Component malposition and clinical outcomes in shoulder arthroplasty - are they related?

It seems intuitive that substantial malposition of shoulder arthroplasty components can lead to poor clinical outcomes.  

The assumption that malposition drives poor outcomes has become the rationale for investment in three-dimensional planning, patient-specific instrumentation, navigation, augmented reality, and robotics. However, examination of published evidence indicates that the relationship between measured component position and patient-reported outcomes is weaker than this narrative implies. For example Negligible Correlation between Radiographic Measurements and Clinical Outcomes in Patients Following Primary Reverse Total Shoulder Arthroplasty concluded that the relationship between measured component position and clinical outcomes is limited. Does postoperative glenoid component retroversion following anatomic total shoulder arthroplasty affect clinical outcomes? A systematic review and meta-analysis found no clinically significant difference in patient-reported outcome scores, range of motion, or complications for anatomic total shoulder arthroplasty glenoid components implanted with <15° versus ≥15° of postoperative retroversion across 15 studies and 1,190 shoulders. 

Humeral and glenoid component malposition in patients requiring revision shoulder arthroplasty: a retrospective, cross-sectional study measured component positions for TSA and RSA on pre-revision radiographs of patients having revision arthroplasty and compared these measures to "ideal" values for glenoid inclination, critical shoulder angle, glenosphere overhang, change in center of rotation, humeral head height, acromio-humeral interval, and humeral stem alignment. These measurements were not made on radiographs obtained immediately after the index arthroplasty, so the extent of postoperative component shift is not known.

The article found that the majority of glenoid components in these revision cases were malpositioned in relation to the "ideal" values for both TSA (51%) and RSA (93%) when all of the measures were considered. Similarly, there was humeral component malposition in 57% of TSA cases and 62% of RSA cases when all of the measures were considered.  

The prevalence of malpositioning in unrevised arthroplasties was not presented in this study.

Data such as that shown in graph A  (showing hypothetical values for unrevised shoulders) would suggest that malposition was not an important driver of revision.

On the other hand, data such as that shown in graph B would suggest that malposition was an important driver of revision.

This article did not provide data on the relationship of the degree of malposition to the rate of revision.

Data such as that shown in hypothetical graph C would suggest that the degree of malposition was tightly related to the revision rate.

Data such as that shown in hypothetical graph D would suggest that smaller degrees of malposition did not affect revision rate, whereas substantial degrees of malposition were clinically important.

What the literature does provide is evidence against a meaningful dose-response relationship. 

Below is a Forest plot of some key published studies relating glenoid component version to patient-reported clinical outcomes for aTSA and RSA. The effect sizes near zero with confidence intervals crossing the null line suggest the lack of a clinically meaningful dose-response relationship between glenoid component version and clinical outcome.

Below is a scatterplot showing the lack of a relationship between SANE and ASES scores and glenoid component version (data from Glenoid retroversion does not impact clinical outcomes or implant survivorship after total shoulder arthroplasty with minimal, noncorrective reaming).

Conclusion: A search of the currently available literature did not show a relationship between immediate postoperative radiographic measures of component position on one hand and clinically meaningful measures (such as patient-reported outcomes and revision rates) on the other. Such data will be important in demonstrating the potential clinical value of preoperative plan transfer technologies such as robotics, patient-specific instrumentation, navigation, and virtual/augmented reality. The thought that "continued improvements in component positioning technologies for both the glenoid and humeral implants are needed" will need to be supported by these analyses.

References

1. Checketts JX, Sanchez B, Norris G, Williamson TK, Hachadorian ME, Hsu JE, Schiffman CJ, Matsen FA III. Does postoperative glenoid component retroversion following anatomic total shoulder arthroplasty affect clinical outcomes? A systematic review and meta-analysis. J Shoulder Elbow Surg. 2026;35(5):1103–1116.

2. Sperling JW, Anderson MB, Jobin CM, Verborgt O, Duquin TR. Humeral and glenoid component malposition in patients requiring revision shoulder arthroplasty: a retrospective, cross-sectional study. J Shoulder Elbow Surg. 2025;34(8):1886–1896.

