Review of “Humeral and glenoid component malposition in patients requiring revision shoulder arthroplasty: a retrospective, cross-sectional study” (1)
Introduction
Due to the rapid growth of shoulder arthroplasty procedures worldwide, the rates of complications and revisions are outpacing those reported for hip and knee replacements. Cumulative percent revision (CPR) rates of 12.7% for stemmed anatomic total shoulder arthroplasty (TSA) and 5.7% for reverse shoulder arthroplasty (RSA) have been reported from the Australian Orthopaedic Associations National Joint Replacement Registry (AOANJRR) (2). As primary shoulder arthroplasty becomes more common, the incidence of revision surgery and the related economic impact on the U.S. health-care system will also increase (3). Shoulder arthroplasty (TSA, RSA, HA – hemiarthroplasty) most often fails due to instability, rotator cuff dysfunction, infection, or loosening (2, 4); however, a comprehensive understanding of component malposition as a failure mechanism may be equally important.
Summary
The authors of this retrospective cross-sectional study aimed to assess the incidence of glenoid and humeral component malposition in failed primary shoulder arthroplasty requiring revision.
Materials and Methods
Quantitative and qualitative reviews were performed on 234 consecutive cases (94 TSA, 72 HA, 68 RSA) from 3 institutions. Relevant past surgical and radiographic data was collected, and the radiographs were reviewed by each investigator and an independent reviewer. Of the revisions, 84% were revised to RSA, 8% to TSA, 4% to HA, and 4% to antibiotic spacer. The humerus was revised in 77% of cases and the glenoid was revised in 84% of cases.
Component malposition was considered according to the table below:
| Glenoid Component | Humeral Component |
| If TSA, inclination <85 degrees or >95 degrees | COR ≥5mm from anatomic COR |
| If RSA, inclination <90 degrees or >100 degrees | ≥10mm superior to apex of GT |
| If TSA, CSA >35 degrees | If TSA, AHI ≥15mm |
| If RSA, CSA <25 degrees | If RSA, AHI ≥30mm |
| Glenosphere overhang <0mm or >5mm | |
| Presence of glenohumeral subluxation |
AHI, acromiohumeral interval; COR, center of rotation; CSA, critical shoulder angle; GT, greater tuberosity
Results
Findings from quantitative radiographic evaluation, physician assessment, and independent review are summarized as follows:
| Glenoid Component Malposition Rate (Quantitative Radiographic Review) |
||
| RSA Overall
93% |
Overhang | 65% |
| Inclination (superior tilt) | 88% | |
| CSA>35 | 36% | |
| Dislocation | 26% | |
| Subluxation (severe) | 1% | |
| TSA Overall
51% |
Inclination (superior tilt) | 54% |
| CSA<25 | 19% | |
| Dislocation | 3% | |
| Subluxation (severe) | 35% | |
| Humeral Component Malposition Rate (Quantitative Radiographic Review) |
||
| TSA Overall
57% |
COR (superior & medial) | 45% |
| Humeral tuberosity-head height | 24% | |
| AHI | 16% | |
| HA Overall
54% |
COR (superior & medial) | 55% |
| Humeral tuberosity-head height | 28% | |
| AHI | 12% | |
| RSA Overall
62% |
Humeral tuberosity-head height | 56% |
| AHI | 42% | |
| Glenoid and Humeral Component Malposition Rates (Qualitative Review) |
||||
| Glenoid | Humeral | |||
|
Investigator |
RSA | 68% | RSA | 24% |
| TSA | 19% | TSA | 65% | |
| HA | 85% | |||
|
Independent |
RSA | 54% | RSA | 24% |
| TSA | 17% | TSA | 71% | |
| HA | 74% | |||
Discussion
Glenoid and humeral malposition are recognized as potential causes of rotator cuff failure and instability following total shoulder arthroplasty. In this quantitative study, glenoid and humeral component malposition were present in greater than 50% of revision cases. Component malposition occurred most in failed RSA cases at 93%. Data demonstrated that humeral component malposition occurred consistently with a superior and medial COR. Regarding the glenoid component, malposition occurred consistently with glenoid inclination, followed by outliers of sphere-bone overhang distance. These results underscore the importance of recognizing and preventing component malposition to reduce the risk of failure.
Reviewer Comment
While technological advances such as PSI, navigation, and AR/MR have been shown to improve glenoid component position, this article highlights the need to further improve component position technologies for both the glenoid and humerus.
Key Takeaway
In this reviewer’s opinion, optimal glenoid implant positioning in RSA should be neutral inclination, with less than 5mm overhang, while optimal humeral implant positioning in TSA/HA should be within 5mm of the anatomic COR.
References
- Sperling, John W., et al. “Humeral and glenoid component malposition in patients requiring revision shoulder arthroplasty: A retrospective, cross-sectional study.” Journal of Shoulder and Elbow Surgery, vol. 34, no. 8, Aug. 2025, pp. 1886–1896, https://doi.org/10.1016/j.jse.2024.11.015.
- Australian orthopaedic association national Joint replacement registry (AOANJRR). Hip, Knee & Shoulder Arthroplasty: 2023 Annual Report; 2023. Available at: https://aoanjrr.sahmri.com/documents/10180/1579982/AOA_NJRR_AR23.pdf/c3bcc83b-5590-e034-4ad8-802e4ad8bf5b?t¼1695887126627.2023.
- Farley, KX, et al. “Prevalence of shoulder arthroplasty in the United States and the increasing burden of revision shoulder arthroplasty.” JBJS Open Access 2021;6. https://doi.org/10.2106/JBJS.OA.20.00156
- NJR-UK. The national Joint registry 19th annual report 2022. Available at: https://reports.njrcentre.org.uk/Portals/0/PDFdownloads/NJR%2019th%20Annual%20Report%202022.pdf
- Nashikkar, Piyush S et al. “Computer navigation re-creates planned glenoid placement and reduces correction variability in total shoulder arthroplasty: an in vivo case-control study.” Journal of shoulder and elbow surgery 28,12 (2019): e398-e409. doi:10.1016/j.jse.2019.04.037