Characterising the proximal patellar tendon attachment and its relationship to skeletal maturity in adolescent ballet dancers

Effect of sex on muscle-tendon imbalances and tendon micromorphology in adolescent athletes-A longitudinal consideration

Imbalances between muscle strength and tendon stiffness may cause high-level tendon strain during maximum effort muscle contractions and lead to tendon structural impairments and an increased risk for tendinopathy in adolescent athletes. However, it remains unclear whether the development of musculotendinous imbalances is influenced by sex. At four measurement time points during a competitive season, we measured quadriceps femoris muscle strength and patellar tendon mechanical properties in 15 female (14.3 ± 0.7 years) and 13 male (16.0 ± 0.6 years) elite handball players of similar maturity using dynamometry and ultrasonography. To estimate the tendon's structural integrity, the peak spatial frequency (PSF) of proximal tendon ultrasound scans was determined. Females demonstrated significantly lower muscle strength (p < 0.001) and patellar tendon stiffness (p < 0.001) than males with no significant changes over time (p > 0.05). Tendon strain during isometric maximum voluntary contractions and PSF neither differed between sexes nor changed significantly over time (p > 0.05). We found lower fluctuations in muscle strength (p < 0.001) in females during the season but no differences in the fluctuations of tendon strain, stiffness, and PSF (p > 0.05). Descriptively, there was a similar frequency (~40%) of athletes with high-level tendon strain (>9%) in both sexes. These findings suggest that the lower strength capacity of female athletes is paralleled by lower tendon stiffness. Thereby, muscle-tendon imbalances occur to a similar extent in both sexes leading to increased strain levels during the season, which indicates the need for specific tendon training.

The mid-term effect of Osgood-Schlatter disease on knee function in young players from elite soccer academies

BACKGROUND

The aim of the study was to evaluate the effect of Osgood-Schlatter disease (OSD) on knee joint function in elite young soccer players. Our hypothesis was that knee joint function in elite young soccer players was impaired following OSD compared with soccer players with no history of OSD.

METHOD

In young male soccer players (n = 36) from elite academies (mean ±SD, age: age: 15,3 ± 1,7 years; height: 1,7 ± 0,06 m; weight: 63,5 ± 8 kg; BMI: 20,7 ± 2). The duration between the completion of treatment or the last complaint to the study commencement was 31 ± 19 months.

RESULTS

The average treatment duration of OSD among study participants was 18,5 ± 12 days (95%, 14-23), and the disease most often manifested in winter and spring, 33% and 31% of cases, respectively. Soccer players with a history of OSD were statistically different in IKDC and KOOS scores when compared with soccer players with no previously reported OSD (Mann-Whitney, p < 0,0001). The soccer players with a history of OSD also use NSAIDs more frequently compared with soccer players with no history of OSD (36% vs 3% respectively).

CONCLUSIONS

OSD among young soccer players, when symptoms resolve, continue about one month and they can return to regular training and participation in games. Wherein, the negative effects in knee joint function were significantly more likely in soccer players with previous OSD history when compared with their peers with no history of OSD. While oral non-steroidal anti-inflammatory drugs was also more widely employed in soccer players with previous OSD history. Potentially this may lead to performance deficits and disadvantages for their future careers and coaches and physicians should be informed.

Proximal patellar tendon abnormalities on ultrasound can develop in male adolescent basketball players: A longitudinal study

INTRODUCTION

Adolescent patellar tendinopathy is reported but the pubertal-stage of onset of abnormal tendon structure has not been investigated with grayscale ultrasound.

AIMS

To investigate abnormal tendon structure using grayscale ultrasound and its association with pubertal-stage and pain.

METHODS

Forty-three male basketball players aged 13.7 years (SD 1.0) had patellar tendon ultrasound scans every 6 months for 2.5 years. Pubertal-stage (peak height velocity) was calculated using the Mirwauld equation. Tendon thickness, hypoechogenicity and pain during single leg decline squat (SLDS) were recorded. Tendons were classified: hypoechoic, normal or immature.

RESULTS

Two tendons were hypoechoic at baseline. Six developed hypoechogenicity over 2.5 years (eight tendons [9%], six participants [14%]), all in peri and post-PHV players. Twenty-six tendons (17 participants) were classified as immature during the study. Hypoechoic tendons were thicker (5.3 mm SD 1.2) than normal (3.9 mm SD 0.7) tendons (p < 0.001). There was no difference in the proportion of participants reporting pain during SLDS in the hypoechoic (N = 3) and normal (N = 11) groups (p = 0.33), or in hypoechoic tendon thickness between those reporting pain (6.5 mm, SD 1.7) or not (5.2 mm, SD 0.9, p = 0.17).

