Implementation of new algorithms for calculating muscle length changes of lower extremities and mechanical energy of whole body during walking in children with cerebral palsy

Aim: Walking is a fundamental movement pattern and the most common mode of physical activity. Cerebral palsy is a common clinical description of sensorimotor dysfunction that results in increased muscle activity and abnormal posture and movement and which has a prenatal, perinatal and postnatal etiology. Scientists fascinated by human movement have performed an extensive range of studies to describe these elements and the study of human movement, and in particular walking, can nowadays rely on two quantitative methods of clinical evaluation and modeling: gait analysis and musculoskeletal models. Gait analysis (GA), which is the quantitative 3D analysis of walking, allows the integrated recording of spatiotemporal, kinematic, kinetic and EMG data during gait. The aims of this study are: • Analysis of muscular length change and mechanical energy exchanges during gait, based on data integrated with spatiotemporal, kinematic, kinetic and EMG generally obtained from GA by implementation new algorithm. • Definition of normative data of muscular length change and mechanical energy exchanges during gait. • Comparison of different kind of treatments to find out the advantages, disadvantages and best kind of treatment based on quantitative assessment of mechanical indices of gait. • Proposing new suggestions for improving rehabilitation methods Materials and Methods: A dedicated software (BTS Bioengineering) has been developed by implementation of new algorithm to compute the insertion and origin points of the lower extremities muscles and also to compute kinetic and potential energies of whole body during movement and internal work of lower limbs related to the whole body by approximating mass center of whole body and mass center of each lower limb segment. The model has been validated not only by standard graphs and from scientific books and papers for muscle length changes and potential and kinetic energy during walking but also validated by comparison the results of another musculoskeletal model with same inputs. The implemented algorithm works faster, easier and more flexible comparing to the other softwares and also it is more user-friendly which not only engineer and professionals but also other people could use it simply. Data of 80 subjects haven been considered in this study (20 for normal subjects and 60 for children with cerebral palsy). Cerebral palsy group has been considered as three subgroups due to the treatment method. In each treatment, the data of before and after of that treatment have been investigated separately. The data of the subjects have been captured with high speed cameras while opto-electrical markers attached on subject's body in the motion analysis lab. All the muscle length and mechanical energy data have been normalized by height and weight of the subjects. Gait parameters: Three groups of parameters have been assessed in this study. a) Spatiotemporal parameter b) muscle length changes parameters c) mechanical energy parameters. Also as there were many parameters which make assessment of gait more time consuming and more complicated a new index defined in term of muscle length changes and also previous defined energy recovery index used in modified form. Results: The results of model include gait data tables of muscle length changes (68 parameters) and mechanical energy exchanges (20 parameters) plus graphs of muscle length changes, potential, kinetic and total mechanical energy. Later statistical analysis applied to the results to find significant differences (p<0.05) between normal and cerebral palsy subjects and also between patients in each treatment group including before and after treatment. Conclusion: In general view, this research has its originality on developing clinical software by implementation new algorithms to calculate muscle length changes and mechanical energy exchanges and also assessing walking of children with cerebral palsy quantitatively for the first time. It means beside the technical and other restrictions it is possible to develop software integrated with clinical data and also it will possible assessing any motion more quantitatively easier and faster. This project also gathers a big data base of processed data including normative bands, motion indices which will be useful for both subjects (healthy and patient) and also preparing reports including all mechanical parameters for researchers involved in clinical matters. One of the most important aims of bioengineering besides helping patients is helping medical doctors, surgeons, physiotherapists and other clinical staffs' who aren't professional in engineering. Scientifically this project has tried to overcome technical problem of calculating mechanical energy exchanges and muscle length changes by using a different kind of software that could be used by engineering and physiotherapists both and also it provide new clinical indices that could be easily understood by non-engineering and provide assessing motion ( in particular gait) more quantitatively which means it is possible to go more deep about percentages of improvement after treatment, the advantages of different rehabilitation methods and new suggestions about designing medical equipment. The results show that there are significant differences in terms of what we expected at the first place. The muscles, which had been affected more by cerebral palsy, had more effect on efficiency of gait in comparison with the others and also children generally had lesser energy recovery comparing to the adults meanwhile the patients have lesser energy recovery comparing to the normal children. Symmetry index directly and indirectly includes the effect of other muscle length changes parameters. It is easy to compute, to compare and consequently time saving .Based on all considerations the best therapy is which one put a long enough rehabilitation period after treatment and only surgery group confirmed this situation.