Walking after incomplete spinal cord injury with an implanted neuromuscular electrical stimulation system and a hinged knee replacement: a single-subject study

Study design Single-subject repeated measures study. Objectives Neuromuscular electrical stimulation (NMES) can enhance walking for people with partial paralysis from incomplete spinal cord injury (iSCI). This single-subject study documents an individual's experience who both received an experimental implanted NMES system and underwent clinical bilateral hinged total knee arthroplasty (TKA). She walked in the community with knee pain prior to either intervention. Walking performance improved with an implanted NMES system. Knee pain and instability continued to worsen over time and eventually required TKA. This study evaluates the effects of these interventions. Setting Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland OH, USA. Methods The differential and combined effects of NMES and hinged knee replacement were assessed in terms of walking speed, toe clearance, knee angle, and participant perceptions with and without stimulation assistance both before and after TKA. Results The combined approach both reduced pain and restored walking ability to levels achieved prior to developing significant knee pain that prevented walking without NMES. There was an interaction effect between NMES and TKA on walking speed. Toe clearance consistently improved with stimulation assistance and TKA prevented significant knee hyperextension. The greatest impact was on endurance. Knee replacement re-enabled long distance walking with the addition of stimulation again more than doubling her maximum walking distance from 214 to 513 m. Conclusions These data support further research of combined implantable interventions that may benefit people with iSCI. Furthermore, joint laxity and pain may not necessarily be contraindications to NMES if addressed with conventional clinical treatments.