An experimental study of low-level laser therapy in rat Achilles tendon injury

An experimental study of the heterogeneity and anisotropy of porcine meniscal ultimate tensile strength

Characterizing the ultimate tensile strength (UTS) of the meniscus is critical in studying knee damage and pathology. This study aims to determine the UTS of the meniscus with an emphasis on its heterogeneity and anisotropy. We performed tensile tests to failure on the menisci of six month old Yorkshire pigs at a low strain rate. Specimens from the anterior, middle and posterior regions of the meniscus were tested in the radial and circumferential directions. Then the UTS was obtained for each specimen and the data were analyzed statistically, leading to a comprehensive view of the variations in porcine meniscal strength. The middle region has the highest average strength in the circumferential (43.3 ± 4.7 MPa) and radial (12.6 ± 2.2 MPa) directions. This is followed by the anterior and posterior regions, which present similar average values (about 34.0MPa) in circumferential direction. The average strength of each region in the radial direction is approximately one-fourth to one-third of the value in the circumferential direction. This study is novel as it is the first work to focus on the experimental methods to investigate the heterogeneity and anisotropy only for porcine meniscus.

Photobiomodulation and amniotic membrane for treat tendon injury in rats

Tendons, complex fibrous structures, are subjected to great tensions, which can give rise to the so-called tendinopathies. This study aimed to evaluate photobiomodulation and human Amniotic Membrane applied as single or combined therapies to treat induced Achilles tendon lesions. Seventy-five rats were divided into five groups (n=15): C- control Sham surgery; I- tendon injury; LA- tendon injury treated with photobiomodulation; AM- tendon injury treated with Amniotic Membrane; LAM- tendon injury + photobiomodulation and Amniotic Membrane, subdivided into three groups (n=5) with analysis at 3, 7, and 14 days. The tendon injuries were made with a 20 g weight released from a mini guillotine onto the ankle in dorsiflexion. AM and LAM groups received an Amniotic Membrane fragment while LA and LAM groups received transcutaneous photobiomodulation, using a 660 nm wavelength laser. The inflammatory cells showed statistical differences between groups C and I (p<0.05), I and AM (p<0.01), I and LA (p<0.05), and I and LAM (p<0.01). Both photobiomodulation and Amniotic Membrane were shown to enhance tendon repair, and the association of photobiomodulation plus Amniotic Membrane was the most effective treatment. We conclude that the association of photobiomodulation plus Amniotic Membrane was effective in accelerating and improving the tendon regeneration process.

Histological, Physiological and Biomechanical Effects of Low-Level Laser Therapy on Tendon Healing in Animals and Humans: A Systematic Review

Low-level Laser Therapy (LLLT) was widely used in clinical practice for tendon disorders. However, the underlying mechanisms and effectiveness of LLLT in treating tendon injury remain unclear. Therefore, the present study was conducted aiming to summarize the evidence regarding the histological, physiological, and biomechanical effects of LLLT on tendon healing in animal and human models. Four databases were searched for relevant literature. Four independent reviewers screened abstracts and full-text articles, extracted relevant data, evaluated the risk of bias, and quantified the quality of evidence. Database searches yielded 1400 non-duplicated citations. Fifty-five studies were included (50 animal and five human studies). Animal studies revealed that LT had stimulating effects on collagen organization, collagen I and collagen II formation, matrix metalloproteinase (MMP)-8, transforming growth factor β1, vascular endothelial growth factor, hydroxyproline, maximum load, maximum elongation before breaking, and tendon stiffness. However, LLLT had inhibitory effects on the number of inflammatory cells, histological scores, relative amount of collagen III, cyclooxygenase-2, prostaglandin E2 (PGE2), interleukin-6, tumor necrosis factor-α, MMP-1, and MMP-3. Although one human study found that LLLT reduced the concentration of PGE2 in peritendinous tissue of the Achilles tendon, other human studies revealed that the effects of LLLT on the physiology and biomechanics of human tendons remained uncertain. LLLT facilitates tendon healing through various histological, physiological, and biomechanical effects in animal models. Only post-LLLT anti-inflammatory effects were found in human studies.

Comparison of three different dosages of low-level laser therapy on expression of cell proliferation and inflammatory markers following ovariohysterectomy in rats

The objective of the current study was to evaluate Low-level laser therapy (LLLT) on the healing of incisional wounds following ovariohysterectomy in rats, by means of subjective histopathological and immunohistochemical analysis. A total of 72 female Wistar rats were categorised into four treatment groups (Group I; sacrification 4 hours following only one LLLT application, Group II; sacrification 7 days following only one LLLT application, Group III; sacrification 4 hours after two LLLT applications, and Group IV; sacrification 7 days after two LLLT applications). Each group was further divided into four different doses subgroups (Group Control [C, off mode LLLT application], L1 [1 J/cm2], L3 [3 J/cm2], and L6 [6 J/cm2]), with equal representation in each subgroup. Ovariohysterectomy was employed using two 2-cm-length midline abdominal incisions in the left and right sides of line alba. The Group C was assigned to the left side incision to each rat in the study. After irradiation, the tissue was subjected to histopathological analysis to determine the extent of mononuclear cell infiltration, edoema, and epithelialization. Additionally, immunohistochemical analysis was performed to evaluate the expression of proliferating cell nuclear antigen (pCNA) and inducible nitric oxide synthase (iNOS). Group L1 and L3 significantly decreased mononuclear cell infiltration compared with Group C in all treatment groups (p < 0.05). Group L3 significantly decreased edoema compared with Group C in all groups except for treatment Group I (p < 0.05). Group L2 and L3 significantly increased epithelization in treatment Group IV (p < 0.05). Moreover, Group L2 and L3 significantly increased pCNA in all groups, while L2 and L3 significantly decreased iNOS expression in treatment Group II, III, and IV (p < 0.05). However, no statistical difference was found between subgroups of treatment Group I in iNOS expiration (p > 0.05). The results of the current examination demonstrated that LLLT can modulate mononuclear cell infiltration and edoema, and improve epithelization, as well as increase pCNA expression, whereas decrease iNOS expression during the wound healing process, therefore enhancing wound healing following ovariohysterectomy in rats.

