Exploring low back pain and spinal movement asymmetries in people with non-dysvascular lower limb amputation

Abstract

Background and aim Low back pain (LBP) is a major secondary impairment following lower limb amputation including those with transfemoral (TFA) and transtibial amputation (TTA). The two main aims of this thesis were to explore, (1) the LBP prevalence, nature, and perceptions of LBP and (2) asymmetrical movements of the spinal and pelvic segments during common functional tasks in people with TFA and TTA due to non-dysvascular aetiology (i.e. trauma and tumours).

Methods This thesis comprised four studies that addressed the overall aims of thesis. A systematic review (Study 1) of literature was undertaken to investigate the spinal and pelvic movement asymmetries during functional tasks in people with lower limb amputation. A focus group study (Study 2) explored the LBP perceptions and common functional activities related to LBP in people with lower limb amputation and ongoing LBP. Reflections on common daily activities increasing LBP symptoms informed the development of functional activity questions for the national survey study (Study 3). The survey study then investigated the LBP prevalence and identified functional activities and postures which often aggravate LBP symptoms in people with lower limb amputation in New Zealand. Results from survey and focus group studies informed the functional tasks (i.e. walking, lifting, and sit-to-stand) for further biomechanical analysis in the motion analysis study (Study 4). A cross-sectional biomechanical laboratory study was conducted to explore the differences in three-dimensional spinal and pelvic kinematics during three common functional tasks (i.e. walking, lifting, and sit-to-stand) in people with TFA and TTA, with and without LBP.

Results The systematic review found no previous study specifically investigating spinal and pelvic movement asymmetries during functional tasks other than walking (e.g. stair climbing, ramp walking, and obstacle crossing) in people with TFA and TTA. The results from the focus group study suggest participants with ongoing LBP believe ‘uneven movements of the back’ during functional tasks to be a main contributing factor to their symptoms. Uneven movements during functional tasks were perceived to be affected by ‘fatigue’ and ‘prosthesis-related factors’, such as limb-length discrepancy, prosthetic fit, and type of prosthesis. Participants felt ‘being physically active’ and improved physical fitness levels following amputation may be beneficial to minimise uneven movements and LBP. From the results of the national survey, LBP is highly prevalent, affecting up to 67% of people with TFA and TTA and appears to be both chronic and intermittent in nature. Non-mechanical factors such as phantom limb pain, residual limb problems, and the presence of comorbid health conditions (e.g. heart disease, diabetes, and depression) increase the risk of developing LBP up to 30 times in people with TFA and TTA. Standing (88.5%), adopting a bent posture (80%), walking (77.5%), and sitting (72%) were reported as common pain provoking activities and postures in people with TFA and TTA. The biomechanical laboratory study identified preliminary evidence for the presence of differences in spinal and pelvic movements of people with TFA-LBP and TFA-No LBP during walking. There were no differences in the spinal and pelvic kinematics of people with TTA-LBP and TTA-No LBP during walking, lifting, and sit-to-stand tasks.

Conclusion Low back pain is a highly prevalent yet overlooked chronic pain condition in people with lower limb amputation due to non-dysvascular aetiology. The nature of LBP appears to be chronic and intermittent with ‘uneven movements of the back’ perceived as a main contributor to LBP. The results from the biomechanical laboratory study highlight the potentially important kinematic differences between the LBP and no LBP groups in persons with TFA during walking. They provide a background for future hypothesis-based studies investigating the potential causal links between the identified spinal and pelvic asymmetries and LBP as well as to devise prevention and treatment strategies for LBP in this population. Clinicians involved in treating LBP in people with lower limb amputation may have to be cognisant about the multifactorial nature of LBP and the potential for other pain conditions (i.e. phantom limb and residual limb pain) influencing the chronicity of LBP symptoms. Furthermore, individuals with a lower limb amputation need to be educated about the underlying biomechanical issues associated with common functional tasks in order to minimise the risk of developing musculoskeletal impairments such as LBP.