Summary

Ultrasound examination provides a low-risk method of examining microvascular changes seen in tendons after injury and during recovery. This study investigates the potential for utilization in future treatment and recovery monitoring.

Abstract

Introduction

Tears to the rotator cuff tendons are among the most common clinical tendon complications in the aging population [1]. Tendons are dense, highly organized, and relatively avascular tissues; however, tendon structural integrity and vascularity decrease with age and may be related to increased injury risk with age [1-3]. Further, tendon vascularity may change in the presence of tendon pathology consistent with acute inflammatory and healing processes such as in response to rotator cuff tears [4,5]. The aim of this study is to examine the microvasculature of the supraspinatus tendon (SSP) and long head of the biceps tendon (LHBT) using an ultrasound technique for superb microvascular imaging (SMI) in asymptomatic, torn, and repaired rotator cuff tendons.

Methods

This prospective study was approved by the institutional IRB and included 18 volunteers with asymptomatic shoulders (55 ± 18 y BMI 22.6 ± 3.0 kg/m2, 7 males), 6 with an unrepaired rotator cuff tear involving the SSP (64 ± 3 y, BMI 24.6 ± 4.1 kg/m2, 5 males, mean 28 months since tear), and 6 who had undergone a rotator cuff repair and biceps tenodesis surgery at least 4 months prior (57 ± 10 y, BMI 25.5 ± 1.5 kg/m2, 5 males, mean 7 months since repair). An ultrasound examination was performed using an Aplio i800 system and an i18LX5 linear array transducer (PLI-1205BX/FS, Canon Medical Systems, Inc.). Two orthopedic surgeons with 6 years of experience with musculoskeletal ultrasonography measured microvasculature in the SSP and proximal LHBT with the SMI mode. The area of the vascular signal (cm2) within the tendons was recorded in both transverse and longitudinal orientations. Correlations between tendon vascular signal and age were assessed for asymptomatic subjects using a Pearson’s correlation coefficient. Differences between asymptomatic, tear, and repair cohorts and between readers were compared using a two-way ANOVA statistical test with a Tukey post-hoc analysis.

Results

There was significantly greater vascular signal in the longitudinal direction of torn supraspinatus (p = 0.036, Figures 1 and 2) and biceps tendons (p = 0.002, Figure 1) compared to asymptomatic and post-operative tendons. There were no differences between groups when vascularity was measured in the transverse direction (SSP p = 0.728, biceps p = 0.264). Correlations could not be found between the age of asymptomatic participants and the vascular signal within the SSP (R = 0.1732, p = 0.5063) and LHBT (R = -0.3594, p = 0.1566) in the longitudinal direction, nor in the transverse direction for the SSP (R = -0.2903, p = 0.2583) or LHBT (R = 0.2498, p = 0.3335).

Discussion

There was minimal vascular signal within asymptomatic tendons. The vascularity signal increased in individuals with unrepaired SSP tears. Approximately 4-8 months following SSP repair and biceps tenodesis, tendon vascularity was not significantly different from asymptomatic tendons. Overall, results suggest that ultrasound techniques that evaluate tendon microvasculature in the absence of contrast agents may represent a low-risk and reliable method to monitor rotator cuff tendons following injury and during recovery. Further investigation will examine if the increased vascularity in the torn state could be a potential target for medication to increase healing rates.
SIGNIFICANCE/CLINICAL RELEVANCE: Ultrasound examination provides a low-risk method of examining microvascular changes seen in tendons after injury and during recovery. This study investigates the potential for utilization in future treatment and recovery monitoring.