Changes In Tendon Structure Research Articles

Does aerobic exercise training promote changes in structural and biomechanical properties of the tendons in experimental animals? A systematic review.

To develop a systematic review to evaluate, through the best scientific evidence available, the effectiveness of aerobic exercise in improving the biomechanical characteristics of tendons in experimental animals. Two independent assessors conducted a systematic search in the databases Medline/PUBMED and Lilacs/BIREME, using the following descriptors of Mesh in animal models. The ultimate load of traction and the elastic modulus tendon were used as primary outcomes and transverse section area, ultimate stress and tendon strain as secondary outcomes. The assessment of risk of bias in the studies was carried out using the following methodological components: light/dark cycle, temperature, nutrition, housing, research undertaken in conjunction with an ethics committee, randomization, adaptation of the animals to the training and preparation for the mechanical test. Eight studies, comprising 384 animals, were selected; it was not possible to combine them into one meta-analysis due to the heterogeneity of the samples. There was a trend to increasing ultimate load without changes in the other outcomes studied. Only one study met more than 80% of the quality criteria. Physical training performed in a structured way with imposition of overloads seems to be able to promote changes in tendon structure of experimental models by increasing the ultimate load supported. However, the results of the influence of exercise on the elastic modulus parameters, strain, transverse section area and ultimate stress, remain controversial and inconclusive. Such a conclusion must be evaluated with reservation as there was low methodological control in the studies included in this review.

Tendon structure changes after maximal exercise in the Thoroughbred horse: Use of ultrasound tissue characterisation to detect in vivo tendon response

Investigations into the response of the superficial digital flexor tendon (SDFT) of the Thoroughbred horse to mechanical stimuli have been limited to in vitro cell culture studies focused primarily on gene expression of critical matrix proteins. It is uncertain how well in vitro outcomes translate to the tendon of the horse during exercise. The current study examined changes in tendon structure in response to maximal exercise using ultrasound tissue characterisation (UTC) to scan the SDFT prior to and after competitive racing. UTC uses contiguous transverse ultrasound images to assess the dynamics of the echopattern, which has a close relationship with changes in the 3-D ultra-structure of the tendon. Using UTC, it was possible to detect subtle changes in the dynamics of the echopattern, with a reduction in pixels that represent aligned and integer collagen tendon bundles on days 1 and 2 post-race when compared to pre-race (P<0.05). The echopattern of these tendons returned to baseline on day 3. This change in echopattern was not seen in control horses. It was concluded that short-term changes in the SDFT following maximal exercise could be detected using UTC.

Tendon Structure’s Lack of Relation to Clinical Outcome After Eccentric Exercises in Chronic Midportion Achilles Tendinopathy

Chronic midportion Achilles tendinopathy is a common and hard-to-treat disorder characterized by degenerative changes of the tendon matrix. Ultrasonographic tissue characterization (UTC) was successfully used to quantify structural human Achilles tendon changes. This novel and reliable technique could be used in follow-up studies to relate tendon structure to symptoms. To quantify structural tendon changes and assess clinical change in patients with tendinopathy. Prospective observational study. Orthopedic department in a university medical center. 23 patients with chronic midportion Achilles tendinopathy. The patients performed a 16-wk home-based eccentric exercise program. An experienced researcher performed the ultrasonographic data collection with the UTC procedure. These data were assessed by a blinded observer. The severity of symptoms was established with the validated Victorian Institute of Sport Assessment-Achilles (VISA-A) questionnaire. UTC was performed to quantify tendon structure through measuring the proportion of 4 echo types. Echo types I and II represent more or less organized tendon bundles, and echo types III and IV represent disintegrated tendon structure. On the VISA-A, the total possible score is divided by 100 for a percentage score, with a perfect score of 100. Follow-up was at 2, 8, 16, and 24 wk. The mean percentage of echo types I and II changed by 0.3% after 24 wk (P = .92, 95% CI -5.8 to 5.3). The mean VISA-A score increased slightly but significantly by 11.3 points after 24 wk (P = .01, 95% CI 2.6-20.0). An increased VISA-A score was not correlated with an increased percentage of echo types I and II (P = .94, r = -.02), and the baseline percentage of echo types I and II did not correlate with an increased VISA-A score (P = .74, r = .07). There is no short-term increase in organized tendon structure after eccentric exercises. Tendon structure is not related to symptom severity and cannot be used as a predictor of clinical outcome.

