The primary indications for reverse total shoulder arthroplasty include glenohumeral arthrosis associated with rotator cuff deficiency, failed unconstrained total shoulder arthroplasty, and tumor reconstruction [3, 4]. Some surgeons have advocated its use for other clinical scenarios such as massive rotator cuff tears without arthritis and proximal humerus fractures [4, 13, 14]. Annual volume regarding shoulder arthroplasty has increased dramatically with a corresponding increase in the number of reverse total shoulder arthroplasties, which has been tempered by complication rates approaching 30 % [15]. Due to continued concerns regarding implant longevity and complication rates, patient selection remains of paramount importance when performing this procedure.

Axillary nerve injury, glenoid vault deficiency precluding baseplate fixation, and infection are all absolute contraindications to reverse total shoulder arthroplasty. The patient must be aware of the increased complication rate regarding reverse shoulder arthroplasty and that historical data has indicated clinical deterioration approximately 6–8 years post implantation [16, 17].

Current reverse shoulder implant designs may be traced to Paul Grammont’s original foray in 1985. The construct consisted of an all polyethylene humeral component and a 42 mm glenosphere (Fig. 2). Both components were cemented through a trans-acromial approach in seven of the eight cases performed. Three patients demonstrated 60° or less of forward elevation [18]. Dissatisfied with these results and cognizant of the historical issues related to constrained designs, Grammont realized that the semi-constrained implant would require medialization of the center of rotation. This change from a lateral to medialized position would reduce torque at the glenoid implant interface and convert shearing force vectors to compression with increasing degrees of abduction. Medialization of the center of rotation and inferior displacement of the humerus would result in deltoid recruitment and subsequent improvement in active forward flexion and abduction [19]. In 1991, Grammont subsequently revised the glenoid component to an uncemented design with a central peg and divergent screws to counteract shearing forces at the glenoid. The glenoid component was reduced to a half sphere with two sizes, 36 and 42 mm. With regard to the humeral side, a non-anatomic inclination angle of 155° was chosen to maximize motion stability while reducing component impingement [19]. The Delta III design contained five parts: the metaglene (baseplate), glenosphere, humeral cup liner, epiphyseal component, and the humeral stem. A monoblock humeral stem was made available for cement fixation purposes. The metaglene contained four peripherally divergent screws. In 1996, a Morse taper with a centrally countersunk screw was incorporated into the Delta III design to reduce the risk of glenosphere-metaglene disassociation [18, 19]. The original Grammont design has served as a foundation by which various iterations of the device have been released. Currently, most reverse shoulder arthroplasty systems demonstrate modularity for both the humeral and glenoid components allowing for appropriate soft tissue balancing and tensioning intraoperatively. A common theme among implant designs involves metaglene fixation with multidirectional locking and nonlocking screws around a central post or screw. The degree of lateral offset is dictated by specific surgical technique regarding the implant system. Humeral neck shaft inclination also varies by implant type. Most modern reverse shoulder arthroplasty systems have multiple humeral cup liner depths with metallic extensions for use during revision scenarios.

The Grammont design medializes the center of rotation, allowing for recruitment of anterior and posterior deltoid fibers (Fig. 3) [18]. With a fixed center of rotation and humeral lengthening, the individual should demonstrate improved active forward flexion and abduction. It is these same design characteristics that negatively affect external and internal rotation arcs. Decreased lateral offset, medialized center of rotation, and teres minor atrophy are all factors that affect postoperative external rotation. Gerber and coauthors have suggested combined latissimus and teres major tendon transfers to improve external rotation in the setting of reverse shoulder arthroplasty [20]. Increasing retroversion of the humeral implant may allow for improved external rotation but at the expense of internal rotation. Internal rotation may not improve with reverse shoulder arthroplasty due the altered force vectors even with an intact subscapularis. Additionally, the anterior deltoid cannot compensate in the setting of subscapularis deficiency. To maximize internal rotation, some surgeons have advocated the subscapularis sparing superior-lateral approach [21–23].

