Duration and efficacy of a single pulsed electromagnetic field (PEMF) therapy on lameness associated with osteoarthritis of the tarsus

Pulsed electromagnetic field (PEMF) therapy is utilized in sports medicine due to its perceived impact on bone formation, tissue repair, and anti-inflammatory properties. However, there is limited research on the efficacy and duration of PEMF treatments in horses. This study evaluates the impact of PEMF on horses with lameness associated with osteoarthritis of the tarsus joint. We hypothesized that PEMF would reduce lameness, influenced by timing of therapy before lameness assessment. Six Thoroughbred mares with a history of tarsal osteoarthritis participated in a randomized switch-back design. After establishing baseline measurements, each mare received a 30-min PEMF treatment at 5 Hz, via the small butterfly coil directly to the tarsus, with 7 d between treatments. TxHour was administered one hour before flexion, TxDay was administered one day before, and TxWeek was administered one week before flexion. Lameness was assessed subjectively with response to flexion measured on a 4-point scale, and measures performed by a practitioner blinded to treatment. Statistics were performed utilizing SAS 9.4, and all data were assessed for normality and equal variances before analyses. Following, the impact of duration of PEMF treatment on flexion scores was assessed utilizing a general linear model, with post hoc analysis performed utilizing Tukey LSD. Significance was set to P ≤ 0.05, with trends noted between P > 0.05 and P < 0.1. There was a trend toward an overall impact of PEMF treatment on flexion scores, regardless of time to flexion (P = 0.09). When spliced for time, significance was noted in the TxHour group (P = 0.03) but not in the TxDay (P = 0.17) or TxWeek groups (P = 0.18). In conclusion, PEMF therapy decreased lameness associated with osteoarthritis of the tarsus, but this was only noted when PEMF was performed immediately before flexion test. Future research is needed to assess the efficacy of varying PEMF protocols (power, duration, frequency) to create standardized protocol guidelines.