Quantitative parameters of the kinetics and kinematics of the iatrogenic Crouch gait pattern

The pattern of pathological crouch gait in patients with spastic paralysis is characteristic of diplegic forms and in natural development manifests itself usually after the age of 10-12 years. This pathological gait may develop earlier after early surgical interventions that weaken the triceps of the lower leg, especially the soleus muscle. The heterogeneity of the crouch gait pattern is diverse. Qualitative assessment of the difference in the decompensated crouch pattern, especially associated with stiff-knee gait, according to the graphs of kinematics and kinetics of the joints can be difficult, and quantitative criteria for differentiation have not been reflected in the literature. The purpose of the study was to conduct a comparative analysis of the quantitative parameters of the compensated, decompensated and associated stiff-knee gait crouch pattern. Materials and methods The assessment of the locomotor profile by 3D gait analysis (3DGA) was carried out in stationary conditions in 27 children (54 limbs) with spastic diplegia, who had previously undergone percutaneous fibromyotomy according to the Ulzibat method, or open lengthening of the Achilles tendon. The mean age at the time of the survey was 13.0 (8-17) years. Control group: 19 children without orthopedic pathology (38 limbs) of the same age. Three groups of changes within the crouch gait pattern, recorded on separate limbs, were distinguished: I - model of the crouch pattern of the “compensated” type (n = 30); II - model of the crouch pattern of the "decompensated" type (n = 14); III - models of crouch pattern of the "stiff-knee" type (n = 10). Results An analysis of the evaluation of the models of compensated, decompensated, and stiff-knee patterns of crouch gait revealed criteria for their differentiation in terms of quantitative indicators of kinematics and kinetics. GPS: compensated and decompensated crouch gait up to 25.0, stiff-knee gait - more than 25.0. The angle of maximum dorsiflexion of the foot in the stance phase: compensated and decompensated crouch pattern up to 35.0°, stiff-knee crouch pattern - more than 35.0°. Knee joint extension range: compensated crouch over 11.0°, stiff-knee gait up to 6.0°. Flexion knee joint range: compensated crouch more than 11.0°, stiff-knee gait - up to 6.0°. The strength of the leg extensor muscles during the formation of the support push: compensated and decompensated crouch less than 1.0 H*m/kg, stiff-knee - more than 1.0 N*m/kg. The strength of the leg flexor muscles in the midstance period: compensated crouch less than 0.25 H*m/kg, stiff-knee - more than 0.75 N*m/kg. Absorption power (negative) of the knee joint: compensated and decompensated crouch more than 0.9 W/kg, stiff-knee less than -0.9 W/kg. Useful peak power of the joints: compensated and decompensated crouch patterns - more than 0.40 W/kg, stiff-knee gait - less than 0.40 W/kg. Conclusions The development of the crouch gait pattern in the absence of a tertiary compensatory deviation (torso tilt) can be formed with or without a decrease in the power of the joints. The decompensated and compensated types of the crouch pattern have a significant difference in the kinematics of the knee joint and in the duration of the internal moment of extension, while the power parameters of the joints do not have significant differences. Stiff-knee associated crouch pattern is the most severe type in which all the power parameters of the joints are decreased. The manifestation of the severity of this pathological pattern may vary between the right and left limbs of the individual.