Blood flow of the achilles tendon during military training

BackgroundThe link between the hypervascularisation and the pain symptoms in a tendinopathy is still obscure. It can be hypothesised that it is important to take the stage of the tendinopathy...

Effect of anabolic steroid, IGF-1 and loading on expression of genes involved in collagen metabolism in bovine extensor tendon

BackgroundTendon ruptures have been linked to anabolic steroid usage, suggesting pathological changes in tendon structure due to steroid intake. Anecdotal reports from athletes suggest a protective effect of GH on...

Treadmill running exercise results in the presence of numerous myofibroblasts in mouse patellar tendons

Mechanical loading is known to alter tendon structure, but its cellular mechanisms are unclear. This study aimed to determine the effect of mechanical loading on tendon cells in vivo. C57BL/6J female mice were used in a treadmill running study. The treadmill running protocol consisted of treadmill training for 1 week, followed by sustained moderate running at 13 m/min for 50 min/day, 5 days/week, for 3 weeks. Immunohistochemical staining of tendon sections of mice after treadmill running revealed that numerous cells in the tendon section expressed alpha-SMA, whereas in the tendon sections of control mice, only a few cells exhibited weak alpha-SMA signals. Furthermore, mouse patellar tendon cells (MPTCs) derived from treadmill running mice were generally larger in culture, proliferated faster, expressed a higher level of alpha-SMA, and formed more abundant stress fibers compared to MPTCs from control mice. In addition, MPTCs from treadmill running mice generated larger traction forces (169 +/- 66.1 Pa) than those from control mice (102 +/- 34.2 Pa). Finally, cells from treadmill running mice produced higher levels of total collagen (516.4 +/- 92.7 microg/10,000 cells) than their counterparts (303.9 +/- 34.8 microg/10,000 cells). Thus, mechanical loading via treadmill running increased the presence of myofibroblasts in mouse patellar tendons. As myofibroblasts are activated fibroblasts, their presence in the tendon following treadmill running indicates that they actively repair and remodel tendon tissue under strenuous mechanical loading, leading to known changes in tendon structure.

In vivo estimation and repeatability of force–length relationship and stiffness of the human achilles tendon using phase contrast MRI

To devise a method using velocity encoded phase contrast MRI and MR-compatible dynamometry, for in vivo estimation of elastic properties of the human Achilles tendon and to assess within-session and day-to-day repeatability of this technique. Achilles tendon force and calcaneus-movement-adjusted displacement were measured during a submaximal isometric plantarflexion in 4 healthy subjects, four repeated trials each. The measured force-length (F-L) relationship was least-squares fitted to a cubic polynomial. Typical error was calculated for tendon displacement at multiple force levels, stiffness from the "linear region," and transition point from the displacement point separating the linear and nonlinear parts of the curve. Displacements of the tendon were determined up to a maximum force of 500 N, with mean stiffness of 234 +/- 53 N/mm, mean transition point of 2.70 +/- 0.23 mm and maximum tendon displacement of 3.38 mm. Variability of tendon displacement was not dependent on the force level. Overall typical errors were 0.09 mm and 0.16 mm for within-session and between days, respectively. Typical error of transition point was 0.05 mm and 0.14 mm. Stiffness had typical errors of 47.24 N/mm and 51.95 N/mm. The tendon cross-sectional area and calcaneus displacement were found to be very significant factors in minimizing the individual differences in F-L curves. The method yielded F-L relationships, stiffness, and transition point values that showed good within and day-to-day repeatability. The technique compared well with the more conventional one using ultrasonography. Its reliability indicates potential for measuring tendon structural changes after an injury, disease, and altered loading.

