A preliminary evaluation of Microprocessor knee (MPK) prescription for primary amputees during the pandemic

Name: Sophie Campbell

E-mail: sophie.campbell11@nhs.net

Occupation: Physiotherapist

Birmingham Community Healthcare NHS Foundation Trust, West Midlands Rehabilitation Centre, Birmingham, UK

Other authors (name only, alphabetical order): Dr Poornashree H Ramamurthy

Abstract

Introduction
The benefits of microprocessor knees (MPK) have been widely publicised. These include reduced number of stumbles and falls, reduced cognitive demands of ambulation, increased confidence whilst walking, improved balance, improved quality of life, improved gait and reduced energy expenditure when walking (1). Previously, in our service, MPKs were provided to patients who had been established on their prosthesis for more than 12 months. During lock-down we were unable to provide MPKs to our established patients so to use our time effectively; we selected several primary patients to go onto an MPK. We predicted that in addition to the benefits mentioned above, using an MPK as the patients’ primary prosthesis may reduce long standing gait deviations typically seen in established patients using non-MPKs and potential musculoskeletal conditions related to these, we assessed our potential patients on a femurett and if they could walk with a free knee out of the parallel bars, we thought they would achieve the criteria for an MPK.

Objectives
To evaluate the outcomes of these patients and decide on the most appropriate process for providing an MPK to primary patients.

Method
To date we have prescribed seventeen MPKs to our primary patients, six Kenevos and eleven C-leg 4. This is a retrospective study, reviewing our primary patients’ outcomes compared to some who went onto a non-MPK. We compared timed up and go (TUG), two-minute-walk (2MW), number of physiotherapy and prosthetic appointments, type of suspension used and the number of falls.

Results
Improved balance and minimal falls, out of the patients that have reached six months post-delivery (n=15) ten had no falls. Fifteen primary MPK patients walked on a free knee at 6 months post-delivery, two are walking in mode B+ on a Kenevo. On average, in the first six months post-delivery there were 9.9 physiotherapy appointments for an MPK compared to 8.3 for a non-MPK. There were 3.3 prosthetic appointments for an MPK compared to 2.8 for a non-MPK. Sixteen primary MPK patients completed the 2MW with the majority improving post trial (n=15). Eight patients had a reliable change (r=0.96). Fourteen patients completed the six-minute walk (6MW) with the majority improving post trial (n=12). Seven had a reliable change. Sixteen patients completed TUG with fifteen patients improving post trial. Nine patients had a reliable change (r=0.98). Out of the patients (n=15) who had a rigid pelvic band (RPB) (n=10) or TES (n=5) data shows that the average number of physiotherapy appointments from start trial to discharge was less for RPB.

Discussion
Primary patients have benefited from being prescribed an MPK with reduced falls which in the long term will help improve confidence and quality of life. They trust the knee and can use the yield function on slopes and stairs as they have not developed habits to stay safe on a non-MPK. The majority are walking on a free knee.

References
1. Stevens, PM, Wurdeman, SR. Prosthetic knee selection for individuals with unilateral transfemoral amputation: a clinical practice guideline. J Prosthet Orthot 2019; 31: 2–8.