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

Relationship between compressive stiffness and tensile stiffness in the human Achilles tendon in vivo

BACKGROUND

Tendon elongation is measured using ultrasound images during isometric ramp contractions in traditional measurement techniques for human tendon mechanical properties, and tendon tensile stiffness (TS) is calculated from the slope of specific force intervals in the tendon force-elongation curve. Recently, the compressive stiffness (CS) of tendons, measured using a myotonometer, has attracted attention as a new technique for investigating tendon mechanical properties in vivo. This study aimed to clarify the relationship between tensile and compressive Achilles tendon stiffness in vivo.

METHODS

Thirty young healthy adults (20.7 ± 18 years) participated in this study. TS was measured using B-mode ultrasonography and a dynamometer and calculated from the slope of the specific force intervals (25-45%, 30-70%, 50-100%, and 90-100% maximum voluntary contraction) in the tendon force-elongation curve. CS in the resting condition was measured at 3, 4, 5, 6, and 7 cm proximal to the calcaneus Achilles tendon insertion. The data obtained from each measurement region, as well as the average of those data, were used for further correlation analysis. The relationship between TS and CS was evaluated using Spearman rank correlation coefficient.

RESULTS

Correlation analysis demonstrated no relationship between TS and CS regardless of the force intervals in TS (r = - 0.019-0.251, P = 0.181-0.980).

CONCLUSION

The current results suggest that each measurement technique for the TS and CS evaluates different tendon mechanical properties. Researchers and clinicians should consider the characteristics of these two measurement techniques and select the appropriate method depending on the research purpose.

Prognostic value of ultrasound tissue characterisation for a recurrence of mid-portion Achilles tendinopathy in military service members: a prospective cohort study

INTRODUCTION

Tendon structure in mid-portion Achilles tendinopathy (mid-AT) appears poorly associated with symptoms. Yet, degenerative tendon changes on imaging have been associated with an increased risk of mid-AT. We aimed to investigate the prognostic value of ultrasound tissue characterisation (UTC) for a mid-AT recurrence in service members reporting to be recovered following standard care.

METHODS

Mid-portion aligned fibrillar structure was quantified post-treatment in 37 participants. Recurrences were determined after 1 year of follow-up, based on self-perceived recurrence (yes/no) combined with a decrease in post-treatment Victorian Institute of Sports Assessment-Achilles score of at least the minimal important change of 7 points. Receiver operating characteristic curve analyses were used to determine a threshold for dichotomisation of outcomes for aligned fibrillar structure (normal representation/under-representation). Using multivariable logistic regression, the association between a mid-AT recurrence (yes/no) and the dichotomised aligned fibrillar structure was determined.

RESULTS

Eight participants (22%) experienced a recurrence. The threshold for aligned fibrillar structure was set at 73.2% (95% CI: 69.4% to 77.8%) according to Youden's index. Values below this threshold were significantly associated with a mid-AT recurrence (odds ratio (OR) 9.7, 95% CI: 1.007 to 93.185). The OR for a mid-AT recurrence was 1.1 (95% CI: 1.002 to 1.150) for each additional month of symptom duration. The explained variance of our multivariable logistic regression model was 0.423; symptom duration appeared to be a better predictor than aligned fibrillar structure.

CONCLUSIONS

This study identified mid-portion aligned fibrillar structure and symptom duration as potential prognostic factors for a mid-AT recurrence in military service members. The threshold for aligned fibrillar structure of 73.2% can guide preventative interventions (eg, training load adjustments or additional tendon load programmes) aiming to improve tendon structure to minimise the future recurrence risk.

TRIAL REGISTRATION NUMBER

https://www.toetsingonline.nl/to/ccmo_search.nsf/Searchform?OpenForm, file number ToetsingOnline NL69527.028.19.

Tendon structure, clinical tests, and pain during-loading in young female competitive gymnasts

To examine the relationship between Achilles-tendon (AT) and patellar-tendon (PT) structure, clinical-examination and tendon pain in young gymnasts; and, to explore the associations between these factors and age, maturation, and training-load. Two hundred and seventy-four female gymnasts (aged 12.1±1.9 yrs) were assessed for anthropometric measures, pubertal-stage, and training-load. They had clinical-tests (pain-on-palpation for AT and pain-on-palpation and Royal-London Hospital-Test for PT), were asked about tendon-pain during-loading and were assessed for tendon-structure. Gymnasts with positive clinical-tests (with and without pain during-loading) presented a significantly higher prevalence of disorganized AT and PT compared to gymnasts with negative clinical-tests (with and without pain during-loading) (p<0.05). A significant pubertyXpositive clinical-test interaction was found for disorganized PT structure, whereby a disorganized structure was more prevalent among post-pubertal gymnasts with positive clinical-tests compared to pre-pubertal participants with negative clinical-tests (F(1, 263)=9.436, p=0.002). In gymnasts with positive clinical-tests, significant correlations were found between disorganized AT and PT structures and age, and training-load (p<0.05). An increased prevalence of disorganized tendon structure (regardless of pain during-loading) was seen in participants with positive clinical-tests. This disorganized tendon-structure was found to be significantly related to increased age, post-pubertal stage, and higher training hours in gymnasts with positive clinical-tests.

Intra- and Inter-Rater Reliability of Processing Ultrasound Tissue Characterization Scans in Midportion Achilles Tendinopathy

Purpose

Ultrasound tissue characterization (UTC) is used to visualize and quantify the Achilles tendon structure. We investigated the intra-rater and inter-rater reliability of UTC for quantifying the midportion tendon structure and the area of maximum degeneration (AoMD) in military personnel with midportion Achilles tendinopathy.

Method

UTC scans of 50 patients (16-60 years) were processed twice by rater 1 and once by rater 2. First, the midportion tendon structure was quantified and subsequently the AoMD. The intraclass correlation coefficient (ICC) was calculated for echo-types I, II, III, IV, aligned fibrillar structure (echo-types I + II), and disorganized tendon structure (echo-types III + IV).

Results

For midportion tendon structure, all ICC values were excellent for intra-rater reliability (range: 0.97 to 0.99) and inter-rater reliability (range: 0.98 to 0.99). Regarding the AoMD, intra-rater reliability showed excellent ICC values for all echo-types (range: 0.94 to 0.98) except for echo-type II (0.85). Inter-rater reliability showed excellent ICC values for all echo-types (range: 0.92 to 0.98).

Conclusion

Processing of UTC scans is highly reliable in quantifying the midportion Achilles tendon structure and the AoMD.