Cutaneous Photorejuvenation of Light Emitting Diodes via the Melatonin Membrane Receptor Pathway

BACKGROUND

Melatonin receptors are present in the human skin and retina. These receptors can be stimulated by light emitting diodes (LEDs) at specific wavelengths, thereby inducing cutaneous photorejuvenation. However, the underlying mechanism remains unclear.

OBJECTIVE

To evaluate the influence of LEDs at specific wavelengths on melatonin membrane receptor (MT1) and cutaneous photorejuvenation via the MT1 pathway in vitro.

METHODS

Normal human dermal fibroblasts (HDFs) were irradiated using LEDs at different wavelengths (410~940 nm) at a dose of 1 J/cm². MT1 activity was evaluated after melatonin stimulation and LED irradiation. Thereafter, the expressions of collagen (COL) and matrix metalloproteinases (MMPs), with and without luzindole (MT1/2 receptor antagonist), were investigated via semi-quantitative reverse transcription polymerase chain reaction (PCR), real-time PCR, western blotting, and enzyme-linked immunosorbent assay.

RESULTS

In HDFs, the MT1 mRNA and protein levels increased significantly in response to melatonin (dose, 50 nM) (p<0.01) and LED irradiation at 595, 630, 850, and 940 nm (p<0.01). LED irradiation up-regulated COL type I and down-regulated MMP-1. Compared to LED irradiation without luzindole, LED irradiation with luzindole produced no significant increase in COL type I mRNA and protein levels (p<0.01).

CONCLUSION

We found that LED irradiation induces collagen synthesis and MMP-1 inhibition in HDFs via MT1 activation. Additionally, multiple LED wavelengths (595, 630, 850, and 940 nm) stimulated MT1 in HDFs, unlike in the eyes, where only blue light induced plasma melatonin suppression. This suggests the possibility of the melatoninergic pathway in photorejuvenation.

Photobiomodulation Associated With Conservative Treatment for Achilles Tendon Rupture: A Double-Blind, Superiority, Randomized Controlled Trial

Objective

To investigate the effects of photobiomodulation on Achilles tendon rupture (ATR) treated conservatively.

Design

Prospective, patient- and assessor-blinded, parallel, randomized controlled trial.

Setting

Patients with acute ATR treated conservatively.

Participants

Thirty-four male individuals with acute unilateral ATR treated conservatively (N=34), equally divided in 2 groups: photobiomodulation group (PBMG) and sham group, with mean age of 45.5±9.47 and 48.7±8.38 years, respectively.

Intervention

All participants underwent through an immobilization period, followed by rehabilitation sessions (2 d/wk for 12 weeks) comprising strengthening, range of motion, and balance/weightbearing exercises. In PBMG, the tendon was irradiated with a photobiomodulation cluster (1 904 nm/50 mW infrared laser, 4 858 nm/50 mW infrared diodes, and 4 658 nm/40 mW red diodes; power density of 105 mW/cm² per cluster area) during the immobilization period (2 d/wk for 8 weeks) and the sham group received a simulation of the procedure with no irradiation. Outcomes were assessed at the removal of the immobilization 12 and 16 weeks after tendon rupture.

Main Outcome Measures

Primary outcome was the Achilles Tendon Rupture Score. Secondary outcomes included Numerical Pain Rating Scale at rest and during effort, plantar flexor strength, and ankle range of motion.

Results

Both groups demonstrated an increase in the Achilles Tendon Rupture Score and improvements in range of motion, plantar flexor strength, and pain. There were no significant differences in outcomes between the 2 groups (P>.05) except in pain during walking, which was significantly lower in the PBMG in week 12 (P<.01, effect size=0.56) and week 16 (P<.01, effect size=0.55).

Conclusion

Photobiomodulation associated with conservative treatment is not superior to conservative treatment alone for improving function in patients with acute ATR.

Effectiveness of low-power laser therapy in improvement of the peripheral neuropathy induced by xenobiotics in rats

BACKGROUND

Peripheral neuropathy (PN) is the damage and dysfunction of neurons of the peripheral nervous system. The present study was conducted to estimate the effectiveness of low-power laser therapy (LPLT) in the management of PN in a rats' model.

METHODS

PN was induced by giving dichloroacetate (DCA) (250 mg/kg/day) for up to 12 weeks. Four groups of rats were used: control group, PN group, PN group treated with gabapentin and PN group treated with LPLT. The study was conducted for 8 weeks. The management of PN was estimated by behavioral tests which included hot plate and Morris water maze tests. Blood biochemical analysis were carried out.

RESULTS

Using of hot plate test indicated thermal hypoalgesia and using Morris water maze test showed cognitive decline in PN rats. Treatment with LPLT or gabapentin improved both the pain sensations and deteriorated memory that occurred in the PN rats. Biochemical analysis showed that LPLT significantly decreased the elevated beta-endorphin level in PN rats, while gabapentin could not reduce it. Treatment PN rats with LPLT or gabapentin shifted the high levels of TNF-α, IL-1β and IL-10 cytokines back to their normal values. Serum nitric oxide and MDA significantly increased in the PN group together with significant reduction in the rGSH level, these values were significantly improved by LPLT application while this was not the case with gabapentin treatment. Furthermore, treatment with gabapentin or LPLT significantly reduced serum ALAT and ASAT activities which are otherwise increased in the PN group. S100B, PGE2, total cholesterol, triglycerides, LDL-cholesterol, HDL-cholesterol, urea and creatinine showed insignificant changes among all groups.

