Introduction: Microprocessor knees have been shown to improve gait biomechanics and to reduce the frequency of falls, but evidence of their influence on psychosocial health is limited.
Study Design: Retrospective analysis.
Objective: The aim of this study was to evaluate the change in psychosocial outcome measures when prosthetic users change from a non-microprocessor-controlled prosthetic knee (NMPK) to a microprocessor-controlled prosthetic knee (MPK). Methods: Using validated outcome measures, physical and psychological attributes of 26 MPK users were analyzed using data collected at routine appointments. Baseline data were collected using NMPK limbs first, then compared with data collected 4 weeks and 6 months after initial MPK fitting.
Results: A significant improvement of 13.7% in Reintegration to Normal Living Index (RNLI) scores was observed after 6 months ( P = 0.001). The Patient Health Questionnaire-9 (PHQ-9) demonstrated a 64.6% significant reduction in the presence of depression-like symptoms after 6 months of MPK use ( P < 0.001), including four participants who previously scored highly enough to be diagnosed with major depressive disorder. Frequency of falls reduced significantly as well ( P < 0.001). Increases in self-selected walking speed were seen in both the 2-minute walk and 6-minute walk tests.
Conclusions: Significant improvements were seen in all psychosocial outcome measures, indicating participants' psychosocial health improved with the prescription of an MPK despite a lack of clinically important improvements in parallel performance-based outcome measures.
Clinical Relevance: MPKs are well documented to reduce trips and falls, which is corroborated by this research. However, the psychosocial benefits of MPKs are not documented extensively; this study provides evidence of an improvement in psychological wellbeing in this cohort. (J Prosthet Orthot. 2023;35:67-74)
Psychological health is a major concern within the population of individuals with amputation, with the prevalence of depression and depressive symptoms reportedly as high as 28%. In the general population, mental health is a major cause of disability in England, with estimates of one in six adults experiencing a mental health problem at any one time. Therefore, mental health issues are much more common in individuals with amputation than in the general population, and there is a paucity of research in this area. To date, MPK research has focused on gait biomechanics and safety, but with mental health costing £6.5 billion to the UK government in November 2010 (most recent figures),3 there is a need to understand the benefits that advanced technology may have for patients psychologically.
Convincing evidence of improved kinetic and kinematic parameters when using a microprocessor-controlled prosthetic knee (MPK) compared with a non-microprocessor-controlled prosthetic knee (NMPK) already exists. Reductions in the number of falls experienced and increased symmetry of gait have been the most prominent findings in these articles. Increased user satisfaction has also been reported in MPK users, which follows logically from reducing the frequency of adverse incidents. Novel research by Möller et al. demonstrates that NMPK users typically exhibit greater cortical brain activity than MPK users, suggesting that MPK users require less cognitive effort to walk. Outcome measures specifically designed to study psychological health in the population of persons with amputation do exist in published literature, such as the Prosthesis Evaluation Questionnaire (PEQ), and have been used to suggest preference for an MPK over NMPK limbs.
To prescribe an MPK limb to a patient in England, a trial must be carried out in accordance with guidelines set out in the Clinical Commissioning Policy from NHS England. This policy has been in effect since December 2016. The policy requires improvements in patient function and participation in daily life to be demonstrated using an array of outcome measures before the new prosthesis can be prescribed. The authors were granted access to the existing database of these outcome measures for MPK users at one limb fitting centre. Alongside the outcomes mandated by the policy, The Patient Health Questionnaire-9 (PHQ-9) was also included in this research as it was routinely recorded at the limb fitting center and deemed relevant to the aims of this study.
Two hypotheses were formed to guide analysis: 1) improvements would be seen across all outcome measures when comparing the NMPK measures to the MPK measures, and 2) psychosocial health improvements would come with improved physical ability.