Normative ultrasound values for Achilles tendon thickness in the general population and patients with Achilles tendinopathy: A large international cross-sectional study.

The objective of the study was to obtain adjusted ultrasonographic reference values of the Achilles tendon thickness (maximum anterior-posterior distance) in adults without (previous) Achilles tendinopathy (AT) and to compare these reference values with AT patients. Six hundred participants were consecutively included, comprising 500 asymptomatic individuals and 100 patients with clinically diagnosed chronic AT. The maximum tendon thickness was assessed using Ultrasound Tissue Characterization. A multiple quantile regression model was developed, incorporating covariates (personal characteristics) that were found to have a significant impact on the maximum anterior-posterior distance of the Achilles tendon. A 95% reference interval (RI) was derived (50th, 2.5th-97.5th percentile). In asymptomatic participants median (95% RI) tendon thickness was 4.9 (3.8-6.9) mm for the midportion region and 3.7 (2.8-4.8) mm for the insertional region. Age, height, body mass index, and sex had a significant correlation with maximum tendon thickness. Median tendon thickness for the midportion region was calculated with the normative equation -2.1 + AGE × 0.021 + HEIGHT × 0.032+ BMI × 0.028 + SEX × 0.05. For the insertional region, the normative equation was -0.34 + AGE × 0.010+ HEIGHT × 0.018 + BMI × 0.022 + SEX × -0.05. In the equations, SEX is defined as 0 for males and 1 for females. Mean (95% CI) difference in tendon thickness compared to AT patients was 2.7 mm (2.3-3.2, p < 0.001) for the midportion and 1.4 mm (1.1-1.7, p < 0.001) for the insertional region. Compared to the asymptomatic population 73/100 (73%) AT patients exhibited increased tendon thickening, with values exceeding the 95% RI. This study presents novel reference values for the thickness of midportion and insertional region of the Achilles tendon, which were adjusted for personal characteristics. Our novel web-based openly accessible calculator for determining normative Achilles tendon thickness (www.achillestendontool.com) will be a useful resource in the diagnostic process. Trial registration number: This trial is registered in the Netherlands Trial Register (NL9010).

High-resolution ultrasound of the paratenon of the Achilles calcaneal tendon: anatomical study and description of the paratendinous injection technique.

PURPOSE: The aim of this study is to determine if ultrasound (US) allows a precise assessment of the paratenon (PT) of the Achilles calcaneal tendon (AT), and to anatomically describe the US-guided paratendinous injection technique. METHODS: This study was initially conducted on eight cadaveric specimens using high-resolution ultrasound (HRUS) to examine the PT appearance, thickness, and its relationships with the AT, plantaris tendon (PLT), Kager's fat pad (KFP), sural nerve (SN), and fascia cruris (FC). US-guided paratendinous injection of China ink was performed in all specimens, followed by anatomical dissection to assess injectate distribution. Then, HRUS study of the PT was carried out bilaterally in twenty asymptomatic volunteers (40 legs). Two musculoskeletal radiologists recorded all data in consensus except PT thickness in volunteers which was recorded independently in order to calculate intra and inter-observer reliability. RESULTS: The PT was consistently identified with HRUS along its entire course in both cadaveric specimens (8/8) and volunteers (40/40). The mean PT thickness was 0.54 mm in cadavers and 0.39 mm in vivo, without any correlation with the AT thickness. Intra- and inter observer reliability were respectively excellent and good for PT thickness. All eight (100%) ex vivo China ink injections were accurate, demonstrating a circumferential distribution of the injectate between the PT and the AT, associated with an anterior spread to the KFP. CONCLUSION: HRUS allows visualization of the PT along its entire length, and assessment of its relationships to adjacent structures. US-guided paratendinous injections can accurately and safely deliver injectates in the paratendinous sheath.

Ultrasound-guided injection of the achilles paratenon: A cadaveric investigation.

