A preliminary non-randomised study to evaluate the safety and performance of the ActiGait implanted drop-foot stimulator in established hemiplegia Haugland M, Larsen B, Burridge J, Svaneborg N, Iversen H, Brøgger Christensen P, Sinkjaer T
Background Size of the problem Problems with surface systems Need for control over inversion / eversion components
The ActiGait Drop-foot system
The components of the ActiGait drop-foot system Foot-switch Antenna fixing Cuff electrode Antenna Receiver External control unit
Detail of the cuff showing the four tri-polar electrodes
Objectives of the study To test the safety of the system To test the performance of the system To test the efficacy of the system CE marking in preparation for a European multicentre Randomised Controlled Trial
Study design Consecutive sample of subjects acting as their own controls Changes over time and with and without stimulation Outcome measures Statistical analysis
Selection criteria Main inclusion criteria Drop foot inability to achieve heel contact during gait that is correctible by surface FES Passive ankle range >30 degrees Minimum 6 months from stroke Stand with heels touching the floor and knees and hips straight Able to walk 20m in <2 minutes Main exclusion criteria Unable to walk 100m prior to stroke Walking speed>1.2m/s Pacemaker or other neuro-implants Severe medical condition
Outcome measures Safety Device related adverse events and serious adverse events Changes in nerve conduction velocity Performance Ankle movement in response to stimulation Efficacy Walking tests (distance walked in four minutes, speed of walking and PCI) Spasticity (Clonus, reflexes and MAS) Incidence of falls and near falls Quality of life (SF36) London Handicap Scale Falls diary Subjects Satisfaction Questionnaire (SSQ) Assessments Before implantation (two baseline measures) After 45 days After 90 days
Statistical analysis Mean (SD) and 95% CI Changes over time with and without stimulation (Repeated measures ANOVA without Bonferroni correction) Difference at each assessment comparing with and without stimulation (paired t tests) Descriptive statistics for response to questionnaire
Results Recruitment and progress of subjects through the study Demographic data Safety outcome Performance Efficacy Patient s perspective
Subject Flow Chart 23 subjects screened 20 subjects qualified Three did not qualify Two subjects withheld consent - One died before pre-surgery tests The first implantation failed One subject withdrawn due to leg fracture 15 subjects implanted with the new redesigned device 13 subjects completed the study of whom two deviated from the protocol. All continue to use the system. Two subjects did not complete the study, but have now been re-implanted
Demographic data Number of subjects enrolled onto the study Gender distribution Mean age (years) [SD] min - max Side of hemiplegia Total number of strokes prior to recruitment Time since last stroke (years) [SD] min - max Cause of Cerebral Vascular Accident (CVA) 15 4 female 11 male 57 [7.64] 46-68 7 Right 6 Left 7 First stroke 3 Second stroke 2 > Two strokes 1 Number of strokes unknown 4.6 [5.2] 6 months 22 years 4 Haemorrhage 8 Infarct 3 Unknown
Safety No incidence of device related changes in nerve conduction velocity No adverse events other than two incidents of wound infection, one following premature removal of sutures (both successfully treated with antibiotics)
Performance Two systems ceased to function after six weeks and have been re-implanted - both related to selection of the cuff size Minor problem with control unit software corrected by design modification Ongoing problem with RF connection between F/S and Control Unit
Performance: Range of ankle joint movement during stimulation 90 days from implantation Range of ankle movement (degs) Mean (SD) P-value 95% CI Lying 20.23 (13.43) 0.000 12.12, 28.35 Sitting 21.85 (16.20) 0.000 12.06, 31.64
Before and one week after implantation
Orthotic effect of stimulation Variable N=13 Means at 90 days NS S Mean difference (95% CI) P Value Distance walked in 4 mins (m) 115.4 124.9 9.5 (-16.55, -2.53) 0.012 Walking speed (m/s) 0.49 0.53 0.04 (-0.063, -0.004) 0. 028 Figures in bold = p<0.05
