Reverse Shoulder Replacement (Delta joint replacement) for arthritis: Surgery with a reverse prosthesis can lessen shoulder pain and improve function in shoulders with failed surgery or combined arthritis, rotator cuff tears and instability.

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About the procedure

Technical details

Shoulder replacement surgery with a reversed (reverse Delta) prosthesis for cuff tear arthropathy complicated by instability is a highly technical procedure; each step plays a critical role in the outcome.

After the anesthetic has been administered and the shoulder is prepared, an incision is usually made across the side of the shoulder from above the collarbone to the middle of the arm bone as shown in the figure. [Figure 19] The deltoid is split along the direction of its fibers taking care to avoid the axillary nerve that runs on its inferior surface. Opening the shoulder reveals the irregular joint surface of the humeral head. [Figure 20] This surface is resected using a cutting guide. [Figure 21 and 22] Instead of duplicating the normal 30-degree posterior direction of the humeral head joint surface the head is cut so that it faces directly medially.[Figure 23 and 24]. The shaft of the arm bone (humerus) is prepared to receive the stem of the humeral component. [Figures 25, 26 and 27]. Additional reamers are used to prepare the neck of the humerus [Figures 28. 29, and 30]. The definitive humeral prosthesis body [Figure 31] is inserted into the prepared bone [Figure 32].

Attention is then directed to the glenoid, which is surgically exposed [Figure 33] and a pin driven into its center to act as a guide [Figure 34]. The glenoid surface is then drilled [Figure 35] and reamed to a flat surface [Figure 36]. The base of the socket (metaglene) is then inserted onto the prepared surface and fixed into position using four screws. [Figure 37]. The inferior and superior screws lock into the metaglene, while the anterior and posterior screws are not locking. [Figure 38]

The semiconstrained design of the reverse arthroplasty allows loads from the humerus to challenge the fixation of the glenoid component to the scapula. We examined some of the factors affecting the quality of glenoid screw fixation, including the density of the material into which the screws are placed, the purchase of individual screws, and the direction of loading in relation to screw placement. Loads were applied by the humeral component to glenoid components with different conditions of fixation. The load to failure for each set of conditions was measured and compared statistically. Load to failure was less when the glenoid component was fixed to material of lesser density. Each screw contributed to the quality of fixation; the screw nearest the point of load application made the largest contribution. Load to failure was less when the load was co-linear with a line through the non-locking holes in the base plate compared to co-linear with a line through the locking holes. In performing a reverse total shoulder, surgeons should emphasize secure intraosseous placement of the fixation screws in the best quality bone available. The placement of the inferior screw appears to be the most critical.

Once the optimal trial components and the positions of the humeral and glenoid components verified, the definitive glenosphere is screwed onto the metaglene [Figure 43]. The definitive humeral socket is then fixed to the humeral prosthesis. [Figure 44]

At the conclusion of this procedure, the subscapularis tendon is securely repaired to the bone.

X-rays are taken to document the position and orientation of the prosthesis.

Links

• A video of the reversed (reverse Delta) prosthesis for rotator cuff tear arthropathy as performed by Dr Anders Ekelund of Stockholm Sweden can be seen here. (mpg, 15.2MB)
  
• A video of the reversed (reverse Delta) prosthesis for a previously failed shoulder arthroplasty as performed by Dr Anders Ekelund of Stockholm Sweden can be seen here. (mpg, 20.0MB)

Anesthetic

Length of reverse shoulder

The procedure usually takes approximately two hours, however the preoperative preparation and the postoperative recovery may add several hours to this time. Individuals often spend two hours in the recovery room and two to four days in the hospital after surgery.

Surgery for Reverse Shoulder at the University of Washington, Department of Orthopaedics and Sports Medicine, Seattle, Washington

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