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.)

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.

AXIS OF ROTATION

The philosophy of the Coonrad-Morrey device is to use the most reliable landmark to serve as the basis for defining the flexion axis. The landmark selected for this system is the anterior cortex to establish the anterior/posterior position of the axis. The roof of the coronoid fossa is the anatomic reference for depth of insertion, and the plane of the columns define the rotation of the axis of the humeral component (Fig. 53-3).

FIGURE 53-3 Locating the axis of rotation. The Coonrad-Morrey device employs the anterior cortex to identify anterior/posterior location (A); the flange seats against the proximal aspect of the coronoid fossa, identifying the level of proximal insertion (B). Rotation is defined by the posterior plane of the medial and lateral columns (C).

(C, with permission from the Mayo Foundation.)

CEMENTING TECHNIQUE

The cement should be introduced down the medullary canal for stemmed implants with an injection system. Generally speaking, injector systems have dramatically improved the radiographic appearance of the bone-cement interface. It was shown in our early experience^20,23 and subsequently Faber,⁸ that the quality of the cementing technique is inversely related to the presence of lucent lines, and, ultimately, to implant loosening (Fig. 53-4).

FIGURE 53-4 The incidence of prosthesis revision loosening shows an inverse relationship to the technical quality of the cementing.

(With permission from the Mayo Foundation.)

THE SEMICONSTRAINED LINKED IMPLANT

Today, in the United States, several semiconstrained elbow replacements are commercially available, including the Coonrad-Morrey (Zimmer, Warsaw, IN), the Latitude (Tornier, Edina, MN), and the Discovery (Biomet, Warsaw, IN). To date, these two implants have not had sufficient use to document outcomes. The GSB III has evolved through the years and has been frequently used in Europe but its use and support is being discontinued (Fig. 53-5). Experience with the GSB III devices is discussed under the appropriate indications in subsequent chapters. Risung²⁵ has also reported favorable outcomes with a rather novel implant designed termed the Norway elbow.

FIGURE 53-5 A, The Pritchard II was an early and widely used semiconstrained elbow replacement. B and C, The coupling mechanism of the triaxial device has been modified several times. The triaxial began as a snap-fit design to provide joint stability, as does the English Stanmore prosthesis (D). E and F, The GSB III is a popular semiconstrained device used in Europe. G, The Norway elbow designed by Risung is a type of snap-fit design, but with a spool-type snap-fit trochlear design. H, Clinical results have been excellent.

THE COONRAD-MORREY DEVICE

The Mayo modified Coonrad total elbow prosthesis (Coonrad-Morrey) is a semiconstrained device manufactured from Tivanium Ti-6Al-4V alloy. In 1978, the initial design (Coonrad I) Zimmer Company (Warsaw, IN). was modified by the Mayo Clinic to permit 7 to 10 degrees of hinge laxity, or toggle (Coonrad II), which is consistent with the average laxity of the normal elbow joint (Table 53-1). This change accounts for the semiconstrained designation applied to the device. The effect of this design concept is discussed above (see Figs. 53-1 and 53-2). The implant was designed for use with methylmethacrylate and is manufactured in two sizes: a regular and a small size (15-percent reduction). The current limited version was released in 1981. It currently has a basic hinge articulation with a hollow cobalt chrome pin that passes through the ultra-high-molecular weight polyethylene bushings to capture the ulnar component. A second pin is inserted from the opposite side to secure the articulation (Fig. 53-6). The prosthesis is easily disassembled if desired. A flange was incorporated in this version to resist posterior and torsional forces.

TABLE 53-1 Coonrad-Morrey Implant Modifications 1981-1998

FIGURE 53-6 The current Coonrad-Morrey semiconstrained implant. Note redesigned articulation locking pin and plasma spray treatment of the proixmal ulna.

Right and left specificity is attained from the contoured quadrangular ulnar stem. The triangular humeral stem is interchangeable right or left.

