Lower limb prosthesis users might suffer from various musculoskeletal problems due to a lack of part of their lower limb, and body adjustments to this loss. A higher rate of LBP, loading on the intact side, intact-side pain and falling are some critical problems in lower limb amputees’ daily life. In addition, it has been established that the problems of lower limb amputees increase in the more proximal location of the amputation due to the loss of a greater part of the musculoskeletal system. There are fewer studies available related to the biomechanics of TF amputees’ locomotion and balance in comparison to TT amputees, which encourages us to consider it as an opportunity to enhance biomechanical knowledge regarding balance and walking. The referred studies have shown that biomechanical evaluation of the daily activities of impaired people - including the balance of fallers and lower limb amputees (as a group which is at risk of falling in addition to lacking part of their locomotion structure) - through using motion analysis systems can give better insight into the biomechanical differences between them and non-impaired people, and can be beneficial in seeking the solutions required to enhance their balance and safety in their regular daily activities.
To date, the work related to improving the biomechanics of amputees’ locomotion has mostly been focused on the amputated side, and on prosthetic design. It is necessary to remember that the capacity of the prosthetic device has limitations, and in the end, it is the intact-side that adjusts to different conditions to restore balance; thus, its health and support are a matter of great concern. It seems less attention has been paid to solving or preventing intact-side problems. This gap provides an opportunity for investigation into the possibility of enhancing the functionality of amputees (in terms of improving their balance and the spatio-temporal characteristics of walking to bring them closer to non- amputees’ balance and walking characteristics) and preventing unwanted events (such as falling) in their daily activities by applying external changes in the intact side; e.g., using orthotic devices to correct biomechanical variables. The position of the COP in the BOS, and its relationship with the COG, influence human balance during standing and walking. As has been mentioned, the COP is the action point of the ground reaction forces on the plantar surface of the foot (Winter, 1995). Thus, the manipulation of the COP position and GRF distribution by using insoles might affect balance. In spite of equivocal studies about the effectiveness of insoles on the musculoskeletal system and the mechanism of their effects, more studies about different groups of people with musculoskeletal problems can help to enlighten us regarding their use. It should be noted, no study has been found related to the use of insoles among lower limb prosthesis users. Although, some studies confirm the effectiveness of insoles on decreasing lower limb musculoskeletal injuries and pain, or in the improvement of the static and dynamic balance of non-amputees.
By considering the mentioned facts about lower limb amputees’ problems, and according to the different aspects of insoles effectiveness in non-amputees, this thesis assumes that insoles are useful for improving lower limb amputees’ intact-side conditions.
2.7.1 Aims and objectives
The three main purposes of conducting this research were: 1) to provide an up-to-date data collection related to LLAs’ problems, which might be improved via biomechanical interventions; 2) to investigate the effectiveness of insoles use on the biomechanics of perturbed standing balance and level walking of above-knee prosthetic users,; 3) to characterise the biomechanics of above-knee prosthetic users’ perturbed standing balance, and to compare these with the same activities being performed by non- amputees. To achieve these aims, the following objectives were considered:
• To investigate LLAs’ issues in the areas of functionality (mobility and balance during daily living, in addition to fear of falling and falling experience) via a comprehensive online survey and literature review
• To assess the function level of the TF amputees who participated in the biomechanical tests in this study, according to the spatio-temporal variables of level walking and their ABC scale and PEQ-M scores
• To characterise and compare selected biomechanical features of TF amputees and non-amputees walking. These selected variables are: the spatio-temporal variables of walking (including walking speed, step/stride length, stride time, duration of stance and the swing phases of each limb), COM displacements (vertical, mediolateral), the mediolateral displacement of the COP, the distance between the COP- lateral border of the BOS at mid-stance, the distance between the COG and the lateral border of the BOS at mid-stance, the angular motion of the ankle joint in the sagittal plane, the initial stance loading rate, the lower limb’s joint powers and the moments in the sagittal plane
• To investigate the effects of insoles use on the previously mentioned selected biomechanical features of TF amputees’ and non-amputees’ walking
• To characterise and compare the selected biomechanical features of TF amputees’ and non-amputees’ perturbed standing balance. These selected biomechanical features are: the amplitude of each limb’s COP displacements (in anteroposterior and mediolateral directions), the amplitude of the distance between each limb’s COP and COG, the amplitude of each limb’s GRF (anteroposterior, mediolateral, vertical forces), the load sharing of each limb during one second before load release (anteroposterior, mediolateral vertical forces), the load sharing of each limb at five seconds after load release (anteroposterior, mediolateral vertical forces), the amplitude of the joint (ankle and hip) moments in the sagittal plane due to load release, the contribution of the ankle and hip of each limb in the SUM moment during one second before
load release, and the contribution of the ankle and hip of each limb in the SUM moment at five seconds after load release
• To investigate the effects of insoles use on the previously mentioned selected biomechanical features of the amputees’ and non-amputees’ perturbed standing balance