Evaluation of concordance between the 2 kilometers, 6-minute and 2-minute walk tests in patients with transfemoral amputees with a microprocessor-controlled prosthetic knee

Abstract

Lower limb amputee remains in France an important cause of disability. Microprocessor-controlled prosthetic knees (MPK) represent a real breakthrough in management of lower limb amputee patients. However, pertinent and well-validated clinical parameters to assess and prescribe these devices are still missing. The aim of this study was to compare several clinical walking tests: 2 kilometers walking test (2 kmWT), 10 meters walking test (10 mWT), 2 and 6 minute-walk tests (2MWT and 6MWT) with actual reimbursement criteria supported by the French social insurance. We performed a monocentric prospective study (number CPP: 2016-A00054-47) in a physical medicine and rehabilitation Department from May to June 2017. All patients followed-up in our center who had received a MPK were included. Patients with severe medical disorder significantly affecting functional abilities were excluded. Primary endpoint was concordance between the walking speed and ratings of perceived exertion (Borg scale) in 6 MWT, 2 MWT and 10 mWT compared with parameters observed during a 2 kilometers walk test in continuous (2 kmWT). Order of test was randomly attributed. Bland and Altman analysis and Pearson's coefficient were used to assess correlations between walking tests. Differences were assessed by fisher t-test. A P -value < 0.05 was considered as significant. Twenty-seven patients were included. All patients were able to perform actual reimbursement criteria, except 3 patients for moving downstairs. We notice a very strong concordance between walking speed in 6 MWT and 2 kmWT with a mean difference–0.062 km/h, [−0.60; 0.48]. Correlation between walking speed of 6 MWT and 2 kmWT was good with a Pearson's coefficient = 0.84 ( P < 0.001). We did not notice any significant differences in ratings of perceived exertion between 2 kmWT and 2 MWT ( P = 0.12), associated to a very strong concordance in Bland-Altman analysis with a mean difference–0.76, [−4.8; 3.27]. The average speed in 6 MWT was 3.93 ± 0.46 km/h. Ninety-six percent of subjects in 2 MWT and 100% in 10 mWT had a average walking speed ≥ 4 km/h. A 6 MWT could replace the 2 kmWT in terms of walking speed and 2 MWT could replace 2 kmWT in terms of exercise intensity. Evaluation of the walking speed ≥ 4 km/h could be made during a 10 mWT.