Pulsed electromagnetic field therapy alters early healing in a rat model of rotator cuff injury and repair: Potential mechanisms

Abstract

Rotator cuff repair failure remains common due to poor tendon healing, particularly at the enthesis. We previously showed that pulsed electromagnetic field (PEMF) therapy improved the mechanical properties of the rat supraspinatus tendon postoperatively. However, little is known about the mechanisms behind PEMF‐dependent contributions to improved healing in this injury model. The objective of this study was to determine the influence of PEMF treatment on tendon gene expression and cell composition, as well as bone microarchitecture and dynamic bone metabolism during early stages of healing. We hypothesized that PEMF treatment would amplify tendon‐healing related signaling pathways while mitigating inflammation and improve bone metabolism at the repair site. Rats underwent rotator cuff injury and repair followed by assignment to either control (non‐PEMF) or PEMF treatment groups. Gene and protein expression as well as tendon and bone histological assessments were performed 3, 7, 14, 21, and 28 days after injury. Gene expression data demonstrated an upregulation in the bone morphogenetic protein 2 signaling pathway and increases in pro‐osteogenic genes at the insertion, supporting important processes to re‐establish the tendon‐bone interface. PEMF also downregulated genes related to a fibrotic healing response. Anti‐inflammatory effects were demonstrated by both gene expression and macrophage phenotype. PEMF significantly increased the rate of kinetic bone formation directly adjacent to the tendon enthesis as well as the number of cuboidal surface osteoblasts (active osteoblasts) in the humeral head. This study has provided insight into how PEMF affects cellular and molecular processes in the supraspinatus tendon and adjacent bone after injury and repair.

Strategies for promoting tendon-bone healing: Current status and prospects

“…More studies are needed to confirm the efficacy and mechanism of ESW in promoting tendon-bone healing. In addition, intermittent negative pressure and Pulsed electromagnetic field (PEMF) therapy have been preliminarily explored to promote tenoon-bone healing after tendon repair with positive results (Sun et al, 2017;Huegel et al, 2022). More research is needed to confirm their specific efficacy and mechanism.…”

Optimizing repair of tendon ruptures and chronic tendinopathies: Integrating the use of biomarkers with biological interventions to improve patient outcomes and clinical trial design

“…While such variation in endogenous outcomes exists, there is a need to improve on the outcomes for many patients, and thus many studies have turned to the evaluation of biological interventions such as those discussed previously (i.e., PRP, MSC, EV), as well as others such as the use of individual growth factors (94)(95)(96)(97), or even pulsed electromagnetic fields (98). Much of this effort has been focused on preclinical models thus far in an attempt to better understand the optimal parameters (99-103), but a number of clinical trials are evaluating the potential of the use of biologics to enhance healing outcomes.…”

Advanced strategies for constructing interfacial tissues of bone and tendon/ligament

“…Pulsed electromagnetic fields (PEMF) not only improved the early healing of rat rotator cuff enthesis after reconstruction 277 but also promoted osteogenesis at the enthesis site to create a tight tissue connection at the tendon-bone interface. 278 However, there exists a paucity of studies on electromagnetic fields for enthesis TE and its mechanism of action remains to be clarified. That said, the biophysical modulation strategy is most advantageous since biophysical stimulations of the injured enthesis are usually uncomplicated and easily controllable, non-invasive, and repeatable, making it the most economic strategy for prospective clinical applications.…”