Color Doppler Ultrasound Findings in Patellar Tendinopathy (Jumper's Knee)

Background Recent studies have revealed structural changes with neovessels in patients with jumper's knee and Achilles tendinopathy, and treatment with sclerosing injections has shown promising clinical results. Purpose To study the prevalence of neovascularization and structural tendon changes on color Doppler ultrasound examination in elite athletes with clinical symptoms of jumper's knee and to examine the ultrasound characteristics of the tendon after sclerosing injection treatment with polidocanol. Study Design Cohort study; Level of evidence, 3. Methods The authors recruited patients among elite athletes with a clinical diagnosis of jumper's knee who participated in a previous randomized clinical trial. The patients recorded knee function using the Victorian Institute of Sport Assessment score. Patients were examined by color Doppler ultrasound at baseline and, for patients with structural changes and neovascularization who received sclerosing treatment, after treatment. Results Sixty-three patients (11 women and 52 men) with 79 symptomatic tendons were studied. The ultrasound examination revealed that neovascularization was present in 48 of the 79 tendons (60%). Of 33 patients (43 tendons) who received sclerosing injections, 29 patients (37 tendons, 86%) were examined 37 (19 to 53) weeks after their final sclerosing injections. Of these, 7 tendons (18.9%) had no change in neovascularization after treatment, 21 tendons (56.8%) had less neovascularization, and 9 tendons (24.3%) had more visible neovascularization. There were no significant differences in the change in Victorian Institute of Sport Assessment score between patients who had less, more, or unchanged neovascularization after treatment (analysis of variance, P = .9). Conclusion About two thirds of patients with jumper's knee can be expected to have structural tendon changes with neovascularization. There was no relationship between changes in ultrasound characteristic and knee function after sclerosing treatment.

A two-year sonographic follow-up after intratendinous injection therapy in patients with tennis elbow

BackgroundTennis elbow is a tendinopathy affecting the upper extremity. Recent studies have shown high sensitivity for ultrasound (US) examination and high specificity for colour Doppler (CD) examination. There are no...

Sclerosing injections to treat midportion Achilles tendinosis: a randomised controlled study evaluating two different concentrations of Polidocanol

Two to three ultrasound (US) and colour Doppler (CD)-guided injections of the sclerosing substance Polidocanol (5 mg/ml) have been demonstrated to give good clinical results in patients with chronic midportion Achilles tendinopathy. This study aimed to investigate if a higher concentration of Polidocanol (10 mg/ml) would lead to a less number of treatments, and lower volumes, needed for good clinical results. Fifty-two consecutive Achilles tendons (48 patients, mean age 49.6 years) with chronic painful midportion Achilles tendinopathy, were randomised to treatment with Polidocanol 5 mg/ml (group A) or 10 mg/ml (group B). The patients and treating physician were blinded to the concentration of Polidocanol injected. All patients had structural tendon changes and neovascularisation in the Achilles midportion. Treatment was US + CD-guided injections targeting the region with neovascularisation (outside ventral tendon). A maximum of three treatments (6-8 weeks in between) were given before evaluation. Patients not satisfied after three treatments were given additional treatment with Polidocanol 10 mg/ml, up to five treatments. For evaluation, the patients recorded the severity of Achilles tendon pain during activity on a visual analogue scale (VAS), before and after treatment. Patient satisfaction with treatment was also assessed. At follow-up (mean 14 months) after three treatments, 18/26 patients in group A and 19/26 patients in group B were satisfied with the treatment and had a significantly reduced level of tendon pain (P < 0.05). After completion of the study, additional treatments with Polidocanol 10 mg/ml in the not satisfied patients resulted in 26/26 satisfied patients in both groups A and B. In summary, we found no significant differences in the number of satisfied patients, number of injections or volumes given, between patients treated with 5 or 10 mg/ml Polidocanol.

