The Effectiveness and Feasibility of Neuromuscular Electrical Stimulation after Fragility Fracture

Abstract

Frailty, the vulnerable state seen in older people due to the cumulative effects of ageing and disease, is characterised by loss of muscle mass and muscle strength (sarcopenia). Older people living with frailty are prone to falls and fragility fractures, which necessitate hospital admission, resulting in further muscle loss and eventually leading to further disability. Rehabilitation exercise can reduce these consequences but is not always possible or adequate due to factors such as pain and fatigue. An alternative or additional technique is Neuromuscular Electrical Stimulation (NMES), which stimulates muscle contractions via an electrical stimulus applied to the skin overlying the muscles. The aim of this PhD thesis was to investigate the feasibility and efficacy of NMES on neuromuscular function in patients after fragility fracture.

To explore the evidence regarding the effectiveness of NMES in hospitalised patients, I conducted a systematic review and meta analysis. This is reported in Chapter 2. Across the 42 identified papers, NMES was proven to be safe, albeit with a small incidence of minor discomfort. The meta-analysis revealed that NMES had a small effect on muscle strength (moderate certainty) (SMD = 0.33; P < 0.00001), a moderate effect on muscle size (moderate certainty) (SMD = 0.66; P < 0.005), a small effect on walking performance (moderate certainty) (SMD = 0.48; P < 0.0001) and a small effect on functional mobility (low certainty) (SMD = 0.31; P < 0.05). There was a small and non-significant effect on health-related quality of life. However, the effects of NMES on length of hospital stay, and molecular and cellular biomarkers were unclear. These findings showed that NMES may be a promising intervention for rehabilitation after fragility fracture.

I then contributed to and took over the management of a feasibility study of NMES in patients admitted to hospital due to fragility fractures. The main results of this are reported in Chapter 3. The aim of the study was to evaluate the feasibility and effectiveness of NMES in patients with fragility fractures. The objectives included assessing the willingness and ability of patients to receive NMES, examining compliance and acceptability of NMES treatment, and identifying recruitment parameters and suitable outcome measures for a randomised clinical trial with clinical outcomes. The study was conducted in two phases: 1) in the hospital only, and 2) hospital, rehabilitation centres, and participants’ homes. Patients with fragility fracture were randomised to receive NMES for 6 weeks/discharge either to the right or left leg, with the other leg serving as control. NMES was applied to quadriceps and tibialis anterior muscles for 30 minutes, 3 days/week. Sessions were progressed to achieve 60 minutes, 5-7 day/week. Feasibility outcomes included participant characteristics, recruitment rate, tolerability, and number of NMES sessions. Clinical outcomes included muscle strength, and ADL at six months. The findings showed that 1052 patients were identified, of whom 113 (11%) were eligible, and 29 (3%) were recruited (median Clinical Frailty Score 3, median Barthel ADL score 93/100). The recruitment rate was 0.45/week in phase 1 and 0.9/week in phase 2. 53% achieved the target of 24 NMES sessions. 5/29 withdrew due to intolerance of NMES. Leg muscle strength improved in both treated and untreated legs, with marginally greater improvement observed in the tibialis anterior of treated legs.

It became clear during the feasibility study that hospital-based NMES was unlikely to be feasible, but that NMES might be more feasible if home-based NMES. In view of the limited use of this technique in fragility fracture patients at home, I utilised an action research iv approach to optimise the use of NMES in this group and setting whilst the feasibility study continued. The findings of this and those of semi structured interviews of participants reported in Chapter 4. The observational process highlighted issues related to the stimulation of tibialis anterior muscle, which could be overcome. Themes identified through interview included acceptability, safety, practicality, user experience, training, and support, and how and when. This sub-study reinforced the findings of the quantitative aspect of the feasibility study, confirming the safety and acceptability of NMES.

In summary, my literature review has indicated that NMES is a potentially useful treatment to prevent and reverse the muscular consequences of hospitalisation for fragility fracture. Furthermore, the feasibility study has shown that trials of NMES in fragility fractures are feasible, albeit in a minority of mildly frail fragility fracture patients with little premorbid disability. I have argued that such trials should use home-based, self-administered NMES, and should consider this intervention as an adjunct to, rather than a replacement of, a rehabilitation programme. Additionally, the findings derived from this thesis serve as valuable insights for designing future randomised controlled trials, which is a necessary step before NMES becomes a routine part of clinical care.