Comparison of stemless and conventional stemmed shoulder arthroplasties in shoulder arthropathy: A meta-analysis

Stemmed VS stemless total shoulder arthroplasty: a systematic review and meta-analysis

AIM

Anatomic total shoulder arthroplasty (TSA) is commonly used for glenohumeral osteoarthritis (OA) in patients with an intact rotator cuff. The aim of this study was to quantify advantages and disadvantages of the stemmed and stemless designs in terms of clinical outcome and complications.

METHODS

A review was developed based on the PRISMA statement and registered on PROSPERO. Inclusion criteria were comparative studies analyzing stemmed vs. stemless TSA in adults with OA. The literature search was performed in PubMed, Web of Science, and Wiley Cochrane Library up to January 2024. Constant and Murley Score (CMS), Range of Motion, and operative time were documented, as well as complications divided into minor and major complications. The Downs and Black's "Checklist for Measuring Quality" was used to assess risk of bias and quality of evidence.

RESULTS

Out of 1876 articles retrieved; 14 were included in the meta-analysis for a total of 1496 patients (51.4% men, 48.6% women). The CMS was 74.8 points in the stemmed group and 76.9 points in the stemless group, with no differences in both overall score and subscales. No differences were found in elevation and abduction, while external rotation was 3.9° higher in the stemless group (p < 0.05) No differences were found in operating time and overall complications. However, deep infections were higher in the stemless group (2.2% vs. 0.8%, p < 0.05). The quality was assessed as poor, fair, good, and excellent in 0, 2, 7, and 5 studies, respectively.

CONCLUSION

Stemless TSA may offer minor advantages in terms of external rotation, although the clinical relevance appears doubtful. On the other hand, a lower deep infection rate was documented for stemmed implants. Overall, stemmed and stemless TSA provided good clinical results, with similar benefits in terms of clinical outcomes and complications.

Image-based finite element model stiffness and vBMD by single and dual energy CT reconstruction kernel

Single-energy quantitative computed tomography (SEQCT) provides volumetric bone mineral density (vBMD) measures for bone analysis and input to image-based finite element models (FEMs). Dual-energy CT (DECT) improves vBMD by accounting for voxel-specific material variations utilizing scans at multiple x-ray energies. vBMD is also altered by reconstruction kernel that cannot be accounted for using calibration phantoms. This study compared vBMD and FEM stiffness derived from SEQCT and DECT images reconstructed with two common kernels. SEQCT and DECT images of cadaveric shoulders (n = 10) were collected using standard (STD) and boneplus (BONE) kernels. Hounsfield Units were converted to vBMD using specimen-specific calibrations. DECT STD and BONE images were generated using an established material decomposition method with 40 and 90 keV simulated monochromatic images. A proximal humerus bone section below the anatomic neck was used for vBMD analysis and FEM generation. FEMs were loaded to 1% apparent strain for stiffness measurements. Between STD and BONE kernel images, average vBMD differed 0.9 mgK2HPO4/cc and 4.1 mg K2HPO4/cc, in SEQCT and DECT images, respectively. Significant differences occurred in DECT images (p = 0.001). BONE reconstructed images produced higher vBMD measures across both SEQCT and DECT images. The difference between STD and BONE in both SEQCT- and DECT-based FEMs persisted, with larger estimated stiffness in BONE models. For six of the models DECT-based had higher stiffness than SEQCT-based models using the same kernel, although these models differed between STD and BONE kernels. Differences in stiffness between STD and BONE derived models were similar across image types (DECT: 17.5 kN/mm; SEQCT: 19.0 kN/mm). Stiffness values were significantly different within SECT kernels and between SEQCT BONE and DECT STD models. This study shows important differences in vBMD and FEM stiffness that occur due to CT-based imaging parameters alone. These results indicate that consistent imaging parameters should be used for vBMD analysis and FEM input to avoid systematic measurement errors.

Recent Advances in the Design and Application of Shoulder Arthroplasty Implant Systems and Their Impact on Clinical Outcomes: A Comprehensive Review

Purpose of Review

This narrative review comprehensively aims to analyze recent advancements in shoulder arthroplasty, focusing on implant systems and their impact on patient outcomes. The purpose is to provide a nuanced understanding of the evolving landscape in shoulder arthroplasty, incorporating scientific, regulatory, and ethical dimensions.

Recent Findings

The review synthesizes recent literature on stemless implants, augmented glenoid components, inlay vs onlay configurations, convertible stems, and associated complications. Notable findings include improved patient-reported outcomes with stemless implants, variations in outcomes between inlay and onlay configurations, and the potential advantages of convertible stems. Additionally, the regulatory landscape, particularly the FDA's 510(k) pathway, is explored alongside ethical considerations, emphasizing the need for standardized international regulations.

Summary

Recent innovations in shoulder arthroplasty showcase promising advancements, with stemless implants demonstrating improved patient outcomes. The review underscores the necessity for ongoing research to address unresolved aspects and highlights the importance of a standardized regulatory framework to ensure patient safety globally. The synthesis of recent findings contributes to a comprehensive understanding of the current state of shoulder arthroplasty, guiding future research and clinical practices.