Color Doppler Ultrasound Findings in Patellar Tendinopathy (Jumper's Knee)

Recent studies have revealed structural changes with neovessels in patients with jumper's knee and Achilles tendinopathy, and treatment with sclerosing injections has shown promising clinical results.To study the prevalence of neovascularization and structural tendon changes on color Doppler ultrasound examination in elite athletes with clinical symptoms of jumper's knee and to examine the ultrasound characteristics of the tendon after sclerosing injection treatment with polidocanol.Cohort study; Level of evidence, 3.The authors recruited patients among elite athletes with a clinical diagnosis of jumper's knee who participated in a previous randomized clinical trial. The patients recorded knee function using the Victorian Institute of Sport Assessment score. Patients were examined by color Doppler ultrasound at baseline and, for patients with structural changes and neovascularization who received sclerosing treatment, after treatment.Sixty-three patients (11 women and 52 men) with 79 symptomatic tendons were studied. The ultrasound examination revealed that neovascularization was present in 48 of the 79 tendons (60%). Of 33 patients (43 tendons) who received sclerosing injections, 29 patients (37 tendons, 86%) were examined 37 (19 to 53) weeks after their final sclerosing injections. Of these, 7 tendons (18.9%) had no change in neovascularization after treatment, 21 tendons (56.8%) had less neovascularization, and 9 tendons (24.3%) had more visible neovascularization. There were no significant differences in the change in Victorian Institute of Sport Assessment score between patients who had less, more, or unchanged neovascularization after treatment (analysis of variance, P = .9).About two thirds of patients with jumper's knee can be expected to have structural tendon changes with neovascularization. There was no relationship between changes in ultrasound characteristic and knee function after sclerosing treatment.

Treatment of midportion Achilles tendinosis: similar clinical results with US and CD-guided surgery outside the tendon and sclerosing polidocanol injections

Sclerosing polidocanol injections targeting the area with vasculo/neural ingrowth on the ventral side of the tendon have previously been demonstrated to give good clinical results in patients with chronic painful midportion Achilles tendinosis. In this study, 20 consecutive patients (9 men and 11 women, mean age 46 years) with chronic painful midportion Achilles tendinosis were treated with either sclerosing polidocanol injections (Group A) or open surgical revision of the area with vasculo/neural ingrowth on the ventral side of the Achilles tendon (Group B). Before treatment, all patients had structural tendon changes and increased blood flow-neovascularisation demonstrated with US and colour Doppler. Under US and colour Doppler-guidance, both the injections and the surgical revision targeted the area with neovessels just outside the ventral part of the tendon. A maximum of two sclerosing injection treatments, with 6-8 weeks in-between, were given. For evaluation, the patients recorded the severity of Achilles tendon pain during tendon loading activity (their recreational or sport activity), before and after treatment, on a VAS. Patient global satisfaction with treatment was also assessed. At the 3 months follow-up 6/9 (one patient was excluded) patients in Group A, and 8/10 patients in Group B, were satisfied with the treatment and had a significantly reduced level of tendon pain (Group A VAS from 76 to 24, P < 0.05, Group B VAS from 75 to 21, P < 0.05). There was one deep infection in Group B. At the 6 months follow-up, 6/9 patients in Group A, and 10/10 patients in Group B were satisfied. In summary, both treatment with sclerosing polidocanol injections and open surgical revision outside the ventral Achilles midportion show promising short-term clinical results.

Ultrasound- and Doppler-guided arthroscopic shaving to treat Jumper's knee: a technical note

Here we present a new technique for arthroscopic treatment of patellar tendinopthy-Jumper's knee, were arthroscopic shaving and Ultrasound + Doppler examination are performed simultaneously. Using this technique, the tendon and the areas with structural tendon changes and high blood flow are continuously demonstrated in the operating field. By this, the shaving procedure can be more exactly addressed to the area of interest on the dorsal surface of the tendon, and the trauma to the Hoffa fat pad and the tendon is minimized.

