Tendon Cross-sectional Area Research Articles

Changes in Tendon Elongation and Muscle Atrophy Over Time After Achilles Tendon Rupture Repair: A Prospective Cohort Study on the Effects of Early Functional Mobilization

Background: Early functional mobilization (EFM) may improve patient outcome after Achilles tendon rupture (ATR). However, whether EFM affects patient outcome via changes in tendon elongation, thickening, or calf muscle atrophy is unknown. Purpose: To analyze differences in tendon and muscle morphology recovery over time between groups treated with EFM or standard treatment after ATR repair. Study Design: Cohort study; Level of evidence, 2. Methods: This prospective cohort study included 86 patients (20 women) with ATR repair who had a mean (SD) age of 39.3 (8.2) years and were part of a larger prospective randomized controlled trial. Patients were postoperatively randomized to immediate postoperative weightbearing and ankle motion (EFM group) or to immobilization in a below-knee plaster cast for 2 weeks (control group). Patient-reported and functional outcomes were assessed at 6 and 12 months with the Achilles Tendon Total Rupture Score and the heel-rise test for endurance. At 2 and 6 weeks and 6 and 12 months postoperatively, B-mode ultrasound imaging was performed to assess the length and cross-sectional area (CSA) of the Achilles tendon, the gastrocnemius CSA, as well as the thickness of soleus. Results: The Achilles Tendon Total Rupture Score for the EFM and control groups were 65.8 (18.7) and 56.8 (20.1; P = .045), respectively, at 6 months and 79.6 (15.8) and 78.9 (17.2; P = .87), respectively, at 12 months. At 2 weeks, tendon elongation was significantly more pronounced in the EFM group as compared with the control group (mean side-to-side difference, 1.88 cm vs 0.71 cm; P = .005). Subsequently, tendon elongation increased in the control group while it decreased in the EFM group so that at 6 and 12 months no significant differences between groups were found. Mean Achilles tendon elongation at 1 year was 1.73 (1.07) cm for the EFM group (n = 55) and 1.67 (0.92) cm for the control group (n = 27), with a mean difference of 0.06 cm (95% CI, 0.54 to –0.42; P = .80). Achilles tendon CSA and calf muscle atrophy displayed no significant differences between the groups; however, significant changes were demonstrated over time (P ≤ .001) in both groups. Conclusion: EFM results in more Achilles tendon elongation at early healing, but this difference subsides over time. EFM does not seem to affect patient outcome via changes in tendon elongation, thickening, or calf muscle atrophy. Registration: NCT02318472 (ClinicalTrials.gov identifier).

The Free Achilles Tendon Is Shorter, Stiffer, Has Larger Cross-Sectional Area and Longer T2* Relaxation Time in Trained Middle-Distance Runners Compared to Healthy Controls

Tendon geometry and tissue properties are important determinants of tendon function and injury risk and are altered in response to ageing, disease, and physical activity levels. The purpose of this study was to compare free Achilles tendon geometry and mechanical properties between trained elite/sub-elite middle-distance runners and a healthy control group. Magnetic resonance imaging (MRI) was used to measure free Achilles tendon volume, length, average cross-sectional area (CSA), regional CSA, moment arm, and T2* relaxation time at rest, while freehand three-dimensional ultrasound (3DUS) was used to quantify free Achilles tendon mechanical stiffness, Young’s modulus, and length normalised mechanical stiffness. The free Achilles tendon in trained runners was significantly shorter and the average and regional CSA (distal end) were significantly larger compared to the control group. Mechanical stiffness of the free Achilles tendon was also significantly higher in trained runners compared to controls, which was explained by the group differences in tendon CSA and length. T2* relaxation time was significantly longer in trained middle-distance runners when compared to healthy controls. There was no relationship between T2* relaxation time and Young’s modulus. The longer T2* relaxation time in trained runners may be indicative of accumulated damage, disorganised collagen, and increased water content in the free Achilles tendon. A short free Achilles tendon with large CSA and higher mechanical stiffness may enable trained runners to rapidly transfer high muscle forces and possibly reduce the risk of tendon damage from mechanical fatigue.

Muscle and Tendon Morphology in Early-Adolescent Athletes and Untrained Peers.

