Pulsed electromagnetic fields improve pain management and clinical outcomes after medial unicompartmental knee arthroplasty: A prospective randomised controlled trial

Abstract

Background: To assess pain relief and clinical outcomes in patients undergoing unicompartmental knee arthroplasty (UKA) stimulated with pulsed electromagnetic fields (PEMFs) compared to a control group.

Methods: A prospective randomised controlled trial (RCT) was performed in which 72 patients undergoing medial UKA were randomised into a control group or an experimental PEMFs group. The patients allocated to the experimental group were instructed to use PEMFs for 4 h per day for 60 days. They were evaluated before a surgery and then during the time points corresponding to 1 month, 2 months, 6 months, 12 months, and 36 months after the surgery. No placebo group was included in the RCT. Clinical assessment included the Visual Analogue Scale (VAS) for pain, Oxford Knee Score (OKS), the Short Form 36 (SF-36) health survey questionnaire, and joint swelling. During each follow-up visit, the consumption of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) was recorded.

Results: The VAS decreased on follow-up visits in both the groups; a statistically significant difference between the groups was observed during the 6 (p = 0.0297), 12 (p = 0.0003), and 36 months (p = 0.0333) follow-ups in favour of the PEMFs group. One month after UKA, the percentages of patients using NSAIDs in the PEMFs and control group were 71% and 92%, respectively (p = 0.0320). At the 2 months point, 15% of the patients in the PEMFs group used NSAIDs compared to 39% in the control group (p = 0.0317). The objective knee girth evaluation showed a statistically significant difference at 6 (p = 0.0204), 12 (p = 0.0005), and 36 (p = 0.0005) months with improved values observed in the PEMFs group. The subjective assessment of the swelling demonstrated a statistically significant difference at 2 (p = 0.0073), 6 (p = 0.0006), 12 (p = 0.0001), and 36 (p = 0.0011) months with better values noted in the PEMFs group. Last, the OKS result was significant higher in the experimental group during all the follow-ups (1mth: p = 0.0295; 2mths: p = 0.0012; 6mths: p = 0.0001; 12mths: p < 0.0001; 36mths: p = 0.0061).

Conclusions: The use of PEMFs leads to significant pain relief, better clinical improvement, and lower NSAIDs consumption after medial UKA when compared to the control group.

Level of evidence: II.

Keywords: Knee replacement; Pain; Physical therapy; Pulsed electromagnetic fields; Unicompartmental knee arthroplasty.