Ex vivo Mechanical Loading of Tendon

Injuries to the tendon (e.g., wrist tendonitis, epicondyltis) due to overuse are common in sports activities and the workplace. Most are associated with repetitive, high force hand activities. The mechanisms of cellular and structural damage due to cyclical loading are not well known. The purpose of this video is to present a new system that can simultaneously load four tendons in tissue culture. The video describes the methods of sterile tissue harvest and how the tendons are loaded onto a clamping system that is subsequently immersed into media and maintained at 37 degrees C. One clamp is fixed while the other one is moved with a linear actuator. Tendon tensile force is monitored with a load cell in series with the mobile clamp. The actuators are controlled with a LabView program. The four tendons can be repetitively loaded with different patterns of loading, repetition rate, rate of loading, and duration. Loading can continue for a few minutes to 48 hours. At the end of loading, the tendons are removed and the mid-substance extracted for biochemical analyses. This system allows for the investigation of the effects of loading patterns on gene expression and structural changes in tendon. Ultimately, mechanisms of injury due to overuse can be studies with the findings applied to treatment and prevention.

Treatment of Jumper’s knee: promising short-term results in a pilot study using a new arthroscopic approach based on imaging findings

Sclerosing injections targeting the area with neovessels and nerves on the dorsal side of the patellar tendon has been demonstrated as giving promising clinical results in patients with chronic painful Jumper's knee-patellar tendinosis (PT). However, a mean number of three treatments with 6-8 weeks in between were needed for a good clinical result. This study aimed to evaluate a more radical removal of the area with neovessels and nerves by using arthroscopic shaving. Fifteen patients (12 men and three women) with the diagnose Jumper's knee-PT in altogether 15 patellar tendons were included. All patients had a long duration of pain-symptoms (mean 27 months) from the patellar tendon, and ultrasonography (US) + colour Doppler (CD) examination showed structural tendon changes with hypo-echoic areas and a neovascularisation inside and on the dorsal side of the tendon, corresponding to the painful area. All patients were treated with arthroscopic shaving of the dorsal side of the proximal tendon. At follow-up (mean 6 months) after treatment, there was a good clinical result in 13/15 tendons (6/8 elite athletes). The satisfied patients were back to previous (before injury) sport activity level, and the amount of pain recorded on a visual analogue scale (VAS)-scale had decreased significantly (VAS from 79 to 12, P < 0.05). A telephone follow-up 13 months (mean) postoperatively showed that the same 13/15 were still satisfied and active in their sports, and that the 2/15 poor cases were still not satisfied with the treatment. Our short-term results indicate that arthroscopic shaving targeting the area with neovessels and nerves on the dorsal side of the patellar tendon has a potential to reduce the tendon pain and allow for the majority of patients to go back to full tendon loading activity within 2 months after surgery. Further studies evaluating this new technique for treating Jumper's knee-PT are in progress.

Sclerosing polidocanol injections in chronic painful tennis elbow-promising results in a pilot study

Sclerosing polidocanol injections targeting the area with neovessels (vascularity) have been demonstrated to give promising clinical results in patients with chronic painful Achilles and patellar tendinosis. Recently, we demonstrated vascularity in the extensor origin in patients with chronic painful tennis elbow, but not in controls with pain-free elbows. In this pilot study, 11 patients (four men and seven women, mean age 46 years) with the diagnosis of tennis elbow in altogether 13 elbows, were included. All patients had a long duration of pain symptoms (mean 23 months), and ultrasonography (US) + colour Doppler (CD) examination showed structural tendon changes with hypo-echoic areas, and a vascularity, corresponding to the painful area in the extensor origin. All patients were treated with US- and CD-guided injections of the sclerosing substance polidocanol, targeting the area with vascularity. At 8-month follow-up after treatment, there was a good clinical result in 11/13 elbows. Extensor origin pain during wrist loading activities (recorded on a VAS-scale) was significantly reduced (mean VAS from 75 to 34; P < 0.003), and maximal grip strength was significantly increased (from 29 to 40 kg; P < 0.025). Our findings indicate that one treatment with sclerosing polidocanol injections, targeting the area with vascularity in the extensor origin, has a potential to reduce the tendon pain and increase grip strength, in patients with chronic painful tennis elbow.

