**1. Introduction**

In shoulder replacement, the type of shoulder prosthesis chosen for a particular patient is based on the underlying pathology, in particular the status of the rotator cuff, the degree of bony erosion, and the biological age of the patient.

Rotator cuff tendons degenerate progressively with increasing age and with secondary wasting of the muscle belly [1,2], and rotator cuff tears are present in almost 50% of the population in their 8th or 9th decade of life [3]. In the other 50% of older patients with an arthritic glenohumeral joint but an intact rotator cuff requiring a total shoulder replacement (TSR), there is at present uncertainty as to which patients would do better with an aTSR. There is a currently an increasing tendency to recommend a reverse total shoulder replacement (rTSR) in patients older than 70 years with an intact rotator cuff [4], which seems to assume that the result of an aTSR vs. an rTSR in this age group is similar.

This study aims to compare the results both clinically and radiologically, and the rate of complications, between a group of patients 75 years or over who had either an aTSR or

**Citation:** Simon, M.J.K.; Coghlan, J.A.; Bell, S.N. Shoulder Replacement in the Elderly with Anatomic versus Reverse Total Prosthesis? A Prospective 2-Year Follow-Up Study. *J. Clin. Med.* **2022**, *11*, 540. https:// doi.org/10.3390/jcm11030540

Academic Editors: Alexandre Lädermann, Markus Scheibel and Laurent Audigé

Received: 29 December 2021 Accepted: 17 January 2022 Published: 21 January 2022

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**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

an rTSR. The hypothesis is that patients with an aTSR have better clinical outcomes than same age patients receiving an rTSR.

#### **2. Materials and Methods**

#### *2.1. Study Protocol and Patients' Eligibility*

The nested study interrogated two existing databases from the same department. These included consecutive patients 75 years or older with either advanced primary glenohumeral osteoarthritis (OA) with or without an intact rotator cuff (RC), or an irreparable rotator cuff tear with minor osteoarthritis, who had a TSR.

Decision on prosthesis type (aTSR or rTSR) depended on the rotator cuff's status. Initial assessment was made clinically and radiologically with an X-ray and CT scan. If the integrity of the rotator cuff was uncertain, these cases were further assessed with an MRI scan to assess the rotator cuff status, including, if present, tear type (full or partial thickness), extent of muscle atrophy, and degeneration [5,6]. If the patient had osteoarthritis but the RC was intact and not degenerated, with no major muscle atrophy, the decision was made for an aTSR. If the patient had osteoarthritis and the RC was torn or degenerated, including severe fatty atrophy, the decision was made for an rTSR. If imaging demonstrated a massive irreparable RC tear with minor arthritis, an rTSR was indicated.

Inclusion criteria for the group receiving an aTSR were glenohumeral OA and an intact rotator cuff. The criteria for inclusion for the group receiving an rTSR were glenohumeral arthritis with an inadequate rotator cuff for an aTSR (*n* = 25), or a massive irreparable rotator cuff tear (*n* = 26).

Exclusion criteria were age under 75 years before the operation, post fracture/traumatic osteoarthritis, abnormal neurology or inability to comply with the study requirements. Exclusion criterion for performing an aTSR was a full-thickness rotator cuff tear, or inadequate rotator cuff function based on clinical examination and MRI findings. Therefore, all patients with glenohumeral arthritis who had a good rotator cuff had an aTSR, despite their age.

Eligible consecutive patients gave written consent and were prospectively enrolled in the study over the same time period. An identical prospective study protocol was set up for both groups. All patients had a minimum age of 75 years at the time of operation and a minimum follow-up time of 2 years. Written consent for study participation and publication was obtained from all patients. All studies were carried out in accordance with the World Medical Association most recent Declaration of Helsinki.
