The use of ultrasound in the assessment of the glenoid labrum of the glenohumeral joint. Part I: Ultrasound anatomy and examination technique and W. Krzyżanowski, M. Tarczyńska The use of ultrasound in the assessment of the glenoid labrum of the glenohumeral joint. Part II: Examples of labral pathologies.

Abstract

I was very pleased when I received the invitation of the Editors of the “Journal of Ultrasonography” to comment on the articles of Dr Wojciech Krzyzanowski and Dr Marta Tarczynska(1, 2). For the first time, I became familiar with Dr Krzyzanowski's study on the ultrasound imaging of the glenoid labrum of the glenohumeral joint during the clinical and radiological symposium on shoulder diagnostics organized in September 2012 by my medical center in Katowice. The convincing dynamic images of the labrum that I saw during his presentations persuaded me to look through the literature on ultrasound (US) examinations of the labrum with regard to their usefulness in clinical practice. The extraordinary progress of US shoulder diagnostics has made it equally reliable in the recognition of rotator tendon injuries with the magnetic resonance imaging (MRI) which is expensive, time-consuming and uncomfortable for patients. In calcareous degeneration of the tendons the sensitivity and specificity of this imaging method is even superior to MRI. So far, the visualization of the glenoid labrum, whose pathologies constitute the cause of shoulder dysfunctions in a significant number of patients, has not been possible by means of the ultrasound. The first studies on using ultrasonography in the labrum diagnostics were conducted at the end of the 1980s and the latest research was performed at the beginning of the 21st century(3–5). In the subsequent years, this subject was not discussed. Dr Krzyzanowski and Dr Tarczynska decided to verify this avoided issue – is it possible to effectively use ultrasound in the diagnosis of the glenoid labrum injuries of the glenohumeral joint? As a practitioner of shoulder surgery, I am interested not only in the aspect of visualizing the labrum in the ultrasound examination, but above all, in the practical aspect, i.e. the cases in which the labrum US would have a crucial influence on therapeutic decisions. The visualization of the labrum in the case of documented instability in the form of repeated dislocations is of little importance with regard to the diagnosis and therapeutic decision-making. However, when such information has not been obtained during the interview or in the case of other disease entities caused by labrum injuries, a reliable imaging is of great significance. The examples constitute recurrent instability in the form of subluxations, whose direction cannot be determined on the basis of clinical and X-ray examinations, as well as so-called unstable painful shoulder – an entity described by Boileau et al.(6), the authors of internal glenoid impingement syndrome which leads to the damage of posterosuperior labrum in the peel back mechanism. Another example is a specific damage of the posteroinferior labrum which was described by Kim et al.(7) and whose diagnosis may pose difficulties even during arthroscopy due to undamaged superficial and articular part of the labrum. Ultrasound imaging might prove useful in the aforementioned instances as it allows for the visualization of deep layers of the labrum and performance of dynamic examination. Apart from this, it is only an imaging exam which may facilitate the recognition of paralabral cysts and determination of their localizations. Another problematic clinical and diagnostic issue in MR imaging is the injuries of the superior labrum of SLAP type (superior labrum anterior-posterior). In the case of this damage, the outcomes of clinical examination and MRI are similar and equally unsatisfactory. Contrast-enhanced MRI improves the specificity of the diagnostics of superior labrum injuries. One of the factors causing difficulties in imaging diagnostics of pathologies in this part of the labrum is surely a considerable variability of its anatomy. Even during arthroscopy, after filling the glenohumeral joint with fluid, the operator is not able to differentiate between type II SLAP injury and normal meniscoid variant without joint mobilization with the use of a hook probe. The possibility of dynamic US imaging gives a chance to improve the diagnostics in comparison with static US or MRI, even after administration of a contrast medium. In their study, the authors prove that a large part of the labrum and its pathologies may be visualized on ultrasound when proper technique is used. This is not a popular view since currently MRI and MRA are used as routine imaging methods of labrum pathologies. No reliable research results have been published concerning the value and repeatability of the US diagnosis of labrum injuries. Determining the sensitivity and specificity of ultrasound for both particular parts of the labrum and different types of labral injuries, thus determining its clinical usefulness, by means of prospective research associated with arthroscopic verification would certainly be an essential and logical continuation of these quite interesting articles.