CONCLUSIONS

Our results showed that treatment with LPLT is more efficient than gabapentin in ameliorating the peripheral neuropathy induced by xenobiotics.

Development of a Smart Leg Splint by Using New Sensor Technologies and New Therapy Possibilities

Nowadays, after suffering a fracture in an upper or lower limb, a plaster cast is placed on the affected limb. It is a very old and efficient technique for recovery from an injury that has not had significant changes since its origin. This project aims to develop a new low-cost smart 3D printed splint concept by using new sensing techniques. Two rapidly evolving Advanced Manufacturing (AM) technologies will be used: 3D scanning and 3D printing, thus combining engineering, medicine and materials evolution. The splint will include new small and lightweight sensors to detect any problem during the treatment process. Previous studies have already incorporated this kind of sensor for medical purposes. However, in this study it is implemented with a new concept: the possibility of applying treatments during the immobilization process and obtaining information from the sensors to modify the treatment. Due to this, rehabilitation treatments like infrared, ultrasounds or electroshock may be applied during the treatment, and the sensors (as it is showed in the study) will be able to detect changes during the rehabilitation process. Data of the pressure, temperature, humidity and colour of the skin will be collected in real time and sent to a mobile device so that they can be consulted remotely by a specialist. Moreover, it would be possible to include these data into the Internet of Things movement. This way, all the collected data might be compared and studied in order to find the best treatment for each kind of injury. It will be necessary to use a biocompatible material, submersible and suitable for contact with skin. These materials make it necessary to control the conditions in which the splint is produced, to assure that the properties are maintained. This development, makes it possible to design a new methodology that will help to provide faster and easier treatment.

Effects of photobiomodulation on different application points and different phases of complex regional pain syndrome type I in the experimental model

BACKGROUND

Complex regional pain syndrome type I (CRPS-I) consists of disorders caused by spontaneous pain or induced by some stimulus. The objective was to verify the effects of photobiomodulation (PBM) using 830 nm wavelength light at the affected paw and involved spinal cord segments during the warm or acute phase.

METHODS

Fifty-six mice were randomized into seven groups. Group (G) 1 was the placebo group; G2 and G3 were treated with PBM on the paw in the warm and acute phase, respectively; G4 and G5 treated with PBM on involved spinal cord segments in the warm and acute phase, respectively; G6 and G7 treated with PBM on paw and involved spinal cord segments in the warm and acute phase, respectively. Edema degree, thermal and mechanical hyperalgesia, skin temperature, and functional quality of gait (Sciatic Static Index [SSI] and Sciatic Functional Index [SFI]) were evaluated.

RESULTS

Edema was lower in G3 and G7, and these were the only groups to return to baseline values at the end of treatment. For thermal hyperalgesia only G3 and G5 returned to baseline values. Regarding mechanical hyperalgesia, the groups did not show significant differences. Thermography showed increased temperature in all groups on the seventh day. In SSI and SFI assessment, G3 and G7 showed lower values when compared to G1, respectively.

CONCLUSIONS

PBM irradiation in the acute phase and in the affected paw showed better results in reducing edema, thermal and mechanical hyperalgesia, and in improving gait quality, demonstrating efficacy in treatment of CRPS-I symptoms.

Comparison of the Effects of Pulsed Electromagnetic Field and Extracorporeal Shockwave Therapy in a Rabbit Model of Experimentally Induced Achilles Tendon Injury

Achilles tendon injuries are a common cause of complications including adhesions and tendon degeneration. As a result of these complications, the biomechanical properties are lost. Extracorporeal shockwave therapy (ESWT) and pulsed electromagnetic field (PEMF) recover the injured tendon structure; however, detailed studies of changes in tendon biomechanical properties are limited. We hypothesized that PEMF application would improve Achilles tendon biomechanical properties similar to ESWT. The curative effects of a PEMF 4-week application (15 Hz, 1 mT, 260 µs, 1 h/day) and ESWT (3 doses/28 days, 1st dose: 0.12 mJ/mm2 , 15 Hz, 300 impulses; 2nd dose: 0.14 mJ/mm2 , 15 Hz, 500 impulses; 3rd dose: 0.14 mJ/mm2 , 15 Hz, 500 impulses) on rabbits with Achilles tendon injury were investigated in terms of histopathological and biomechanical properties. The clinical feasibility of PEMF application was evaluated by comparing the results of both methods. Fifty New Zealand female rabbits were divided into two groups to be used in either biomechanical or immunohistochemical studies. Each of the two groups was further divided into five groups: C (Control), SH (Sham), TI (tendon injury), TI + ESWT, and TI + PEMF. Biomechanical evaluations revealed that maximum load, toughness, and maximum stress averages of the TI + PEMF group significantly increased (P < 0.05). When immunohistochemical images of the TI + PEMF group were compared with those of the TI group, the amount of fibrous tissue was less, the homogeneity of collagen fibers recovered, and collagen organization was more uniform. We conclude that both ESWT and PEMF are equally efficient for Achilles tendon recovery. PEMF application is effective and can be used in the clinic as a painless alternative treatment method. © 2020 Bioelectromagnetics Society.

