[Fundamentals, possibilities and limitations of sonography of osteofibrous tunnels in the shoulder area. 2].

In the second part of this study on osteo-fibrous pathways within the shoulder region, new ultrasound (US) possibilities for showing these tunnels are described. Following two pilot studies (clarifying the choice of transducers and frequencies, relevance of US-related measurements), 97 volunteers were investigated bilaterally (57 women and 40 men, aged between 18 and 39). The normal sonoanatomy for areas which had not been explored by US for the most part is demonstrated, as are the limits and pitfalls of this method. Types of scapular notches as determined in part one have been confirmed by US. Type V (with a "partially ossified ligament") was hardly ever found in the sample, whereas a true foramen could not be observed at all. Neither of these have any influence on the development of a "scapular notch syndrome", according to the results of this study. As expected from anatomical observations, a very narrow nerve passage was usually associated with type II ("shallow") and type IV ("V-shaped") scapular notches. These types should be regarded as a potential threat to the suprascapular nerve. When identifying the parameters (16 in all), care was taken to see that they approximated to those of the basic anatomical investigation. There was a good match between measurement results in both parts of this study. In addition, there were no significant differences of data between the two sides (even in the same individual). In contrast, women showed significantly lower values for the following measurements: width and depth of the spinoglenoid notch, width and depth of the intertubercular groove, breadth and thickness of the long head of the biceps brachii, and thickness as well as length of the coracoacromial ligament. Comparable data from the sonographic literature are only available for the long head of the biceps brachii. The calculated mean thickness of this tendon is 2.5 mm, thus being far lower than the results previously reported. Overall, US can be regarded as a very precise and reliable method for evaluating the osteo-fibrous passages within the shoulder region. Normal sonoanatomy and standard values of the structures mentioned can be used as a basis for resolving diagnostic problems. The author considers that US, as a prelude to more sophisticated imaging techniques, provides a significant non-invasive contribution to the checking of pre-existing factors or alterations at an early stage of entrapment syndromes of the shoulder.