CHAPTER 16 Results and Complications

The results of unconstrained shoulder arthroplasty have been reported by multiple investigators. The results vary predominantly according to the underlying indication for which the arthroplasty has been performed. To our knowledge, the largest reported database of results of unconstrained shoulder arthroplasty was presented in Nice, France, in 2001.¹ Because of the large number of patients enrolled, this multicenter study has allowed meaningful conclusions to be made about the outcomes and complications of unconstrained shoulder arthroplasty. Our results have largely mirrored those reported in the Nice study. This chapter reports the results of unconstrained shoulder arthroplasty for the treatment of nonfracture conditions by drawing from information in the Nice database and our arthroplasty database that was prospectively established in 2003. Additionally, the most frequent complications and their treatment are outlined.

RESULTS

The results of unconstrained shoulder arthroplasty vary mainly with the cause for which the arthroplasty is performed. The best results are obtained in the treatment of primary osteoarthritis and osteonecrosis, whereas results are least satisfactory for post-traumatic arthritis and rotator cuff tear arthropathy. Tables 16-1 and 16-2 detail the results of unconstrained shoulder arthroplasty for the most common indications for which it is performed.^2–8 These tables express 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.^9,10

Table 16-1 RESULTS OF UNCONSTRAINED SHOULDER ARTHROPLASTY ACCORDING TO UNDERLYING CAUSE IN THE NICE MULTICENTER STUDY

Rights were not granted to include this data in electronic media. Please refer to the printed book.

Table 16-2 RESULTS OF UNCONSTRAINED SHOULDER ARTHROPLASTY ACCORDING TO UNDERLYING CAUSE IN THE AUTHORS’ PROSPECTIVE DATABASE FROM 2003 TO 2006

INTRAOPERATIVE COMPLICATIONS

Intraoperative complications are uncommon during shoulder arthroplasty and may be divided into complications involving the humerus, glenoid, musculotendinous soft tissues (rotator cuff), and neurovascular structures.

Humerus

Intraoperative complications involving the humerus are rare. The most common humeral complication is iatrogenic fracture, which usually results from performing an overly aggressive dislocation maneuver without previous adequate soft tissue release. Patients with osteopenia (i.e., inflammatory arthropathy patients) and those with severe preoperative stiffness (i.e., post-traumatic arthritis) are at most risk for this complication. These fractures may occur at the humeral diaphysis or proximally and involve the tuberosities. Fractures involving the humeral diaphysis should be reduced and a long-stem humeral implant placed. Allograft struts and cerclage cables may be added in patients with severe osteopenia (Fig. 16-1).

Figure 16-1 Fixation of an intraoperative humeral diaphyseal fracture with a long-stem humeral implant, allograft cortical struts, and cerclage cables.

Intraoperative fractures involving the greater or lesser tuberosities (or both) are usually nondisplaced. Many of these fractures are stable or become stable once the humeral implant is placed (Fig. 16-2). If a tuberosity fracture is not satisfactorily stable, suture fixation of the tuberosity is performed and the postoperative rehabilitation adjusted accordingly to allow healing of the tuberosity.

Figure 16-2 Nondisplaced fractures of the greater tuberosity (arrows) are usually sufficiently stable after placement of the humeral implant.

Glenoid

Intraoperative glenoid fractures are more common than humeral injury. These fractures almost always occur during preparation (reaming) of the glenoid. Patients with osteopenia are most at risk. Fractures may involve only the peripheral glenoid rim or may extend significantly into the articular surface. Adequate capsular release helps minimize the risk of glenoid fracture. Additionally, a motorized reamer (not a drill) should be used to prepare the glenoid surface. The reamer should be started before the surgeon applies force to engage the reamer onto the glenoid face. This avoids having the reamer “catch” an edge of the glenoid, which may cause a fracture.

Fractures that involve only a small portion of the peripheral rim usually require no treatment, and the glenoid component can be inserted as planned. Glenoid fractures that extend into the central portion of the glenoid (keel slot or peg holes) should be bone-grafted with the humeral head, and placement of a glenoid component should be avoided. Placement of a glenoid component in a patient with a fracture involving the central portion of the glenoid can result in early glenoid failure (Fig. 16-3).

Figure 16-3 Early glenoid failure caused by placement of a glenoid component despite the occurrence of an intraoperative glenoid fracture.

Rotator Cuff

With proper glenoid exposure, intraoperative injury to the rotator cuff is rare. The key to avoiding rotator cuff injury during unconstrained shoulder arthroplasty is adequate visualization of the rotator cuff before resection of the humeral head (see Chapter 11). If the rotator cuff is adequately visualized, inadvertent damage to the rotator cuff by the saw during humeral head resection can be avoided.

Neurovascular Structures

Catastrophic injury to neurovascular structures around the shoulder is exceedingly rare. Transient neuropraxia involving the axillary nerve, however, is one of the most common complications that we observe in unconstrained shoulder arthroplasty (up to 3% of cases).

The neural structures most at risk during unconstrained shoulder arthroplasty are the axillary and musculocutaneous nerves. During primary arthroplasty these nerves should not be at risk for transection when using accepted operative technique. Neuropraxic injury caused by stretch most commonly involves the axillary nerve, but any nerves within the brachial plexus can be involved. Care should be taken when positioning the patient to maintain the cervical spine in neutral alignment to avoid a stretch injury of the brachial plexus. We have yet to establish risk factors for neuropraxic injury to the axillary nerve. Logic would suggest that patients with the most stiffness creating difficulty in glenoid exposure would be at highest risk for this type of complication. Our clinical experience has not borne this out, however, and currently we are unable to predict which patients are most likely to suffer this complication. Patient education preoperatively is of paramount importance in dealing with neuropraxia because patients are much more accepting if they have heard about the possibility of this complication before surgery. Axillary nerve (and other nerve) neuropraxia is treated by observation, with most patients recovering by 3 to 4 months postoperatively.

Although tearing of the cephalic vein is common and largely without consequence, significant arterial and venous injuries occurring during primary unconstrained shoulder arthroplasty performed for nonfracture indications are exceptionally rare. Injuries to the major upper extremity vessels are generally due to overzealous medial dissection, which is not needed during shoulder arthroplasty. Should one of these injuries occur, after cross-clamping of the injured vessel, emergency intraoperative consultation with a vascular surgeon is required.

POSTOPERATIVE COMPLICATIONS

Postoperative complications are more common than intraoperative complications and occur in up to 20% of cases of unconstrained shoulder arthroplasty.¹ The most common postoperative complications include wound problems (dehiscence, hematoma), glenoid problems, humeral problems, instability, rotator cuff problems, stiffness, and infection.

Wound Problems

Wound problems occur early after unconstrained shoulder arthroplasty. Hematoma is most easily avoided by extensive use of electrocautery during shoulder arthroplasty. Suture ligation, in addition to electrosurgical cauterization, of the anterior humeral circumflex vessels also minimizes the incidence of postoperative wound hematoma. When a hematoma occurs, it is managed by symptomatic nonoperative treatment (warm compresses, pain medication). Operative drainage is reserved for situations in which drainage persists beyond 1 week or infection is suspected (see later) but is rarely necessary.

Wound dehiscence occurs occasionally when susceptible patients have a reaction to dissolving subcutaneous sutures. The presence of minimal serous drainage distinguishes this complication from the more serious deep infection. Superficial wound dehiscence is treated by local wound care, including removal of any residual dissolving suture material and chemical cauterization of any granulating tissue with silver nitrate applicators (Fig. 16-4).

Figure 16-4 Superficial wound dehiscence.

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