Adolescent athletes can feature significantly greater muscle strength and tendon stiffness compared to untrained peers. However, to date, it is widely unclear if radial muscle and tendon hypertrophy may contribute to loading-induced adaptation at this stage of maturation. The present study compares the morphology of the vastus lateralis (VL) and the patellar tendon between early-adolescent athletes and untrained peers. In 14 male elite athletes (A) and 10 untrained controls (UC; 12–14 years of age), the VL was reconstructed from full muscle segmentations of magnetic resonance imaging (MRI) sequences and ultrasound imaging was used to measure VL fascicle length and pennation angle. The physiological cross-sectional area (PCSA) of the VL was calculated by dividing muscle volume by fascicle length. The cross-sectional area (CSA) of the patellar tendon was measured over its length based on MRI segmentations as well. Considering body mass as covariate in the analysis, there were no significant differences between groups considering the VL anatomical cross-sectional area (ACSA) over its length or maximum ACSA (UC: 24.0 ± 8.3 cm2, A: 28.1 ± 5.3 cm2, p > 0.05), yet athletes had significantly greater VL volume (UC: 440 ± 147 cm3, A: 589 ± 121 cm3), PCSA (UC: 31 ± 9 cm2, A: 46 ± 9 cm2), pennation angle (UC: 8.2 ± 1.4°, A: 10.1 ± 1.3°), and average patellar tendon CSA (UC: 1.01 ± 0.18 cm2, A: 1.21 ± 0.18 cm2) compared to the untrained peers (p < 0.05). However, the ratio of average tendon CSA to VL PCSA was significantly lower in athletes (UC: 3.4 ± 0.1%, A: 2.7 ± 0.5%; p < 0.05). When inferring effects of athletic training based on the observed differences between groups, these results suggest that both muscle and tendon of the knee extensors respond to athletic training with radial growth. However, the effect seems to be stronger in the muscle compared to the tendon, with an increase of pennation angle contributing to the marked increase of muscle PCSA. A disproportionate response to athletic training might be associated with imbalances of muscle strength and tendon stiffness and could have implications for the disposition towards tendon overuse injury.

Achilles Tendon Morphology Is Related to Triceps Surae Muscle Size and Peak Plantarflexion Torques During Walking in Young but Not Older Adults.

The interaction of the triceps surae muscles and the Achilles tendon is critical in producing the ankle plantarflexion torque required for human walking. Deficits in plantarflexor output are a hallmark of reduced mobility in older adults and are likely associated with changes in the triceps surae muscles that occur with age. Structural differences between young and older adults have been observed in the Achilles tendon and in the triceps surae muscles. However, less is known about how age-related differences in muscle and tendon morphology correspond with each other and, furthermore, how those morphology differences correlate with age-related deficits in function. The goal of this work was to investigate whether there is a correlation between age-related differences in triceps surae muscle size and Achilles tendon cross-sectional area (CSA) and whether either is predictive of ankle plantarflexion torque during walking. We used magnetic resonance imaging (MRI) to measure triceps surae muscle volumes and tendon CSAs in young (n = 14, age: 26 ± 4 years) and older (n = 7, age: 66 ± 5 years) adults, and we determined peak plantarflexion torques during treadmill walking. We found that individual muscle volumes as a percentage of the total triceps surae volume did not differ between young and older adults, though muscle volumes per body size (normalized by the product of height and mass) were smaller in older adults. Achilles tendon CSA was correlated with body size and muscle volumes in young adults but not in older adults. The ratio of tendon CSA to total triceps surae muscle volume was significantly greater in older adults. Peak ankle plantarflexion torque during walking correlated with body size and triceps surae volume in young and older adults but was correlated with tendon CSA only in the young adults. Structure–function relationships that seem to exist between the Achilles tendon and the triceps surae muscles in young adults are no longer evident in all older adults. Understanding mechanisms that determine altered Achilles tendon CSA in older adults may provide insight into age-related changes in function.

Smaller cross-sectional areas of the hamstring tendon measured from preoperative ultrasonography are likely to need additional gracilis harvesting for double-bundle anterior cruciate ligament reconstructions