This implant is intended to be used with bone cement for both immediate and long-term fixation. The humeral stem comes in 10-, 15-, and 20-cm stem lengths (Fig. 53-7). The 15-cm stem is most often used in nonrheumatoid patients to ensure adequate mechanical resistance to rotation in the humerus. The 4-inch stem is used when a shoulder involved by rheumatoid arthritis has been or may be replaced with a humeral prosthesis.^11,13 The 8-inch stem is used for revision procedures requiring the device to bypass the prior stem tip (see Chapter 66). The ulna implant is made in standard and small dimensions. The small dimension also comes in an extra long size. Finally, for the patient with juvenile rheumatoid arthritis or a very small canal, as is common in those from Asia, a special extra-small implant is available (Fig. 53-8).

FIGURE 53-7 The humeral components are available in 10-, 15-, and 20-cm lengths and in small and standard sizes.

FIGURE 53-8 The ulnar component is available in small (A) and standard sizes. A longer small implant, also available, is commonly used for revision (B). An extra-small, long device is available and can be shortened for very small canals, as in patients with juvenile rheumatoid arthritis (C).

SURGICAL TECHNIQUE FOR COONRAD-MORREY TOTAL ELBOW ARTHROPLASTY

Author’s Preference

Exposure

The patient is positioned supine with a sandbag under the scapula, and the arm is draped free with a nonsterile tourniquet and brought across the chest (Fig. 53-9). The Mayo (Bryan-Morrey) approach is used exclusively for this procedure if condyles are present. In the absence of a distal humerus, the triceps attachment to the olecranon is maintained.⁵ A straight 15-cm incision is centered just lateral to the medial epicondyle and just medial to the tip of the olecranon. The medial aspect of the triceps is identified, and the ulnar nerve is carefully isolated and translocated using ocular magnification and a bipolar cautery. It is gently protected throughout the remainder of the procedure.

FIGURE 53-9 The preferred supine position with a sandbag under the patient’s shoulder and the arm lying across the chest.

(With permission from the Mayo Foundation.)

Over the medial aspect of the proximal ulna, the ulnar periosteum is elevated along with the forearm fascia (Fig. 53-10). The posterior capsule is incised. The triceps is elevated from the proximal ulna by transecting Sharpey’s fibers at the site of insertion. The extensor mechanism, including the anconeus, is reflected laterally, allowing complete exposure of the distal humerus, the proximal ulna, and the radial head. The radial and ulnar collateral ligament complexes are released from their attachments in persons with rheumatoid arthritis (Fig. 53-11). Failure to do this may facilitate a fracture of the medial column as the forearm is manipulated. The tip of the olecranon is removed.

FIGURE 53-10 In the Mayo approach used for the semiconstrained implant, the ulnar nerve is identified and the triceps is released from the tip of the olecranon in continuity with the forearm fascia and periosteum.

(With permission from the Mayo Foundation.)

FIGURE 53-11 The tip of the olecranon is removed along with the medial collateral ligament (MCL) and the lateral collateral ligament (LCL). The ulna is flexed and rotated to expose the humerus. The radial head is resected or débrided, depending on the extent of disease.

(With permission from the Mayo Foundation.)

The Maneuver

The humerus is externally rotated, the elbow is hyperflexed, the forearm is brought lateral to the humeral shaft, and the hand is flexed behind the patient’s ear.

Humeral Preparation

The midportion of the trochlea is removed with a rongeur or a saw, depending on the softness of the bone. The medullary canal of the humerus is identified by entering it with a rongeur or a burr at the roof of the olecranon fossa (Fig. 53-12) and entered with a twist reamer. The medial and lateral aspects of the supracondylar columns should be identified and visualized throughout the preparation of the distal humerus to ensure proper alignment and orientation.

FIGURE 53-12 The medullary canal is identified by perforating the roof of the olecranon fossa with a burr or a rongeur.

(With permission from the Mayo Foundation.)