Stemless shoulder arthroplasty

The concept of stemless shoulder arthroplasty was born in 2005. It is now a valid option in the context of either anatomical or reverse shoulder replacement. Several questions have come up over our 15 years of using this system: How was the stemless shoulder arthroplasty concept born? It was motivated by a desire to have epiphyso-metaphyseal fixation using a corolla-shaped impacted anchor design. What are the features of commercially available stemless shoulder arthroplasty implants? The stemless anatomical implants now available have either a cage or central peg that is impacted or a system that is screwed into the epiphysometaphyseal bone. Several companies have introduced stemless reverse implants, some of which have an onlay configuration. How do the results of stemless implants compare to those of traditional stemmed implants? At a mean follow-up of 10 years, the outcomes of stemless TSA can be superimposed with those of traditional stemmed TSA. What are the advantages of stemless shoulder implants? The advantages are their simple implantation, ability to adapt to patient morphology and any malunions, various orientation angles, no stress-shielding, reduced risk of infection and bleeding and less complex revision surgery (if needed). What are the limitations or drawbacks of using stemless implants? The two main limitations are insufficient metaphyseal bone stock and poor bone quality, especially for reverse configurations. What does the future hold for stemless shoulder arthroplasty? Like with traditional stemmed implants, the longevity of stemless shoulder arthroplasty depends on its tribology, which can still be improved. In the future, a stemless implant will need to be convertible like stemmed humeral implants, and if possible, provide an inlay reverse configuration.

Outcomes of different stem sizes in shoulder arthroplasty

Background

The successive refinement in implant design and operative technique alongwith improved understanding has resulted in increased incidence of total shoulder arthroplasty (TSA). Simultaneously, the indications of TSA have widened and include a range of shoulder pathologies.

Methods

Using the keywords and relevant literature, we have described an overview of the different stem sizes used in shoulder arthroplasty. Relevant description of clinical and radiological outcome is done with regards to different stem sizes.

Discussion

There are plethora of shoulder replacement systems, based on unique philosophy and having their own advantages and disadvantages. Additionally, the rise in ageing population had increased the need for revision TSA, thereby necessitating the judicious choice of implant at primary TSA. We further present the role of cemented and uncemented humeral stems and discuss the findings of finite element analysis. The choice of humeral stem size and use of cemented or uncemented stems have been reported to affect the clinical and radiological outcomes.

Medium-term results of stemless, short, and conventional stem humeral components in anatomic total shoulder arthroplasty: a New Zealand Joint Registry study

BACKGROUND

The purpose of this study was to compare the medium-term results for anatomic total shoulder arthroplasty by humeral component stem length. We hypothesize that the newer stemless implants may have comparable results to short-stem and conventional stemmed implants.

METHODS

The 12 most used anatomic total shoulder arthroplasty implants on the New Zealand Joint Registry were included in the study. Implants were categorized by stem length-conventional, short, and stemless. The primary outcome was revision up to 7 years postsurgery. Secondary outcomes included revision cause, implant survival, and early functional outcomes as evaluated by the Oxford Shoulder Score. Analysis was stratified by age and surgeon volume to control for potential confounding.

RESULTS

A total of 3952 patients (conventional, 3114; short, 360; stemless, 478) were included in the study. No significant difference in revision rate per 100 component-years was found between stemless, short-stem, and conventional stemmed implants (revision rate per 100 component-years: conventional, 1.01 [95% confidence interval (CI) 0.89-1.14]; short, 0.54 [95% CI 0.25-1.03]; stemless, 0.99 [95% CI 0.51-1.74]). This finding was irrespective of patient age or surgeon volume. There were no cases of humeral loosening up to 7 years' follow-up and no cases of intraoperative humeral fracture in the stemless group. Functional outcomes at 6 months postsurgery suggested better outcomes in the stemless group compared with the conventional stem group (mean Oxford Shoulder Score: conventional, 39.4; stemless, 40.7; P value = .023).

CONCLUSION

The medium-term survival of stemless implants for anatomic total shoulder arthroplasty appears comparable to short-stem and conventional stemmed implants. Further follow-up is required to understand the long-term survivorship and functional outcomes between these groups.

Stemless anatomic total shoulder arthroplasty: surgical technique and review of the literature

Stemless anatomic total shoulder arthroplasty (aTSA) is a promising option for the treatment of degenerative disease in patients. This novel technique avoids the stem-related complications associated with the traditional stemmed aTSA. Stemless aTSA offers additional benefits such as decreased operative time, preservation of bone stock, improved radiographic outcomes, and easier revision. Moreover, loading of the metaphyseal region rather than the diaphysial region with traditional stemmed implants can decrease stress shielding. When compared to stemmed-implants, stemless aTSA has demonstrated similar outcomes and complication rates. The purpose of this article is to analyze published outcomes and complications following the utilization of stemless aTSA. Additionally, key aspects of the surgical technique that may promote optimal results in stemless aTSA implantation are presented.