Anatomical basics, variations, and degenerative changes of the shoulder joint and shoulder girdle

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Abstract

This paper summarizes the anatomical basics of the shoulder, their variations, and precise definitions, including differential diagnoses. It also describes the characteristic degenerative changes caused by aging. A typical variation (7–15%) is the os acromiale, which forms the triangular epiphysis of the scapular spine. This abnormality must be differentiated from a fracture of the acromion or a pseudarthrosis. Because ossification of the acromion is complete after age 25, the os acromiale should be diagnosed only after this age. The shape of the acromion is a further important feature. In a recent anatomical study, the following frequencies of the Bigliani-types of the acromial shape were anatomically determined — type 1 (flat), 10.2% and type 2 (curved), 89.8%. Type 3 (hooked) was not observed, which indicates that this type is probably a misinterpretation of the so-called acromial spur. Minor dehiscences and perforations in the infraspinate or supraspinate fossa should not be confused with malignant osteolyses. The scapula has three ligaments of its own, (1) the coracoacromial ligament and its osseous fixations form an osteofibrous arch above the shoulder joint, which plays a part in impingement syndrome; (2) the superior transverse scapular ligament or its ossified correlate arches the scapular incisure and can cause a typical compression syndrome of the suprascapular nerve; (3) the inferior transverse scapular ligament is of no great clinical importance. Two intraarticular structures (glenoid labrum and tendon of the long bicipital head) must be mentioned. The glenoid labrum consists of dense connective tissue and surrounds the margin of the glenoid cavity. Two areas exhibit specialized conditions, cranial at the supraglenoid tubercle an intimate relationship exists to the tendon of the long bicipital head and in about 55% of cases, the labrum is stretched over the glenoid rim at the ventral side. At the area of the biceps-tendon-labrum complex, so-called SLAP-lesions may occur and at the glenoid rim, where the labrum is often not fixed to the bony margin, avulsions of the labrum may occur. This well-established anatomical condition must not be mistaken for a manifest Bankart-lesion. The glenohumeral ligaments, which are located in the ventral articular capsule, have a stabilizing function for the ventral part of the glenoid labrum. The glenohumeral ligaments lift the articular lip where it crosses the glenoid notch. This ‘labrum-lift effect’ supports the stabilizing features of the articular lip and the glenohumeral ligaments. The rotator cuff is composed of the tendons of the teres minor, infraspinatus, supraspinatus, and subscapularis muscles. This cuff has a poorly vascularized area, due to mechanical conditions, about 1.5 cm from the major tubercle, which causes degenerative changes and eventually may lead to ruptures. Results of the impingement-syndrome and the osteoarthrotic changes of the shoulder and acromioclavicular joint are also presented and discussed. Finally, the coracoclavicular joint, which probably represents no congenital entity but appears due to a changed, lowered position of the shoulder girdle, is discussed. The paper also presents instructive figures of anatomical preparations that can be used to make more precise radiological and differential diagnoses. All preparations were done by the author and are part of a series of more than 300 preparations of the shoulder joint and girdle.

Introduction

The upper extremity is articulated with the shoulder girdle in the shoulder joint. The only osseous connection to the trunk is the sternoclavicular articulation. Both, this joint and the acromioclavicular joint, are developmentally appositional articulations. Therefore, both joints contain a fibrocartilaginous disc and fibrocartilaginous articular surface. The shoulder joint provides the upper extremity with an almost unrestricted radius of action, but this freedom of movement makes the anatomical structures of the shoulder very vulnerable. Therefore, the shoulder joint demands close attention by orthopedic surgeons and traumatologists, and especially by radiologists, who now have the technology to image and interpret morphological details with unprecedented precision. This paper focuses on the anatomical essentials, their variations, and changes due to aging and posttraumatic events.

Section snippets

Clavicula

This short tubular bone is s-shaped. Variations on this normal shape, including extreme curvature and almost straight bones, are also within the normal range of the clavicle [1] (Fig. 1). These different ranges of curvature can produce impressions of condensations and thickening in the X-ray image. The medial end of the clavicle, the sternal extremity, has a round cross section that can become enlarged and formed like a pestil with excessive physical strain, while the acromial part is flattened

Proximal part of humerus

The hemispheric humerus head (caput humeri) is demarcated against the shaft by the anatomical neck (collum anatomicum) and bears the 20–30 cm2 articular surface. Several nutrient foramina are located in the anatomical neck, which supply the humerus head with blood. The poor healing process of fractures located medial to the anatomical neck (type II, according to Neer), which often results in pseudarthoses, is a direct result of this anatomical feature. The bicipital groove (sulcus

Acromioclavicular joint

The acromioclavicular joint, categorized as a plane joint, develops as an apposition joint and, therefore, has a rudimentary articular disc and fibrocartilaginous-covered articular facets (Fig. 12a). In rare cases, the articular disc ossifies, forming an acromioclavicular intercalate ossicle [12], [41]. The articular surfaces are normally smooth, oval in shape, and distinctly confined. Curved surfaces can sometimes be found beside the plane articular forms [12]. It is important that the

Acromioclavicular joint

The articular bodies of the acromioclavicular joint develop degenerative changes with increasing age, comparable to osteoarthrosis of the large joints. The effects of the sclerosing and grinding processes of the articular facets and the occurrence of subchondral cysts, which are responsible for the pumice-stone like aspect, are particularly apparent. More severe levels of osteoarthrosis can lead to deformations of the articular structures, which lose their normal shape and appear to be rolled

References (70)

  • L.U Bigliani et al.

