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

OBJECTIVE: To verify the efficacy of high voltage pulsed current in collagen realignment and synthesis and in angiogenesis after the partial rupturing of the Achilles tendon in rats. METHOD: Forty male Wistar rats were randomized into four groups of 10 animals each: sham, cathodic stimulation, anodic stimulation, and alternating stimulation. Their Achilles tendons were submitted to direct trauma by a free-falling metal bar. Then, the treatment was administered for six consecutive days after the injury. In the simulation group, the electrodes were positioned on the animal, but the device remained off for 30 minutes. The other groups used a frequency of 120 pps, sensory threshold, and the corresponding polarity. On the seventh day, the tendons were removed and sent for histological slide preparation for birefringence and Picrosirius Red analysis and for blood vessel quantification. RESULTS: No significant difference was observed among the groups regarding collagen realignment (types I or III collagen) or quantity of blood vessels. CONCLUSION: High voltage pulsed current for six consecutive days was not effective in collagen realignment, synthesis, or angiogenesis after the partial rupturing of the Achilles tendon in rats.

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

ABSTRACT Objective To verify the efficacy of high voltage pulsed current in collagen realignment and synthesis and in angiogenesis after the partial rupturing of the Achilles tendon in rats. Method Forty male Wistar rats were randomized into four groups of 10 animals each: sham, cathodic stimulation, anodic stimulation, and alternating stimulation. Their Achilles tendons were submitted to direct trauma by a free-falling metal bar. Then, the treatment was administered for six consecutive days after the injury. In the simulation group, the electrodes were positioned on the animal, but the device remained off for 30 minutes. The other groups used a frequency of 120 pps, sensory threshold, and the corresponding polarity. On the seventh day, the tendons were removed and sent for histological slide preparation for birefringence and Picrosirius Red analysis and for blood vessel quantification. Results No significant difference was observed among the groups regarding collagen realignment (types I or III collagen) or quantity of blood vessels. Conclusion High voltage pulsed current for six consecutive days was not effective in collagen realignment, synthesis, or angiogenesis after the partial rupturing of the Achilles tendon in rats.

Can transcutaneous electrical nerve stimulation improve achilles tendon healing in rats?

BACKGROUND: Tendon injury is one of the most frequent injuries in sports activities. TENS is a physical agent used in the treatment of pain but its influence on the tendon's healing process is unclear. OBJECTIVE: To evaluate the influence of TENS on the healing of partial rupture of the Achilles tendon in rats. METHOD: Sixty Wistar rats were submitted to a partial rupture of the Achilles tendon by direct trauma and randomized into six groups (TENS or Sham stimulation) and the time of evaluation (7, 14, and 21 days post-injury). Burst TENS was applied for 30 minutes, 6 days, 100 Hz frequency, 2 Hz burst frequency, 200 µs pulse duration, and 300 ms pulse train duration. Microscopic analyses were performed to quantify the blood vessels and mast cells, birefringence to quantify collagen fiber alignment, and immunohistochemistry to quantify types I and III collagen fibers. RESULTS: A significant interaction was observed for collagen type I (p=0.020) where the TENS group presented lower percentage in 14 days after the lesion (p=0.33). The main group effect showed that the TENS group presented worse collagen fiber alignment (p=0.001) and lower percentage of collagen III (p=0.001) and the main time effect (p=0.001) showed decreased percentage of collagen III at 7 days (p=0.001) and 14 days (p=0.001) after lesion when compared to 21 days. CONCLUSIONS: Burst TENS inhibited collagen I and III production and impaired its alignment during healing of partial rupture of the Achilles tendon in rats.

Achilles Tendon Vascularization of Proximal, Medial, and Distal Portion Before and After Partial Lesion in Rats Treated with Phototherapy.

