Repeatability of ultrasound in assessment of distal biceps brachii tendon

Abstract

Objective: Examine the repeatability of ultrasound imaging for capturing cross sectional area (CSA), tendon length and elongation of the distal biceps brachii (dBB) tendon at rest and during submaximal elbow flexion contractions. The secondary purpose was to assess the influence of these architectural measures on tendon mechanics of stress and strain. Methods: Within a testing session and between two days CSA, tendon length and elongation of the dBB were captured with ultrasound. Measures were compared within a session and between days. Pearson's correlations were performed to determine the intra-class correlation coefficients. Bland and Altman plots were used to identify the agreement between measures as well as the bias in measurements. Paired T-test were performed to ensure the calculated variables did not differ between days. Results: Resting tendon CSA was repeatable and strongly correlated (r = 0.98) within a session and between days; however, modest differences were observed in resting tendon length between days (∼1.8 mm) although values were correlated (r = 0.98). During submaximal contractions of 10%-80% maximal tendon elongation (r = 0.83) and CSA (r = 0.98) were also repeatable. From the measures of elongation and CSA, the calculated values of tendon strain (r = 0.97) and stress (r = 0.96) were also repeatable. Conclusions: Elongation and CSA of the dBB tendon captured with ultrasound are repeatable between testing sessions. From these measures tendon mechanics can be calculated to define the tendon's role in upper limb tasks, long-term adaptation and diagnostics.

Influence of biceps brachii tendon mechanical properties on elbow flexor force steadiness in young and old males

“…By reducing the CSA of the tendon through which force is transmitted, leading to increased levels of stress, low forces can be more accurately transferred from the muscle to the bone via the tendon, resulting in the increased stress predicting reduced CV of force at low force levels. In response to the increased load at high forces, increased elongation of the tendon led to further reductions in CSA and higher tendon stress . Due to this reduction in CSA, the tendon may not be able to distribute and transmit the added force in a controlled manner, leading to the elevated stress levels predicting increased CV of force for both young and old at higher forces.…”

“…The hyperechoic marker was measured from the edge of the screen to ensure probe shift did not occur during the contraction. Measures of tendon elongation and CSA of the distal BB tendon are repeatable within and between testing sessions …”

“…As a decrease in strength is associated with reduced tendon stiffness and postural balance, and because the tendon is integral to transferring force from muscle to bone, it is likely that age‐related changes in absolute strength will alter distal biceps brachii (BB) tendon mechanics and contribute to reductions in elbow flexor FS. To date, there has been minimal consideration of distal BB tendon properties, and their functional contribution to age‐related decline in FS remains unidentified. Thus, we sought to determine the influence of mechanical properties of the distal BB tendon on submaximal isometric elbow flexor FS in young and old males.…”

Resting Tendon Cross-Sectional Area Underestimates Biceps Brachii Tendon Stress: Importance of Measuring During a Contraction

“…Participants were seated in a custom-built isometric dynamometer chair (Brown et al, 2010 ; Harwood et al, 2010 ; Smart et al, 2017 , 2018a , b ) with their right arm positioned at 110° of elbow flexion (full extension being 180°), the shoulder forward flexed 15°, and the right hand grasping the manipulandum with the wrist in a neutral position halfway between full supination and pronation. The force transducer (MLP-150, Transducer Techniques, Temecula, CA, USA) was located directly below the hand.…”

“…This experimental approach is appealing, as resting CSA measures are relatively easy to acquire (Stenroth et al, 2012 ; Eriksen et al, 2018 ). Since the tendon CSA decreases as the applied force increases (Vergari et al, 2011 ; Obst et al, 2014b ; Smart et al, 2018b ), utilizing this singular resting CSA measure for all the contraction intensities likely underestimates the tendon stress, and the magnitude of the underestimation is likely greater at higher relative forces when the decrease in tendon CSA is the greatest (Smart et al, 2017 , 2018a , b ). Therefore, applying resting CSA in the calculation of tendon stress fails to account for the dynamic nature of the tendon and likely misrepresents the true amount of stress experienced by the tendon across various force levels.…”