DISCUSSION

This study using grayscale ultrasound found that basketball players with hypoechogenicity were peri or post-PHV. Abnormal structure was not always associated with pain.

Nearly 40% of adolescent athletes report anterior knee pain regardless of maturation status, age, sex or sport played

OBJECTIVE

To report point prevalence of anterior knee pain (AKP) in adolescent athletes by (1) maturation status, (2) chronological age, (3) sex, and (4) primary sport.

DESIGN

Cross-sectional.

METHODS

Male and female participants aged 11-15 years were recruited from specialised sports programs for basketball, volleyball, Australian Rules Football and tennis. Standing height, sitting height, and body mass were measured and used to calculate maturity status. Past injury history, self-reported physical activity, and Victorian Institute of Sport Assessment Questionnaire Patellar Tendon (VISA-P) questionnaires were completed. Anterior knee pain was defined as any pain experienced on the anterior surface of the knee and recorded using a visual analogue scale (VAS). A single leg decline squat (SLDS) was performed for provocation of AKP.

RESULTS

Two hundred and seventeen male and female adolescent athletes participated in this study. Twenty participants were excluded from data analysis. Point prevalence of AKP was 39% (N = 76). Average self-reported physical activity/week was 7.9 ± 4.1 h of their specialised sport and 2.0 ± 2.0 h of other physical activity/week. Maturation status, chronological age, sex nor primary sporting program was statistically significant in explaining the presence or absence of AKP.

CONCLUSION

Due to the right-skewed maturation sample, the authors cannot state conclusively that maturation status was not associated with AKP. Nearly 40% of this cohort reported AKP during a pain provocation test. The presence of AKP was not explained by maturation status, age, sex or primary sport program. Given the chronic nature of AKP and future morbidity reported, this high prevalence provides rationale for intervention or prevention studies targeting younger athletes.

Substantiating the Use of Ultrasound Tissue Characterization in the Analysis of Tendon Structure: A Systematic Review

OBJECTIVE

To determine the role of ultrasound tissue characterization (UTC) in predicting, diagnosing, and monitoring tendon structure and/or tendinopathy. In addition, this study aims to provide recommendations for standardized methodology of UTC administration and analysis.

DATA SOURCE

The PubMed, Embase, and Web of Science databases were searched (up to September 2018). All scientific literature concerning the use of UTC in assessing tendons was collected. The initial search resulted in a total of 1972 hits, and after screening by eligibility criteria, 27 articles were included.

RESULTS

In total, 18 investigating the Achilles tendon, 5 the patellar tendon, and 4 both Achilles and patellar tendons were included. The methods of UTC administration and analysis differed and were not uniform. The studies showed that the use of UTC to predict Achilles tendinopathy (AT) is inconclusive, but that a higher amount of tendon disorganization increases the risk of developing patellar tendinopathy (PT). In terms of diagnosis, UTC might provide additional information in AT cases. In addition, promising results were found for the use of UTC in both AT and PT in monitoring the effect of load or treatment on tendon structure.

CONCLUSION

More research regarding the use of UTC in predicting tendon pathology is required. Ultrasound tissue characterization seems useful as an adjunct diagnostic modality because it can be used to differentiate symptomatic from asymptomatic tendons. In addition, UTC is a promising device to be used to monitor changes in tendon structure in response to load or treatment. Moreover, we provide recommendations of a standardized protocol concerning the methods of UTC measurement and analysis.

Morphological and Mechanical Properties of the Quadriceps Femoris Muscle-Tendon Unit From Adolescence to Adulthood: Effects of Age and Athletic Training