Even among fellowship trained shoulder surgeons, the reverse total shoulder arthroplasty procedure remains technically demanding and is associated with complication rates greater than that of unconstrained total shoulder arthroplasty [24]. Reconstructive failure secondary to instability, component dissociation, infection, or implant loosening presents a clinical scenario that may not have an appropriate solution [3]. Several key steps nonspecific to a defined implant system will be reviewed.

A majority of surgeons utilize the deltopectoral approach, though the European experience has demonstrated viability with the superior-lateral technique. Each approach has its proponents, opponents, advantages, and disadvantages. With regard to the superior-lateral approach, the subscapularis remains intact as the deltoid is split to gain access to the glenohumeral joint through a probable massive rotator cuff tear. Some reports have indicated reduced risk of anterior instability with this approach due to the intact subscapularis. Opponents cite difficulty with glenoid visualization, decreased postoperative external rotation, and an inability to address revision scenarios that require component extraction, tendon transfers, and bone grafting [15, 25]. Our preference is the deltopectoral approach, as this exposure may be extended for revision cases, allowing for improved visualization of the glenoid, and identification and safeguarding of the axillary nerve. The subscapularis is either tenotomized or “peeled” from the lesser tuberosity and later reapproximated or allowed to medialize without reattachment. Advocates of repair cite improved internal rotation and reduced incidence of anterior instability [4]. However, Mole and Favard in their multicenter study of 484 patients who had undergone reverse total shoulder arthroplasty, did not demonstrate statistically different outcomes when comparing subscapularis repair versus tenotomy without repair [16]. Additionally, Clark and coauthors performed a retrospective cohort study of 120 patients, of which 55 underwent repair of the subscapularis during reverse total shoulder arthroplasty. They concluded that reattachment of the subscapularis did not have any positive effect on complication rate, dislocation rate, pain relief, and range of motion gains [26]. Despite these reports, we currently advocate primary repair of the subscapularis when technically feasible to reduce the potential risk of anterior instability and improve the potential for internal rotation.

With regard to humeral preparation, the humeral head is generally osteotomized in neutral to slight retroversion. More recent studies have suggested resecting the humeral head in native version for the patient to maximize active external rotation [27]. Neck shaft inclination varies depending upon the implant system with Grammont-based implants reliant upon the 155° angle [18]. The tendon of the long head of the biceps tendon is tenodesed adjacent to the pectoralis major tendon insertion. Glenoid labrum removal, sequential capsular releases, and partial release of the long head of the triceps tendon from the infraglenoid tubercle should allow adequate exposure for baseplate implantation. Careful attention must be paid to the native version of the glenoid and the amount of glenoid vault available for baseplate fixation. Some systems require placement of a central guidewire from which glenoid reaming is based. It is critical to avoid excessive medialization, superior tilt, and version (anterior or posterior) of the glenoid during the reaming step. Some authors have advocated inferior tilt with baseplate positioning to reduce the incidence of scapular notching, whereas others have indicated minimal benefit with this technique and similar patient outcomes with or without inferior tilt of the glenoid component [28–31]. Most surgeons agree that the baseplate must be placed as inferior as possible on the glenoid face, but not beyond the glenoid rim, to minimize notching and to allow for improved adduction of the arm. Most implant systems achieve baseplate fixation through multiple screw fixation augmented by a central post or screw placement. Superior and inferior screw lengths range from 24 to 36 mm with anterior and posterior screws approaching 18 mm. Central screw length in the DJO/Encore prosthesis is most commonly 30–40 mm (Fig. 4a, b). Locking screws are generally reserved for placement in the base of the coracoid and the lateral pillar of the scapula [32]. When technically feasible, a larger glenosphere (i.e., 42 versus 38 mm), should be utilized to impart improved stability to the construct.