3. Service BC, Hsu JE, Somerson JS, Russ SM, Matsen FA III. Does postoperative glenoid retroversion affect the 2-year clinical and radiographic outcomes for total shoulder arthroplasty? Clin Orthop Relat Res. 2017;475(11):2726–2739.

4. Sheth MM, Mills ZD, Dasari SP, Whitson AJ, Matsen FA III, Hsu JE. Anatomic total shoulder arthroplasty for posteriorly eccentric and concentric osteoarthritis: a comparison at a minimum 5-year follow-up. J Shoulder Elbow Surg. 2025;34(2):473–483.

5. Matsen FA III, Whitson AJ, Somerson JS, Hsu JE. Anatomic total shoulder arthroplasty with all-polyethylene glenoid component for primary osteoarthritis with glenoid deficiencies. JB JS Open Access. 2020;5(4):e20.00002.

6. Grantham WJ, Dekker TJ, Lacheta L, Horan MP, Goldenberg BT, Elrick BP, et al. Total shoulder arthroplasty outcomes after noncorrective, concentric reaming of B2 glenoids. JSES Int. 2020;4(3):644–648.

7. Ma CB, Xiao W, Salesky M, Cheung E, Zhang AL, Feeley BT, et al. Do glenoid retroversion and humeral subluxation affect outcomes following total shoulder arthroplasty? JSES Int. 2020;4(3):649–656.

8. Rutledge JC, Dey Hazra RO, Geissbuhler AR, Yamaura K, Dey Hazra ME, Hanson JA, et al. Does glenoid version and its correction affect outcomes in anatomic shoulder arthroplasty? A systematic review. J Shoulder Elbow Surg. 2024;33(7):e384–e399.

9. Chalmers PN, Granger EK, Orvets ND, Patterson BM, Chamberlain AM, Keener JD, et al. Does prosthetic humeral articular surface positioning associate with outcome after total shoulder arthroplasty? J Shoulder Elbow Surg. 2018;27(5):863–870.

10. Werner BC, Creighton RA, Denard PJ, Lederman E, Romeo A, Griffin JW. Prosthetic humeral head center of rotation shift from ideal is associated with inferior clinical outcomes after anatomic total shoulder arthroplasty. Semin Arthroplasty JSES. 2021;31(4):668–676.

11. Varady NH, Bram JT, Chow J, Taylor SA, Dines JS, Fu MC, et al. Inconsistencies in measuring glenoid version in shoulder arthroplasty: a systematic review. J Shoulder Elbow Surg. 2025;34(2):639–649.

12. Terrier A, Ramondetti S, Merlini F, Pioletti DD, Farron A. Biomechanical consequences of humeral component malpositioning after anatomical total shoulder arthroplasty. J Shoulder Elbow Surg. 2010;19(8):1184–1190.

13. Franta AK, Lenters TR, Mounce D, Neradilek B, Matsen FA III. The complex characteristics of 282 unsatisfactory shoulder arthroplasties. J Shoulder Elbow Surg. 2007;16(5):555–562.

14. Sanchez-Sotelo J, Sperling JW, Rowland CM, Cofield RH. Instability after shoulder arthroplasty: results of surgical treatment. J Bone Joint Surg Am. 2003;85(4):622–631.

15. Burns DM, Frank T, Whyne CM, Henry PDG. Glenoid component positioning and guidance techniques in anatomic and reverse total shoulder arthroplasty: a systematic review and meta-analysis. Shoulder Elbow. 2019;11(2 Suppl):16–28.

16. Navarro RA, Chan PH, Prentice HA, Pearl M, Matsen FA III, McElvany MD. Use of preoperative CT scans and patient-specific instrumentation may not improve short-term adverse events after shoulder arthroplasty: results from a large integrated health-care system. JB JS Open Access. 2023;8(3):e22.00139.

17. Hsu JE, Hackett DJ Jr, Vo KV, Matsen FA III. What can be learned from an analysis of 215 glenoid component failures? J Shoulder Elbow Surg. 2018;27(3):478–486.

18. Walch G, Young AA, Boileau P, Loew M, Gazielly D, Molé D. Patterns of loosening of polyethylene keeled glenoid components after shoulder arthroplasty for primary osteoarthritis: results of a multicenter study with more than five years of follow-up. J Bone Joint Surg Am. 2012;94(2):145–150.

