ABSTRACT
Objectives: Accurate estimation of post-operative clinical parameters in scoliosis correction surgery is crucial. Different studies have been carried out to investigate scoliosis surgery results, which were costly, time-consuming, and with limited application. This study aims to estimate post-operative main thoracic cobb and thoracic kyphosis angles in adolescent idiopathic scoliosis patients using an adaptive neuro-fuzzy interface system. Methods: Distinct pre-operative clinical indices of fifty-five patients (e.g., thoracic cobb, kyphosis, lordosis, and pelvic incidence) were taken as the inputs of the adaptive neuro-fuzzy interface system in four categorized groups, and post-operative thoracic cobb and kyphosis angles were taken as the outputs. To evaluate the robustness of this adaptive system, the predicted values of post-operative angles were compared with the measured indices after the surgery by calculating the root mean square errors and clinical corrective deviation indices, including the relative deviation of post-operative angle prediction from the actual angle after the surgery. Results: The group with inputs for main thoracic cobb, pelvic incidence, thoracic kyphosis, and T1 spinopelvic inclination angles had the lowest root mean square error among the four groups. The error values were 3.0° and 6.3° for the post-operative cobb and thoracic kyphosis angles, respectively. Moreover, the values of clinical corrective deviation indices were calculated for four sample cases, including 0.0086 and 0.0641 for the cobb angles of two cases and 0.0534 and 0.2879 for thoracic kyphosis of the other two cases. Conclusion: In all scoliotic cases, the post-operative cobb angles were lesser than the pre-operative ones; however, the post-operative thoracic kyphosis might be lesser or higher than the pre-operative ones. Therefore, the cobb angle correction is in a more regular pattern and is more straightforward to predict cobb angles. Consequently, their root-mean-squared errors become lesser values than thoracic kyphosis.
ABSTRACT
The most common disorders of the musculoskeletal system are low back disorders. They cause significant direct and indirect costs to different societies especially in lifting occupations. To reduce the risk of low back disorders, mechanical lifting aids have been used to decrease low back muscle forces. But there are very few direct ways to calculate muscle forces and examine the effect of personal lift-assist devices, so biomechanical models ought to be used to examine the quality of these devices for assisting back muscles in lifting tasks. The purpose of this study is to examine the effect of a designed wearable lift-assist vest (WLAV) in the reduction of erector spinae muscle forces during symmetric squat lifting tasks. Two techniques of muscle calculation were used, the electromyography-based method and the optimization-based model. The first uses electromyography data of erector spinae muscles and its linear relationship with muscle force to estimate their forces, and the second uses a developed musculoskeletal model to calculate back muscle forces using an optimization-based method. The results show that these techniques reduce the average value of erector spinae muscle forces by 45.38 (± 4.80) % and 42.03 (± 8.24) % respectively. Also, both methods indicated approximately the same behaviour in changing muscle forces during 10 to 60 degrees of trunk flexion using WLAV. The use of WLAV can help to reduce the activity of low back muscles in lifting tasks by transferring the external load effect to the assistive spring system utilized in it, so this device may help people lift for longer.
