Sagittal plane kinematics of crouch gait in spastic diplegia

Investigators : Ms Jill Rodda, Prof H Kerr Graham, Dr Richard Baker, Prof Mary Galea

The objective of this study was to classify sagittal gait patterns in spastic diplegia according to biomechanical alignment. Cross-sectional and longitudinal studies were undertaken. Inclusion criteria were i) diagnosis of spastic diplegia, ii) age 4-18 years, ambulating with or without mobility aids, iii) 3D kinematics.   Exclusion criteria were i) previous surgery (except to calf ), ii) dystonia, ataxia, LLD (> 2.5cm), iii) scoliosis (Cobb angle > 20 o ).   The longitudinal study required two kinematic studies, more than 12 months apart with no intervening surgery.   Sagittal kinematics at the hip, knee and ankle were classified in mid-late stance as flexed, normal or extended, compared to the range in a normal reference group.

Six sagittal gait patterns were identified (refer to diagram below):

• Mild Gait: all kinematics within normal range.
• Group I, True Equinus: ankle equinus, knee and hip normal.
• Group II, Jump Gait: ankle equinus, knee and hip flexed.
• Group III, Apparent Equinus: ankle normal, knee and hip flexed.
• Group IV, Crouch Gait: ankle dorsiflexed, knee and hip flexed.
• Group V, Asymmetric Gait: any two patterns above, same subject.

These patterns could be reliably distinguished by clinicians.   From Group I to IV, there was progression of:

• involvement from distal to proximal musculature
• ground reaction force from anterior to posterior to the knee
• declining competence of the plantarflexion knee extension couple
• increasing age
• increasing severity

Group V, Asymmetric Gait was not considered as a progression in gait as it is a combination of two patterns from Groups I- IV.

This classification reflects progressive biomechanical changes between patterns and the natural history of gait for some children from true equinus to crouch gait.   Each pattern's biomechanical alignment intuitively implies strategies for spasticity management, contracture surgery and orthotic prescription.   The classification provides a basis on which to link the identification of gait patterns to their consequent management.

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