The alignment stem is placed down the canal (Fig. 53-13). The handle is removed, and a cutting block is attached, which allows accurate removal of the appropriate amount of the articular surface of the distal humerus.

FIGURE 53-13 Sufficient exposure is required to identify the medial and lateral columns. An alignment stem is placed down the canal.

(With permission from the Mayo Foundation.)

The interchangeable side arm of the cutting block is attached laterally to rest on the capitellum and to provide the appropriate depth of cut (Fig. 53-14).

FIGURE 53-14 The appropriate cutting block depth is adjusted by the outrigger, which rests over the capitellum and allows accurate removal of bone to receive an implant of a given size.

(With permission from the Mayo Foundation.)

Note: The flat of the template rests on the posterior columns to ensure accurate replication of the all important rotatory alignment of the humeral implant. With an oscillating saw, the trochlea is removed according to the dimensions of the appropriate cutting block that corresponds to the sizes of the humeral component. Care should be taken to avoid violating either supracondylar bony column because such disruption may cause a stress riser, leading to a fracture.

The humerus involved by rheumatoid arthritis is easily prepared with a rasp in such a way as to receive the appropriately sized humeral component. In younger patients and those with post-traumatic conditions, the canal may be tight, or the anterior humeral bow may make preparation more difficult. A burr is effective to remove bone just proximal to the oriface of the olecranon fossa.

Ulnar Preparation

The medullary canal of the ulna is identified by using a high-speed burr at about a 45-degree angle to the base of the coronoid (Fig. 53-15). The tip of the olecranon is removed, notched, or both, to allow identification of the canal by a small reamer. An appropriately sized rasp is then used, and a mallet is generally required to remove the subchondral bone around the coronoid (Fig. 53-16). The rasp handle is maintained at an orientation perpendicular to the plane of the “flat” of the proximal ulna. This corresponds to the flexion axis and serves to accurately orient the ulnar component. If the canal is tight, flexible reamers are available to prepare and expand the medullary cavity.

FIGURE 53-15 The subcutaneous border of the proximal ulna is visualized and palpated so that the medullary canal may be safely entered with a burr oriented at about a 45-degree angle at the base of the coronoid (A). The olecranon is notched to allow direct entry down the canal (B).

(With permission from the Mayo Foundation.)

FIGURE 53-16 (A) The proximal canal is prepared with an appropriately sized ulnar rasp. (B) The implant rotation is determined by placing the flexion plane perpendicular to the “flat” portion of the proximal ulna.

(With permission from the Mayo Foundation.)

Trial Reduction

A trial reduction allows assessment of depth of insertion and soft tissue restriction to extension. The ulna is inserted to the depth that corresponds to the axis of the implant replicating the axes flexion (Fig. 53-17).

FIGURE 53-17 The ulna is inserted until the center of the ulnar component coincides with the center of the greater sigmoid fossa.

(With permission from the Mayo Foundation.)

Implant Insertion

The medullary cavities of both bones are cleansed with a pulsating lavage irrigation system and dried. A medullary cement restrictor is used in the humerus to avoid proximal cement delivery when a shoulder replacement is to be performed or is being contemplated.

The cement is first injected down the humeral medullary canal to a depth determined by the length of the humeral stem (Fig. 53-18). The cement is then injected down the ulnar canal.

FIGURE 53-18 The humeral canal is filled with the intramedullary cement injector system to accommodate a 4-, 6-, or 8-inch humeral component (A). The injector nozzle is cut for the appropriate length of the ulnar component (B).

(With permission from the Mayo Foundation.)

A bone graft is prepared from the excised trochlea or from the bone bank for revision surgery. The graft should measure about 3 to 4 mm in thickness and should be about 2 cm long and 1.5 cm wide. The bone graft is placed anterior to the anterior cortex of the distal humerus, and the humeral component is inserted down the canal to a point that allows articulation of the device at a level where the bone graft is partially covered by the flange as well (Fig. 53-19). If the canal is tight, the anterior bow of the humerus is accommodated by making a slight bow in the humeral stem with the plate bender (Fig. 53-20).