Systematic Review of Photobiomodulation Therapy (PBMT) on the Experimental Calcaneal Tendon Injury in Rats

This systematic review analyzed the light parameters and the effects of photobiomodulation therapy (PBMT) through low-level laser therapy (LLLT) and/or LED (light-emitting diode) on tendon repair of rats submitted to calcaneal injury. This study was conducted in accordance with the guidelines of the Preferred Reporting Items for Meta-Analysis, and PubMed and MEDLINE databases were accessed to search eligible studies published in English. The search terms were as follows: "Achilles tendon" or "Calcaneal tendon" or "tendon injuries" or "soft tissue injuries" and "tendinopathy" or "tendinitis" and "low-level light therapy" or "low-level laser therapy" or "low intensity power therapy" or "light-emitting diode" or photobiomodulation." The SYRCLE (SYstematic Review Center for Laboratory animal Experimentation) risks of bias was used to assess the risk of bias for selected studies. A total of 225 studies were found based on the descriptors used, and only 33 studies were eligible. Light parameters identified per point of irradiation were approximately 60 mW (continuous mode at infrared spectra), 2 W cm^-2 , 2 J and 45 J cm^-2 . Light parameters at red spectra, continuous versus pulsed mode, and PBMT combined or compared with other therapies such as ultrasound, and studies using unhealthy rats (ovariectomized and/or diabetic models) were also identified and grouped according to these similarities. The main effects found were decreased inflammatory markers and signs of inflammatory process. PBMT (laser/LED) has positive effects in reducing the inflammatory and time for tissue repair in animal models of tendon injury and/or tendinitis using parameters identified.

Effects of Pulsed Electromagnetic Field Therapy on Rat Achilles Tendon Healing

The Achilles tendon is frequently injured. Data to support specific treatment strategies for complete and partial tears is inconclusive. Regardless of treatment, patients risk re-rupture and typically have long-term functional deficits. We previously showed that pulsed electromagnetic field (PEMF) therapy improved tendon-to-bone healing in a rat rotator cuff model. This study investigated the effects of PEMF on rat ankle function and Achilles tendon properties after (i) complete Achilles tendon tear and repair with immobilization, (ii) partial Achilles tendon tear without repair and with immobilization, and (iii) partial Achilles tendon tear without repair and without immobilization. We hypothesized that PEMF would improve tendon properties, increase collagen organization, and improve joint function, regardless of injury type. After surgical injury, animals were assigned to a treatment group: (i) no treatment control, (ii) 1 h of PEMF per day, or (iii) 3 h of PEMF per day. Animals were euthanized at 1, 3, and 6 weeks post-injury. Joint mechanics and gait analysis were assessed over time, and fatigue testing and histology were performed at each time point. Results indicate no clear differences in Achilles healing with PEMF treatment. Some decreases in tendon mechanical properties and ankle function suggest PEMF may be detrimental after complete tear. Some early improvements were seen with PEMF after partial tear with immobilization; however, immobilization was found to be a confounding factor. This body of work emphasizes the distinct effects of PEMF on tendon-to-bone healing and supports trialing potential treatment strategies pre-clinically across tendons before applying them clinically. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:70-81, 2020.

Clinical and Radiographic Alterations in Bilateral Avascular Necrosis of the Femoral Head Following Laser Acupuncture: A Case Report

Introduction: Avascular necrosis (AVN) of the femoral head is an increasingly common cause of musculoskeletal disability with unknown etiology. Traumatic and non-traumatic factors can be effective in its occurrence. About 50% of cases are bilateral. The underlying treatment is prosthetic replacement surgical procedure. Case Presentation: We report a case of bilateral AVN of femoral heads who was a candidate for prosthetic replacement surgery but improved significantly, using laser acupuncture. The patient was a 55-year-old woman with a diagnosis of bilateral osteonecrosis of the femoral head for five years. As the patient declined the surgical option, laser acupuncture was started for pain control. Regarding the signs of bilateral femoral head recovery (according to the MRI scan criteria), a total of 3 courses of laser acupuncture (each course was 20 sessions) with 2 months intervals was performed. Ten acupuncture points: Li4, Li11, St36, SP6, LIV3, GB4, GB5, GB6, GB13, GB14, GB20, GB30, GB31, GB34, were irradiated bilaterally using red 650 nm laser, 100 mW, 1505 Hz frequency, duty cycle 50 3 J/point and near infrared 810 nm laser, 100 mW, 1705 Hz frequency, duty cycle 50 3 J/point, for 2 minutes. The patient received 3 laser therapy courses. During the first-course, laser therapy was done every other day to reduce pain. For the second and third courses, according to pain decrease, therapy was done every week. Results: The results of the MRI scans and x-ray studies show progressive regeneration of the right femoral head from VI to B II and of the left from V to C II (based on the standard table of Pennsylvania). Conclusion: It seems that this procedure may be mentioned in future research projects, especially in cases with high risks of surgery.

Efficiencies of Low-Level Laser Therapy (LLLT) and Gabapentin in the Management of Peripheral Neuropathy: Diabetic Neuropathy

Diabetic neuropathy (DN) is the highly occurred complication of diabetes mellitus; it has been defined as an event of peripheral nerve dysfunction characterized by pain, allodynia, hyperalgesia, and paraesthesia. The current study was conducted to evaluate the efficacy of low-level laser therapy (LLLT) in the management of neuropathy in diabetic rats. The used animals were divided into the following groups: negative control, streptozotocin-induced diabetic rats, and diabetic rats with peripheral neuropathy (DNP) and DNP treated with gabapentin or with LLLT. Behavioral tests were carried out through hotplate test for the determination of pain sensations and the Morris water maze test for spatial reference memory evaluation. Blood samples were collected at the end of treatment for biochemical determinations. In the current study, the latency of hind-paw lick decreased significantly when DNP are treated with gabapentin or LLLT. The Morris water maze test showed that LLLT treatment improved memory that deteriorated in DNP more than gabapentin do. The results of the biochemical study revealed that LLLT could not affect the level of beta-endorphin that decreased in DNP but significantly decreased S100B that rose in DNP. PGE2 and cytokines IL-1β, IL-10, and TNF-α showed significant increase in DNP compared with control group. The gabapentin administration or LLLT application significantly reversed the levels of the mentioned markers towards the normal values of the controls. Levels of serum MDA and nitric oxide increased significantly in the DNP but rGSH showed significant decrease. These markers were improved significantly when the DNP were treated with gabapentin or LLLT. The treatment with gabapentin or LLLT significantly decreased the raised level in total cholesterol in DNP but could not decrease the elevated level of triglycerides, while LDL cholesterol decreased significantly in DNP treated with gabapentin but not affected by LLLT. Values of serum alanine aminotransferase (ALAT), aspartate aminotransferase (ASAT), urea, and creatinine increased significantly in the DPN and diabetic rats without peripheral neuropathy (PN) compared with control group. The treatment of DNP with gabapentin induced significant increases in ALAT and ASAT activities but LLLT treatment induced significant decreases in ALAT and ASAT activities as compared with DNP group. Neither gabapentin nor LLLT could improve the elevated levels of serum urea and creatinine in the DNP. It could be concluded that LLLT is more safe and effective than gabapentin in the management of neuropathy in diabetic rats.