BACKGROUND: Injections around the Achilles tendon (AT) are commonly performed in clinical practice to manage non-insertional Achilles tendinopathy, but the presence/distribution of the injectate with relation to its sheath has not been assessed specifically. Accordingly, the aim of this cadaveric investigation was to demonstrate the feasibility of Achilles paratenon injection under ultrasound guidance - by confirming the exact needle positioning as well as the dye distribution inside the paratenon lumen. METHODS: A descriptive laboratory study with three human cadaveric specimens (one fresh cadaver and two cadavers embalmed using the Fix for Life (F4L) method) was performed in a tertiary-care academic institution. The interventional technique and the related anatomical findings were illustrated. During the injection, the needle was advanced inside the Achilles paratenon under ultrasound guidance i.e. in-plane medial-to-lateral approach. With the objective to confirm its correct placement, the needle was kept in situ on the right AT of the fresh cadaver. Likewise, to demonstrate the location of the dye inside the lumen of Achilles paratenon, the other five ATs - four on the embalmed cadavers and one on the fresh cadaver - were injected with 5 mL of green color dye. After removal of the needle, a layer-by-layer anatomical dissection was performed on all three cadavers. RESULTS: On the right AT of the fresh cadaver, the position of the needle's tip within the Achilles paratenon was confirmed. Accurate placement of the dye inside the paratenon lumen was confirmed in four (80%) ATs, one of the fresh and three of the embalmed cadavers. No spread inside the crural fascia compartment or between the AT and the Kager's fat pad was observed. Herewith, unintentional spilling of the dye within the superficial soft tissues of the posterior leg was reported in the left AT of one of the two embalmed cadavers (20%). CONCLUSIONS: Ultrasound-guided injection using the in-plane, medial-to-lateral approach can accurately target the lumen of Achilles paratenon.

Development and growth of the calcaneal tendon sheath with special reference to its topographical relationship with the tendon of the plantaris muscle: a histological study of human fetuses.

BACKGROUND AND PURPOSE: The calcaneal tendon sheath has several vascular routes and is a common site of inflammation. In adults, it is associated with the plantaris muscle tendon, but there are individual variations in the architecture and insertion site. We describe changes of the tendon sheath during fetal development. MATERIALS AND METHODS: Histological sections of the unilateral ankles of 20 fetuses were examined, ten at 8-12 weeks gestational age (GA) and twelve at 26-39 weeks GA. RESULTS: At 8-12 weeks GA, the tendon sheath simply consisted of a multilaminar layer that involved the plantaris tendon. At 26-39 weeks, each calcaneal tendon had a multilaminar sheath that could be roughly divided into three layers. The innermost layer was attached to the tendon and sometimes contained the plantaris tendon; the multilaminar intermediate layer contained vessels and often contained the plantaris tendon; and the outermost layer was thick and joined other fascial structures, such as a tibial nerve sheath and subcutaneous plantar fascia. The intermediate layer merged with the outermost layer near the insertion to the calcaneus. CONCLUSION: In spite of significant variations among adults, the fetal plantar tendon was always contained in an innermost or intermediate layer of the calcaneal tendon sheath in near-term fetuses. After birth, mechanical stresses such as walking might lead to fusion or separation of the multilaminar sheath in various manners. When reconstruction occurs postnatally, there may be individual variations in blood supply routes and morphology of the distal end of the plantaris tendon.

Anatomy of the Sural Nerve in the Posterolateral Approach to the Ankle: A Cadaveric Study.

Sural nerve injury may occur during the posterolateral approach to the ankle during fracture fixation. We aimed to map its location in a posterolateral approach in cadaveric specimens. A posterolateral approach was used in 28 cadaver legs with the incision made halfway between the medial border of the fibula and the lateral border of Achilles tendon, extending proximally from the tip of the lateral malleolus. The sural nerve was identified and the distance from the distal tip of the incision to where it crossed the incision proximally was measured. The mean distance was 3.4 ± 1.2 (range 0.5-7.0) cm. In 22 cases (78.5%), the distance from the lowest part of the incision to the inferior part of the nerve was between 2.7 and 4.5 cm. The nerve did not cross the incision in 2 cases. We have demonstrated that the sural nerve crossed the posterolateral incision between 2.7 and 4.5 cm proximal to the tip of the fibula in the majority of cases. However, there remains individual anatomical variation, and we would recommend that care should be taken to look for the nerve closer to the Achilles tendon proximally and nearer the fibula distally. We hope that this information can help surgeons plan their approach and minimize iatrogenic injury to the sural nerve.

Identifying achilles tendon structure differences by ultrasound tissue characterization in asymptomatic individuals.

