In the present study the EA group showed a slight trend towards greater treatment effectiveness based on the increase in the PPT, which was not significant. Some studies suggest that PPT assessment must be performed in patients with knee OA because it allows evaluation of the local and generalised sensitisation.35 High- and low-frequency TENS increased PPT in patients with knee OA after a single treatment session.38 The difference between the characteristics of the therapeutic modalities (TENS vs MA or EA) may be responsible for the discrepancy in the observed results.
The study has some limitations. The major limitation refers to the realisation of a single session of MA and EA, and only the immediate effect of the two treatment techniques was evaluated. Further studies are needed to assess the effects of cumulative MA or EA treatment sessions with longer follow-up times. Additionally, due to the nature of the interventions, it was not possible to blind the therapist.