Once the glenosphere has been implanted, the humeral side is reamed and broached. Modern reverse shoulder arthroplasty designs demonstrate modularity that allows for press fit reconstruction. Controversy remains regarding the amount of version necessary to maximize range of motion and functional outcome. Mole and Favard’s study in 2007 recommended neutral version based upon better outcomes involving activities of daily living, strength, Constant scores, and implant failure rate [16]. More recently, Favard et al. noted diminished inferior impingement and scapular notching rates with near anatomic version of the humerus. The authors cautioned regarding the adoption of this technique as the effects on external rotation, internal rotation, and anterior-posterior impingement have not been clearly defined [27]. Humeral cup liner depths vary based upon implant systems, but most allow for multiple thicknesses, degrees of constraint, and metallic spacers for revision situations. Intraoperative reduction is generally accomplished by gentle longitudinal traction and downward push on the humerus. Stability and assessment of soft tissue tensioning remains a qualitative analysis. We will generally perform the following assessments to assure appropriate stability of the construct: the conjoint tendon should demonstrate increased but not excessive tension (i.e., bowstring); dislocation with abduction and internal rotation of the arm should not occur; minimal gapping should occur with adduction of the arm; and humeral cup glenosphere dissociation should not occur with longitudinal traction of the arm. The final construct may result in lengthening of the arm with reports indicating an average of 2–3 cm [33]. We reapproximate the subscapularis to the remaining portion of the lesser tuberosity and use a closed circuit suction drain to reduce the risk of hematoma formation. Postoperatively, the patient is placed into a sling and allowed to perform active elbow, wrist, and digital exercises for the first one to two weeks. At that point, pendulum and active assisted forward flexion exercises are allowed with the use of a home pulley system. Sling use is generally discontinued at 4–6 weeks after surgery.

Prior to surgical intervention, a thorough history and physical exam should be performed. Particular attention must be paid to previous or remote history of infection, prior shoulder surgery, and medical comorbidities, which may contribute to a suboptimal outcome for the patient. The physical exam should focus on evaluation of the soft tissue envelope, integrity of the deltoid and teres minor, and co-existing cervical spine issues, which may affect the ability to achieve pain relief and improved function after reverse shoulder arthroplasty. Appropriate imaging with plain radiographs and CT scan will allow for preoperative templating (Fig. 5a, b). Unless otherwise contraindicated, all anticoagulant and antiplatelet therapy should be discontinued at least 5–7 days prior to intervention. Glycemic control should be optimized to reduce the risk of postoperative infection. Perioperative IV antibiotics such as a first generation cephalosporin or Vancomycin (for patients allergic to penicillin) are administered within an hour of intervention. In the setting of revision surgery when an infection has been confirmed or suspected, antibiotics are withheld until soft tissue samples have been obtained for frozen section and culture. Pain management is achieved through a multimodal approach involving peripheral nerve blocks (interscalene) and the use of a patient controlled intravenous analgesia device.

The patient after induction is placed in the semi-Fowler position on the operative table utilizing a commercially available beach chair positioner that permits unencumbered access to the shoulder (Fig. 6). The operative extremity is prepped and draped free for the intervention (Fig. 7). Implantation of the Depuy Delta Xtend reverse shoulder prosthesis can be achieved through a superior lateral or deltopectoral approach. We prefer the deltopectoral approach as it affords improved ability to visualize the glenoid and to address revision scenarios. The skin incision begins from the inferior border of the clavicle and transverses over the coracoid process and toward the deltoid insertion (Fig. 8). The subcutaneous tissue planes are elevated to identify the cephalic vein, which is mobilized laterally in a majority of cases. Incise the clavipectoral fascia from the coracoacromial ligament to the superior border of the pectoralis major insertion (Fig. 9a, b). Humeroscapular interface will need to be released with careful blunt and sharp dissection. Adhesions posterior to the conjoint tendon should also be carefully released and the musculocutaneous nerve identified. Palpate the axillary nerve at the anterior-inferior border of the subscapularis. Intermittent reassessment of the nerve should be performed to confirm its integrity. The anterior humeral circumflex vessels should be ligated with electrocautery (Fig. 10). Tenodese the biceps tendon at the level of the pectoralis major insertion and transect it proximally. Perform a peel of the subscapularis off of the lesser tuberosity and tag the tendon with three to four #2 nonabsorbable sutures. A Darrach retractor is placed inferiorly at the humeral insertion of the capsule. A fishtail elevator and knife are used to release the capsule to the 6 o’clock position. The humeral head should be easily dislocated with gentle extension and adduction of the arm (Fig. 11). With the shoulder dislocated, position the starting reamer at the most superior lateral location and create a pilot hole to gain intramedullary access to the humerus (Fig. 12). All reaming steps should be performed by hand to avoid iatrogenic injury to the humerus. Ream the humeral canal until the endosteal surface provides torsional resistance (Fig. 13). Select the appropriate handle size and cutting jig and seat the two devices on top of the humeral head. An orientation pin is placed proximally to calculate the degree of retroversion. We generally place the humeral component in neutral to slight retroversion to preserve internal rotation. The cutting jig is stabilized with three pins approximately 2 mm inferior to the proximal region of the greater tuberosity. The humeral head resection is performed with a sagittal saw. A metallic coverplate is then placed to protect the osteotomy site (Fig. 14a–d).

