How to choose a humeral component in shoulder arthroplasty: ASES Podcast 155

Hat's off to Drs Chalmers and Waterman for yet another outstanding ASES podcast: Episode 155, in which they were joined by Drs Athwal, Cuff and Hatzidakis to discuss fixation of humeral arthroplasty components: "standard" length stems (100-150 mm), short stems (60-90 mm) and stemless designs. 

Here are some takeaways from that presentation coupled with some additional thoughts from the U.W..

(1) The evolution in humeral components is attributed to (a) mitigation of complications (periprosthetic fracture, stress shielding from high canal-filling ratios, early loosening from certain ingrowth surfaces), (b) matching competitor features, and (c) responding to market forces.

The Standard Stem

(2) A standard length stem uses the canal as an alignment guide. As pointed out a the end of this post, it does not require stabilization by (a) a bony ingrowth surface, (b) cement, or (c) reaming to a tight diaphyseal fit.

(3) Osteoporosis or altered humeral anatomy may drive the use of a longer stem for better fixation and durability.

The Short Stem

(4) The short stem depends on loading at the metaphyseal level in bone that has variable shape and quality making both fixation and orientation challenging.

The short stem may not have enough leverage to reduce loosening.

Canal filling can lead to stress shielding

And periprosthetic fracture

The absence of the control provided by a standard length stem can enable malpositioning of a short stem

(5) Stemless implants depend on fixation at the anatomic neck where a thin cortical shell surrounds cancellous bone. Bone density at this level is of variable quality, especially in patients in the arthroplasty age range. While some surgeons claim "100% stemless", this claim is not realistic for all patients having shoulder arthroplasty.

The big question about stemless: how does a surgeon decide whether good fixation of a stemless can be achieved? While preoperative imaging may give some clues, it all comes down to the intraoperative findings. Some have advocated the "thumb" test,

but a better approach may be to insert the trial nucleus and determine if it's solid. If it's not solid because of "mushy" bone; adding bone graft has not proven effective in our experience. The ability to get better fixation with longer fins is limited.

 

So...in the real world, the stemless-loving surgeon needs to have a plan "B" when trial stemless fixation is unstable. Conversion to a stemmed component seems the most attractive option. A caveat: if the issue is mushy cancellous bone, fixation of a short stem can be challenging - fat stem vs bone graft, how to assure durability in the desired position?

Progressive failure of fixation of a short stem

Might an impaction grafted standard stem have been a better choice?

Avoiding Trouble with the Stemless

Be aware of common technical mistakes - assure complete head resection and avoid excessive varus or valgus. 

The free-hand cut is key.

Revision

(6) Two concerns arise when the humeral component needs revision: (1) removal of a well fixed implant can risk fracture of the tuberosity, bone loss, shaft fracture and may require a humeral osteotomy or window. (2) while some humeral implants are "convertible" (meaning the humeral fixation system remains in place), the case for retaining the implant requires that it be well fixed at an appropriate height and acceptable version (one participant found that 25–40% of nominally convertible stems cannot actually be converted) - thus the routine use of "convertible" implants seems unattractive, 

Another approach

(7) Our experience is that secure, safely revisable humeral component fixation can be achieved with a smooth, standard length stem with a small filling ratio fixed with impaction autografting (using bone from the resected humeral head that one of our fellows named "God's Own Glue")(see "Procrustean Method"). 

 A low filling ratio protects the humerus from stress shielding

 

Two year followup

Six year followup

Impaction grafting with a low filling ratio avoids incomplete seating of the humeral stem (humerus captivus)

Impaction grafting a standard stem in revising a failed short stem

Impaction grafting a thin long stem  in humeral deformity

Impaction grafting after fracture fixation

Impaction grafting a thin standard stem enables easy, safe removal followed by new implant insertion

 should revision be necessary, 

Thus "revisability" does not require "convertibility"

If we go back to the opening comment: "The evolution in humeral components is attributed to (a) mitigation of complications (periprosthetic fracture, stress shielding from high canal-filling ratios, early loosening from certain ingrowth surfaces), (b) matching competitor features, and (c) responding to market forces". 

the impaction grafting of a thin smooth stem represents an approach to "mitigation of complications (periprosthetic fracture, stress shielding from high canal-filling ratios, early loosening from certain ingrowth surfaces", but is not driven by "matching competitor features" or "responding to market forces". Impaction grafting is not proprietary to any implant; rather it can be a generic part of a surgeon's method in both anatomic and reverse shoulder arthroplasty. In primary cases it uses free autograft that would otherwise be discarded.

"Radiographic outcomes of impaction-grafted standard-length humeral components in total shoulder and ream-and-run arthroplasty: is stress shielding an issue?" (reference 9) concluded "When inserted with impaction autografting, a smooth, standard-length humeral stem offers a secure bone-preserving approach for humeral component fixation in shoulder arthroplasty. These results with a conventional prosthesis can serve as a basis for comparison for new component designs and fixation methods."

Should we be thinking straight?

Beauty in Simplicity

Tundra Swan

Union Bay Natural Area

Disclaimer: the author has no financial relationships with companies whose products are shown in this post.

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References of interest

1. The ASES Podcast (American Shoulder and Elbow Surgeons), Episode 155: standard, short, and stemless humeral components and convertible designs. Available at: https://www.youtube.com/watch?v=q_s_g8oQgPg

2. Razfar N, Reeves JM, Langohr GDG, Willing R, Athwal GS, Johnson JA. Comparison of proximal humeral bone stresses between stemless, short stem, and standard stem length: a finite element analysis. J Shoulder Elbow Surg. 2016;25(7):1076–1083. doi:10.1016/j.jse.2015.11.011. PMID 26810016.