FIGURE 53-19 The bone graft placed simultaneously behind the distal humerus engages the flange before the joint is articulated. This ensures that the bone graft will be positioned accurately when the humeral component is finally seated.

(With permission from the Mayo Foundation.)

FIGURE 53-20 When the canal is small, the normal slight anterior bow may require that the 15- or 20-cm implant be bent slightly anteriorly (A) with a plate bender (B). This allows the stem to avoid posterior penetration of the humeral cortex (C).

(With permission from the Mayo Foundation.)

The ulnar component is articulated with the humeral device by placing the hollow axis through the humerus and ulna and securing it with the solid pin inserted from the opposite direction (Fig. 53-21). After the prosthesis has been coupled, the ulna is placed at a 90-degree angle, and the humeral component is impacted down the medullary canal (Fig. 53-22). In general, the device is inserted to a point at which the axis of rotation of the prosthesis is at the level of the normal anatomic axis of rotation. This is approximated when the base of the flange is flush to the anterior bone of the olecranon fossa and the distal aspect of the humeral component is flush or slightly proximal to the distal aspect of the capitellum.

FIGURE 53-21 The articulation is coupled by a pin-within-a-pin mechanism (A) that is very easy to apply. Removal is equally easily done with a special device (B).

(With permission from the Mayo Foundation.)

FIGURE 53-22 A specially designed instrument allows impaction of the humeral implant down the canal.

(With permission from the Mayo Foundation.)

The Triceps

If the triceps has been reflected, it is secured to the ulna with a heavy (No. 5) nonabsorbable suture. The first stitch penetrates the lateral tendon in the reduced position and is locked. A second locked throw is placed in the medial tendon, the suture then penetrates the tendon in line with the proximal medial tunnel. It passes through the tunnel from proximal medial to distal lateral. It then is brought through the soft tissue there and is tied to itself. An additional transverse suture is placed across the olecranon, locks at the posterior aspect of the olecranon in the center portion of the tendon and is tied to itself (Fig. 53-23). Sutures are tied beneath the tendon because were they subcutaneous, they might irritate or cause stitch abscess.

FIGURE 53-23 Bone tunnels are placed in the proximal ulna (A). The triceps is reattached with a suture that goes through the forearm and the periosteal sleeve and then through one of the diagonal holes placed in the proximal ulna (B). A criss-cross suture is placed on the triceps. The suture is then brought through a second diagonal hole in the forearm and the ulnar periosteum and is tied (C). A second suture is placed through the tip of the olecranon and through the triceps to ensure firm apposition of the triceps at the site of its previous insertion (D).

(By permission of Mayo Foundation for Medical Education and Research. All rights reserved.)

Closure

The tourniquet is deflated, the arm is elevated and compressed for 4 to 5 minutes, and hemostasis is obtained. Drains are optional and the wound is closed in layers. A suture closes the subcutaneous tissue over the translocated ulnar nerve at the medial epicondyle. The rest of the closure is routine.

A compressive dressing is applied with the elbow in full extension. The plaster splint is no longer used.

RESULTS

Experience with this device for several conditions is discussed in subsequent chapters. The intermediate and long-term experience is emerging for those with rheumatoid arthritis (Fig. 53-24) and for post-traumatic conditions (Fig. 53-25). The results remain gratifying.

FIGURE 53-24 A and B, Patient with severe grade III rheumatoid arthritis. C and D, Excellent 8-year result after replacement.

FIGURE 53-25 Two years after sustaining a supracondylar fracture, the patient had painful nonunion and tapering of the distal humeral shaft, as shown on the anteroposterior (A) and lateral (B) radiographs. C, Gross instability is evidenced by 45 degrees of varus angulation against gravity. The patient was treated with the newer design of elbow arthroplasty that incorporates an anterior flange to control the rotational and posterior displacement stresses. D, Anteroposterior and lateral views 16 years after replacement.