Effects of Low-Voltage Microamperage Stimulation on Tendon Healing in Rats

Abstract

a chilles tendon ruptures are common in athletes and the middle-aged, and there have been increasing reports of Achilles tendon ruptures in recent decades. 25,28 Despite the intrinsic capacity of spontaneous recovery in injured tendons, 26,27 the process often takes a long time and the qualities of the repaired tendons are inferior to those of intact tendons. 16,20,19,31,32 To restore the optimal function of injured tendons it is important to develop therapeutic interventions that facilitate the process of healing. Low-voltage microamperage stimulation (LVMAS), characterized as an electrical stimulation with very low current, is advocated to promote tissue healing. It is theorized that healthy tissue is the result of the direct flow of electrical current throughout the body. 6,40,39 It is the opinion of Becker and Sheldon 7 that when the body is injured, the electrical balance is disrupted in that particular region, causing the electrical current to change course. The use of LVMAS over the injured site is thought to realign this t STuDy DeSign: Randomized controlled prospective experimental study. t ObjeCTiveS: To examine the effects of trans-cutaneous low-voltage microamperage stimulation (LVMAS) on the mechanical strength of Achilles tendon repair in rats at 4 weeks after injury. t baCKgrOunD: Understanding the effect of LVMAS on the healing of injured tendons is hampered by the lack of related experimental studies , especially from the aspect of biomechanical outcome measures. t MeTHODS anD MeaSureS: Fourteen 3-month-old male Sprague-Dawley rats received surgical transection to the medial portion of their right Achilles tendon. The rats were divided into a LVMAS group (n = 7) and control group (n = 7). From day 6 postsurgery onwards, the LVMAS group received daily treatment of transcutaneous LVMAS (2.5 V, 100 μA/cm 2 , 10 pulses per second, positive current) for a total of 22 sessions, while the control group received placebo LVMAS by the same investigator during that period. On day 31, the Achilles tendons were harvested for biomechanical testing for load relaxation, stiffness, and ultimate tensile strength along the longitudinal direction. t reSulTS: The normalized Achilles tendon ultimate tensile strength of the LVMAS group (mean 6 SD, 110.5% 6 25.0%) was higher than that of the control group (75.3% 6 20.8%) (P = .014), but no significant difference was found in normalized stiffness and load relaxation between the 2 groups (P = .239 and .350, respectively). t COnCluSiOn: The results of this study suggest that the administration of transcutane-ous LVMAS could improve healing and consequently the tensile strength of partially transected Achilles tendons of rats at 4 weeks after injury.

Tensiometric evaluation of the effect of lowfrequency electric stimulation on healing Achilles tendons in rats

“…Electric stimulation with a frequency of 10 Hz, albeit without explaining the details of the current, showed greater maximum tension in rat tendons. This study did not take into account the cross section of the tendon 40 . Nevertheless, a study of rats electrically stimulated at a low frequency (10 Hz) and with a positive (anodic) polarized current confirmed the increased maximum tension of the tendons.…”

High voltage pulsed current in collagen realignment, synthesis, and angiogenesis after Achilles tendon partial rupture

“…The time and frequency of HVPC application are important factors in the healing process. Other studies were found in the literature that obtained satisfactory results with an electrical current for tendon healing, but the evaluations were made 14 days after the injury 23 , 24 . However, there are studies that used low level laser therapy (LLLT) on tendons submitted to partial rupture of the Achilles tendon in rats using the same lesion model as this study, and they observed an increase in collagen realignment 8 , 9 , 11 and type I collagen percentage after 5 days of treatment 8 , 11 and increase of blood vessel numbers after 3 and 5 treatment days 10 .…”

“…There are other important results using different types of current for electrical stimulation, such as enhancement of intrinsic tenoblastic repair in vitro 29 and increase in capillaries and fibroblasts at the early stage of tissue repair 23 ; in terms of low voltage microamperage stimulation, an improved tensile strength of partially transected Achilles tendons at four weeks after injury 24 and burst transcutaneous electrical nerve stimulation (TENS) that inhibited collagen I and III production and impaired its alignment during healing of partial rupture of the Achilles tendon in rats 30 . More studies should be conducted with different parameters, e.g., analysis of collagen synthesis using real-time polymerase chain reaction (RT-PCR) or immunohistochemistry, identifying some key genes and proteins important for healing tendon such as vascular endothelial growth factor (VEGF), transforming growth factor-β (TGF-β), insulin-like growth factor (IGF), connective tissue growth factor (CTGF), matrix metalloproteinases (MMPs), tenascin C, and important proteoglycans.…”

Microcurrent and adipose‐derived stem cells modulate genes expression involved in the structural recovery of transected tendon of rats

“…[19][20][21] The electrotherapeutic effects of the microcurrent, which presents low cost and an easier application, 21 trigger a series of events, among which we can mention the increase of cellular metabolism, local pH normalization, fibroblast proliferation, tissue contractility actions, increased protein synthesis, increased permeability of cell membranes, and tissue bioelectricity normalization. 20,21 Chan et al 22 demonstrated that the application of the microcurrent in the Achilles tendon of rats 4 weeks after the injury, increased its mechanical resistance. Ahmed et al 23 used the microcurrent in the Achilles tendon of rabbits on the 3rd, 5th, and 8th weeks after the injury and concluded that the electrical stimuli reduced the inflammation and promoted the reorganization of the collagen fibers.…”