3. Reeves JM, Langohr GDG, Athwal GS, Johnson JA. The effect of stemless humeral component fixation feature design on bone stress and strain response: a finite element analysis. J Shoulder Elbow Surg. 2018;27(12):2232–2241. doi:10.1016/j.jse.2018.06.002. PMID 30104100.

4. Synnott S, Langohr GDG, Reeves JM, Johnson JA, Athwal GS. The effect of humeral implant thickness and canal fill on interface contact and bone stresses in the proximal humerus. JSES Int. 2021;5(5):881–888. doi:10.1016/j.jseint.2021.05.006.

5. Aibinder WR, Uddin F, Bicknell RT, Krupp R, Scheibel M, Athwal GS. Stress shielding following stemless anatomic total shoulder arthroplasty. Shoulder Elbow. 2023. doi:10.1177/17585732211058804. PMID 36895609.

6. Raiss P, Edwards TB, Deutsch A, Shah A, Bruckner T, Loew M, Boileau P, Walch G. Radiographic changes around humeral components in shoulder arthroplasty. J Bone Joint Surg Am. 2014;96(7):e54. doi:10.2106/JBJS.M.00378. PMID 24695931.

7. Denard PJ, Raiss P, Gobezie R, Edwards TB, Lederman E. Stress shielding of the humerus in press-fit anatomic shoulder arthroplasty: review and recommendations for evaluation. J Shoulder Elbow Surg. 2018;27(6):1139–1147. doi:10.1016/j.jse.2017.12.020. PMID 29422391.

8. Sheth MM, Kahsai EA, Yang J, Whitson AJ, Matsen FA III, Hsu JE. What is the clinical importance of radiographic changes around the humeral component in anatomic shoulder arthroplasty? A minimum 4-year follow-up study. J Shoulder Elbow Surg.2025;34(8):1877–1885. doi:10.1016/j.jse.2024.11.024. PMID 39800107.

9. Denard PJ, Hsu JE, Whitson A, Neradilek MB, Matsen FA III. Radiographic outcomes of impaction-grafted standard-length humeral components in total shoulder and ream-and-run arthroplasty: is stress shielding an issue? J Shoulder Elbow Surg.2019;28(11):2181–2190. doi:10.1016/j.jse.2019.03.016. PMID 31272887.

10. Kim SC, Park JH, Bukhary H, Yoo JC. Humeral stem with low filling ratio reduces stress shielding in primary reverse shoulder arthroplasty. Int Orthop. 2022;46(6):1341–1349. doi:10.1007/s00264-022-05383-4.

11. Lee M, Chebli C, Mounce D, Bertelsen A, Richardson M, Matsen FA III. Intramedullary reaming for press-fit fixation of a humeral component removes cortical bone asymmetrically. J Shoulder Elbow Surg. 2008;17(1):150–155. doi:10.1016/j.jse.2007.03.032. PMID 18029200.

12. Boorman RS, Hacker SA, Lippitt SB, Matsen FA III. A conservative broaching and impaction grafting technique for humeral component placement and fixation in shoulder arthroplasty: the Procrustean method. Tech Shoulder Elbow Surg.2001;2(3):166–175. doi:10.1097/00132589-200109000-00004.

13. Hacker SA, Boorman RS, Lippitt SB, Matsen FA III. Impaction grafting improves the fit of uncemented humeral arthroplasty. J Shoulder Elbow Surg. 2003;12(5):431–435. doi:10.1016/s1058-2746(03)00053-3. PMID 14564262.

14. Lucas RM, Hsu JE, Gee AO, Neradilek MB, Matsen FA III. Impaction autografting: bone-preserving, secure fixation of a standard humeral component. J Shoulder Elbow Surg. 2016;25(11):1787–1794. doi:10.1016/j.jse.2016.03.008. PMID 27262410.

15. Lee et al. Stress shielding effects of short stem alignment and bone density in reverse shoulder arthroplasty. J Orthop Res. 2026. doi:10.1002/jor.70140.

16. Vasiliadis AV, Giovanoulis V, Lepidas N, Bampis I, Servien E, Lustig S, Gunst S. Stress shielding in stemmed reverse shoulder arthroplasty: an updated review. SICOT J. 2024;10:37. doi:10.1051/sicotj/2024029.

17. Ritter D, Raiss P, Denard PJ, Werner BC, Müller PE, Woiczinski M, Wijdicks CA, Bachmaier S. Volumetric humeral canal fill ratio effects primary stability and cortical bone loading in short and standard stem reverse shoulder arthroplasty: a biomechanical and computational study. J Imaging. 2024;10(12):334. doi:10.3390/jimaging10120334.

18. Kramer M, Olach M, Zdravkovic V, Manser M, Raiss P, Jost B, Spross C. The effects of length and width of the stem on proximal humerus stress shielding in uncemented primary reverse total shoulder arthroplasty. Arch Orthop Trauma Surg. 2024. doi:10.1007/s00402-023-05129-w.

19. John PB, Nageswaran S. Mechanobiological evaluation of solid and multiple porous humeral stem architectures in reverse shoulder arthroplasty based on design and materials: a finite element study. Front Bioeng Biotechnol. 2026;13:1675726. doi:10.3389/fbioe.2025.1675726.

20. Takayama K, Ito H. Association between the canal filling ratio and bone resorption in trabecular metal stems in reverse total shoulder arthroplasty: a radiographic analysis using tomosynthesis. JSES Int. 2024;8(5):1077–1086. doi:10.1016/j.jseint.2024.05.010.