    The relationship of acromial architecture to rotator cuff disease

    Clin. Sports Med.

    (1991)
  • I Kolts et al.

    The structure and vascularization of the biceps brachii long head tendon

    Ann. Anat.

    (1994)
  • A Ravelli

    Über die Torsion und die Frontalkrümmung des Schlüsselbeines

    Anat. Anz.

    (1955)
  • W Gruber

    Ueber das Tuberculum deltoideum und den Processus deltoideus des Schlüsselbeines

    Arch. Anat.

    (1871)
  • E Fischer

    Tubercula für Muskel- und Bandansätze am Schlüsselbein

    Röfo

    (1958)
  • L.F Dos Santos

    The vascular anatomy and dissection of the free scapular flap

    Plast. Reconstr. Surg.

    (1984)
  • E Fischer

    Lochförmiger Defekt im Schulterblatt

    Fortschr. Röntgenstr.

    (1957)
  • H.V Vallois

    Variations de l’echancrure coracoı̈dienne de l’omoplate

    Bull. Soc. Anthropol. Paris

    (1926)
  • A Hrdlička

    The scapula: visual observations

    Am. J. Phys. Anthropol.

    (1942)
  • A Hrdlička

    The adult scapula

    Am. J. Phys. Anthropol.

    (1942)
  • M.B Grundlagen

    Möglichkeiten und Grenzen der Sonographie osteofibröser Kanäle im Schulterbereich Teil 1

    Ann. Anat.

    (1997)
  • M.B Grundlagen

    Möglichkeiten und Grenzen der Sonographie osteofibröser Kanäle im Schulterbereich Teil 2

    Ann. Anat.

    (1997)
  • J Zeiss et al.

    MRI of suprascapular neuropathy in a weight lifter

    J. Comput. Assist. Tomogr.

    (1993)
  • R Fick

    Handbuch der Anatomie des Menschen. Bd II, 1. Abt., 1. T. 1: Handbuch der Anatomie und Mechanik der Gelenke

    (1904)
  • A Macalister

    Notes on the acromion

    J. Anat. Physiol.

    (1892)
  • W Pfitzner

    Beiträge zur Kenntnis des Menschlichen Extremitätenskelets. VIII: die morphologischen Elemente des menschlichen Handskelets

    Morphol. Anthropol.

    (1900)
  • J Symington

    On separate acromion process

    J. Anat. Physiol.

    (1900)
  • Cruveilhier J. Traité d’anatomie descriptive. Paris,...
  • A Lilienfeld

    Über das Os acromiale und seine Beziehungen zu den Affektionen der Schultergegend

    Fortschr. Röntgenstr.

    (1914)
  • W Schär et al.

    Das Os acromiale und seine klinische Bedeutung

    Brun’s Beitr. Klin. Chirurg.

    (1936)
  • W Gruber

    Über den Acromialknochen und das accidentelle Acromialgelenk des Menschen

    Bull. Acad. Sc. St. Petersbourg Mélanges biologiques

    (1859)
  • W Gruber

    Ueber die arten der acromialknochen und accidentellen Acromialgelenke

    Arch. Anat. Physiol. Wiss. Med.

    (1863)
  • F Liberson

    Os acromiale — a contested anomaly

    J. Bone Jt. Surg.

    (1937)
  • D.A Dennis et al.

    Acromial stress fractures associated with cuff-tear arthropathy

    J. Bone Jt. Surg. (Am)

    (1986)
  • A.E.W Miles

    Non-union of the epiphysis of the acromion in the skeletal remains of a Scottish population of ca. 1700

    Int. J. Osteoarchaeol.

    (1994)
  • J Jerosch et al.

    Castro WHM. An unfused acromial epiphysis

    Acta. Orthop. Belg.

    (1991)
  • S Burkhart

    Os acromiale in a professional tennis player

    Am. J. Sports Med.

    (1992)
  • F Becker

    Das Os acromiale und seine Differentialdiagnose

    Fortschr. Gebiete. Röntgenstr.

    (1934)
  • Freese A. Anatomische Untersuchungen zur ossären Morphologie und Stellung des Akromions und deren Bedeutung für die...
  • A Prescher et al.

    Does the area of the glenoid cavity of the scapula show sexual dimorphism?

    J. Anat.

    (1995)
  • R Putz

    Anatomie und Biomechanik des Schultergelenks

    Therapiewoche

    (1985)
  • C von Langer

    Lehrbuch der systematischen und topographischen Anatomie. 2. Aufl

    (1882)
  • A Prescher et al.

    The glenoid notch and its relation to the shape of the glenoid cavity of the scapula

    J. Anat.

    (1997)
  • A.K Saha

    Rezidivierende Schulterluxation: Pathophysiologie und operative Korrektur

    (1978)
  • R Ziegler

    Die dorsale Instabilität der Schulter und ihre Behandlung

    Orthop. Praxis.

    (1980)
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