**1. Introduction**

In 1985, Dr. Paul Grammont introduced a new system for reverse total shoulder prosthesis that revolutionized the field by focusing on four key features: (1) the prosthesis must be inherently stable; (2) the lever arm of the deltoid must be effective from the initiation of the movement; (3) the glenosphere must be large and the humeral cup small to create a semiconstrained articulation; (4) the center of rotation must be fixed, medialized and distalized with respect to the glenoid surface [1, 2]. To this day, Grammont's core features are still the mainstay. Of course, modern prosthetics have been modified since 1985 to avoid scapular

Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons

notching and impingement between the greater tuberosity and the coracoacromial arch and to maximize compressive forces while minimizing shear forces [2, 3].

order to gain proper stability and range of motion. Then the real implants are seated and the shoulder is reduced. Lastly, the subscapularis is reattached and the biceps are tenodesed with heavy nonabsorbable sutures that are placed through drill holes in the humeral metaphysis prior to seating of the final implant. However, recent research acknowledges the controversy surrounding the reattachment of the subscapularis due to the potential for increasing the likelihood of dislocation [13]. The deltopectoral-interval is re-approximated and the incision closed. The patient is placed in a shoulder abduction sling for a period of immobilization lasting two to 6 weeks with a home physical therapy program [14]. As with all orthopedic procedures, the rehabilitation protocol is patient specific and additional rehabilitation may be

Current Outcomes Following Reverse Total Shoulder Arthroplasty: A Composite

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What constitutes a short-term versus a long-term outcome? One of the objectives of this review is to address the lack of clarity in the literature regarding the timeline of shortterm and long-term outcomes [15]. Bacle and colleagues [15] identified that the majority of mechanical loosening reports occurred outside of the first 2 years following a reverse total shoulder arthroplasty. In contrast, dislocation, infection, and poor seating of the glenoid component were reported within the first 2 years postoperatively; a ratio of 3 to 1 for complications reported before and after the two-year mark [15]. Furthermore, Bacle and colleagues [15] defined medium-term follow-up as a mean of 39 months and long-term follow-up as a mean of 150 months. Similarly, Otto and colleagues [16] argued that a follow-up of period of 24 months was a relatively short time frame to adequately capture long-term complications. Thus, 2 years may be a respectable partition between short-term and long-term outcomes.

The language of RTSA outcomes is a complex task given the wide range of outcomes metrics. The most common scoring methods include the following: Range of Motion (ROM), Constant-Murley Score (CMS), American Surgeons of Elbow and Shoulder score (ASES), Visual Analogue Score (VAS), and the Simple Shoulder Test (SST). Other methods include but are not limited to the UCLA Shoulder Score and the Shoulder Pain and Disability Index (SPADI) [17–19]. The CMS, first published in 1987, is comprised of four sections: two of which are self-reported by the patient—pain and activities of daily living, the remaining two are reported by the physician—range of motion and strength [20]. Concerns were raised regarding the score's ability to account for age and gender; thus, the modified version adjusts for both [17]. The ASES was created with the goal of developing a universal outcome measure; it too contains patient-reported and physician-reported parts. In addition, the ASES has demonstrated appropriate validity and reliability in assessing operative and non-operative interventions for shoulder pathology [17]. However, it's appraisal of functionality may be somewhat limited among the older adult population; for example, the questions about "do usual sport"

deemed necessary if the patient needs to strengthen external rotation [14].

**3. Outcome timeline**

**4. Outcome quantification**

These advancements contributed directly to the increased utilization of Reverse Total Shoulder Arthroplasty (RTSA) [4]. In fact, in the last ten years, the number of RTSAs nearly tripled in the United States [5]. Reverse Total Shoulder Arthroplasty (RTSA) is a popular treatment for patients with rotator cuff damage, glenohumeral arthritis, complex fractures, and previously failed total shoulder arthroplasty given its ability to alleviate pain and increase range of motion and function. Although RTSA significantly improves functionality, pain, and satisfaction, patients need to be given realistic expectations for when to expect improvements, peak performance, and plateaus as well as potential risks for negative outcomes. As with any surgical procedure, patients are at risk for intraoperative, perioperative, short-term, and long-term complications. Thus, the purpose of this review is to discuss the short-term and long-term complications, metrics, and length of follow-up for patients who have undergone RTSA. In addition, we provide recommendations for a cut-off point between short-term and long-term outcomes for RTSA.

Ease range of motion and function in patients with glenohumeral joint disease, displaced proximal humeral fractures, rotator cuff tear arthropathy, severe irreparable rotator cuff tears, rheumatoid arthritis, and failed shoulder arthroplasty [1–3, 6–8].
