Towards optimal reverse total shoulder arthroplasty design: reconsidering the role of lateralized implants

Article information

Clin Shoulder Elb. 2024;27(1):1-2
Publication date (electronic) : 2024 February 28
doi :
Department of Orthopedic Surgery, Yeungnam University Medical Center, Daegu, Korea
Corresponding Author: Sam-Guk Park Department of Orthopedic Surgery, Yeungnam University Medical Center, Yeungnam University College of Medicine, 170 Hyeonchung-ro, Nam-gu, Daegu 42415, Korea Tel: +82-53-620-3640 Fax: +82-53-628-4020 E-mail:
Received 2024 January 8; Revised 2024 February 6; Accepted 2024 February 7.

The current reverse total shoulder arthroplasty (RTSA) concept was introduced by Grammont in 1985 based on the deltoid compensating for rotator cuff function and stabilizing the shoulder joint [1]. In the initial design, a medial shift of the center of rotation (COR) allowed for greater deltoid use during forward flexion and abduction, and a distal shift of the COR extended the deltoid moment arm for better function [2,3]. However, problems such as loss of shoulder contour, reduced stability of the artificial joint, weaker external and internal rotation, and scapular notching were associated with medialization of the COR in early implants [4-6].

The concept of lateralization was introduced to address issues related to tension in the rotator cuff and deltoid, to restore active external rotation, and to increase impingement-free range of motion, thereby improving both active and passive internal rotation [7,8]. The lateralization of RTSA includes both glenoid and humeral lateralization, collectively referred to as global lateralization. Grammont's Delta III prosthesis is commonly used as a reference point for RTSA and has a global lateralization of 13.1 mm [9]. Most prior meta-analyses [4,10] agree that lateralized RSA provides better restored axial rotation compared to the original Grammont-style prosthesis, and Hao et al. [11] should be congratulated that further clarified that lateralized RSA produces superior axial rotation. While lateralization of the COR addresses many disadvantages of the conventional implant, excessive lateralization may induce complications such as stress fracture of the scapular spine and subacromial notching [12]. Therefore, to improve clinical outcome, it is important to balance the advantages of medialization and lateralization [13]. Future research should focus on identifying patient variables identifying appropriate candidates for each prosthesis design.

Hao et al. [11] also considered subscapularis repair an important factor for axial rotation. Several studies have been conducted on the effectiveness of subscapularis repair following RTSA. One meta-analysis revealed that subscapularis repair significantly reduced the risk of dislocation [14]. According to another meta-analysis, subscapularis repair led to superior results in internal rotation but inferior results in abduction compared to a control group [15]. In contrast to these studies, Clark et al. [16] found that subscapularis repair did not significantly affect the rate of complications, dislocation events, range of motion, or pain.

Therefore, the strength of this study is that the authors performed a subgroup analysis that included the degree of lateralization and subscapularis repair, even though the study did not include a lateralized RSTA without subscapularis repair group. This is in contrast to previous meta-analyses that only differentiated between lateralization and medialization of the COR. Although the quality of the included studies and heterogeneity of the axial rotation evaluation method is a weakness of this study, the results are expected to help shoulder surgeons determine the degree of preoperative medialization or lateralization.


Author contributions

Conceptualization: SGP. Supervision: SGP. Writing – original draft: SGP. Writing – review & editing: HGS, SGP.

Conflict of interest

Sam-Guk Park is an editorial board member of the journal but was not involved in the peer reviewer selection, evaluation, or decision process of this article. No other potential conflicts of interest relevant to this article were reported.



Data availability





1. Grammont PM, Baulot E. Delta shoulder prosthesis for rotator cuff rupture. Orthopedics 1993;16:65–8.
2. Kazley JM, Cole KP, Desai KJ, Zonshayn S, Morse AS, Banerjee S. Prostheses for reverse total shoulder arthroplasty. Expert Rev Med Devices 2019;16:107–18.
3. Dickerson P, Pill SG, Longstaffe R, Shanley E, Thigpen CA, Kissenberth MJ. Systematic review of reversing pseudoparalysis of the shoulder due to massive, irreparable rotator cuff tears. J Shoulder Elbow Surg 2020;29:S87–91.
4. Cho SH, Lee HJ, Aldhafian OR, Kim YS. Comparison of lateralized versus medialized reverse total shoulder arthroplasty: a systematic review and meta-analysis. Orthop J Sports Med 2022;10:23259671211063922.
5. Youn SM, Lee HS, Rhee SM, Rhee YG. Medialized vs. lateralized humeral implant in reverse total shoulder arthroplasty: the comparison of outcomes in pseudoparalysis with massive rotator cuff tear. J Shoulder Elbow Surg 2022;31:736–46.
6. Boileau P, Watkinson DJ, Hatzidakis AM, Balg F. Grammont reverse prosthesis: design, rationale, and biomechanics. J Shoulder Elbow Surg 2005;14:147S–161S.
7. Crum RJ, de Sa DL, Su FL, Lesniak BP, Lin A. Decreased complication profile and improved clinical outcomes of primary reverse total shoulder arthroplasty after 2010: a systematic review. Shoulder Elbow 2021;13:154–67.
8. Callegari J, Haidamous G, Lädermann A, Phillips C, Tracy S, Denard P. Factors influencing appropriate implant selection and position in reverse total shoulder arthroplasty. Orthop Clin North Am 2021;52:157–66.
9. Werthel JD, Walch G, Vegehan E, Deransart P, Sanchez-Sotelo J, Valenti P. Lateralization in reverse shoulder arthroplasty: a descriptive analysis of different implants in current practice. Int Orthop 2019;43:2349–60.
10. Berton A, Gulotta LV, Longo UG, et al. Medialized versus lateralized center of rotation in reverse total shoulder arthroplasty: a systematic review and meta-analysis. J Clin Med 2021;10:5868.
11. Hao KA, Cueto RJ, Gharby C, et al. Influence of lateralized versus medialized reverse shoulder arthroplasty design on external and internal rotation: a systematic review and meta-analysis. Clin Shoulder Elb 2023 Nov 14 [Epub].
12. Nyffeler RW, Altioklar B, Bissig P. Causes of acromion and scapular spine fractures following reverse shoulder arthroplasty: a retrospective analysis and literature review. Int Orthop 2020;44:2673–81.
13. Oh JH, Jeong HJ, Won YS. Implant selection for successful reverse total shoulder arthroplasty. Clin Shoulder Elb 2023;26:93–106.
14. Matthewson G, Kooner S, Kwapisz A, Leiter J, Old J, MacDonald P. The effect of subscapularis repair on dislocation rates in reverse shoulder arthroplasty: a meta-analysis and systematic review. J Shoulder Elbow Surg 2019;28:989–97.
15. Corona K, Cerciello S, Ciolli G, et al. Clinical outcomes and joint stability after lateralized reverse total shoulder arthroplasty with and without subscapularis repair: a meta-analysis. J Clin Med 2021;10:3014.
16. Clark JC, Ritchie J, Song FS, et al. Complication rates, dislocation, pain, and postoperative range of motion after reverse shoulder arthroplasty in patients with and without repair of the subscapularis. J Shoulder Elbow Surg 2012;21:36–41.

Article information Continued