Background/PurposeHamstring tendon autografts are commonly used for double-bundle anterior cruciate ligament reconstruction (DB-ACLR). If the volume of the semitendinosus (ST) tendon is insufficient, the gracilis (G) tendon is also harvested. Additional harvesting of the G autograft can affect patients’ short-term postoperative outcome, such as muscle recovery; thus, preoperative information about whether an additional G autograft is needed would be useful. The purpose of this study was to investigate whether preoperative measurement of the ST tendon using ultrasonography could inform the intraoperative decision to harvest the G tendon.MethodsWe enrolled 20 patients (13 men and seven women) who underwent DB-ACLR between October 2017 and March 2019. The mean patient age was 28.5 years. The ipsilateral ST tendon was measured using ultrasonography before surgery. Measurements included the diameter and breadth of the short-axis image. The cross-sectional area (CSA) was calculated from these measurements. During surgery, when two grafts with diameters of ≥ 5.0 mm could not be made, the G tendon was also harvested. Patients were categorized into two groups: the ST group where only the ST tendon was harvested, and the semitendinosus gracilis tendon (STG) group where the ST and G tendons were both harvested. The CSA value was compared between the two groups, and the cutoff value was calculated.ResultsIn the ST group (n = 8), the mean diameter and breadth of the semitendinosus tendon were 4.21 and 2.34 mm, respectively. In the STG group (n = 12), the mean diameter and breadth of the ST tendon were 3.39 and 1.78 mm, respectively. The CSAs calculated for the ST group and the STG group were 7.74 mm2 and 4.79 mm2, respectively. A cutoff value of 7.0 mm2 was found to correspond to a specificity and sensitivity to harvest the G tendon of 87.5% and 75.0%, respectively.ConclusionsThe preoperative CSA of the ST tendon determined using ultrasonography can, therefore, be informative for deciding whether to harvest the G tendon for DB-ACLR. The results of this study provide valuable information for graft selection in anterior cruciate ligament reconstruction.Level of EvidenceIV (Retrospective case series design).

In vivo Sonographic Characterization of The Achilles Tendons in Healthy Young Collegiate Athletes as a Function of Ankle Position

This study aims to describe the normative Achilles tendon properties in a collegiate subject cohort. Achilles tendon evaluations in 65 asymptomatic college-level athletes by ultrasound B mode on two tendon positions (neutral state and active maximum dorsiflexion). Correlation was made to BMI, tibial/foot length, maximal calf circumference, type of sports, resting/maximal dorsiflexion-plantar flexion angles among other factors. The mean Achilles tendon length was found to be 14.9 cm, mean transverse dimension of 1.38 cm, thickness of 0.49 cm and cross-sectional area of 0.61 cm2 in the relaxed state. Males had greater tendon length than the female athletes (15.5 (M) vs 14.3cm (F) in the relaxed position and 16.1 (M) vs 15.2cm (F) in the stretched position), tendon width (1.4 vs 1.3 cm), tendon thickness (0.51 vs 0.46 cm), tendon cross-sectional area (0.65 vs 0.57 cm2) and foot length (27.6 cm vs 26.6 cm). The Achilles tendon parameters such as length in the relaxed state had a statistically significant correlation with the height, weight, and foot length, while the tendon length in the dorsiflexed-stretched position had a statistically significant relationship to foot length, tibia length, calf circumference and range of motion (both in maximum dorsiflexion and plantar flexion positions; p < .05 for all comparison). Differences in the correlation between the Achilles tendon parameters and body habitus was recorded as a function of ankle position. Tendon dimensions and cross-sectional areas were larger in male vs female athletes. Calf circumferences and Achilles tendon resting angle were outlined. No significant difference was found in the Achilles tendon dimensions regardless of the leg dominance with similar range of motion regardless of athlete gender.

Morphological and Functional Outcomes &gt;13 Years After Achilles Tendon Rupture Treated Operatively and Non-operatively

Objectives:In patients >13yrs after treatment for acute Achilles tendon rupture (AATR), 1) investigate side-to-side differences in MRI-defined morphological changes in the Achilles tendon and surrounding calf musculature, 2) investigate side-to-side differences in single-limb functional tasks, and 3) compare patients who received operative vs non-operative treatment.Methods:28 patients (11 operative, 17 non-operative) from a previous randomized trial returned 15±1 years post-AATR for testing (age: 57±7 years; BMI: 30±5 kg/m2). Patients underwent bilateral 3T MRI (MAGNETOM Prisma, Siemens) including sagittal and axial T1 and T2-weighted turbo spin echo (TSE), axial T1-weighted inversion recovery, and sagittal T2-weighted 3D isotropic TSE sequences. The maximum anteroposterior Achilles tendon diameter (MAD) and cross-sectional area (CSA), distance from the MAD to the superior margin of the calcaneus, tendon length, gastrocnemius and soleus CSA, and calf circumference were measured using distance and area software tools (Figure 1; AGFA Healthcare). Functional measures included single-legged heel-rise repetitions and maximum vertical jump height. All outcomes were compared between limbs and between groups.Results:Overall, there were significant side-to-side differences in most MRI and functional measures, with the injured limb Achilles tendon typically wider and thicker (MAD often twice as large), calf musculature CSA smaller, number of heel raises lower, and vertical jump height lower (Table 1). The only differences between treatment groups was in MAD and the distance from the MAD to the superior margin of the calcaneus, with a greater side-to-side difference for patients treated operatively (Table 1).Conclusion:Substantial side-to-side differences in tendon diameter, thickness, muscle bulk and functional performance persist beyond a decade after treatment for AATR. There were no differences favoring operative treatment over non-operative treatment.