Ultrasound Tissue Characterization (UTC) is a modality that can be utilized to characterize tendon tissue structure using ultrasonographic imaging paired with a computer algorithm to distinguish echo-types. Several studies have demonstrated UTCs ability to distinguish Achilles tendon morphology changes, but no study has established normative data of the Achilles tendon in the general population. The aim of this study was to determine UTC echo-type distribution in the Achilles tendon in an asymptomatic population. UTC scans were completed and analyzed on 508 participants without Achilles tendinopathy. Dedicated UTC-algorithms were used to distinguish and calculate echo-type percentages and the fiber type distribution was compared. The overall sample echo-type percentages demonstrated greater levels of Type I and II echo-types, 65.73% and 32.00%, respectively, and lower levels of Type III and IV echo-types, 1.74% and 0.57%, respectively. In addition, females had lower levels of Echo-type I compared to men and greater levels of echo-type II (p < 0.001). We also found that African-Americans had significantly greater amounts of echo-type I and lesser amounts of echo-type II when compared to Caucasians (p < 0.05). The results of this study create a normative data set for future UTC studies to utilize as a baseline for the evaluation of Achilles tendons. In addition, it demonstrated tendon type differences between sexes and races that need to be accounted for in future studies.

Can Achilles and patellar tendon structures predict musculoskeletal injuries in combat soldiers?

Aiming to investigate whether Achilles tendon (AT) structure and patellar tendon (PT) structure are risk factors for musculoskeletal injuries in combat soldiers, 168 participants were recruited from an infantry commander's course. The AT and PT were examined pre-course using UTC to capture the structure of four echo-type fibers (I-IV). All injuries were assessed by military physicians pre-course and throughout the 14-week course. Soldiers who were injured during the course had a significantly higher pre-course prevalence of AT and PT echo-type III and echo-type IV compared to soldiers that were not injured during the course. Variables that were found to be associated with injured/non-injured participants were echo-type III + IV of the PT (OR = 1.44, 95% CI = 1.24-1.68) and echo-type III of the AT (OR = 1.69, 95% CI = 1.35-2.12). ROC analyses showed that the best model, exhibiting both high sensitivity and low specificity, was that participants with PT echo-type III + IV > 10% or AT echo-type III >8.5% had the highest risk of being injured during the course. In conclusions, the tendon structure at the beginning of high-intensity activity or physical training program might be a risk factor for subsequent injury during the course. Soldiers and high-level athletes should be aware of the cutoff points for fiber types in tendon structure that might put them at high risk for future injury. At-risk soldiers/athletes should be provided with an intervention program before they start their training program, with the aim of improving the tendon structure and preventing subsequent injury.

The posterior fibulotalocalcaneal ligament complex: a forgotten ligament.

PURPOSE: The purpose of the present anatomical study was to define the exact morphology of the posterior fibulotalocalcaneal ligament complex (PFTCLC), both for a better orientation and understanding of the anatomy, especially during hindfoot endoscopy. METHODS: Twenty-three fresh frozen specimens were dissected in order to clarify the morphology of the PFTCLC. RESULTS: In all specimens, the ligament originated from the posteromedial border of the lateral malleolus between the posterior tibiofibular ligament (superior border) and the calcaneofibular ligament (CFL), (inferior border). This origin functions as the floor for the peroneal tendon sheath. The origin of the PFTCLC can be subdivided into two parts, a superior and inferior part. The superior part forms an aponeurosis with the superior peroneal retinaculum and the lateral septum of the Achilles tendon. From this structure, two independent laminae can be identified. The inferior part of the origin has no role in the aponeurosis and ligamentous fibres run obliquely to insert in the lateral surface of the calcaneus, in the same orientation as the CFL, but slightly more posterior, which was a consistent finding in all examined specimens. The PFTCLC is maximally tensed with ankle dorsiflexion and is located within the fascia of the deep posterior compartment of the leg. CONCLUSIONS: The PFTCLC is part of the normal anatomy of the hindfoot and therefore should be routinely recognized and partly released to achieve access to the posterior ankle anatomical pathology, relevant for hindfoot endoscopy. The origin of the ligament complex forms the floor for the peroneal tendon sheath. The superior part of the origin plays a role in the formation of an aponeurosis with the superior peroneal retinaculum and the lateral septum of the Achilles tendon.