Orthotic effect of stimulation (excluding three subjects whose foot-switches were not working effectively at the 90 day assessment) Variable N=10 Means at 90 days NS S Mean difference (95% CI) P Value Distance walked in 4 mins (m) 109.4 122.7 13.3-20.750, -5.850 0.003 Walking speed (m/s) 0.47 0.52 0.05-8.127, -1.873 0.006 Figures in bold = p<0.05
Effect of stimulation over time Variable N=13 Distance walked in 4mins (m) B2 115.7 Means 90 days (S) 124.9 Baseline 2 vs 90 days Mean difference (95% CI) 9.2 (-19.13, 0.067) P Value 0.065 Walking speed (m/s) 0.48 0.53 0.05 (-0.089, 0.001) 0.054 Figures in bold = p<0.05
Effect of stimulation over time (excluding three subjects whose foot-switches were not working effectively at the 90 day assessment) Variable N=10 Distance walked in 4mins (m) B2 109.8 Means 90 days (S) 122.7 Baseline 2 vs 90 days Mean difference (95% CI) 12.9 1.177, 24.623 P Value 0.034 Walking speed (m/s) 0.46 0.52 0.63-0.111, -1.530 0.015 Figures in bold = p<0.05
Response to questionnaire 13 subjects were sent the questionnaire and 12 complete responses were received Eight sets of multiple choice questions: Use of the stimulator Effect on mobility Comparison with splints Effect on QoL Donning and doffing How well it worked Discomfort
Some examples of responses to the questionnaire Question How often do you use your ActiGait? When I use the ActiGait my walking is faster When I use the ActiGait I can walk further When I use the ActiGait my walking is less effort When I use the ActiGait I am less likely to trip or fall When I use the ActiGait I am more independent I prefer to use the ActiGait than a splint The ActiGait has improved my quality of life Response 11/12 everyday 8/12 agreed or strongly agreed 8/12 agreed or strongly agreed 10/12 agreed or strongly agreed 11/12 agreed or strongly agreed 10/12 agreed or strongly agreed 11/12 agreed or strongly agreed 11/12 agreed or strongly agreed
Questionnaire responses 2 Criteria Response Donning and doffing How well it worked Discomfort 2/12 needed help to put it on 8/12 <3 minutes and all <6minutes 8/12 agreed or strongly agreed that it was reliable Only 5/12 said it always activated at the correct time when walking 1/12 had occasional discomfort from the electrodes 3/12 some discomfort from the sensation of stimulation
Discussion and future work What are the most appropriate outcome measures? What evidence should we present to convince re-imbursers? How can we improve the control of activation of stimulation? When is surface stimulation the treatment of choice and when implanted?
Conclusions The ActiGait drop foot stimulator is a safe and effective way of correcting drop foot in stroke patients Good patient acceptance Improved quality of life reported in the questionnaire
Acknowledgments Therapists at the clinical centres: Bodil Ottosen, Ulla Sonnenborg, Bodil Enevoldsen and Rene Ellebo Patients who took part in the study Support team at Neurodan Colleagues at Aalborg University involved with the development of the system
Orthotic effect of stimulation (alternative slide) N=13 Means 45 days S-NS 90 days S-NS NS 45 days S NS 90 days S Mean difference (95% CI) P Value Mean difference (95% CI) P Value Distance walked in 4 mins (m) 111.5 128.2 115.4 124.9 16.69 (-27.064, -6.339) 0.004 9.54 (-16.549, -2.528) 0.012 Walking (m/s) speed 0.47 0.53 0.49 0.52 0.06 (-9.905, -1.942) 0.007 0.03 (-6.330, -4.393) 0.028 PCI (beats/min -1 ) 1.17 0.99 0.97 0.89-0.19 (-4.955, 0.426) 0.110-0.08 (-6.193, 0.225) 0.239
Effect of stimulation over time (alternative slide) N=13 Means Baseline 2 vs 45 days Baseline 2 vs 90 days B2 45 days 90 days Mean difference (95% CI) P Value Mean difference (95% CI) P Value Distance walked in 4 mins (m) 115.69 128.15 124.92 12.46 (-21.175, -3.748) 0.009 9.23 (-19.127, - 0.665) 0.065 Walking speed (m/s) 0.48 0.53 0.52 0.05 (-8.578, -1.268) 0.012 0.04 (-8.856, 8.701) 0.054 PCI (beats/min -1 ) 1.03 0.99 0.89 0.05 (-0.124, 0.216) 0.566-0.15 (-0.118, 0.412) 0.251