Progressive resistance training for adolescents with cerebral palsy: the STAR randomized controlled trial.

To evaluate the effect of progressive resistance training of the ankle plantarflexors on gait efficiency, activity, and participation in adolescents with cerebral palsy (CP). Sixty-four adolescents (10-19y; 27 females, 37 males; Gross Motor Function Classification System [GMFCS] levels I-III) were randomized to 30 sessions of resistance training (10 supervised and 20 unsupervised home sessions) over 10 weeks or usual care. The primary outcome was gait efficiency indicated by net nondimensional oxygen cost (NNcost). Secondary outcomes included physical activity, gross motor function, participation, muscle strength, muscle and tendon size, and muscle and tendon stiffness. Analysis was intention-to-treat. Median attendance at the 10 supervised sessions was 80% (range 40-100%). There was no between-group difference in NNcost at 10 (mean difference: 0.02, 95% confidence interval [CI] -0.07 to 0.11, p=0.696) or 22 weeks (mean difference: -0.08, 95% CI -0.18 to 0.03, p=0.158). There was also no evidence of between-group differences in secondary outcomes at 10 or 22 weeks. There were 123 adverse events reported by 27 participants in the resistance training group. We found that 10 supervised sessions and 20 home sessions of progressive resistance training of the ankle plantarflexors did not improve gait efficiency, muscle strength, activity, participation, or any biomechanical outcome among adolescents with CP. Thirty sessions of progressive resistance training of the ankle plantarflexors over 10 weeks did not improve gait efficiency among ambulatory adolescents with cerebral palsy. Resistance training did not improve muscle strength, activity, or participation. Ninety percent of participants experienced an adverse event. Most adverse events were expected and no serious adverse events were reported.

Functional morphology of the ankle extensor muscle-tendon units in the springhare Pedetes capensis shows convergent evolution with macropods for bipedal hopping locomotion.

This study assesses the functional morphology of the ankle extensor muscle-tendon units of the springhare Pedetes capensis, an African bipedal hopping rodent, to test for convergent evolution with the Australian bipedal hopping macropods. We dissect and measure the gastrocnemius, soleus, plantaris, and flexor digitorum longus in 10 adult springhares and compare them against similar-sized macropods using phylogenetically informed scaling analyses. We show that springhares align reasonably well with macropod predictions, being statistically indistinguishable with respect to the ankle extensor mean weighted muscle moment arm (1.63 vs. 1.65cm, respectively), total muscle mass (41.1 vs. 29.2g), total muscle physiological cross-sectional area (22.9 vs. 19.3 cm2 ), mean peak tendon stress (26.2 vs. 35.2MPa), mean tendon safety factor (4.7 vs. 3.6), and total tendon strain energy return capacity (1.81 vs. 1.82J). However, total tendon cross-sectional area is significantly larger in springhares than predicted for a similar-sized macropod (0.26 vs. 0.17 cm2 , respectively), primarily due to a greater plantaris tendon thickness (0.084 vs. 0.048 cm2 ), and secondarily because the soleus muscle-tendon unit is present in springhares but is vestigial in macropods. The overall similarities between springhares and macropods indicate that evolution has favored comparable lower hindlimb body plans for bipedal hopping locomotion in the two groups of mammals that last shared a common ancestor ~160 million years ago. The springhare's relatively thick plantaris tendon may facilitate rapid transfer of force from muscle to skeleton, enabling fast and accelerative hopping, which could help to outpace and outmaneuver predators.

Achilles tendon loading is lower in older adults than young adults across a broad range of walking speeds.