19. Harold RE, Sweeney PT, Torchia MT, Chamberlain AM, Keener JD. Total shoulder arthroplasty in patients with a B2 glenoid addressed with corrective reaming: mean 8-year follow-up. J Shoulder Elbow Surg. 2023;32(6 Suppl):S8–S16.

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Does the position of the humeral articular surface matter in total shoulder arthroplasty?

Does prosthetic humeral articular surface positioning associate with outcome after total shoulder arthroplasty?

These authors sought to determine the effect of humeral articular component positioning on changes in patient-reported outcomes after anatomic total shoulder arthroplasty in retrospective series of consecutive patients at 2 high-volume referral centers.

Distance and direction from the ideal COR to the reconstructed center of rotation was measured:

Among 95 patients the center of rotation shift was >2 mm in 62% of patients and >4 mm in 15%.

 On multivariate analysis, there were no significant associations between any change in measured prosthetic radiographic parameters and changes in the visual analog scale, Simple Shoulder Test, or ASES scores (P > .05).

The authors concluded that in this retrospective analysis of total shoulder arthroplasty in which most components were well positioned, humeral component positioning did not associate with change in postoperative outcomes.

Comment: This is an analysis of total shoulders performed by highly experienced surgeons who were able to reproducibly place the humeral component in the desired position. 

While the logistic regression did not show a clinical effect of humeral component position, it would of interest to compare the clinical outcomes of the 85% of cases with less than 4 mm shift of the center of rotation to the 15% of the shoulders that had >4 mm shift. 

In any event, their results cannot be interpreted as demonstrating that the humeral head position is unimportant to the outcome of shoulder arthroplasty. Several cases referred to us demonstrate the importance of proper humeral head position.

We have a new set of shoulder youtubes about the shoulder, check them out at this link.

Be sure to visit "Ream and Run - the state of the art"  regarding this radically conservative approach to shoulder arthritis at this link and this link

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Glenoid malposition in total shoulder.

When the glenoid component of a total shoulder is placed in a low and superiorly inclined position, it cannot stabilize the humeral head against the upwardly directed force of the deltoid. The resulting superior displacement of the humeral head can result in failure of the rotator cuff. Such a phenomenon is demonstrated in the radiograph below.

Removal of the glenoid component and cement left a large defect in the scapula.

The humeral head was revised to a CTA head with an extended articular surface. This improved the centering of the humeral joint surface on the glenoid and enabled immediate postoperative active assisted elevation.

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How you can support progress in shoulder surgery

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Rocking horse glenoid loosening when humeral component is cemented too high

The most common malposition of a humeral component is 'too high' as shown in the films below. Revision is complicated if it is cemented in this position.

A too high humeral component typically leads to rocking horse loosening of the glenoid component as shown in this case.

Revision of a cemented humeral component and a failed glenoid component is always a challenge because of the difficulty in removing the humeral component and the loss of quality glenoid bone. Fortunately, our colleague, Winston Warme, was up to the challenge as shown below.

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Consultation for those who live a distance away from Seattle.

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Information about shoulder exercises can be found at this link.

Use the "Search" box to the right to find other topics of interest to you.

You may be interested in some of our most visited web pages including:shoulder arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'

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Don't get high in shoulder arthroplasty

Getting the height of the humeral component just right can be a challenge.
In the case below, the position of the humeral component is a bit high with respect to the greater tuberosity.

The ideal relationship is shown in the upper figure below. As shown in the lower figure, a high position of the humeral head can place unwanted stress on the rotator cuff.

At surgery it is useful to expose the 'berm' (the superior edge of the humeral neck osteotomy shown by the red arrow) and to assure that the upper edge of the humeral component is slightly below it.

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Consultation for those who live a distance away from Seattle.

Click here to see the new Shoulder Arthritis Book

Click here to see the new Rotator Cuff Book

To see the topics covered in this Blog, click here

Use the "Search" box to the right to find other topics of interest to you.

You may be interested in some of our most visited web pages including:shoulder arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'

See from which cities our patients come.

See the countries from which our readers come on this post.