BACKGROUND: The Achilles tendon is one of the tendons most commonly injured by microtraumas and overuse during sports practice. This tendon is especially fragile because of the low blood supply in its central part. Nevertheless, the literature does not offer enough scientific support to explain the composition and vascular dynamic of animal tendons, despite the relevance of being able to observe if the animal tendon undergoes the same processes of vascularization in different regions, as occurs in humans. METHODS: We used 28 rats weighing 280 ± 20 g, which were divided into four groups with seven animals each (control, sham, 830 nm, 660 nm). The laser parameters were: power output 60 mW for both lasers, 40 J/cm(2) of energy density, total energy 1.1 J, power density 2.14 W/cm(2), and application time 18.6 sec. This study evaluated the vascular constitution of healthy and injured calcaneous tendons. The tendons of each animal were processed to be embedded in Paraplast and, after that, they were divided into three parts: proximal, medial, and distal. Afterwards, they were cut in slices of 6 µm were made, then they were stained with hematoxylin and eosin. Using an ocular lens reticulated with magnification × 400, we analyzed the number and the area density of the blood vessels using morphometric methods. Data were analyzed with the Shapiro-Wilk test, followed by Tukey, considering p as <0.05. RESULTS: The area density and the number of blood vessels in the proximal part were 36% and 42%, respectively, of the values found in the medial part. The distal part had 64% more vessels and 52.8% more area density (p < 0.05) than the medial part. CONCLUSIONS: Low-level laser therapy (LLLT) had no effect on the studied parameters. The vascularization of rat tendon is similar to that of humans, which contributes to the studies of therapies that have been applied in humans.

Can transcutaneous electrical nerve stimulation improve achilles tendon healing in rats?

BACKGROUND: Tendon injury is one of the most frequent injuries in sports activities. TENS is a physical agent used in the treatment of pain but its influence on the tendon's healing process is unclear. OBJECTIVE: To evaluate the influence of TENS on the healing of partial rupture of the Achilles tendon in rats. METHOD: Sixty Wistar rats were submitted to a partial rupture of the Achilles tendon by direct trauma and randomized into six groups (TENS or Sham stimulation) and the time of evaluation (7, 14, and 21 days post-injury). Burst TENS was applied for 30 minutes, 6 days, 100 Hz frequency, 2 Hz burst frequency, 200 µs pulse duration, and 300 ms pulse train duration. Microscopic analyses were performed to quantify the blood vessels and mast cells, birefringence to quantify collagen fiber alignment, and immunohistochemistry to quantify types I and III collagen fibers. RESULTS: A significant interaction was observed for collagen type I (p=0.020) where the TENS group presented lower percentage in 14 days after the lesion (p=0.33). The main group effect showed that the TENS group presented worse collagen fiber alignment (p=0.001) and lower percentage of collagen III (p=0.001) and the main time effect (p=0.001) showed decreased percentage of collagen III at 7 days (p=0.001) and 14 days (p=0.001) after lesion when compared to 21 days. CONCLUSIONS: Burst TENS inhibited collagen I and III production and impaired its alignment during healing of partial rupture of the Achilles tendon in rats.

Mast cell curve-response in partial Achilles tendon rupture after 830 nm phototherapy.

OBJECTIVE: The aim of this study was to quantify mast cells at different time intervals after partial Achilles tendon rupture in rats treated with low-level laser therapy (LLLT). BACKGROUND DATA: There is a high incidence of lesions and ruptures in the Achilles tendon that can take weeks and even months to heal completely. As the mast cells help in the healing repair phase, and LLLT has favorable effects on this tissue repair process, study of this modality on the quantity of mastocytes in the ruptured tendon is relevant. METHODS: Sixty Wistar rats were subjected to partial Achilles' tendon rupture by direct trauma, randomized into 10 groups, and then divided into the group treated with 80 mW aluminum gallium arsenide infrared laser diode, continuous wave, 2.8 W/cm(2) power density, 40 J/cm(2) energy density, and 1.12 J total energy, and the simulation group. Both the groups were subdivided according to the histological assessment period of the sample, either 6 h, 12 h, 24 h, 2 days, or 3 days after the rupture, to quantify the mastocytes in the Achilles' tendon. RESULTS: The group subjected to LLLT presented a greater quantity of mastocytes in the periods of 6 h, 12 h, 24 h, 2 days, and 3 days after rupture, compared with the simulation groups, but differences were detected between the sample assessment periods only in the simulation group. CONCLUSIONS: LLLT was shown to increase the quantity of mastocytes in the assessment periods compared with the simulation groups.