15 April 2026
From Concept to Clinical Impact: Enovis’ Journey with Inverted Bearings in Reverse Shoulder Arthroplasty
Do you know Enovis introduced the inverted bearings in Reverse shoulder prosthesis trough different products in its portfolio?
First, in 2005, SMR Reverse HP Glenospheres started changing the design of SMR reverse, being the first full polyethylene glenosphere with its peculiar shape available in the market. While the chamfered design allows for the use of larger diameter glenospheres even in smaller anatomies (i.e. a dia. 40mm glenospheres has the same volumetrical dimension as a dia. 36mm glenosphere), the inversion of materials enables the use of metal liners, offering more possibilities to balance soft tissues (for example, using the lateralizing liners). Further to improving Range of Motion and stability(1-3), this also avoids the secondary effects of mechanical impingement(2,4), since HP metal liners avoid the formation of polyethylene particles which can cause an inflammatory reaction. (5)
In 2007, Affinis Inverse also introduced the inversion of the materials in the tribological pairing, reducing polyethylene abrasion on the scapular neck and surrounding structures. (6) This results in a reduced risk of polyethylene-induced disorders such as osteolyses.(7-10) To invert materials, Affinis Inverse features innovative materials such as vitamys (a highly crosslinked polyethylene enriched with vitamin E) for the glenosphere and high-quality ceramics for the inlay liner. Vitamys offers different benefits: The good mechanical strength allows long-term mechanical performance, and the high wear resistance reduces the risk of osteolyses.(8-10) The addition of vitamin E furthermore ensures resistance to oxidation(11). On the humeral side, ceramics features low wear rates, high strength and toughness, good wettability as well as biologically inert behaviour. (7, 11)
Bibliography
[1] Bloch H.R., Budassi P., Bischof A., Agneskirchner J., Domenghini C., Frattini M., Borroni M., Zoni S., Castagna A., “Influence of glenosphere design and material on clinical outcomes of reverse total shoulder arthroplasty”, Shoulder & Elbow (2014) 6,156-64
[2] Chou J., Malak S.F., Anderson I.A., Astley T., Poon P.C., “Biomechanical evaluation of different designs of glenospheres in the SMR reverse total shoulder prosthesis: Range of motion and risk of scapular notching”, J Shoulder Elbow Surg (2009) 18, 354-359
[3] Müller A.M., Born M., Jung C., Flury M., Kolling C., Schwyzer H.K., Audigé L., “Glenosphere size in reverse shoulder arthroplasty: is larger better for external rotation and abduction strength?”, J Shoulder Elbow Surg (2018) 27, 44–52
[4] Fattori A., Kontaxis A., Chen X., Vidoni G., Castagna A., Pressacco M., “Articular Impingement in Reverse Shoulder During Activities of Daily Living: A Biomechanical Analysis With the SMR Prosthesis”, ISTA (2018)
[5] Castagna A., Borroni M., Dubini L., Gumina S., Delle Rose G., Ranieri R., “Inverted-Bearing Reverse Shoulder Arthroplasty: Consequences on Scapular Notching and Clinical Results at Mid-Term Follow-Up”, J. Clin. Med. (2022) 11(19), 5796
[6] Kohut G, Dallmann F, Irlenbusch U. Wear-induced loss of mass in reversed total shoulder arthroplasty with conventional and inverted bearing materials. J Biomech. 2012;45(3):469-73.
[7] Alexander J J, Bell S N, Coghlan J, Lerf R, Dallmann F. The effect of vitamin E-enhanced cross-linked polyethylene on wear in shoulder arthroplasty-a wear simulator study. J Shoulder Elbow Surg. 2019;28(9):1771-8.
[8] Boileau P, Moineau G, Morin-Salvo N, Avidor C, Godeneche A, Levigne C, Baba M, Walch G. Metalbacked glenoid implant with polyethylene insert is not a viable long-term therapeutic option. J Shoulder Elbow Surg. 2015;24(10):1534-43.
[9] Harris W H. Wear and periprosthetic osteolysis: the problem. Clin Orthop Relat Res. 2001(393):66-70.
[10] Huang C H, Lu Y C, Chang T K, Hsiao I L, Su Y C, Yeh S T, Fang H W, Huang C H. In vivo biological response to highly cross-linked and vitamin e-doped polyethylene--a particle-Induced osteolysis animal study. J Biomed Mater Res B Appl Biomater. 2016;104(3):561-7.
[11] Willmann G. Improving Bearing Surfaces of Artificial Joints. Advanced Engineering Materials. 2001;2(3):135-41
