RESULTS

The results of unconstrained shoulder arthroplasty for fracture are largely related to two prognostic factors: age and the presence of tuberosity complications (nonunion, malunion). These two factors are related in that older patients are more likely to have osteopenia of the tuberosities and hence complications with tuberosity healing. Although age-related osteopenia is beyond the surgeon’s control, advances in prosthetic design and tuberosity fixation techniques continue to decrease the rate of tuberosity-related complications. Table 23-1 details the results of unconstrained shoulder arthroplasty in the treatment of proximal humeral fracture.² This table expresses the results in terms of active mobility; patient satisfaction; the Constant score, a shoulder-specific outcomes device incorporating pain, mobility, activity, and strength; and the age- and gender-adjusted Constant score.^3,⁴

Table 23-1 RESULTS OF UNCONSTRAINED SHOULDER ARTHROPLASTY IN THE TREATMENT OF PROXIMAL HUMERAL FRACTURES

INTRAOPERATIVE COMPLICATIONS

Intraoperative complications are uncommon during unconstrained shoulder arthroplasty for proximal humeral fractures and are usually related to neurovascular injury or iatrogenic humeral shaft fracture.

Neurovascular Structures

Catastrophic injury to neurovascular structures around the shoulder, though rare, are more common during performance of shoulder arthroplasty for fracture than for performance of shoulder arthroplasty for nonfracture indications. Many patients with proximal humeral fractures suffer neuropraxic injury to the axillary nerve, and this should be documented on clinical examination before surgery. Additionally, the implications of axillary nerve injury secondary to fracture should be discussed with the patient extensively before surgery. Treatment of axillary nerve injury is observation, with less than 2% of patients sustaining a permanent axillary nerve deficit.⁵

Vascular injuries during unconstrained shoulder arthroplasty performed for fracture most often involve injury to the axillary artery. Such injury is usually a consequence of overzealous medial dissection or retraction (or both), combined with vasculature that has been compromised by aging (plaques, calcification). Should one of these injuries occur after cross-clamping of the injured structure, emergency intraoperative consultation with a vascular surgeon is required.

Humeral Shaft Fracture

Intraoperative humeral shaft fractures are very rare when performing unconstrained shoulder arthroplasty for the treatment of proximal humeral fractures. Stiffness is rarely a problem in these cases, thus minimizing the torsional stress placed on the humeral shaft during manipulation of the arm. More commonly, humeral injury occurs during reaming of the humeral shaft. The diaphyseal cortex in many elderly patients is very thin and hence has an increased risk of diaphyseal penetration. When this complication occurs, it is often unrecognized (Fig. 23-1).

Figure 23-1 Radiograph of cement extravasation after unrecognized diaphyseal perforation during insertion of a humeral stem for a proximal humeral fracture.

POSTOPERATIVE COMPLICATIONS

Postoperative complications are much more common than intraoperative complications and occur in more than 50% of cases of unconstrained shoulder arthroplasty performed for fracture.⁵ Most complications involve the greater or lesser tuberosities (or both) but also may include wound problems (dehiscence, hematoma), glenoid problems, humeral problems, instability, stiffness, and infection.

Nonunion and malunion of the greater and lesser tuberosities are the most common complications after unconstrained shoulder arthroplasty in fracture cases (Fig. 23-2). The occurrence of a tuberosity complication compromises the outcome significantly in most cases. The best way to handle tuberosity complications is to avoid them by using the techniques described in this section. When tuberosity complications do occur, there is no simple solution that provides a reliable result. Even early recognition and reattachment of a migrated tuberosity yields unsatisfactory results in nearly all cases. Similarly, tuberosity osteotomy produces poor results in cases of malunion. The most predictable results are obtained with revision arthroplasty to a reverse prosthesis in these cases (Fig. 23-3; see Section Six).