Factors Associated with Internal Rotation After Reverse Shoulder Arthroplasty: A Narrative Review

Abstract

Reverse shoulder arthroplasty (RSA) leads to improvement in pain and function with a durable outcome in most cases. While improvement in forward flexion and to a lesser degree external rotation is predictably seen after RSA, restoration of internal rotation (IR) is much less predictable. The purpose of this review was to provide a narrative of the modifiable factors, including prosthetic design and surgical factors, that may impact postoperative IR after RSA. Overall, the available data suggest that postoperative IR is improved with a lower humeral neck shaft angle and lateralization of the glenoid. Decreasing humeral retroversion to 20° or less improves IR at the cost of decreasing active external rotation. Increasing glenosphere diameter improves IR but often within the setting of additional variables. The association between subscapularis repair is less clear but overall suggests that IR is improved postoperatively when it is repaired.

Keywords: Complications; PROMs; Prosthesis; Range of motion; Results.

Figure 1

Variations of different humeral neck shaft angle. (Reproduced with permission, from Churchill JL, Garrigues GE. Current controversies in reverse total shoulder arthroplasty. JBJS Rev. 2016;4(6):01874474-201606000-00002. https://doi.org/10.2106/JBJS.RVW.15.00070.)

Figure 2

Diagrams show medialization of the glenoid component versus lateralization in RSA. (A) Medialization of the center of rotation recruits more deltoid force; thus, increasing muscle utilization but increasing the risk of scapular notching and reducing ROM. (B) Lateralization of the COR diminishes necessary deltoid force but decreases the risk of scapular notching and increases overall ROM. (Reproduced with permission, from Boileau P, Moineau G, Roussanne Y, O'Shea K. Bony increased-offset reversed shoulder arthroplasty: minimizing scapular impingement while maximizing glenoid fixation. Clin Orthop Relat Res. 2011;469(9):2558-2567. https://doi.org/10.1007/s11999-011-1775-4.)

Figure 3

Comparison of predicted probabilities for size (38 mm) and (42 mm) glenospheres across a variety of different heights. (Reproduced with permission, from Schoch B, Vasilopoulos T, LaChaud G, Wright T, Roche C, King J, et al. Optimal glenosphere size cannot be determined by patient height. J Shoulder Elbow Surg. 2019;29(2):258-265. https://doi.org/10.1016/j.jse.2019.07.003.)

Figure 4

Varying degrees of humeral retroversion as defined as the angular orientation of the humeral head component and the distal axis of the elbow. (Reproduced with permission, from Gulotta LV, Choi D, Marinello P, et al. Humeral component retroversion in reverse total shoulder arthroplasty: a biomechanical study. J Shoulder Elbow Surg. 2012;21(9):1121-1127. https://doi.org/10.1016/j.jse.2011.07.027.)

Figure 5

Glenosphere position resultant of the resting face of the glenoid in (A) neutral position, (B) medialized position, (C) lateralized position at 10 mm, (D) superiorly translated +6 mm, (E) inferiorly translated –6 mm, (F) 10° superior inclination, (G) 10° inferior inclination. (Reproduced with permission, from Li X, Knutson Z, Choi D, et al. Effects of glenosphere positioning on impingement-free internal and external rotation after reverse total shoulder arthroplasty. J Shoulder Elbow Surg. 2013;22(6):807-813. https://doi.org/10.1016/j.jse.2012.07.013.)

Figure 6

Glenosphere position relative to the glenoid placement (A) in native configuration (center of the glenoid), (B) inferior offset (1 cm inferior to center of glenoid). (Reproduced with permission, from Virani NA, Cabezas A, Gutiérrez S, Santoni BG, Otto R, Frankle M. Reverse shoulder arthroplasty components and surgical techniques that restore glenohumeral motion. J Shoulder Elbow Surg. 2013;22(2):179-187. https://doi.org/10.1016/j.jse.2012.02.004.)