The purpose of this study was to investigate age-related differences in Achilles tendon loading during gait. Fourteen young (7F/7M, 26±5years) and older (7F/7M, 67±5years) adults without current neurological or orthopaedic impairment participated. Shear wave tensiometry was used to measure tendon stress by tracking Achilles tendon wave speed. The wave speed-stress relationship was calibrated using simultaneously collected tensiometer and force plate measures during a standing sway task. Tendon stress was computed from the force plate measures using subject-specific ultrasound measures of tendon moment arm and cross-sectional area. All subjects exhibited a highly linear relationship between wave speed squared and tendon stress (mean R2>0.9), with no significant age-group differences in tensiometer calibration parameters. Tendon wave speed was monitored during treadmill walking at four speeds (0.75, 1.00, 1.25, and 1.50m/s) and used to compute the stress experienced by the tendon. Relative to young adults, older adults exhibited 22% lower peak tendon wave speeds. Peak tendon stress during push-off in older adults (24.8MPa) was 32% less than that in the young adults (36.7MPa) (p=0.01). There was a moderate increase (+11%) in peak tendon stress across both groups when increasing speed from 0.75 to 1.50m/s (main effect of speed, p=0.01). Peak tendon loading during late swing did not differ between age groups (mean 3.8MPa in young and 4.2MPa in older adults). These age-related alterations in tendon tissue loading may affect the mechanobiological stimuli underlying tissue remodeling and thereby alter the propensity for tendon injury and disease.

Relationship between Stature and Length of Tendo Achilles in Adult Male and Female of Bangladesh

Background: Tendo Achilles injuries are usually related to poor ankle flexibility and strength and to overuse. Morphology of tendo Achilles is an important tool for its assessment which can be done by measuring tendon thickness, cross-sectional area and length of tendon.&#x0D; Objective: The aim of the study was to correlate length of tendo Achilles with stature in several age groups of sedentary people as measured by ultrasonography.&#x0D; Materials and method: This cross sectional analytical type of study was conducted in the department of Anatomy, Dhaka Medical College Hospital, Dhaka, Bangladesh from July 2013 to June 2014. The present study was performed on 200 tendo Achilles of 100 people (50 male and 50 female) randomly selected from the patients who came to the Radiology department of Dhaka Medical College Hospital for ultrasonography of any region of their body other than leg.&#x0D; Results: In this study length of tendo Achilles was measured in both legs of adult people and was correlated with stature. Highly significant correlation was found between length of tendo Achilles with stature (p&lt;0.001).&#x0D; Conclusion: The data of length of tendo Achilles obtained from the present study may provide valuable information in different aspects of medical science as a guide line for physiotherapists, radiologists, sports professionals and ortho-surgeons in early detection and monitoring of rehabilitation especially of professional athletes.&#x0D; Delta Med Col J. Jul 2019 7(2): 80-83

Differences Between Long Distance Road Runners and Trail Runners in Achilles Tendon Structure and Jumping and Balance Performance.

Load and joint kinematics change with differences in running surface. Running regularly on trails compared to roads might influence the load on the Achilles tendon and its adaptations, along with other factors such as balance, strength, and proprioception. To investigate Achilles tendon structure and functional tests in road and trail runners. Cross-sectional study. Laboratory, sport sciences college. The study included 26 road and 17 trail runners who run at least three times per week with a minimum of 20 km per week and who participated in running competitions over the preceding 2 years. Each participant was examined for Achilles tendon structure (via ultrasound tissue characterization [UTC] imaging) and underwent functional tests in addition to completing a demographic questionnaire. The percentages of echo types I, II, III, and IV (degree of structural homogeneity) within the tendon, tendon length and width, tendon cross-sectional area (via UTC imaging); Ankle inversion movement discrimination ability (via Active Movement Extent Discrimination Apparatus device); dynamic postural balance (via Y balance test); jumping performance (by Triple hop distance test); and Hip muscle abduction muscle strength (by hand-held dynamometry). Percentage of echo type I was significantly lower while echo type II was higher in the road group compared with the trail group (67.3% type I and 28.9% type II in the road group compared with 74.1% type I and 22.1% type II in the trail group, P < .001). No differences between genders were found and no significant differences between groups were found for the other tests. Tendon integrity as examined with UTC is different between road and trail runners. This suggests an influence of running surface on Achilles tendon structure. This difference was not reflected in other tests, thus the influence of tendon structure on function needs further examination.

