Effectiveness of Functional Electrical Stimulation (F.E.S.) of the vastus medialis muscle in the rehabilitation of patients undergoing total knee arthroplasty.

Mr. Kyriakos Avramidis, MD, FRCS Specialist Registrar in Orthopaedics, Macclesfield District General Hospital

Email: kavramidis@tiscali.co.uk

Introduction and Aims

Functional electrical stimulation of muscles, successfully improves the speed and effort of walking of patients suffering from Multiple Sclerosis, Stroke, Cerebral Palsy and Spinal cord injuries. In this study Neuromuscular Electrical Stimulation of the Vastus Medialis muscle of patients recovering from total knee replacement was applied in addition to the standard rehabilitation programme in an attempt to:

(a) investigate a possible effect on their walking speed, Hospital for Special Surgery (H.S.S.) functional knee score and Physiological Cardiac Index (PCI) in the immediate post-operative period

(b) assess whether a "carry over effect" on the same parameters existed six weeks after it’s discontinuation.

Methods

A prospective, randomised, controlled trial was conducted with 30 consecutive primary total knee arthroplasties. All patients received the same cemented prosthesis (AMK–DePuy), inserted through a medial parapatellar arthrotomy. Patients were randomly assigned to two equal in number groups (n=15). The Control group followed the standard physiotherapy programme after their operation, while the Experimental (FES) group received, in addition to that, transcutaneous electrical stimulation of their Vastus Medialis muscle for the first 6 weeks. The patients were clinically evaluated by the use of HSS knee scoring system pre-operatively and at 1,6 and 12 weeks after the knee replacement. Measurements of their Walking Speed and PCI score were obtained pre-op and at 6 and 12 weeks post-op.

Results

A marked increase in walking speed was observed in the FES group at both 6 weeks (P=0.0002) and 12 weeks (P<0.0001) post-operatively. No such differences were observed in relation to the PCI or H.S.S. knee-score variables. The magnitude of the walking-speed treatment effect is consistent with a practically important benefit to the patient.

Discussion and Conclusions

Histological studies demonstrated that electrical stimulation of quadriceps fibres following total knee arthroplasty is efficacious in attenuating post-surgical muscle atrophy. Similar findings have been reported with other orthopaedic conditions such as after anterior cruciate ligament reconstructions.

Our study has proven that functional electrical stimulation of the Vastus Medialis during the first 6 weeks following TKA can lead to rapid rehabilitation of the patients, clinically evidenced by a significant improvement of their Walking Speed. This improvement was also evident 6 weeks after discontinuation of the FES treatment (week 12), clearly indicating a "carry over effect".

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