Glenoid exposure is of paramount importance for proper positioning of the glenosphere. The remaining labrum and biceps tendon origin are excised sharply with a knife. A 360° release of the subscapularis, if intact, is performed. The posterior, inferior, and superior capsules are released with careful attention paid to the location of the axillary nerve at all times. To adequately visualize the lateral pillar of the glenoid, the origin of the long head of the triceps tendon may be partially released. A forked retractor or modified Sonnabend are then utilized to displace the proximal humerus (Fig. 15). All osteophytes may be removed with small osteotomes or small rongeur. Metaglene position should be chosen to obtain adequate glenoid fixation while minimizing the risk of mechanical impingement. The metaglene central peg ought to be positioned posterior and inferior to the intersection of the glenoid axis. Particular attention should be pain to glenoid morphology on preoperative imaging studies, as metaglene position will need to be adjusted based upon adequacy of and screw and post fixation. The metaglene positioner is placed flush with the inferior glenoid rim and a guide pin is advanced perpendicular to the glenoid face. Avoid superior tilt of the pin placement, which may result in suboptimal positioning of the metaglene and glenosphere (Fig. 16a, b). A two-step reaming process allows for appropriate preparation of the glenoid followed by a central cannulated drill bit to prepare for the metaglene post (Fig. 17a–d). Implant the final metaglene into position using autograft to address minor deficiencies in the glenoid surface. The metaglene rotation should be positioned to allow for inferior screw placement within the scapular neck and superior screw placement within the coracoid base. The metaglene allows for ± 10° of angulation for the locking screws (Fig. 18). A soft tissue drill guide and 2.5 mm drill bit are both used to cannulate the glenoid for placement of the inferior screw. We recommend interval drilling and “sounding” of the pilot hole with the depth gauge to measure the appropriate length screw. If the screw is deemed to be inadequate (less than 36 mm), reposition the drill within the 20° cone. If this fails, rotate the metaglene to achieve adequate inferior and superior screw fixation. Seat the screw into position using a 1.2 mm guide pin, but do not lock the screw until all screws have been placed (Fig. 19). After seating of the peripheral screws, tighten the interior screw head with the internal rod to lock the implants. We will generally place the final glenosphere, which comes in 38- and 42 mm diameters and standard/eccentric sphericities. The 42 mm glenosphere provides improved range of motion and stability, but may not be feasible to use in patients with smaller glenoids. A 1.5 mm guide pin is placed within the central hole of the metaglene followed by engagement of the 3.5 mm hex screwdriver with the final glenosphere. Slide the glenosphere until it comes into contact with the metaglene, avoiding cross threading of the central screw and post. Rotate the glenosphere in a clockwise fashion until the scapula rotates with movement. Intermittently tap with the soft impactor and a mallet followed by clockwise tightening of the glenosphere (Fig. 20a, b). After final glenosphere implantation, the shoulder is re-dislocated for proximal humerus preparation.