Classification by degree of twisted structure of the fetal Achilles tendon.

BACKGROUND: The purpose of this study was to classify the twisted structure of the fetal Achilles tendon. METHODS: The study was conducted using 30 legs from 15 Japanese fetuses (mean weight, 1764.6 ± 616.9 g; mean crown-rump length, 283.5 ± 38.7 mm; 16 males, 14 females). According to attachment to the deep layer of the calcaneal tuberosity, cases showing only soleus attachment were classified as least twist (Type I), cases showing both lateral head of the gastrocnemius and soleus were classified as moderate twist (Type II), and cases with only lateral head of the gastrocnemius were classified as extreme twist (Type III). RESULTS: Viewing the Achilles tendon from cranially shows a structure twisted counterclockwise on the right side and clockwise on the left. The Achilles tendon was Type I in 4 legs (13%), Type II in 23 legs (77%), and Type III in 3 legs (10%). CONCLUSIONS: The twisted structure of the Achilles tendon can be classified as early as the second trimester and is similar to that seen in adults.

Achilles Tendon Length Is Not Related to 100-m Sprint Time in Sprinters.

This study examined the relationship between Achilles tendon (AT) length and 100-m sprint time in sprinters. The AT lengths at 3 different portions of the triceps surae muscle in 48 well-trained sprinters were measured using magnetic resonance imaging. The 3 AT lengths were calculated as the distance from the calcaneal tuberosity to the muscle-tendon junction of the soleus, gastrocnemius medialis, and gastrocnemius lateralis, respectively. The absolute 3 AT lengths did not correlate significantly with personal best 100-m sprint time (r = -.023 to .064, all Ps > .05). Furthermore, to minimize the differences in the leg length among participants, the 3 AT lengths were normalized to the shank length, and the relative 3 AT lengths did not correlate significantly with personal best 100-m sprint time (r = .023 to .102, all Ps > .05). Additionally, no significant correlations were observed between the absolute and relative (normalized to body mass) cross-sectional areas of the AT and personal best 100-m sprint time (r = .012 and .084, respectively, both Ps > .05). These findings suggest that the AT morphological variables, including the length, may not be related to superior 100-m sprint time in sprinters.

Achilles Tendinopathy: Evaluation, Rehabilitation, and Prevention.

ABSTRACT: Achilles tendinopathy is a common overuse condition that is characterized by degenerative, cumulative tissue microtrauma. It is largely a clinical diagnosis in which the patient typically presents with localized pain that is worse with tendon-loading activities. Imaging modalities may be helpful with the diagnosis of difficult cases or in the planning of interventional procedures. Midportion (noninsertional) and insertional tendinopathy have distinct features and differences for therapeutic paradigms. Overall, Achilles tendinopathy has a good clinical prognosis with most patients improving with activity modification and rehabilitation, with a focus on progressive tendon-loading. Recalcitrant cases may require adjuvant treatment with procedures (e.g., injections, shockwave therapy) and rarely surgical intervention.

Anatomic relationship of the sural nerve when performing Achilles tendon repair using the percutaneous Achilles repair system, a cadaveric study.

BACKGROUND: Minimally invasive techniques for Achilles tendon repair are increasing due to reports of similar rerupture rates using open and percutaneous techniques with fewer wound complications and quicker recovery with percutaneous methods. The goal of this study was to investigate quantitatively the relationship and risk of injury to the sural nerve during Achilles tendon repair when using the Percutaneous Achilles Repair System (PARS) (Arthrex®, Naples, FL), by recording the distance between the passed needles and the sural nerve as well identifying any direct violation of the nerve with needle passage or nerve entrapment within the suture after the jig was removed. The hypothesis of the study is that the PARS technique can be performed safely and without significant risk of injury to the sural nerve. METHODS: A total of five needles were placed through the PARS jig in each of 10 lower extremity cadaveric specimens using the proximal portion after simulation of a midsubstance Achilles tendon rupture. Careful dissection was performed to measure the distance of the sural nerve in relation to the passed needles. The sutures were then pulled out through the incision as the jig was removed from the proximal portion of the tendon and observation of the suture in relation to the tendon was documented. RESULTS: Of the 10 cadaveric specimens, none had violation of the sural nerve. Zero of the 50 (0%) needles directly punctured the sural nerve. In addition, upon retraction of the jig, all sutures were noted to reside within the tendon sheath with no entrapment of the sural nerve noted. CONCLUSION: This study demonstrated the variable course of the sural nerve and identifies the potential risk for sural nerve injury when using the PARS for Achilles tendon repair. However, this study provides additional evidence of safety from an anatomic standpoint that explains the outcomes demonstrated in the clinical trials. With this information the authors believe surgeons should feel comfortable they can replicate those outcomes while minimizing risk of sural nerve injury when the technique is used correctly.