The combined effects of mechanical loading and maturation during adolescence are still not well understood. The purpose of the study was to investigate the development of the quadriceps femoris muscle-tendon unit from early adolescence (EA), late adolescence (LA) to young adulthood (YA), and examine how it is influenced by athletic training in a cross-sectional design. Forty-one male athletes and forty male non-athletes from three different age groups (EA: 12-14 years, n = 29; LA: 16-18 years, n = 27; and YA: 20-35 years, n = 25) participated in the present study. Maximum strength of the knee extensor muscles, architecture of the vastus lateralis (VL) muscle and patellar tendon stiffness were examined using dynamometry, motion capture, electromyography, and ultrasonography. Muscle strength and tendon stiffness significantly increased (p < 0.001) from EA to LA without any further alterations (p > 0.05) from LA to YA. Athletes compared to non-athletes showed significantly greater (p < 0.001) absolute muscle strength (EA: 3.52 ± 0.75 vs. 3.20 ± 0.42 Nm/kg; LA: 4.47 ± 0.61 vs. 3.83 ± 0.56 Nm/kg; and YA: 4.61 ± 0.55 vs. 3.60 ± 0.53), tendon stiffness (EA: 990 ± 317 vs. 814 ± 299 N/mm; LA: 1266 ± 275 vs. 1110 ± 255 N/mm; and YA: 1487 ± 354 vs. 1257 ± 328), and VL thickness (EA: 19.7 ± 3.2 vs. 16.2 ± 3.4 mm; LA: 23.0 ± 4.2 vs. 20.1 ± 3.3 mm; and YA: 25.5 ± 4.2 vs. 23.9 ± 3.9 mm). Athletes were more likely to reach strain magnitudes higher than 9% strain compared to non-athlete controls (EA: 28 vs. 15%; LA: 46 vs. 16%; and YA: 66 vs. 33%) indicating an increased mechanical demand for the tendon. Although the properties of the quadriceps femoris muscle-tendon unit are enhanced by athletic training, their development from early-adolescence to adulthood remain similar in athletes and non-athletes with the major alterations between early and LA. However, both age and athletic training was associated with a higher prevalence of imbalances within the muscle-tendon unit and a resultant increased mechanical demand for the patellar tendon.

Patellar Tendon Strain Associates to Tendon Structural Abnormalities in Adolescent Athletes

High mechanical strain is thought to be one of the main factors for the risk of tendon injury, as it determines the mechanical demand placed upon the tendon by the working muscle. The present study investigates the association of tendon mechanical properties including force, stress and strain, and measures of tendon micromorphology and neovascularization, which are thought to be indicative of tendinopathy in an adolescent high-risk group for overuse injury. In 16 adolescent elite basketball athletes (14–15 years of age) we determined the mechanical properties of the patellar tendon by combining inverse dynamics with magnetic resonance and ultrasound imaging. Tendon micromorphology was determined based on a spatial frequency analysis of sagittal plane ultrasound images and neovascularization was quantified as color Doppler area. There was a significant inverse relationship between tendon strain and peak spatial frequency (PSF) in the proximal tendon region (r = −0.652, p = 0.006), indicating locally disorganized collagen fascicles in tendons that are subjected to high strain. No such associations were present at the distal tendon site and no significant correlations were observed between tendon force or stress and tendon PSF as well as between tendon loading and vascularity. Our results suggest that high levels of tendon strain might associate to a micromorphological deterioration of the collagenous network in the proximal patellar tendon, which is also the most frequent site affected by tendinopathy. Neovascularization of the tendon on the other hand seems not to be directly related to the magnitude of tendon loading and might be a physiological response to a high frequency of training in this group. Those findings have important implications for our understanding of the etiology of tendinopathy and for the development of diagnostical tools for the assessment of injury risk.

Patellar tendon structure responds to load over a 7-week preseason in elite male volleyball players

The purpose of this study was to investigate the relation between external and internal load and the response of the patellar tendon structure assessed with ultrasound tissue characterization (UTC) in elite male volleyball players during preseason. Eighteen players were followed over 7 weeks, measuring four load parameters during every training and match: volume (minutes played), rating of perceived exertion (RPE) (ranging from 6 to 20), weekly load (RPE*volume), and jump frequency (number of jumps). Patellar tendon structure was measured biweekly using UTC, which quantifies tendon matrix stability resulting in four different echo types (I‐IV). On average, players spent 615 min/wk on training and matches with an RPE of 13.9 and a jump frequency of 269. Load evaluation shows significant changes over the 7 weeks: Volume and weekly load parameters were significantly higher in week 3 than week 7 and in week 4 than week 2. Weekly load performed in week 4 was significantly higher than week 7. No significant changes were observed in tendon structure. On the non‐dominant side, no significant correlations were found between changes in load parameters and echo types. At the dominant side, a higher weekly volume and weekly load resulted in a decrease of echo type I and a higher mean RPE in an increase of echo type II. The results of this study show that both external and internal load influence changes in patellar tendon structure of elite male volleyball players. Monitoring load and the effect on patellar tendon structure may play an important role in injury prevention.