Tendon morphological changes after a prolonged ski race can be detected by ultrasound echo intensity

BackgroundUltrasound imaging techniques have been used to assess the characteristics of skeletal muscles and tendons. Such techniques (gray scale analysis) allow qualitative evaluation and have been used recently to assess the internal structure of muscles and tendons by computer-aided gray scale analysis. We hypothesized that changes in the internal structure of the Achilles and patellar tendons after a ski mountaineering race competition could be detected with ultrasound.MethodsTwenty athletes were recruited during the 19th Millet Tour du Rutor extreme, a three-day ski mountaineering competition. Ultrasound measurements of the Achilles and patellar tendons were carried out before the first race and immediately after each of the three competition days. Tendon thickness, cross-sectional area (CSA), and ultrasound gray scale analysis were calculated.ResultsSignificant differences (p < 0.05) were observed between the pre- and post-race measurements for the Achilles tendon thickness and CSA, while no significant differences were noted for the patellar tendon thickness and CSA. However, gray scale analysis of both the Achilles and patellar tendons showed significantly higher post-race values, than the pre-race values (p < 0.05).ConclusionsAchilles and patellar tendons of healthy athletes are highly responsive to an acute increase in mechanical load. Those changes can be detected from classical (thickness and CSA) and innovative (gray scale) ultrasound-based parameters.Trial registrationThis study was approved by the Azienda USL Valle d’Aosta Ethics Committee (protocol no. 23/03/2018.0026243.I).

Reliability of Magnetic Resonance Imaging Prediction of Anterior Cruciate Ligament Autograft Size and Comparison of Radiologist and Orthopaedic Surgeon Predictions.

Background:In anterior cruciate ligament (ACL) reconstruction, hamstring tendon autografts <8 mm have been associated with increased failure rates. There has been no established modality by which orthopaedic surgeons can preoperatively predict graft sizes.Purpose/Hypothesis:The purposes of this study were to (1) determine whether routine magnetic resonance imaging (MRI) measurement of hamstring tendon cross-sectional area (CSA) can reliably be used by sports medicine fellowship–trained orthopaedic surgeons to predict graft size and (2) determine whether radiologists and sports medicine surgeons are able to discriminate grafts below a predetermined cutoff value. We hypothesized that radiologists will find a correlation between MRI measurement and intraoperative graft size. Similarly, orthopaedic surgeons will be able to correctly estimate the graft size based on MRI measurement.Study Design:Cohort study (diagnosis); Level of evidence, 2.Methods:Included in this study were 30 consecutive patients (15 women and 15 men) (mean age, 23 years [range, 13-43 years]) for whom MRI-determined hamstring tendon CSA and graft size measurements could be compared. Patients were included if they had a preoperative MRI demonstrating acute ACL rupture and were scheduled with 1 of 3 surgeons for a reconstruction performed using the ST and GR tendons. Operative data were collected over 1 year. Sectra imaging software was used to measure the CSA of the semitendinosus (ST) and gracilis (GR) tendons on the preoperative MRIs. Control measurements were performed intraoperatively using a graft sizing block with 0.5-mm increments. Simple linear regression analysis was used to evaluate the ability of MRI measurements to predict autograft size. Logistic regression was used to determine the minimum CSA for a graft of 8 mm. The intraclass correlation coefficient (ICC) was used to evaluate interrater reliability.Results:MRI CSA measurement of the average STGR (ST CSA added to the GR CSA) was a significant predictor of graft size (adjusted R 2 = 0.186; P < .001). The 3 measurements with the strongest correlations with graft size were the ST at the medial femoral condyle (MFC), the STGR at the MFC, and the average STGR. The minimum CSA for the average STGR on MRI to achieve a graft size of 8 mm was 17.168 mm2 (P < .001). The area under the receiver operating characteristic curve was 0.765. The overall ICC was 0.977.Conclusion:Routine preoperative MRI can be used by both radiologists and orthopaedic surgeons to predict the expected ACL autograft size and identify those below a cutoff of 8 mm. This will help in preoperative planning and graft selection.

Early development of tendinopathy in humans: Sequence of pathological changes in structure and tissue turnover signaling

Overloading of tendon tissue with resulting chronic pain (tendinopathy) is a common disorder in occupational-, leisure- and sports-activity, but its pathogenesis remains poorly understood. To investigate the very early phase of tendinopathy, Achilles and patellar tendons were investigated in 200 physically active patients and 50 healthy control persons. Patients were divided into three groups: symptoms for 0-1 months (T1), 1-2 months (T2) or 2-3 months (T3). Tendinopathic Achilles tendon cross-sectional area determined by ultrasonography (US) was ~25% larger than in healthy control persons. Both Achilles and patellar anterior-posterior diameter were elevated in tendinopathy, and only later in Achilles was the width increased. Increased tendon size was accompanied by an increase in hypervascularization (US Doppler flow) without any change in mRNA for angiogenic factors. From patellar biopsies taken bilaterally, mRNA for most growth factors and tendon components remained unchanged (except for TGF-beta1 and substance-P) in early tendinopathy. Tendon stiffness remained unaltered over the first three months of tendinopathy and was similar to the asymptomatic contra-lateral tendon. In conclusion, this suggests that tendinopathy pathogenesis represents a disturbed tissue homeostasis with fluid accumulation. The disturbance is likely induced by repeated mechanical overloading rather than a partial rupture of the tendon.

