43.1 Goals of Procedure

The anatomic shoulder arthroplasty aims to reduce the pain and preserve or enhance the mobility of the shoulder in patients suffering from end-stage shoulder arthritis without rotator cuff tear (RCT). Conservative management (such as physical therapy, medication, or cortisone injections) should precede any shoulder replacement. Stemless anatomic shoulder arthroplasty ( Fig. 43.1 ) is a relatively new system designed to reduce stem-related complications, such as periprosthetic fractures or difficult revisions.

43.2 Advantages

The main improvement of the stemless shoulder arthroplasty is preserving bone stock in the humeral medullary canal. The position of the humeral anchor is independent of the location of the humeral canal, allowing for an anatomically driven reconstruction. The principle is to use an easily revisable prosthesis instead of a convertible one. The landmarks are the rotator cuff tendons. It is a soft tissue–driven implantation. These prostheses provide similar clinical outcomes compared to stemmed prosthesis with numerous advantages, such as decreased operating time, more anatomical placement, decreased intraoperative complications, less intraoperative blood loss, decreased risk of periprosthetic fracture, and, if necessary, easier revisions. ^{1 – 3} Minimal blood loss and a nonviolated humeral canal have led us to perform this surgery in an outpatient protocol.

43.3 Indications

Stemless anatomic shoulder replacement has the same indications as stemmed arthroplasty. The main indication for its use is glenohumeral osteoarthritis in the presence of a normal rotator cuff. Clearly, the proximal metaphysis has to be intact with sufficient bone stock. Evaluation of bone quality is crucial as it is highly correlated to the initial stability of the implant. This type of prosthesis is very helpful in posttraumatic arthritis with or without necrosis. In these cases, the anatomy is severely disturbed by tuberosity malunions. When the anatomy is severely disturbed by tuberosity malunions the results of anatomical implants associated with tuberosity osteotomies are poor. ⁴ In these cases a reverse shoulder arthroplasty would be the good option and the stemless humeral implant allows to compose with the malunion. ⁵ ( Fig. 43.2 ).

43.4 Contraindications

An RCT and active infection are classic contraindications to anatomical shoulder replacement. Many authors recommend reverse shoulder arthroplasty in B2- or C-type glenoid. Stemless arthroplasty has a specific contraindication related to the fixation of the humeral component. Primary stability is achieved with fins and press-fit impaction inside the spongy bone. A hydroxyapatite coating with titanium porous or trabecular metal permits secondary osteointegration. To avoid secondary displacement, the bone quality needs to be sufficient. Osteoporosis, a severe osteopenia or large cysts or tuberosity nonunions are contraindications to stemless implants ( Fig. 43.5a). Pre- and perioperative evaluation of the bone quality is therefore of great importance.

43.5 Preoperative Preparation/Positioning

The preoperative planning includes standard X-rays and either an MRI or a CT arthrogram of the shoulder. Contraindications to the stemless implants must be eliminated with these examinations. One should evaluate the bone stock in the humeral metaphysis and the glenoid wear. The presence of large osteophytes should also be noted. The rotator cuff is also evaluated. An RCT is an absolute contraindication to the total anatomic shoulder replacement.

The patient is positioned in the beach-chair position and the use of a pneumatic arm holder is helpful. A stemmed prosthesis should always be available as a backup if a poor bone quality is discovered during surgery.