Neuromuscular electrical stimulation to improve muscle weakness in hip osteoarthritis: A feasibility study.

Abstract

Current rehabilitation practice in joint replacement surgery for the treatment of end-stage hip osteoarthritis may be ineffective at producing a level of neuromuscular activation required to induce a muscle strength adaption before and after surgery and therefore innovations are required. Neuromuscular electrical stimulation (NMES) is the elicitation of muscle contraction using electric impulses that can restore and increase skeletal muscle mass when voluntary exercise is limited due to pain during joint loading. The scoping review conducted in this integrated thesis identified i) a paucity of research exploring NMES interventions in individuals with hip osteoarthritis and ii) emerging evidence in related patient populations to support NMES for improving muscle strength and function. These findings shaped the design of a case-control study that compared lower limb strength in individuals with hip osteoarthritis to their healthy counterparts. When compared to a control group, weakness was observed in the maximal strength of the knee extensors (-22%), knee flexors (-34%) and hip abductors (-46%), but knee extensor endurance was the most considerably impaired measure in the affected (-70%) and contralateral limb (-62%) of those with hip osteoarthritis. An acceptability study followed and found that NMES of the knee extensors was tolerable and effective at producing an involuntary muscle contraction. However, it was difficult to stimulate the hip abductor muscles at an intensity acceptable to the participant due to pain and discomfort. A systematic review was later conducted to evaluate adherence levels to NMES interventions in orthopaedic populations and identify strategies to increase compliance. These strategies were combined with findings from the early experimental work to underpin a feasibility study that evaluated a six-week, home-based NMES intervention applied to improve knee extensor endurance in older adults. The intervention was successful at improving bilateral knee extensor endurance, maximal strength, mobility, and muscle size, and found high adherence to the intervention with favourable feedback from the NMES users. This study suggests that NMES of the knee extensors is a feasible and acceptable treatment modality for people with hip osteoarthritis that may lead to improvements in muscle endurance and mobility. Due to the non-weight bearing nature of NMES, this intervention could be applied before or after joint replacement surgery, and therefore these findings are important to inform current rehabilitation practice in hip osteoarthritis. Future research should involve assessing the intervention described here in a clinical setting, with a longitudinal design, to establish the long-term benefits of NMES on patient mobility.