Infrared Laser Improves Collagen Organization in Muscle and Tendon Tissue During the Process of Compensatory Overload

BACKGROUND

The photobiomodulation using the low-level laser therapy (LLLT) exerts a positive modulating effect on the synthesis of collagen in skeletal muscles and tendons. However, few studies have addressed this effect during the compensatory overload.

OBJECTIVE

Evaluate the effect of infrared laser on the deposition and organization of collagen fibers in muscle and tendon tissue during compensatory overload of the plantar muscle in rats.

MATERIALS AND METHODS

Wistar rats were submitted to bilateral ablation of the synergist muscles of the hind paws and divided in groups: Control, Hypertrophy, and Hypertrophy (H)+LLLT (780 nm, 40 mW, 9.6 J/cm² and 10 s/point, 8 points, total energy 3.2 J, daily), evaluated at 7 and 14 days. Muscle cuts were stained with Picrosirius-Red and hematoxylin-eosin and tendon cuts were submitted to birefringence for determination of collagen distribution and organization.

RESULTS

After 7 days an increase was observed in the area between beam muscles in H+LLLT (25.45% ± 2.56) in comparison to H (20.3% ± 3.31), in mature fibers and fibrilis in H+LLLT (29346.88 μm² ± 2182.56; 47602.8 μm² ± 2201.86 respectively) in comparison to H (26656.5 μm² ± 1880.46; 45630.34 μm² ± 2805.82 respectively) and in the collagen area in H+LLLT (2.25% ± 0.19) in comparison to H (2.0% ± 0.15). However, after 14 days a reduction was observed in the area between beam muscles in H+LLLT (13.88% ± 2.54) in comparison to H (19.1% ± 2.61), in fibrils and mature fibers in H+LLLT (17174.1 μm² ± 2563.82; 32634.04 μm² ± 1689.38 respectively) in comparison to H (55249.86 μm² ± 1992.65; 44318.36 μm² ± 1759.57) and in the collagen area in H+LLLT (1.76% ± 0.16) in comparison to H (2.09 ± 0.27). A greater organization of collagen fibers in the tendon was observed after 7 and 14 days in H+LLLT groups.

CONCLUSIONS

Infrared laser irradiation induces an improvement in collagen organization in tendons and a reduction in the total area of collagen in muscles during compensatory atrophy following the ablation of synergist muscles.

Amniotic membrane as an option for treatment of acute Achilles tendon injury in rats

PURPOSE

To evaluate the effect of human amniotic membrane (hAM) fragment on inflammatory response, proliferation of fibroblast and organization of collagen fibers in injured tendon.

METHODS

Sixty rats were divided into 3 groups: C - surgical procedures without tendon lesion and with simulation of hAM application; I - surgical procedures, tendon injury and simulation of hAM application; T - surgical procedures, tendon injury and hAM application. These groups were subdivided into four experimental times (3, 7, 14 and 28 days). The samples underwent histological analysis and ATR-FTIR spectroscopy.

RESULTS

Histological analysis at 14 days, the T group showed collagen fibers with better alignment. At 28 days, the I group presented the characteristics described for the T group at 14 days, while this group presented aspects of a mature connective tissue. FT-IR analysis showed a clear distinction among the three groups at all experimental times and groups T and I presented more similarities to each other than to group C.

CONCLUSION

Acute injury of tendon treated with human amniotic membrane fragment showed a faster healing process, reduction in inflammatory response, intense proliferation of fibroblasts and organization of collagen fibers.

Effect of MLS(®) laser therapy with different dose regimes for the treatment of experimentally induced tendinopathy in sheep: pilot study

OBJECTIVE

The aim of this preliminary study was to investigate the effect of Multiwave Locked System (MLS(®)), a particular model of low-level laser, in the acute phase of collagenase-induced tendon lesions in six adult sheep randomly assigned to two groups.

BACKGROUND DATA

Tendon injuries are common among human athletes and in sport horses, require a long recovery time, and have a high risk of relapse. Many traditional treatments are not able to repair the injured tendon tissue correctly. In recent years, the use of low-level laser therapy (LLLT) produced interesting results in inflammatory modulation in different musculoskeletal disorders.

METHODS

Group 1 received 10 treatments of MLS laser therapy at a fluence of 5 J/cm(2) on the left hindlimb. Group 2 received 10 treatments of MLS laser therapy at a fluence of 2.5 J/cm(2) on the left hindlimb. In every subject in both groups, the right hindlimb was considered as the control leg.

RESULTS

Clinical follow-up and ultrasonography examinations were performed during the postoperative period, and histological examinations were performed at day 30 after the first application of laser therapy. In particular, results from histological examinations indicate that both treatments induced a statistically significant cell number decrease, although only in the second group did the values return to normal. Moreover, the MLS laser therapy dose of 2.5 J/cm(2) (group 2) caused a significant decrease of vessel area.

CONCLUSIONS

In this study, clinical and histological evaluation demonstrated that a therapeutic dose <5 J/cm(2) furnished an anti-inflammatory effect, and induced a decrease of fibroblasts and vessel area. Overall, our results suggest that MLS laser therapy was effective in improving collagen fiber organization in the deep digital flexor tendon.

