Functional electrical stimulation following anterior cruciate ligament reconstruction: a randomized controlled pilot study

BackgroundInadequate quadriceps strength following anterior cruciate ligament reconstruction (ACLR) often results in alterations in gait pattern that are usually reported during loading response. Neuro-muscular electrical stimulation (NMES) is frequently used to overcome this quadriceps weakness. Despite the beneficial effects of NMES, persistent deficits in strength and gait are reported. The aim of this study was to investigate the feasibility of applying quadriceps functional electrical stimulation (FES) during walking in addition to standard rehabilitation, in the initial stage of ACLR rehabilitation.MethodsSubjects were randomized to quadriceps FES synchronized with walking group (n=10) or quadriceps NMES (duty cycle of 10s on/10s off) group (n=13). Both interventions were performed for 10min three days a week, in addition to a standard rehabilitation program. Assessments were performed up to 2weeks before the ACLR (pre-ACLR), and 4weeks postoperatively. Outcomes measured were gait speed, single limb stance gait symmetry, quadriceps isometric peak strength ratio (peak strength at 4weeks/peak strength pre-ACLR) and peak strength inter-limb symmetry. Gait outcomes were also assessed 1-week post-surgery.ResultsSubjects in both groups regained pre-ACLR gait speed and symmetry after 4weeks of rehabilitation, with no difference between groups. However, although pre-ACLR quadriceps peak strength was similar between groups (FES - 205Nm, NMES -225Nm, p=0.605), subjects in the FES group regained 82% of their pre-quadriceps strength compared to 47% in the NMES group (p=0.02). In addition, after 4weeks, the FES group had significantly better inter-limb strength symmetry 0.630.15 vs. 0.390.18 in the NMES group (p=0.01).Conclusions Quadriceps FES combined with traditional rehabilitation is a feasible, early intervention treatment option, post-ACLR. Furthermore, at 4weeks post-surgery, FES was more effective in recovering quadriceps muscle strength than was NMES. While spatiotemporal gait parameters did not differ between groups, kinetic and kinematic studies may be useful to further understand the effects of quadriceps FES post-ACLR. The promising results of this preliminary investigation suggest that such studies are warranted.Trial registration ISRCTN 02817399. First posted June 29, 2016.