Microprocessor Knee Versus Non-Microprocessor Knee for Backup Device in Lower Limb Prostheses: A Qualitative Study

Abstract: Current policy in the Canadian Armed Forces (CAF) and Veterans Affairs Canada (VAC) is to provide individuals who require a prosthesis for a knee disarticulation (KD) or transfemoral (TF)-level amputation a microprocessor knee (MPK) unit for daily use and a non-microprocessor knee unit (N-MPK) as a backup prosthesis. Given the known functional differences between these two types of prosthetic knee units, the purpose of this study was to gain an understanding of user device preference and the impact of switching between the MPK and N-MPK. Four currently serving CAF members and two Veterans with unilateral TF or KD amputation participated in semi-structured interviews. Qualitative content analysis identified key themes reflecting their experiences using prostheses. Seven major categories emerged that helped shape prosthesis preferences: functionality, physical aspects, mental aspects, activity, maintenance, safety, and health-related quality of life. The MPK was superior in all categories, resulting in considerably fewer falls and improved cognitive and physical performance. The four participants who had an N-MPK backup did not use this device and instead received a loaner MPK from their prosthetist when required. For individuals who do not have ready access to their prosthetist to obtain a loaner knee unit, consideration should be given for a backup prosthesis with the same MPK unit as their daily-use prosthesis, as participants identify significant issues when trying to function with an N-MPK unit. Individuals with ready access to a loaner knee unit through their prosthetist may not require a backup prosthesis.