The influence of aging on the insertion of the Achilles tendon: A magnetic resonance study.

The aim of this study was to examine the variations of the Achilles tendon (AT) insertion point into the calcaneal bone (CB) in relation to age and sex using magnetic resonance imaging (MRI). A total of 202 foot and ankle MRIs were reviewed and patients were allocated into three age groups: (I) <18, (II) 18-65, and (III) >65 years. All measurements were obtained on a mid-sagittal scan. The mean measurement values were used to assess the relationships among the AT insertion point, sex, and age. Our main findings revealed that (1) the distance between the most inferior point of the CB and the most inferior part of the AT insertion into the CB increases with age, (2) the height of the AT insertion into the posterior aspect of the CB decreases with age, and (3) the length of the AT insertion into the posterior aspect of the CB decreases with age. The terminal insertion point of the AT on the CB in younger subjects was more distal, whereas in older individuals it was more proximal. These results could help in developing novel strategies for the treatment and prophylaxis of AT injuries in particular patient age groups. Anatomical data about the AT insertion are crucial for developing a computer model of the AT and for biomechanical considerations regarding this tendon. Clin. Anat. 33:545-551, 2020. © 2019 Wiley Periodicals, Inc.

The Achilles Tendon Response to a Bout of Running is not affected by Triceps Surae Stretch Training in Runners.

An acute bout of distance running decreases Achilles tendon CSA. The purpose of this study was to examine if three-week stretch training of the Achilles tendon alters the Achilles tendon thinning response to running. Thirty-three recreational runners were divided into a control group (n = 17) and an intervention group (n = 16). The intervention included a three-week soleus stretch (knee flexed) and gastrocnemius stretch (knee extended). Three gastrocnemius stretches and three soleus stretches were performed each day, six days per week. Stretches were held for 30 s per repetition for a total duration of 180 s per leg per day. Achilles tendon CSA and range of motion measures were completed pre and post-run before and after the three-week stretching intervention. The runs prior to and following the three-week stretch training intervention both resulted in a 6% decrease in Achilles tendon CSA (p < 0.0001). There was no interaction across time between control and intervention groups in CSA (p = 0.446). Only the intervention group experienced a significant increase in dorsiflexion range of motion following the stretch training (p = 0.009). We therefore conclude that even when an increased dorsiflexion range of motion occurs, three weeks of triceps surae stretching does not alter the response of the Achilles tendon CSA.

3D-T1ρ prepared zero echo time-based PETRA sequence for in vivo biexponential relaxation mapping of semisolid short-T2 tissues at 3 T.