Analysis of experimental tendinitis in rats treated with laser and platelet-rich plasma therapies by Raman spectroscopy and histometry

The objective of this controlled experimental study was to analyze the changes in the Achilles tendons of rats with experimentally induced tendinitis after treatment with platelet-rich plasma (PRP) and/or laser therapies by histometry to quantify fibroblasts and by Raman spectroscopy to determine the biochemical concentration of collagen types I and III. Fifty-four male Wistar rats were divided into six treatment groups: control (G1); PRP only (G2); irradiation with 660 nm laser (G3); irradiation with 830 nm laser (G4); PRP plus 660 nm laser irradiation (G5); and PRP plus 830 nm laser irradiation (G6). Injuries (partial tenotomy) were inflicted in the middle third of the Achilles tendon, with PRP added prior to suture in the appropriate experimental groups. A diode laser (model Laser Flash® III, DMC Equipamentos Ltda, São Carlos, SP, Brazil) that can be operated in two wavelengths 660 and 830 nm was used for irradiation treatments. The irradiation protocol was energy density of 70 J/cm², 20 s irradiation time, and 0.028 cm² spot area, per point in three points in the injured. The histometry was made in micrographical images of the H&E stained sections and evaluated by ImageJ (version 1.46r)®. Raman spectra were collected using a dispersive spectrometer at 830 nm excitation, 200 mW power, and 10 s integration time (P-1 Raman system, Lambda Solutions, Inc. MA, USA). The relative amount of type I collagen was significantly greater in the PRP plus 830 nm laser irradiation group (468 ± 188) than in the control (147 ± 137), 630 nm laser only (191 ± 117), and 830 nm laser only (196 ± 106) groups (p < 0.01), while the quantity of type III collagen was significantly greater in the PRP-only group compared to both irradiated groups without PRP (p < 0.05). Treatment with PRP combined with irradiation at 830 nm resulted in a larger number of fibroblasts and increased concentration of type I collagen, thus accelerating the healing of the injured tendon.

LASERTERAPIA EM AFECÇÕES LOCOMOTORAS: REVISÃO SISTEMÁTICA DE ESTUDOS EXPERIMENTAIS

RESUMO Introdução: Ao longo dos anos a fisioterapia tem contribuído para o tratamento das lesões musculotendíneas e osteoarticulares pela utilização de diversos recursos eletrotermofototerapêuticos como, por exemplo, o laser de baixa potência. Objetivo: A finalidade desse estudo foi identificar mediante revisão sistemática, o efeito da laserterapia de baixa potência em afecções do sistema locomotor de ratos, com destaque para a dose de energia e o comprimento de onda utilizado, assim como para a resposta ao tratamento. Métodos: Foram consultadas as bases de dados Medline, Lilacs, PEDro e SciELO, entre janeiro de 2005 a maio de 2013, utilizando os termos "tendinopathy", "laser therapy", "rats", "tendon", "muscle", "bone", "low-level laser therapy", assim como "tendinopatia", "laserterapia", "ratos", "tendão", "músculo", "osso" e "laser de baixa potência". Apenas foram incluídos estudos experimentais publicados nos idiomas português e inglês, que induziram lesão em tendões, músculos, ossos e/ou articulação, tratada com laserterapia, associada ou não a outros tratamentos. Resultados: Foi encontrado um total de 30 estudos experimentais nas bases de dados consultadas, dos quais 15 (50%) foram realizados em tendão, 10 (33,33%) em músculo e cinco (16,66%) em osso e/ou articulação. As doses de energia mais comumente utilizadas foram de 3 J (26,66%) e 1 J (16,66%). Já os comprimentos de onda foram de 904 nm (21,21%) e 830 nm (21,21%). Conclusão: A informação mais expressiva obtida com a terapia foi a diminuição da resposta inflamatória (36,66%) em lesões ortopédicas agudas.

Achilles tendon of wistar rats treated with laser therapy and eccentric exercise

ABSTRACT Introduction: Both laser therapy and eccentric exercises are used in tendon injuries. However, the association of these physiotherapeutic modalities is yet little investigated. Objective: To evaluate the effect of low-level laser therapy associated to eccentric exercise (downhill walking) on Achilles tendinopathy of Wistar rats. Method: Eighteen Achilles tendon from 15 adult male Wistar rats were used. Tendons were distributed in six groups (laser, eccentric exercise, laser and eccentric exercise, rest, contralateral tendon, and healthy tendon). Unilateral tendinopathy was surgically induced by transversal compression followed by scarification of tendon fibers. The treatments laser therapy (904 nm, 3J/cm²) and/or eccentric exercise (downhill walking; 12 m/min; 50 min/day; 15o inclination treadmill) began 24 hours after surgery and remained for 20 days. Clinical and biomechanical analyzes were conducted. Achilles tendon was macroscopically evaluated and the transversal diameter measured. Euthanasia was performed 21 days after lesion induction. Tendons of both limbs were collected and frozen at -20°C until biomechanical analysis, on which the characteristic of maximum load (N), stress at ultimate (MPa) and maximum extension (mm) were analyzed. Results: Swelling was observed within 72 hours postoperative. No fibrous adhesions were observed nor increase in transversal diameter of tendons. Animals with the exercised tendons, but not treated with laser therapy, presented lower (p=0.0000) locomotor capacity. No difference occurred be-tween groups for the biomechanical characteristics maximum load (p=0.4379), stress at ultimate (p=0.4605) and maximum extension (p=0.3820) evaluated, even considering healthy and contralateral tendons. Conclusion: The concomitant use of low-level laser and the eccentric exercise of downhill walking, starting 24 hours after surgically induced tendinopathy, do not result in a tendon with the same biomechanical resistance or elasticity as a healthy tendon. On the other hand, it also does not influence negatively the structure and function of the Achilles tendon.