Application of shear wave elastography and B-mode ultrasound in patellar tendinopathy after extracorporeal shockwave therapy.

The purpose of this study was to investigate changes in morphological and elastic properties, as estimated by B-mode ultrasound (B-US) and shear wave elastography (SWE), in volleyball athletes with patellar tendinopathy (PT) and changes after extracorporeal shockwave therapy (ESWT) as well as their relationships with US measurements and Victorian Institute of Sport Assessment-Patella (VISA-P) scores in PT. Twelve healthy athletes (24 patellar tendons) and 31 volleyball athletes with PT (48 tendons) were included. All were examined by US and received VISA-P scores before the start of the study. The athletes received 3months of ESWT and underwent US and VISA-P at 1month and 3months. VISA-P scores were used to evaluate therapeutic efficacy. Tendon thickness and cross-sectional area (CSA) were detected by B-US, and the elastic modulus was measured by SWE. Correlations between VISA-P and US measurements were calculated. Thickness, CSA, and elastic modulus of the patellar tendon in PT were higher than those in healthy athletes (P < 0.000). In PT with ESWT, VISA-P scores decreased by 22.1% (P < 0.000) and thickness decreased by 11.2% relative to baseline (P < 0.000). CSA decreased by 1.4% (P < 0.000). The elastic modulus decreased by 15.2% (P < 0.000). Elastic modulus, thickness, and CSA had significant negative correlations with VISA-P scores (P ≤ 0.005), with a stronger correlation between elastic modulus and VISA-P. Athletes with PT had stiffer and larger tendons than healthy athletes. SWE combined with B-US could clearly show the changes in tendon thickness, CSA, stiffness in PT, and changes after treatment. SWE combined with B-US provided visualization with quantitative, reproducible, and noninvasive imaging in the follow-up evaluation of PT and is worth promoting clinically.

Low-load blood flow restriction training induces similar morphological and mechanical Achilles tendon adaptations compared with high-load resistance training.

Low-load blood flow restriction (LL-BFR) training has gained increasing interest in the scientific community by demonstrating that increases in muscle mass and strength are comparable to conventional high-load (HL) resistance training. Although adaptations on the muscular level are well documented, there is little evidence on how LL-BFR training affects human myotendinous properties. Therefore, the aim of the present study was to investigate morphological and mechanical Achilles tendon adaptations after 14 wk of strength training. Fifty-five male volunteers (27.9 ± 5.1 yr) were randomly allocated into the following three groups: LL-BFR [20-35% of one-repetition maximum (1RM)], HL (70-85% 1RM), or a nonexercising control (CON) group. The LL-BFR and HL groups completed a resistance training program for 14 wk, and tendon morphology, mechanical as well as material properties, and muscle cross-sectional area (CSA) and isometric strength were assessed before and after the intervention. Both HL (+40.7%) and LL-BFR (+36.1%) training induced significant increases in tendon stiffness (P < 0.05) as well as tendon CSA (HL: +4.6%, LL-BFR: +7.8%, P < 0.001). These changes were comparable between groups without significant changes in Young's modulus. Furthermore, gastrocnemius medialis muscle CSA and plantar flexor strength significantly increased in both training groups (P < 0.05), whereas the CON group did not show significant changes in any of the evaluated parameters. In conclusion, the adaptive change in Achilles tendon properties following low-load resistance training with partial vascular occlusion appears comparable to that evoked by high-load resistance training.NEW & NOTEWORTHY Low-load blood flow restriction (LL-BFR) training has been shown to induce beneficial adaptations at the muscular level. However, studies examining the effects on human tendon properties are rare. The findings provide first evidence that LL-BFR can increase Achilles tendon mechanical and morphological properties to a similar extent as conventional high-load resistance training. This is of particular importance for individuals who may not tolerate heavy training loads but still aim for improvements in myotendinous function.