BACKGROUND: In addition to the articular cartilage, osteoarthritis (OA) affects several other tissues such as tendons, ligaments, and subchondral bone. T1ρ relaxation study of these short T2 tissues may provide a more comprehensive evaluation of OA. PURPOSE: To develop a 3D spin-lattice relaxation in the rotating frame (T1ρ ) prepared zero echo time (ZTE)-based pointwise encoding time reduction with radial acquisition (3D-T1ρ -PETRA) sequence for relaxation mapping of semisolid short-T2 tissues on a clinical 3 T scanner. STUDY TYPE: Prospective. POPULATION: Phantom, two bovine whole knee joint and Achilles tendon specimens, 10 healthy volunteers with no known inflammation, trauma or pain in the knee or ankle. FIELD STRENGTH/SEQUENCE: A customized PETRA sequence to acquire fat-suppressed 3D T1ρ -weighted images tissues with semisolid short T2 / T2* relaxation times in the knee and ankle joints at 3 T. ASSESSMENT: Mono- and biexponential T1ρ relaxation components were assessed in the patellar tendon (PT), anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), and Achilles tendon (AT). STATISTICAL TESTS: Kruskal-Wallis with post-hoc Dunn's test for multiple pairwise comparisons. RESULTS: Phantom and ex vivo studies showed the feasibility of T1ρ relaxation mapping using the proposed 3D-T1ρ -PETRA sequence. The in vivo study demonstrated an averaged mono-T1ρ relaxation of (median [IQR]) 15.9 [14.5] msec, 23.6 [9.4] msec, 17.4 [7.4] msec, and 5.8 [10.2] msec in the PT, ACL, PCL, and AT, respectively. The bicomponent analysis showed the short and long components (with their relative fractions) of 0.65 [1.0] msec (46.9 [15.3]%) and 37.3 [18.4] msec (53.1 [15.3]%) for PT, 1.7 [2.1] msec (42.5 [12.5]%) and 43.7 [17.8] msec (57.5 [12.5]%) for ACL, and 1.2 [1.9] msec (42.6 [14.0]%) and 27.7 [14.7] msec (57.3 [14.0]%) for PCL and 0.4 [0.02] msec (58.8 [13.3]%/) and 31.3 [10.8] msec (41.2 [13.3]%) for AT. Statistically significant (P ≤ 0.05) differences were observed in the mono- and biexponential relaxation between several regions. DATA CONCLUSION: The 3D-T1ρ -PETRA sequence allows volumetric, isotropic (0.78 × 0.78 × 0.78 mm), biexponential T1ρ assessment with corresponding fractions of the tissues with semisolid short T2 / T2* . LEVEL OF EVIDENCE: 2 Technical Efficacy Stage: 1 J. Magn. Reson. Imaging 2019;50:1207-1218.

Differential pattern of Doppler signals at lower-extremity entheses of healthy children.

BACKGROUND: Ultrasonography might be an important imaging method for assessing the pediatric enthesis. To diagnose pathology, knowledge of physiological findings is essential but limited. OBJECTIVE: To provide a detailed ultrasonographic assessment of four lower-extremity entheses in healthy adolescents as a reference for the correct interpretation of findings in children with rheumatic diseases. MATERIALS AND METHODS: The quadriceps tendon, proximal and distal patella tendon, and Achilles enthesis were examined in B-mode, Power and color Doppler in 41 boys and girls ages 11-14 years in neutral position and 30° flexion. We assessed Doppler signals at various distances from the enthesis and analyzed the data using a marginal logistic regression model with generalized estimating equation. We assessed agreement between observers using weighted kappa and we determined agreement on repeat scans using prevalence- and bias-adjusted kappa. RESULTS: Doppler signals were predominantly in the quadriceps and distal patella tendon with odds ratios of 50.85 and 21.35 (P<0.001) compared to the Achilles tendon. They were within 2 mm or 5 mm of the enthesis (odds ratios [ORs] of 4.58 and 4.24, P<0.001), without significant difference between flexion and neutral position and between the right and the left legs. Agreement between first and second assessment was good, with aggregate kappas from 0.79 to 0.90. The inter-reader agreement was also good, with aggregate kappas ranging from 0.75 to 0.95. CONCLUSION: We found a differential Doppler pattern in lower-extremity entheses, with signals present mostly in the quadriceps and distal patella entheses.

Reliability of a measurement technique for achilles tendon length.

Recently, there has been an increasing amount of literature dealing with new methods of Achilles tendon (AT) length measurement. However, most of these studies measured the AT length between the calcaneus and medial head of the gastrocnemius and the reliability of such a measurement has not been satisfactorily presented. The purpose of this study was to determine the reliability of the measurement of AT length within and between sessions. AT length was measured by using a combination of ultrasound imaging and optoelectronic stereophotogrammetry. Nineteen healthy athletes visited the lab on six different days where the AT length was measured on both lower extremities: 1) from the calcaneus to the mid-point of the medial and lateral heads of the gastrocnemius; and 2) from the calcaneus to the soleus musculotendinous attachment. The reliability results indicated high intraclass correlation coefficients (ICC > 0.8), a low typical error (< 0.6) and a standard error of measurement (SEM < 5.5 mm) for all measured AT lengths on within and between sessions. This non-invasive reliable measurement method may be recommended for sport science research purposes.

