Mobility and Perceived Functioning of Unilateral Transfemoral Amputees, Comparison of Hydraulic and Magneto-rheologic Microprocessor Controlled Knees.

Recruiting and participants:

A convenience sample of 15 transfemoral amputee users was recruited at 4 study sites. Potential subjects were identified from the customer base of study sites, local investigators evaluated , based on previous experience of interaction with and servicing of patients, if a potential participant is cognitively capable. If a potential participant fitted the inclusion and exclusion criteria the local investigator (CPO-Certified prosthetist/orthotist) contacted them via telephone. During the telephone call the investigator verified if they were interested in participating in the study. If interest was expressed and eligibility criteria was met an appointment was made for enrollment in the study. Informed consent was obtained from all participants at the beginning of the first visit, prior to clinical testing and prosthetic fitting.

Setting:

Testing was conducted in four US locations with daily mean temperature during the testing period between 79.3 to 85.3 degrees Fahrenheit, Fort Worth (Baker orthotics & prosthetics), Jackson (Methodist Rehabilitation Center), Roanoke (Virginia Prosthetics & orthotics) and Orlando (Ossur facility, Florida gait lab) . Participants had to visit the study location twice, for approximately 3 hours per visit. First time for the baseline measure and initial fitting and secondly after 3 weeks of accommodation on the Rheo knee XC, performing the same measures as for the baseline. No standard exists for follow up time needed for amputees to adapt to a new prosthesis however, a follow up time of at least 3 weeks is widely used and considered sufficient for functional comparison.

All users used their existing sockets throughout the testing without modifications. One group consisted of 9 previous MPK-magnetorheologic (MPK-MR), Rheo knee II and III, users and the second group of 4 previous MPK-hydraulic knee (MPK-HY), Genium, users. By maintaining alignment and foot choice in the previous Rheo knee group confounding factors could be minimized. The previous MPK-HY was provided with an alignment offset adapter and a consistent foot choice, XC Vari-Flex, at initial fitting. The load line was controlled to be equal prior and post initial fitting. During the initial fitting the MPK-HY users which were new to the XC Vari-Flex had to undergo an evaluation for the foot stiffness as defined by the manufacturer (Ossur ehf). Foot configuration had to be rated acceptable or better with all users that were provided with a XC Vari-Flex.