Primary and secondary arthritis of the shoulder are the common indications. The prosthesis has been used for osteoarthritis (OA), rheumatoid arthritis, avascular necrosis (AVN), cuff arthropathy, instability arthropathy, post-traumatic arthritis, postinfectious arthritis, arthritis secondary to glenoid dysplasia, and epiphyseal dysplasia. It is not intended for use in fresh fractures.

While resurfacing arthroplasty of the shoulder is a concept that has been utilized since the 1970s, it was in 1979 that this implant, the Copeland design, was initially designed by Stephen A. Copeland, FRCS (Br), at the Reading Shoulder Unit in Reading, United Kingdom. It was first implanted in 1986. Early designs of this device (i.e., Copeland implant) included a cobalt chromium alloy implant with a central peg and screw. It was initially used in conjunction with a glenoid component. Several modifications were made resulting in the current version of a cobalt chromium shell with a central peg and hydroxyapatite coating, suitable for noncemented applications (Fig. 39-1).

The ideal humeral replacement implant should be designed so as to reproduce normal anatomy (1). This includes variable humeral version of 5-degree anteversion to 55-degree retroversion and variable radius of curvature. An ideal implant should preserve bone stock, restore lateral offset, be flexible and adaptable intraoperatively, be revisable, and be durable (including bearing surface and method of fixation). Altering offset, inclination, or version can alter shoulder kinematics. Given the variations, implants must allow for adaptability during surgery. These criteria for any shoulder arthroplasty are embodied in the most widely used resurfacing implant, that designed by Dr. Copeland.

The rationale for using a resurfacing implant over one of the stemmed designs, include (a) true anatomic head coverage (not replacement), (b) bone preservation, (c) easy revisability to total shoulder arthroplasty (TSA), and (d) easy conversion to arthrodesis, in rare cases. Retention of the native head and neck of the humerus will preserve the biomechanics of the joint. This technique also eliminates the risk of humeral fracture or perforation during implantation and allows the head position to be independent of the shaft. The latter is important in cases where proximal humerus malunions or other deformity may preclude access to the humeral shaft. As the shaft is not violated, it minimizes the risk of periprosthetic fractures postoperatively. The design inherently allows placement in infinite variations of version, offset, and angulation. Since no humeral canal reaming or cementing is required, it eliminates the risk of fat embolus or hypotension during humeral preparation and implantation.

In cases of prior elbow arthroplasty, intramedullary nailing of the humerus and prior plating of the humerus resurfacing allow for anatomic arthroplasty without having to remove all of the hardware. If there has been a proximal humeral malunion, this can be left undisturbed without worry about the head offset relative to the shaft.

Specific indications for resurfacing arthroplasty vary among authors. Copeland and colleagues prefer this implant for all cases of primary shoulder arthroplasty where a stemmed implant would be considered, except fresh fractures (2). For primary arthroplasty, we have focused on the use of resurfacing in the younger or more active patient where a stemmed implant may force an alteration in lifestyle as a result of implant failure concerns.
Although we have not directly compared the resurfacing implants and standard stemmed hemiarthroplasty or TSA in active patients, we have observed a much greater return to sports and active lifestyle in the resurfacing population and have not observed implant failure as a result. This includes in several of our cases athletes who participate in collision sports.

Currently, our choice in primary arthroplasty is to reserve resurfacing arthroplasty for active individuals (generally younger than 60 years of age, although age alone is not an indicator) who do not have contraindications; we continue to utilize stemmed TSA, when possible, for all others (3).

There are few absolute contraindications to a resurfacing arthroplasty. As with any other partial or total shoulder replacement, active infection or paralysis of both deltoid and rotator cuff muscles are contraindications. Additional contraindications, in our practice, include (a) significant subchondral cystic changes on either side of the joint as can be seen with advanced rheumatoid arthritis (RA) or postarthroscopic glenohumeral chondrolysis (PAGCL) from prolonged intra-articular infusion of local anesthetics, (b) acute fracture, (c) uncontained humeral head defects that may compromise component fixation, (d) soft humeral head bone that may collapse under the implant (may be determined at time of surgery), (e) contained AV N involving more than 40% of the humeral head, (f) tumors, and (g) significant glenoid erosion requiring a glenoid replacement. The latter situation could be addressed as a resurfacing TSA, but we find it simpler and more predictable to do a standard stemmed TSA in those cases. However, there have been rare cases where we have used a biologic resurfacing technique for the glenoid. This has included (a) cases of lateral meniscus allograft when there is posterior subluxation from an early biconcave glenoid in a highly active individual and (b) the use of dermal allograft covering of contained defects of the glenoid that we have filled with bone graft, as frequently seen in failed Bristow procedures. Because biologic glenoid resurfacing tends to be less predictable, we have started to be less aggressive on the glenoid side if we have chosen a hemiarthroplasty instead of a TSA. More often, the glenoid is either left alone or only the remaining articular cartilage (in the case of 50% loss or more) is removed without altering the subchondral plate and version of the glenoid face. As stated previously, resurfacing is done in primary arthroplasty in approximately one-third of our cases.