. Ten healthy control subjects were recruited. They performed a

repeated heel raise exercise to fatigue the plantaflexor muscles and stength was

monitored with fixed myometry. Gait was characterised using the same methods as

study 1 and gait speed was

constrained to pre fatigue values Kinematic and kinetic data were compaired

using paired T-tests.

Results .. Plantarflexor strength reduced by 25% Gait analysis revealed an

increase in hip and knee kinetics in early stance (knee extensor moment: p=O.03;

knee power generation: p=0.03;

hip power generation p=OOOI) and increased hip power generation (p=003) at

pre-swing.

Conclusion of studies:

It is hypothesised that people with CMT appeaI to use trunk motion and changes

in knee kinetics at pre-swing to compensate for plantarflexor weakness whereas

healthy subjects appeaI to use hip and knee extension in earlyy stance.

Differences in these strategies may be due to variation in the time taken to

develop compensatory strategies.