Preoperative Planning and Imaging

Published on 18/03/2015 by admin

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Last modified 18/03/2015

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CHAPTER 18 Preoperative Planning and Imaging

Preoperative planning is important for all shoulder arthroplasty indications, but it is most crucial for fracture cases. Although proximal humeral anatomy may be somewhat distorted by prolonged wear and osteophyte formation in cases of chronic disease for which shoulder arthroplasty is performed, most reliable anatomic landmarks remain consistent despite the disease process. In fracture cases, however, these normally reliable landmarks are often displaced, thus making them useless as points of reference. Because of the lack of recognizable landmarks, preoperative planning becomes of paramount importance when attempting to establish the proper position for humeral stem implantation. Thorough preoperative planning minimizes the risk of placing the humeral stem at the incorrect height or version. We have successfully used two techniques to place the humeral stem at the appropriate height. Preoperative planning is of paramount importance for both these techniques and is detailed in this chapter. Additionally, important aspects of the clinical history and physical examination, the radiographic examination, and secondary imaging studies are highlighted.

CLINICAL HISTORY AND EXAMINATION

A thorough history is taken of the antecedent trauma responsible for the fracture. Most often, these proximal humeral fractures are caused by a fall from a standing position. Elucidation of the reason for the fall should be sought to assist in evaluation of any underlying contributing medical conditions (i.e., syncope as a symptom of cardiac arrhythmia). The presence of any shoulder problems before the fracture should be noted in the history. A previous history of shoulder pathology, such as a massive rotator cuff tear or glenohumeral arthritis, influences surgical decision making (i.e., the type of prosthesis to be implanted, such as an unconstrained fracture prosthesis, reverse shoulder prosthesis, or unconstrained shoulder arthroplasty with a glenoid component).

Physical examination in a patient with an acute proximal humeral fracture is limited so that the patient is not unnecessarily subjected to pain. A detailed neurovascular examination is performed with specific attention to the sensory and motor function of the axillary nerve. The sensory function of the axillary nerve can always be evaluated by testing sensibility to touch of the posterior aspect of the upper part of the arm (superior lateral brachial cutaneous branch of the axillary nerve). Motor function of the axillary nerve may be more difficult to evaluate because pain induced by the fracture may inhibit deltoid contraction. The condition of the soft tissues, particularly anterior at the planned surgical site, is meticulously evaluated.

RADIOGRAPHY

Three radiographic views are obtained in all patients with a proximal humeral fracture. We prefer the same radiographic views that we obtain for patients being considered for unconstrained shoulder arthroplasty for chronic conditions: an anteroposterior view of the glenohumeral joint with the arm in neutral rotation (Fig. 18-1), an axillary view (Fig. 18-2), and a scapular outlet view (Fig. 18-3). These radiographs are used to evaluate the fracture pattern (two part, three part, four part), the amount of displacement of the fracture fragments, the presence of humeral head dislocation, and the presence of a split in the humeral head fragment. Frequently, the patient has radiographs obtained in an emergency department that are of poor quality. We always repeat these radiographs to obtain better-quality films and to assess for progressive displacement. Once it is determined that the patient is a potential candidate for shoulder hemiarthroplasty, anteroposterior full-length radiographs of both humeri taken with the arm in neutral rotation are obtained for use in preoperative determination of appropriate humeral head height. These radiographs must include the entire length of the humerus and must be controlled for magnification (Fig. 18-4).