Preserving humeral bone with short stems and stemless implants is a recent trend in total shoulder arthroplasty (TSA), but the first and most bone-conserving implant, the humeral head resurfacing (HHR), evolved from the hip resurfacing experience over 40 years ago.¹ Copeland’s development of his humeral resurfacing design began in 1979, and it was first implanted in 1986.² Since then, a variety of systems and implants have been developed.

The benefits of HHR are well documented. It is the most bone conserving shoulder arthroplasty option, even with the development of newer stemless and short-stem implant designs. By eliminating humeral canal reaming, HHR is a more streamlined surgery with decreased blood loss and decreased operative time.³ In addition, because the HHR avoids violating the canal, the threat of a periprosthetic humeral diaphyseal fracture is greatly diminished,² as is the threat of infection violating the humeral shaft. As HHR is not bound by the humeral canal, it has the freedom of expanded inclination and version options and potentially is a more anatomic shoulder replacement.⁴ Finally, with minimal bone removal and with a less aggressive implant, revision of an HHR to a stemmed implant is much less complicated (VIDEO 16.1).

HHR is contraindicated in all circumstances in which a standard TSA is contraindicated; ie, active infections, nerve injury, and neuropathic arthropathy. In addition, HHR is contraindicated in cases where the proximal humerus bone will not support a nonstemmed implant owing to extreme proximal humeral bone loss (greater than 60% of the humeral head), excessively soft bone, or bone containing large cysts.² Those patients with acute proximal humerus fractures or chronic humeral neck fracture nonunions are also not candidates for HHR.²,³,⁹

Relative contraindications to preforming a resurfacing TSA include conditions that make glenoid exposure difficult or impossible. These conditions include patients with significant retroversion (Walch B or C glenoids),⁸ obese or well-muscled patients, and patients with advanced arthritis with significant loss of motion and joint contracture.

Relative contraindications for an HHR include conditions that make hemiarthroplasties more likely to fail. These include excessive glenoid bone loss leading to instability or predisposing the glenoid to rapid medial wear. These are situations in which biconcave glenoids (Walch B2)⁸ and posterior humeral head subluxation lead to decreased implant survival.¹⁰

The operating room setup and positioning for HHR is the same as that of any TSA. Unless contraindicated, all patients receive a regional block along with general anesthesia. In addition to the block, complete muscle paralysis may improve retraction and aid in difficult glenoid exposures. Once asleep, the patient is placed in the beach chair position with the head secured in the head rest and the operative arm freely mobile either on a Mayo stand or in an arm positioner.

A standard deltopectoral approach is routinely used (FIGURE 16.1), but an anterosuperior approach, preferred by Copeland and Levy, could also be utilized.¹¹

The subscapularis can be approached in a variety of ways. I prefer to do a subscapularis peel, but a tenotomy or lesser tuberosity osteotomy can also be performed with equal efficacy. Savoie has described a partial subscapularis sparing approach, which only releases the lower portion of the subscapularis.⁵,¹² In this approach, the tendinous portion of the upper subscapularis remains intact while the more muscular inferior portion of the subscapularis is removed along with the inferior capsule. The humerus is then abducted and externally rotated to slide under the intact upper subscapularis (FIGURE 16.2). This approach can make visualizing the superior aspect of the humerus more challenging as the subscapularis lays across the top of the humerus, but it can allow for a more aggressive rehabilitation and quicker recovery because the important tendinous portion of the upper subscapularis remains intact.⁵,¹²

Regardless of how the subscapularis is addressed, it is critical to perform ample soft tissue releases, especially if the glenoid is going to be resurfaced. The subscapularis and capsular release must proceed down the inferior and medial aspect of the humeral neck continuing all the way to the posterior aspect of the humerus, making sure to protect the axillary nerve. Some authors prefer to excise the capsule, but I prefer to do an aggressive capsular release off the humerus and glenoid, leaving the remaining capsule attached to the undersurface of the subscapularis. I feel this decreases trauma to the subscapularis and adds mass to the tendon improving its repair.