Therapeutic interventions in children and adolescents with patellar tendon related pain: a systematic review

Objective

Evaluate effectiveness and harms of interventions for patellar tendon related pain in children and adolescents.

Design

Systematic review and meta-analysis.

Data sources

Medline via Pubmed, Embase via OVID, CINAHL via Ebsco, SportDiscus up until 24 November 2017 were searched.

Eligibility criteria for selecting studies

Inclusion criteria were (1) controlled or randomised controlled clinical trials (RCTs), (2) participants with diagnosis of patellar tendon related disorder, (3) participants≤18 years of age at enrolment and (4) published in a peer-reviewed English or Scandinavian language journal.

Results

Of 530 studies identified, eight were included after screening, with three included in data synthesis. To be included in data synthesis, we required studies to have included (and have data available for) a minimum of 10 participants under 18 years. All studies were rated as being at high risk of bias. For adolescents with patellar tendinopathy, one RCT compared eccentric exercises to usual care and found no difference between groups. In adolescents with Osgood-Schlatter disease (OSD), injection of local anaesthetic with dextrose proved superior to either usual care or local anaesthetic alone (three armed RCTs). In a retrospective case controlled study in adolescents with OSD, surgery provided no benefit over conservative management in terms of persistent symptoms and had a higher complication rate.

Conclusion

There is weak evidence to support the use of dextrose injection with local anaesthetic and no evidence to support the use of specific types of exercises to treat children/adolescents with OSD/patellar tendinopathy. Until further evidence arises, clinicians should include load modification and advise on a return to sport based on symptoms.

Quantifying proximal patellar tendon changes during adolescence in elite ballet dancers, a 2-year study

Patellar tendon pathology appears to develop in young athletes. It is not known how this tendon develops through adolescence. This longitudinal study investigated proximal patellar tendon development during the adolescent growth spurt in young ballet dancers and identified whether puberty (estimated by maturity offset) had an effect on tendon development. Fifty two dancers (32 female and 20 male dancers, ages 11-18 at baseline) had ultrasound images of their tendons every 6 months for 2 years. Changes in tendon size (anterior-posterior diameter) on grayscale images and echogenicity, as quantified using ultrasound tissue characterization, were recorded each time. Maturity offset was calculated used to estimate peak height velocity (adolescent growth spurt). Maturity offset did not affect effect tendon composition before peak height velocity; however, after participants passed peak height velocity, maturity offset increased the composition of stable echopattern (P < .05): a 4% differential increase in type I echopattern, indicative of normal tendon structure, and a decrease in type III echopattern (more disorganized echopattern) by 0.7% per year. Anterior-posterior thickness increased by 0.2 mm/y (P < .05) measured 2 cm below the patella. Following peak height velocity, the proximal patellar tendon attachment increased in thickness and demonstrated a more stable echopattern representative of aligned fibrillar structure. Future research is required to further understand this normal maturation and the factors that support this process, with the aim of reducing the development of patellar tendon pathology in the adolescent jumping athlete.

Proximal patellar tendon pathology can develop during adolescence in young ballet dancers-A 2-year longitudinal study

Patellar tendinopathy (tendon pain and dysfunction), or jumper's knee, is prevalent in adult jumping athletes. Pathology in the proximal patellar tendon is a key risk factor for developing patellar tendinopathy. When pathology develops in the proximal patellar tendon is not known, although it is reported to exist in adolescent athletes. The aim of this study was to follow young jumping athletes (ballet dancers) through adolescence to identify whether pathology develops and its relation to the adolescent growth spurt. Fifty-seven elite ballet students between ages 11 and 18 were monitored for 2 years. Data were collected every 6 months, including an ultrasound scan on their left tendons using ultrasound tissue characterization (UTC) to quantify intratendinous changes, anthropometric data to calculate peak height velocity (adolescent growth spurt), participant reports of any injuries or dance modifications, and a VISA-P and single leg decline squat for patellar tendon pain. Nine percentage of adolescent dancers developed pathology during this study, and development was not associated with growth spurt. Peak height velocity and dance participation/volume both at the start and throughout the study were similar in those who did develop pathology and those who did not. Only 2 of 5 participants who developed pathology reported pain associated with their tendon. Pathology in the proximal patellar tendon can develop during adolescence.