Morphological and functional outcomes of operatively treated Achilles tendon ruptures

ABSTRACT Objectives: Achilles tendon rupture leads to functional impairments and these may be underpinned by morphological changes in the muscle-tendon unit. The functional performance of the injured limb will be impaired regardless of time since surgery and these impairments occur alongside changes in muscle-tendon morphology. Methods: Following operative treatment of Achilles tendon rupture and short-term immobilization, 12 patients completed a battery of tests during a single visit to the laboratory (performed an average of 4.4 ± 2.6 years post-surgery). Patients completed the Achilles’ tendon rupture score (ATRS), tests of the ankle and hip range of motion (ROM) and ultrasound measurements of muscle-tendon architecture. Data on isokinetic (30°/s, 60°/s) plantar flexion strength, jumping performance and walking-running were also collected on the same visit. Percentage deficits were expressed relative to the non-injured limb and determined for statistical significance (p < 0.05). Relationships between outcome measures and time since surgery were tested using Pearson’s correlation coefficients (p < 0.05). Results: The repaired limb showed a shorter muscle fascicle length (12.1–19.6%), increased fascicle pennation (18.0 ± 22.14%) and reduced muscle thickness (9.1–20.1%) in the gastrocnemius and/or soleus along with greater tendon cross-sectional area (46.7 ± 34.47%). Functionally, the repaired limb displayed lower countermovement jump height (−12.6 ± 15.68%) and longer drop jump contact times (5.5 ± 5.7%). Also, the repaired limb showed reduced hip internal-external ROM (6.3 ± 8.2%) but no differences existed between limbs for plantar flexion ROM and strength or gait characteristics. Good ATRS outcomes were reported (mean: 87.9 ± 16.2, range: 43–100) which related to time since surgery (r = 0.79) but individual ATRS items did not correlate with corresponding objective measures. Conclusion: Plantar flexor atrophy following surgically treated Achilles tendon rupture is partially compensated for by remodeling of the fascicles; however, impairments may still persist many years into the postoperative period although these may be more pronounced in high-velocity activities.

Reliability and Validity of Ultrasonography for Measurement of Hamstring Muscle and Tendon Cross-Sectional Area

The purpose of this study was to determine the reliability and validity of ultrasonography for measurement of hamstring muscle and semitendinosus (ST) tendon cross-sectional area (CSA). On two consecutive days, muscle anatomical CSA (ACSA) and ST tendon CSA were measured at standardized positions (30%–80% of thigh length; half the distance from the distal muscle-tendon junction to the popliteal crease) on 12 legs using ultrasonography and compared with corresponding magnetic resonance imaging measures. Inter-day intraclass correlation coefficients were good-to-excellent (0.882–0.996) for all assessed muscle and tendon sites. The limits of agreement widths were narrowest (range: 17%–52%) when muscle ACSA was large but were wide at sites with relatively small ACSA (≤184%) and for ST tendon CSA (range: 72%). Results suggest ultrasound-based measures of individual hamstring muscle maximal ACSA are reliable and valid and ST tendon CSA measures are reliable but require comparison with cadaveric or intra-operative measurements to verify validity.

Effect of metacarpophalangeal joint position on A1 pulley and flexor digitorum tendons in trigger digit.

The aim of this study was to evaluate and compare the cross-sectional area (CSA) of flexor digitorum tendons and the thickness of first annular (A1) pulleys between contralateral normal digits and trigger digits (TDs) at positions of finger flexion and extension using a noninvasive ultrasound system. Seventeen affected fingers of 17 patients (6 men and 11 women) with TDs in one hand, and 17 contralateral normal digits without trigger finger symptoms were examined. The sonographic appearances of flexor digitorum tendons and A1 pulleys were observed at two positions of metacarpophalangeal (MCP) joint flexion: 0° and 60°. The findings of this study indicate that CSA of flexor digitorum tendons and A1 pulley thickness were significantly larger in both positions of 0° and 60° flexion of MCP joint compared with contralateral normal digits (p < 0.01). In TDs, there was a significantly thicker A1 pulley at 60° flexion of MCP joint than that at 0° flexion (p < 0.01), but no significant change on CSA of flexor tendons. Our results suggested that TDs lead to the thicker A1 pulley and larger CSA of the flexor digitorum tendons. The mismatch in volume change between CSA of flexor digitorum tendons and A1 pulley thickness during MCP flexion may lead to the trigger phenomenon.