Shoulder Instability

Which of the following statements about shoulder instability is true ... 

Papalia, R., FrancescM, R, Diaz Beilzani, L., et eil. The arthroscopic treatment of shoulder instability bioabsorbable and standard meteillic anchors produce equivalent clinical results. Arthroscopy (2014)... 

Knowledge of the complex pathophysiology and biomechanics underlying rotator cuff impingement and shoulder instability is an essential prerequisite for a correctly executed US examination and interpretation of the imaging findings. 

Rotator cuff disease is the commonest cause of shoulder pain and dysfunction in adults. It derives from a wide range of pathologic conditions, including acute and chronic trauma, arthritis and shoulder instability (Laredo and Bard 1996). Most tears, however, occur in patients who lack a definite clinical history of trauma or systemic disease. In these cases, rota-... 

Fig. 6.67a,b. Anterior shoulder instability, a Chronic anterior instability in an elderly patient. Note the anterior dislocation of the humeral head (HH) relative to the acromion (Acr) and the coracoid (asterisk).b Anterior glenohumeral dislocation, subcoracoid type. Anteroposterior radiograph demonstrates anterior displacement of the humeral head, which appears located inferior to the coracoid process. A Hill-Sachs deformity is present (arrow)... 

Avulsion lesions of the tuberosities can also be encountered in shoulder instability. Greater tuberosity fractures are the commonest and derive from an excessive pulling force exerted by the supraspinatus on its bony insertion. The examiner must be aware that these fractures can also be secondary to a direct blow on the shoulder and that they are often missed on standard radiographs. Therefore, in a post-traumatic setting, US examination of the shoulder must include a careful search of bone irregularities in the greater tuberosity, even in the presence of previous... 

Rasmussen OS (2004) Anterior shoulder instability sonographic evaluation. J Clin Ultrasound 32 430-437 Read JW, Perko M (1998) Shoulder ultrasound diagnostic accuracy for impingement syndrome, rotator cuff tear, and biceps tendon pathology. J Shoulder Elbow Surg 7 264-271... 

Yen CH, Chiou HJ, Chou YH et al (2004) Six surgery correlated sonographic signs for rotator cuff tears emphasis on partial-thickness tear. Clin Imaging 28 69-76 Zarins B, Rowe CR (1984) Current concepts in the diagnosis and treatment of shoulder instability in athletes. Med Sci Sports Exerc 16 444-448... 

At autopsy, a ruptured plaque features a thin fibrous cap overlying cell-rich regions with a lipid-rich necrotic core (<3 mm ) containing cell debris. The indicators for plaque instability include an inflammatory infiltrate with lipid-rich macrophages (foam-cells) and a decreased collagen and smooth muscle cell (SMC) content in the fibrous caps as well as at the shoulders of the atheroma, respectively. Therefore, one of the challenges of modern medicine is the design of... 

The piled area should extend to a distance beyond the edge of the shoulder of tiie embankment to ensure that differential settlement or instability outside the piled area wiU not affect the embankment crest. The edge limit of the outer pile cap is given by the following equation (see also Figure 10.6) (Carlsson 1987). 

In general, the success rate of TSR exceeds 90% for a wide range of common shoulder problems. As in THA and TKA, the aim of TSA is to reduce pain, restore damaged anatomy, and restore function. As for hip and knee arthroplasty, there are continuing concerns about component fixation and persisting instability of the joint. 

Gerber A., N. Ghalambor, and J.J. Warner. 2001. Instability of shoulder arthroplasty Balancing mobility and stability. Orthop Clin North Am 32 661-670. 

Warren R.F., S.H. Coleman, and J.S. Dines. 2002. Instability after arthroplasty The shoulder. J Arthroplasty 17 Suppl 1 28-31. 

This is usually the result of forces transmitted through the axial skeleton from an impact into the head and shoulders through to the lower limbs. There may be symphyseal diastasis, anterior arch fractures or posterior disruption of the sacroiliac joints with cephalic displacement. Vertical injuries are often severe with disruption of all the ligaments plus associated pelvic instability. Radiographs demonstrate ipsilateral or contralateral pubic rami fractures, with disruption of the sacroiliac joint. The major differentiating feature from compression injuries is the cephalic displacement of the pelvis on the side of the impact (Fig. 12.14). 

Radiologically the Hill-Sachs compression lesion maybe evident. The Hill-Sachs lesion is a compressive fracture of the humeral head and is an important bony sign of previous anterior shoulder dislocation and instability and is significant more common in adult patients. There may also be an avulsion injury to the glenoid rim indicative of an associated Bankart lesion (detachment of the anteroinferior capsule from the glenoid neck). 

Isolated fractures of the lesser tuberosity are rare. They are avulsion injuries of the apophysis and are likely to present with chronic shoulder pain following a sporting injury (Levine et al. 2005). If associated with instability reconstruction of subscapularis is indicated. Fractures of the greater tuberosity have been described in association with luxatio erecta. 

The shoulder has the largest range of motion in the body, which results from a shallow ball and socket joint, which allows a combination of rotation and sliding motions between the joint surfaces. To compensate for the compromise in congruity, the shoulder has an elaborate capsular and Kgamentous structure, which provides the basic stabilization. In addition, the muscle girdle of the shoulder provides additional dynamic stability. A decrease in the radius of curvature of the implant to compensate for soft tissue instability will result in a decrease in the range of motion [Neer, 1990]. 

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