CHAPTER 53 Linked Elbow Arthroplasty: Rationale, Indications, and Surgical Technique

INTRODUCTION

As noted in Chapter 52 and further described in Chapters 54 through 60, the results of total elbow arthroplasty are improving with increased basic knowledge of elbow mechanics,²⁴ better designs, and greater surgical experience.²¹ The general principles of the surgical technique and improved designs^2,^9,^14,^18,²⁴ and a detailed description of my specific method of inserting the Coonrad-Morrey implant are presented. The results of semiconstrained joint replacement arthroplasty emphasize the Mayo Clinic experience with the modified Coonrad device.

RATIONALE

The selection and the rationale for unlinked elbow replacement are described in Chapter 52. The reason for continuing to use a semiconstrained linked implant is simple: the current design works well, is reproducible, and can address a broad spectrum of pathology. The Coonrad-Morrey linked device and similar implants are distinctly different, both conceptually and clinically, from the original, fully constrained articulated devices. In today’s linked prostheses, the one feature in common is that the ulnar component is coupled to the humerus with angular and rotatory laxity of 5 to 10 degrees (Fig. 53-1). The theoretical advantage has been confirmed in the laboratory in which it was demonstrated that the articulation tracks within the limits of its tolerance (Fig. 53-2). This decreases stresses on the bone-cement interface.²⁴ Documentation of improved clinical results attests to the effectiveness of the semiconstrained linked design.^2,^4,^13,^14,^16,^18,²¹ Of particular note is that the linked implant dramatically broadens the indications for reconstructive surgery of the elbow. Whereas unlinked devices may be very effective for rheumatoid arthritis, the potential for instability limits their use when deformity and osseous and ligamentous deficiency is present. The linked implant may be used with equal effectiveness in patients with rheumatoid arthritis,²⁰ for post-traumatic arthrosis,¹⁹ and for revision surgery.¹⁸ The enhanced stability supplied by the coupling is provided without transmission of excessive stress to the bone-cement interface with the semiconstrained design.²⁴

FIGURE 53-1 A semiconstrained implant, whether it be of an axle or a snap-fit design, is characterized by varus-valgus and axial rotation tolerances of several degrees at the articulation.

FIGURE 53-2 The semiconstrained articulation provides flexion motion that replicates normal kinematics (A) and constraints of the design and thus reduces stress at the bone-cement interface (B). TEA, total elbow arthroplasty.

(With permission from the Mayo Foundation.)

INDICATIONS

The indication for the semiconstrained linked joint replacement design may be summarized in general terms as constituting the full spectrum of elbow pathology. Hence, patients with rheumatoid arthritis can usually be managed regardless of the degree of bone or soft tissue present or destroyed. The stiff, deformed, or unstable elbow may also be effectively managed with linked devices. Primary or revision procedures with minimal or extensive bone loss were also amenable to management by linked devices.

CONTRAINDICATIONS

As for any total elbow arthroplasty, the absolute contraindications for a linked arthroplasty are active infection, inadequate soft tissue protection, and the lack of adequate motor muscle power to flex the elbow to ensure proper functioning of the device. Relative contraindications are lack of patient compliance. Primary degenerative joint disease is also a relative contraindication because patients with this disease are usually younger and active, and alternative selections are effective (see Chapter 60). High demand and a dysfunctional hand are also relative contraindications for total elbow arthroplasty.

PRINCIPLES OF SURGICAL TECHNIQUE

One of the most important factors in the improved results of elbow joint replacement in the past and particularly with those being developed is improved surgical technique. Here, we describe our current technique.

POSITIONING

The patient is placed in the position of the surgeon’s preference. I place the patient supine with sandbags under the hip and the scapula. The arm is draped free, a nonsterile tourniquet is used, and the extremity is brought across the chest.

SURGICAL INCISION

A straight posterior skin incision is preferred. If a previous incision is present it is employed when possible. If the patient is older than 4 or 5 years of age, it may be repaired if it cannot be incorporated. The incision need not and should not be curved.

THE ULNAR NERVE

Opinions are divided with respect to the management of the ulnar nerve. Some surgeons believe that it should not be exposed,^7,^9,^12,^16,²⁷ whereas today most believe that the ulnar nerve should be directly visualized and moved as an integral part of the surgical approach and procedure.^4,^10,^15,²³ We favor the latter philosophy.

THE TRICEPS

The fascial tongue exposure of Campbell (Van Gorder) causes a good deal of soft tissue dissection, with a significant amount of dead tissue that provides an environment favorable to infection, which may result in weakness.^5,²² Splitting the triceps in the midline is enjoying a resurgence of popularity. In our experience, this tends to cause detachment of the medial insertion. Therefore, I continue to prefer the Mayo technique of reflecting the triceps in continuity with the ulnar periosteum and forearm fascia described by Bryan and Morrey.⁵ The important point, however, is a meticulous repair (see later).