Assessing the biochemical changes of tendons of rats in an experimental model of tenotomy under therapeutic ultrasound and LEDs (625 and 945 nm) by near-infrared Raman spectroscopy

Given the complexity of the tendon repair process, where the neoformed scar tissue tends to prevent or hamper the tendon from performing its normal functions, ultrasound (US) and light-emitting diode (LED) devices have been applied to modulate the tendon repair process. This study aimed to compare the anti-inflammatory and healing effects of therapeutic US and LED in an experimental model of tenotomy using histomorphometry and Raman spectroscopy. Forty Wistar rats (235 ± 8.3 g) were separated into four groups: tenotomy (TC; control), tenotomy associated with ultrasound (US; 1 MHz, 0.5 W/cm(2)), tenotomy associated with LED at 625 nm (LR; 4 J/cm(2)), and tenotomy associated with LED at 945 nm (LIR; 4 J/cm(2)), in two experimental periods of 7 and 14 days. Histomorphometry showed a decrease of inflammatory cells (macrophages and polymorphonuclear leukocytes) for the group treated with US compared to the TC group (ANOVA, p < 0.0001) and the LIR group compared to the TC group (p < 0.05) at the seventh day, indicating an anti-inflammatory effect. In relation to the LR and TC groups, there was no significant difference. Raman spectroscopy revealed that the LR group presented an increased synthesis of collagen I compared to the other treatments and the TC groups on the 14th day (p < 0.01). US therapy showed an adjuvant effect with anti-inflammatory action, and the LED therapy at 625 nm showed an increase in collagen synthesis, contributing to the process of tendon healing.

An experimental study of muscular injury repair in a mouse model of notexin-induced lesion with EPI® technique

BACKGROUND

The mechanisms of muscle injury repair after EPI® technique, a treatment based on electrical stimulation, have not been described. This study determines whether EPI® therapy could improve muscle damage.

METHODS

Twenty-four rats were divided into a control group, Notexin group (7 and 14 days) and a Notexin + EPI group. To induce muscle injury, Notexin was injected in the quadriceps of the left extremity of rats. Pro-inflammatory interleukin 1-beta (IL-1beta) and tumoral necrosis factor-alpha (TNF-alpha) were determined by ELISA. The expression of receptor peroxisome gamma proliferator activator (PPAR-gamma), vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor-1 (VEGF-R1) were determined by western-blot.

RESULTS

The plasma levels of TNF-alpha and IL-1beta in Notexin-injured rats showed a significant increase compared with the control group. EPI® produced a return of TNF-alpha and IL-1beta values to control levels. PPAR-gamma expression diminished injured quadriceps muscle in rats. EPI® increased PPAR-gamma, VEGF and VEGF-R1 expressions. EPI® decreased plasma levels of pro-inflammatory TNF-alpha and IL-1beta and increased anti-inflammatory PPAR-gamma and proangiogenic factors as well as VEGF and VEGF-R1 expressions.

CONCLUSION

The EPI® technique may affect inflammatory mediators in damaged muscle tissue and influences the new vascularization of the injured area. These results suggest that EPI® might represent a useful new therapy for the treatment of muscle injuries. Although our study in rats may represent a valid approach to evaluate EPI® treatment, studies designed to determine how the EPI® treatment may affect recovery of injury in humans are needed.

The effects of laser treatment in tendinopathy: a systematic review

Tendons have as main function transmit forces from the muscle to the bones. Tendinopathy is an inflammatory process that occurs in and around the tendon, when these are affected by some injury. Low level laser therapy consists in a local application of a monochromatic, coherent and short wavelength light. Its use began in 60's and since then several benefits for tendon injuries have been reported. The objective of this study is to collect the most recent studies about the use of laser on the tendinopathy treatment. We performed searches on the following electronic databases PubMed, Medline, CAPES journals portal and LILACS. After the analysis, we selected three articles that showed that the use of low-level laser therapy, compared to placebo, is effective in treatment of tendinopathy. Despite the need for more studies about this theme, the low-level laser therapy demonstrates consistent results in the treatment of tendinopathy.

Biomechanical and biochemical protective effect of low-level laser therapy for Achilles tendinitis

For three decades, low level laser therapy (LLLT) has been used for treatment of tendinitis as well as other musculoskeletal diseases. Nevertheless, the biological mechanisms involved remain not completely understood. In this work, the effects of LLLT and of the widely used nonsteroidal anti-inflammatory drug, diclofenac, have been compared in the case of collagenase-induced Achilles tendinitis. Wistar rats were treated with diclofenac or laser therapy. The tensile behavior of tendons was characterized through successive loading-unloading sequences. The method considered 11 characteristic parameters to describe the mechanical behavior. It was shown that during the acute inflammatory process of the tendon, the mechanical properties were significantly correlated to the high levels of MMP-3, MMP-9 and MMP-13 expression presented in a previous paper (Marcos, R.L., et al., 2012). The treatment by non-steroidal anti-inflammatory drugs such as diclofenac sodium produces a low protective effect and can affect the short-term biochemical and biomechanical properties. On the contrary, it is shown that LLLT exhibits the best results in terms of MMPs reduction and mechanical properties recovery. Thus, LLLT looks to be a promising and consistent treatment for tendinopathies.

