Total Elbow Arthroplasty for Distal Humerus Nonunion and Dysfunctional Instability

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CHAPTER 59 Total Elbow Arthroplasty for Distal Humerus Nonunion and Dysfunctional Instability

INTRODUCTION

Dysfunctional elbow instability may be defined as a condition in which the elbow joint has lost its fulcrum properties and is no longer able to provide enough support for the hand to be functionally controlled in space (Fig. 59-1).10 In the most extreme circumstances, destruction of the elbow leads to a flail extremity. In less severe cases, stability may be maintained with the arm adducted against the body, but not in other positions (Fig. 59-2). This condition may result from situations such as distal humerus nonunion, severe rheumatoid destruction of the humerus, extensive post-traumatic bone loss, and bone resection for the treatment of deep infection or tumors. Linked elbow arthroplasty provides a dramatic improvement in the function and quality of life of these patients, but the improvements need to be balanced against the risk of complications and mechanical failure.

As noted above, distal humerus nonunion is one of the conditions commonly presenting as dysfunctional instability. Even in cases with less severe instability, elbow arthroplasty is a very attractive treatment alternative for the salvage of distal humerus nonunion. This chapter reviews the presentation, surgical technique, and outcomes of total elbow arthroplasty for distal humerus nonunion and dysfunctional elbow instability.

ELBOW ARTHROPLASTY FOR DISTAL HUMERUS NONUNION

As noted in Chapter 23, nonunion is one of the most challenging complications of distal humerus fractures. Internal fixation is the treatment of choice whenever possible. Modern series have reported a high union rate when internal fixation is used, but the reoperation rate has remained high and function is not always re-established.6,11 Total elbow arthroplasty is an excellent surgical alternative for the salvage of distal humerus nonunions when fixation is considered to be impractical or expected to be associated with a high rate of failure.

Elbow arthroplasty has emerged as a safe and effective treatment option for selected patients with distal humerus nonunion. Although some theoretical interest has been expressed in the use of distal humerus hemiarthroplasty for nonunions, the associated stiffness and bone loss make it less attractive compared to the acute setting. Most patients requiring arthroplasty for a distal humerus nonunion will benefit from the use of a total elbow arthroplasty. A linked implant is of choice in this situation, as the humeral attachments of the collateral ligaments are removed as part of the procedure.

SURGICAL TECHNIQUE

The elbow is exposed through a posterior midline skin incision and the ulnar nerve is identified and treated according to the location of the nerve and preoperative symptoms as mentioned in Chapter 23 on internal fixation for distal humerus nonunions. The extensor mechanism is left undisturbed and the procedure is performed working on both sides of the triceps unless an associated olecranon nonunion, or triceps detachment provides the opportunity for exposure (Fig. 59-3) (see also Chapter 7, Surgical Exposures). Retained hardware is removed, and the nonunited distal humerus is resected subperiosteally and saved for bone grafting behind the flange of the humeral com-ponent. Tissue samples are sent for pathology and microbiology.

The working space created by resection of the distal humerus is ample enough to instrument the canals andimplant the components. The surgical technique for implantation of a linked elbow arthroplasty is detailed in Chapter 52. A capsular release should be associated routinely. Use of a humeral component with an intermediate length stem provides secure fixation. In the presence of severe humeral bone loss, an implant with a longer flange may be cemented proud to make up for part of the lost humeral length (Fig. 59-4

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