In SituMonitoring of Tendon Structural Changes by Elastic Scattering Spectroscopy: Correlation with Changes in Collagen Fibril Diameter and Crimp

The aim of this study was to monitor structural changes in loaded rabbit digital flexor tendons in situ and ex situ via elastic scattering spectroscopy (ESS). The optical setup consisted of a xenon white light source (lambda = 320-860 nm), connected to a fiber optic probe (with a source-detector separation of approximately 350 microm) and a spectrometer, controlled by a personal computer (PC). Cadaveric rabbit tendons were studied in situ under 3 tensional regimens: unloaded (no extrinsic tension applied), stretched, and 1-kg loaded and compared with excised tendons (i.e., no tension). Four times more light was detected in in situ unloaded tendons perpendicular to the tendon long axis than parallel to it. Backscatter anisotropy was expressed as the anisotropy factor (AF600nm: ratio of greatest to least backscatter intensity, measured with orthogonal probe positions). Differences in backscatter anisotropy between tendons from different digits were not significant. AF600nm had the smallest value (2.72 +/- 0.38) for the least aligned tendon preparations (excised tendons), and increased to 7.17 +/- 0.54 (1-kg loaded) as in situ loads were applied. Electron microscopy revealed that the distribution of collagen fibril diameters changed as loads were applied, with the diameter of larger fibrils decreasing approximately 33% for 1-kg loaded compared with excised tendons. Polarized light microscopy showed a characteristic crimp pattern in excised tendons, but this was hardly detectable in unloaded tendons and not detectable in tendons fixed in situ under a 1-kg load. We propose that the increase in optical anisotropy is a function of collagen fibril straightening and reducing fibril diameter as the tendon undergoes progressive loading. These findings are important for monitoring structure in vivo and in bioreactors for tissue engineers.

In Situ Monitoring of Tendon Structural Changes by Elastic Scattering Spectroscopy: Correlation with Changes in Collagen Fibril Diameter and Crimp

In Situ Monitoring of Tendon Structural Changes by Elastic Scattering Spectroscopy: Correlation with Changes in Collagen Fibril Diameter and Crimp

Is the chronic painful tendinosis tendon a strong tendon?

The chronic painful tendinosis tendon is generally considered a degenerated and weak tendon. However, this has not been scientifically verified, and is to be considered a hypothesis. We present here a case study involving a high-level Olympic weightlifter with chronic painful patellar tendinosis who started heavy-weight training very early after successful treatment with sclerosing injections. A 25-year-old super heavy-weight (+105 kg) Olympic weightlifter with 9 months duration of severe pain (prohibiting full training) in the proximal patellar tendon, where ultrasound and Doppler showed a widened tendon with structural changes and neovascularisation, was given one treatment with ultrasound and Doppler-guided injections of the sclerosing agent polidocanol. The injections targeted the neovessels posterior to the tendon. The patient was pain-free after the treatment, and already after 2-weeks he started with heavy-weight training (240 kg in deep squats) to try to qualify for the Olympics. Additional very heavy training on training camps, most often without having any discomfort or pain in the patellar tendon, resulted in Swedish records and ninth place at the European Championships 17 weeks after the treatment. Despite beating the national records, he did not qualify for the Olympics. Ultrasound and Doppler follow-ups have shown only a few remaining neovessels, and little structural tendon changes. This case questions previous theories about the weak tendinosis tendon, and stresses the importance of studies evaluating tendon strength.

Neovascularisation and pain in jumper’s knee: a prospective clinical and sonographic study in elite junior volleyball players

Background: The nature of tendon neovascularisation associated with pain over time has not been studied. Objective: To prospectively study the patellar tendons in elite junior volleyball players. Methods: The patellar...