In Vivo Architectural Properties of the Gastrocnemius Muscle in Cerebral Palsy Amir A Mohagheghi, PhD Institute for Biophysical & Clinical Research into Human Movement, MMU Cheshire, Alsager

Conventional Treatment Methods  Medical:  Toxin injection  Serial casting  Surgery  Rehabilitation:  Positioning  Stretching  FES

Why examine MTU adaptation to the physiological stimuli?  Muscles are adaptive tissues:  Response to the volume of exercise  Response to stretch/tenotomy  Muscle-Tendon Unit is the mean by which treatment is applied  Muscle-Tendon Unit is affected by the applied Treatment

What to examine and at what level?  Structure and Mechanical Behaviour in vitro  Muscle Fibre (length, size, type, stiffness)  Architectural Parameters in vivo  Muscle (muscle, tendon, and MTU length)  Muscle Fascicles (fascicle length, pennation angle)

Muscle Architectural Parameters

CP Muscle Fibre Structural & Behavioural Properties  Short  Small (greater variability in size)  Stiff  Predominantly Type I

In Vivo CP Muscle Architectural Properties  Normal Fascicle Length (scaled to the leg length)  Shorter MTU Length (SIMM modelling)  Smaller Pennation Angle

MMU Cheshire CP Project - CEREBRA  Aim: determination of the medial gastrocnemius muscle (GM) architectural properties in vivo determination of the medial gastrocnemius muscle (GM) architectural properties in vivo  Hypotheses: MTU length will be shorter in the CP MTU length will be shorter in the CP Normal fascicle length Normal fascicle length Smaller pennation angle Smaller pennation angle

MMU Cheshire CP Project - CEREBRA  Apparatus: A linear array ALOKA ultrasound system (10.5 MHz; B-mode real-time) A linear array ALOKA ultrasound system (10.5 MHz; B-mode real-time)  Participants (6 M:1 F): CP group: 7 ambulatory Hemiplegic participants (10.7 ± 5.1 years) CP group: 7 ambulatory Hemiplegic participants (10.7 ± 5.1 years) Healthy group: 7 participant (11.0 ± 3.7 years) Healthy group: 7 participant (11.0 ± 3.7 years)

MMU Cheshire CP Project - CEREBRA  Procedure: Prone position Prone position No correction of the posture No correction of the posture Hand goniometry of the ankle joint Hand goniometry of the ankle joint Leg length Leg length Determination of the knee joint line, MTJ, Achilles tendon insertion point: Determination of the knee joint line, MTJ, Achilles tendon insertion point: Muscle length Muscle length Tendon length Tendon length

MMU Cheshire CP Project - CEREBRA  Procedure: Sagittal scanning of the GM ImageJ software ImageJ software  Statistical Analysis: Paired t-test for within-groups comparisons Paired t-test for within-groups comparisons Un-paired t-test for between-groups comparisons Un-paired t-test for between-groups comparisons α =.05 α =.05

MMU Cheshire CP Project - CEREBRA  Results (between-groups comparisons): Similar resting ankle joint angle (32) Similar resting ankle joint angle (32) Muscles were 11% shorter in CP Muscles were 11% shorter in CP Tendons were 8% longer in CP Tendons were 8% longer in CP muscle and tendon length differences disappeared when muscle and tendon lengths were scaled to the leg length muscle and tendon length differences disappeared when muscle and tendon lengths were scaled to the leg length

MMU Cheshire CP Project - CEREBRA  Results (between-groups comparisons): Fascicles were 25% shorter in CP Fascicles were 25% shorter in CP Fascicle length difference disappeared when scaled to the leg length Fascicle length difference disappeared when scaled to the leg length Similar Pennation angles: Similar Pennation angles: SPA: 14.5 ± 1.9 vs 14.5 ± 4.4 (CP) DPA: 17.8 ± 1.6 vs 18.3 ± 4.6 (CP)

MMU Cheshire CP Project - CEREBRA  Discussion: Similarity of the architectural parameters at rest should not be generalised to the dynamic conditions: Tonic Stretch Reflex Mechanical behaviour of the spastic fibres Mechanisms (neural and/or muscular) that control muscle length at rest are not altered in CP.

THANK YOU