Greater tuberosity involvement has been reported in 15 to 40% of proximal humerus fractures. Isolated tuberosity fractures, however, have a significantly lower reported in- cidence.1–6In a review of 930 operatively treated proximal humerus fractures at the AO Documentation Center (Davos Platz, Switzerland), fewer than 2% were isolated displaced tuberosity fractures.7Several authors have sug- gested that isolated greater tuberosity fractures may be underreported due to misdiagnosis caused by commonly encountered subtle radiographic findings.1,8–12The general consensus in the literature is that nondisplaced tuberosity fractures may be treated without operative intervention.
However, treatment of displaced greater tuberosity frac- tures is a subject of controversy with regard to indications for operative management, surgical approach, and selec- tion of optimal fixation to maintain an anatomic reduc- tion. These injuries can be deceptively difficult to treat surgically as they frequently consist of suboptimal frag- ments for traditional internal fixation techniques and the muscle forces acting on the greater tuberosity may make obtaining and maintaining reduction more challenging than the preoperative images would suggest. Although acute anterior glenohumeral dislocations13,14 and con- comitant rotator cuff tears15 are frequently associated with greater tuberosity fractures, in this chapter we will focus on the diagnosis and optimal treatment of isolated tuberosity fractures with an emphasis on the determina- tion of surgical indications, operative techniques, and postoperative management.
4 Isolated Tuberosity Fractures
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14.7 mm. The articular surface-to-tendon insertion dis- tance was less than 1 mm along the anterior 2.1 cm of the supraspinatus/infraspinatus insertion. This distance progressively increased to an average distance of 13.9 mm at the inferior-most aspect of the teres minor insertion.
The average anteroposterior distances of the supraspina- tus, infraspinatus, teres minor, and subscapularis inser- tions were noted to be 1.63, 1.64, 2.07, and 2.43 cm, respectively.20Another cadaveric study by Ruotolo et al21 examined 17 normal rotator cuffs and reported the supraspinatus tendon insertion was an average 1.7 mm
from the articular margin. With regard to the osseous anatomy of the greater tuberosity, a three-dimensional analysis of the proximal humerus by Robertson et al22 reported the mean vertical distance from the superior aspect of the greater tuberosity to the superior aspect of the humeral head was 6 2 mm. Knowledge of the rota- tor cuff footprint dimensions and osseous anatomy is important for restoring the normal anatomical relation- ships when treating greater tuberosity fractures and may be of assistance when intraoperatively determining options for treatment of comminuted fracture patterns, Figure 4–1 (A)Plain film true anteroposterior (AP) radiograph demon-
strating a large fragment with posteromedial displacement. (B)Plain film AP radiograph demonstrating superior displacement. (C)Plain film
axillary radiograph demonstrating posterior displacement. (D)Plain film radiograph demonstrating an impacted greater tuberosity fracture.
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fractures with concomitant rotator cuff tears, and frac- ture fragments with insufficient cortical density for stable fixation.
The primary blood supply to the proximal humerus is the anterior lateral branch of the anterior humeral circum- flex artery.23,24The anterior humeral circumflex artery is derived from the third division of the axillary artery approximately 1 cm distal to the inferior border of the pec- toralis minor. It then travels laterally posterior to the cora- cobrachialis and approaches the surgical neck of the humerus at the lower border of the subscapularis. The an- terolateral branch of the anterior humeral circumflex artery travels superiorly in the lateral aspect of the intertu- bercular groove to penetrate bone as it approaches the greater tuberosity and this branch then becomes the arcuate artery. Multiple extraosseous anastomoses exist between the anterior humeral circumflex artery, the poste- rior humeral circumflex artery, the thoracoacromial artery, suprascapular artery, subscapular artery, and profunda brachii artery.23By selecting the most appropriate opera- tive approach (see below), minimizing excessive dissection, and with a thorough knowledge of the regional vascular anatomy, the risks of nonunion, delayed union, and avascu- lar necrosis may be minimized.
Patient Assessment
The rationale for more aggressive operative intervention in the treatment of displaced tuberosity fractures is predi- cated on concern for malunion resulting in symptomatic subacromial impingement, functional loss from decreased shoulder abduction, and an alteration in rotator cuff func- tion due to a shortening of the lever arms for forward elevation and external rotation.8,25–27Hence, a rigorous approach to assessing the patient with an isolated tuberosity fracture is critical. After a thorough history and physical examination documenting the neurovascular status of the involved extremity, the initial plain radi- ographic evaluation consists of anteroposterior (AP), true AP, axillary, and scapular-Y or acromial outlet views. Plain radiographs may underestimate both the degree of displacement and extent of comminution. In addition, accurate assessment may be impaired by a small size fragment, comminution, or superimposition of the frag- ment on the humeral head.1,11,28A study by Parsons et al1 was the first to examine the accuracy and reliability of image interpretation for known displacements of the greater tuberosity. In this cadaveric study, the authors re- ported that no one fluoroscopic view was significantly more accurate than any other and they noted a trend toward increased accuracy for imaging minimally displaced fragments (5 mm or less displacement) with the AP view in external rotation.
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Solutions for Complex Upper Extremity TraumaWhen a sufficient index of suspicion exists despite normal-appearing radiographs, consideration of further diagnostic imaging is appropriate. Computed tomography (CT) may be of assistance for its ability to accurately detail the osseous anatomy about the proximal humerus; how- ever, its ability to adequately image the pertinent rotator cuff anatomy is limited (Fig. 4–2).28As a result, magnetic resonance imaging (MRI) is more commonly employed and is a more practical modality (Fig. 4–3).9,26,29Although Figure 4–2 Three-dimensional computed tomography reconstruction image of a greater tuberosity fracture with superior displacement.
Figure 4–3 Magnetic resonance image of an impacted nondisplaced greater tuberosity fracture.
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rarely used to evaluate for a possible greater tuberosity fracture, ultrasound has been reported as a method to diagnose occult nondisplaced greater tuberosity fractures.30