Acute effects of capacitive and resistive electric transfer (CRet) on the Achilles tendon.

This study aimed to investigate the acute effects of capacitive and resistive electric transfer (CRet) on Achilles tendon elongation during muscle contraction, as well as the circulation in the peritendinous region. Sixteen healthy men participated in this study. All 16 participants underwent 2 interventions: (1) CRet trial and (2) CRet without power (sham trial). Tendon elongation was measured four times. Using near-infrared spectroscopy, the blood circulation (volume of total-hemoglobin (Hb), oxygenated hemoglobin (oxy-Hb), and deoxygenated hemoglobin (deoxy-Hb)) was measured for 5 min before the intervention and for 30 min after the intervention. The differences between the measurements obtained before and after intervention were compared between the two interventions. The changes in tendon elongation and deoxy-Hb were not significantly different between the interventions. Total- and oxy-Hb were significantly increased in the CRet trial compared with the sham trial. In addition, the increases in total-Hb and oxy-Hb lasted for 30 min after the CRet intervention (CRet vs. sham: oxy-Hb: F = 8.063, p = 0.001, total-Hb: F = 4.564, p = 0.011). In conclusion, CRet significantly improved blood circulation in the peritendinous region.

Ultrasonography effectiveness of the vibration vs cryotherapy added to an eccentric exercise protocol in patients with chronic mid-portion Achilles tendinopathy: A randomised clinical trial.

Tendinopathy is a very common disease in the general population as well as in athletes. The aim of the present study was to examine the tendon thickness and cross-sectional area (CSA) in subjects with chronic mid-portion Achilles tendinopathy (AT) who engaged in either an eccentric exercise (EE) programme with vibration training or an EE programme combined with cryotherapy. A sample of 61 patients with chronic mid-portion AT were recruited and divided into two groups: EE programme vibration training (n = 30) and EE programme combined with cryotherapy (n = 31). Three ultrasound assessments were performed: pre-intervention and at 4, and at 12 weeks. The comparison of thickness and CSA measures at baseline, 4, and 12 weeks showed a significant (P < 0.05) increase at 0, 2, 4, and 6 cm in maximal isometric contraction and at rest in subjects with chronic mid-portion AT. The EE vibration training resulted in a statistically significant CSA increase compared with the cryotherapy group in patients with chronic mid-portion AT.

Non-uniform Stiffness within Gastrocnemius-Achilles tendon Complex Observed after Static Stretching.

Higher stiffness of the Achilles tendon (AT) and gastrocnemius have been found to be risk factors associated with Achilles tendinitis. Static stretching (SS) is one intervention that has been investigated to improve the flexibility and therefore reduce injury risk. Previous studies have investigated the acute effect of SS on one region for AT and gastrocnemius morphology and stiffness; however, there is a lack of knowledge about the effect of SS on other regions of the AT and gastrocnemius (e.g., proximal vs. distal, within gastrocnemius). The aims of the present study were: (1) to investigate the acute effects of SS on the shear modulus of the medial gastrocnemius muscles (MG) and lateral gastrocnemius muscles (LG) and AT for different regions; (2) to examine the differences in range of motion (ROM) before and after SS; and (3) to investigate the change of thickness of AT and fascicle length of MG and LG before and after SS. The stiffness of AT and the gastrocnemius, fascicle length of the muscles, thickness of the AT, and maximal ankle joint dorsiflexion angle were measured in thirty healthy subjects (15 males, 15 females) before(pre) and immediately after (post) 5-minute SS. Stretching effects are not homogeneous among different regions. After SS administration, the proximal, middle, and distal regions of MG stiffness decreased by 34.12%, 22.45%, and 25.27%, respectively (p = 0.000), and LG stiffness decreased by 37.71%, 30.47%, and 22.13%, respectively (p = 0.000), whereas AT stiffness increased by 25.73%, 17.01%, and 19.53%, respectively (p= 0.000). ROM of ankle joint increased by 8.02% (p=0.00). Nevertheless, there were no changes in the thickness of AT and fascicle length of the gastrocnemius. These results suggest that non-uniform behaviour is consistently present within the gastrocnemius and AT, and the gastrocnemius heterogeneity is reduced after SS. The stretching maneuver could be effective to increase the flexibility.