Low-level light-emitting diode therapy increases mRNA expressions of IL-10 and type I and III collagens on Achilles tendinitis in rats

The present study investigated the effects of low-level light-emitting diode (LED) therapy (880 ± 10 nm) on interleukin (IL)-10 and type I and III collagen in an experimental model of Achilles tendinitis. Thirty male Wistar rats were separated into six groups (n = 5), three groups in the experimental period of 7 days, control group, tendinitis-induced group, and LED therapy group, and three groups in the experimental period of 14 days, tendinitis group, LED therapy group, and LED group with the therapy starting at the 7th day after tendinitis induction (LEDT delay). Tendinitis was induced in the right Achilles tendon using an intratendinous injection of 100 μL of collagenase. The LED parameters were: optical power of 22 mW, spot area size of 0.5 cm(2), and irradiation time of 170 s, corresponding to 7.5 J/cm(2) of energy density. The therapy was initiated 12 h after the tendinitis induction, with a 48-h interval between irradiations. The IL-10 and type I and III collagen mRNA expression were evaluated by real-time polymerase chain reaction at the 7th and 14th days after tendinitis induction. The results showed that LED irradiation increased IL-10 (p < 0.001) in treated group on 7-day experimental period and increased type I and III collagen mRNA expression in both treated groups of 7- and 14-day experimental periods (p < 0.05), except by type I collagen mRNA expression in LEDT delay group. LED (880 nm) was effective in increasing mRNA expression of IL-10 and type I and III collagen. Therefore, LED therapy may have potentially therapeutic effects on Achilles tendon injuries.

Low-level laser therapy combined with platelet-rich plasma on the healing calcaneal tendon: a histological study in a rat model

The objective of this study was to investigate the effects of low-level laser therapy (LLLT) treatment alone (λ = 660 nm and λ = 830 nm) or associated with platelet-rich plasma (PRP). We used 54 male rats divided into six groups, with nine animals each: group 1, partial tenotomy; group 2 (GII), PRP; group 3 (GIII): λ660 nm; group 4 (GIV), λ830 nm; group 5 (GV), PRP + λ660 nm; and group 6 (GVI), PRP + λ830 nm. The protocol used was power density 0.35 W/cm(2), energy 0.2 J, energy density 7.0 J/cm(2), time 20 s per irradiated point, and number of points 3. Animals in groups GII, GV, and GVI received treatment with PRP, consisting of a single dose of 0.2 mL directly into the surgical site, on top of the tenotomy. Animals were killed on the 13th day post-tenotomy and their tendons were surgically removed for a quantitative analysis using polarization microscopy. The percentages of collagen fibers of types I and III were expressed as mean ± SD. Higher values of collagen fibers type I were obtained for groups GV and GVI when compared with all other groups (p < 0.05), whereas groups GIII and GIV showed no significant difference between them (p > 0.05). For collagen type III, a significant difference was observed between GII and all other groups (p < 0.5), but no significant difference was found between GIII and GIV and between GV and GVI. Results showed that the deposition of collagen type I was higher when treatment with PRP and LLLT was combined, suggesting a faster regeneration of the tendon.

Skin penetration time-profiles for continuous 810 nm and Superpulsed 904 nm lasers in a rat model

OBJECTIVE

The purpose of this study was to investigate the rat skin penetration abilities of two commercially available low-level laser therapy (LLLT) devices during 150 sec of irradiation.

BACKGROUND DATA

Effective LLLT irradiation typically lasts from 20 sec up to a few minutes, but the LLLT time-profiles for skin penetration of light energy have not yet been investigated.

MATERIALS AND METHODS

Sixty-two skin flaps overlaying rat's gastrocnemius muscles were harvested and immediately irradiated with LLLT devices. Irradiation was performed either with a 810 nm, 200 mW continuous wave laser, or with a 904 nm, 60 mW superpulsed laser, and the amount of penetrating light energy was measured by an optical power meter and registered at seven time points (range, 1-150 sec).

RESULTS

With the continuous wave 810 nm laser probe in skin contact, the amount of penetrating light energy was stable at ∼20% (SEM±0.6) of the initial optical output during 150 sec irradiation. However, irradiation with the superpulsed 904 nm, 60 mW laser showed a linear increase in penetrating energy from 38% (SEM±1.4) to 58% (SEM±3.5) during 150 sec of exposure. The skin penetration abilities were significantly different (p<0.01) between the two lasers at all measured time points.

CONCLUSIONS

LLLT irradiation through rat skin leaves sufficient subdermal light energy to influence pathological processes and tissue repair. The finding that superpulsed 904 nm LLLT light energy penetrates 2-3 easier through the rat skin barrier than 810 nm continuous wave LLLT, corresponds well with results of LLLT dose analyses in systematic reviews of LLLT in musculoskeletal disorders. This may explain why the differentiation between these laser types has been needed in the clinical dosage recommendations of World Association for Laser Therapy.

Low-level laser therapy in experimental model of collagenase-induced tendinitis in rats: effects in acute and chronic inflammatory phases

A variety of treatments for tendinopathies is currently used or has been trialed. However, in fact, there is a remarkably little evidence that any conventional therapies are effective. In the last years, low-level laser therapy (LLLT) has been showing interesting results in inflammatory modulation in different musculoskeletal disorders, but the optimal parameters and mechanisms behind these effects are not fully understood. The aim of this study is to investigate if the LLLT modulates the acute and chronic phase of collagenase-induced tendinitis in rat by interfering in mRNA expression for matrix metalloproteinases (MMP13 and MMP1), vascular endothelial growth factor (VEGF), and anti-inflammatory mediator (interleukin (IL)-10). For such, tendinitis was induced by collagenase injection in male Wistar rats. Animals were treated with LLLT (780 nm, potency of 22 mW, 107 mW/cm(2), energy density of 7.5 J/cm(2), and energy delivered of 1.54 J) with different number of treatments in accordance with the inflammatory phase analyzed. LLLT was able to modulate mRNA gene expression of IL-10, VGEF, MMP1, and MMP13 both in acute than in chronic inflammatory phase (p<0.05). Our results suggest that LLLT with parameters employed in the present study was able to modulate IL-10, VEGF, MMP1, and MMP13 mRNA gene expression both in acute than in chronic tendon inflammation. However, further studies are needed to establish optimal parameters for LLLT.