Fig. 3

Walking distance in longitudinal follow up. Walking distance under different conditions preoperatively, at activation day and after 3 months. Stimulation therapy led to increased walking distance in both patients. In patient 1 walking distance increased from 517 m to 1884 m after 3 months of stimulation (orthotic effect of FES). Moreover, the patient could walk 1075 m when stimulation was turned off, suggesting a therapeutic effect of FES in addition. Postoperatively, walking distance was significantly increased in patient 1 with the stimulation activated compared with off (one-sided paired T-test: T = 14.3, p = 0.022). In patient 2 maximum walking distance improved from 52 m preoperative with an AFO to 506 m after 3 months of using FES and to 176 m with AFO. Postoperatively, walking distance was significantly increased with the stimulation activated compared with off (one-sided paired T-test: T = 7.85, p = 0.040) and with AFO in the absence of stimulation (one-sided paired T-test: T = 6.86, p = 0.046). Remarkably, the patient was able to walk a distance of 46 m without an AFO or FES 3 months after activation