Stemless total shoulder - are the clinical outcomes better than those with stemmed implants?

There is a lot of interest in stemless humeral implants for total shoulder arthroplasty.

Some articles, such as the recent Radiographic comparison of eccentric stemmed versus concentric stemless prosthetic humeral head positioning after anatomic total shoulder arthroplasty focus on the degree to which the arthroplasty created the desired head position and concluded that "stemless and stemmed aTSA implants have similar rates of reproducing satisfactory postoperative humeral head center of rotation." 

Of course, both types of humeral arthroplasty are dependent on the surgeon "getting it right".  The example below shows overstuffing of a stemless component resulting from an improper humeral neck cut.

Another recent article Impact of Humeral Stem Length on Calcar Resorption in Anatomic Total Shoulder Arthroplasty pointed out that while resorption of calcar bone occurred with stemless, short stemmed and standard stemmed implants, higher degrees of resorption were less common with the stemless design because it directly loads the calar.

in contrast to designs where calcar is unloaded in favor of loading of the metaphysis

Clinical significance of these loading-related differences was not found by these authors: "Clinical outcomes were similar amongst all three stem designs in this study, suggesting that the boney adaptive changes observed do not influence clinical outcomes."

An important question, then, is "are the outcomes experienced by the patient better for stemless implants than for standard stems?" A look at 22 articles published over the last 10 years does not provide evidence that the clinical outcomes for stemless humeral implants are better than standard stems:

The authors of Stemless shoulder prosthesis versus conventional anatomic shoulder prosthesis in patients with osteoarthritis: a comparison of the functional outcome after a minimum of two years follow-up 2013 concluded "There was no significant difference in the Constant scores of the groups treated with the stemless shoulder prosthesis (65.0 points) and the stemmed shoulder prosthesis (73.2 points)."

Stemmed versus stemless total shoulder arthroplasty: a preliminary report and short-term results 2014 reported "No differences were detected after 2 years from surgery in the two groups in terms of functional scores and range of motion"

Are there differences between stemless and conventional stemmed shoulder prostheses in the treatment of glenohumeral osteoarthritis? 2015 found that "in patients with glenohumeral osteoarthritis, treated with TSA, the functional and the proprioceptive outcome is comparable between a stemless and a standard stemmed anatomic shoulder prosthesis at early followup".

Functional midterm follow-up comparison of stemless total shoulder prostheses versus conventional stemmed anatomic shoulder prostheses using a 3D-motion-analysis 2017. "Both types of shoulder prostheses achieve a similar and good active ROM and similar results in Constant score" .

A clinical trail, Patient-reported outcome after stemmed versus stemless total shoulder arthroplasty for glenohumeral osteoarthritis: a patient-blinded randomized clinical trial 2019 sounds promising, but the results have yet to be reported.

Radiographic restoration of native anatomy: a comparison between stemmed and stemless shoulder arthroplasty 2019 reported that "Radiographic restoration of anatomy is similar for stemmed and stemless shoulder arthroplasty implants"

Stemless shoulder arthroplasty: review of short and medium-term results 2019 "In the studies reporting similar outcome measures, there were reliable improvements on par with stemmed counterparts. Aggregate complication rates appear similar to those published in the literature for stemmed components."

The short-term survival of total stemless shoulder arthroplasty for osteoarthritis is comparable to that of total stemmed shoulder arthroplasty: a Nordic Arthroplasty Register Association study 2019 concluded "The short-term survival of total stemless shoulder arthroplasty appears comparable with total stemmed shoulder arthroplasty"    

The authors of Early migration of stemless and stemmed humeral components after total shoulder arthroplasty for osteoarthritis-study protocol for a randomized controlled trial 2020 have yet to report their results.

Prospective, Blinded, Randomized Controlled Trial of Stemless Versus Stemmed Humeral Components in Anatomic Total Shoulder Arthroplasty: Results at Short-Term Follow-up 2020 "At 2 years of follow-up, the safety and effectiveness of the stemless humeral implant were noninferior to those of the stemmed humeral implant in patients managed with aTSA for the treatment of osteoarthritis."

Stemless anatomic total shoulder arthroplasty: a systematic review and meta-analysis 2020. "Stemless anatomic TSA resulted in similar functional outcomes and complication rates to stemmed TSA "

Long-term survival and failure analysis of anatomical stemmed and stemless shoulder arthroplasties 2021 reported that "The use of anatomical stemless shoulder prosthesis yielded good and reliable results and did not differ from anatomical stemmed shoulder prosthesis over a mean period of ten years. The differences in periprosthetic humeral bone adaptations between both implants have no clinical impact during the follow-up"

Assessing the Value to the Patient of New Technologies in Anatomic Total Shoulder Arthroplasty 2021 did not identify evidence that the results of TSA were statistically or clinically improved over the 2 decades of study or that any of the individual technologies, such as stemless designs were associated with significant improvement in patient outcomes.

Comparison of stemless and conventional stemmed shoulder arthroplasties in shoulder arthropathy: A meta-analysis 2021 "This meta-analysis revealed that postoperative Constant score and complication rates did not differ significantly between the 2 treatment methods, stemless shoulder prosthesis and conventional stemmed shoulder prosthesis for shoulder arthropathy."

Short-term survival and patient-reported outcome of total stemless shoulder arthroplasty for osteoarthritis are similar to that of stemmed total shoulder arthroplasty: a study from the Danish Shoulder Arthroplasty Registry 2022 found that the differences in clinical outcomes were "not clinically relevant". 

Outcomes Between Stemmed and Stemless Total Shoulder Arthroplasty: A Systematic Review and Meta-analysis of Randomized Controlled Trials 2022 reported "TSA with stemless versus stemmed humeral components was not associated with notable differences in functional and clinical outcomes, the rate of humeral fracture or risk of revision."

Stemless anatomic total shoulder arthroplasty: surgical technique and review of the literature 2022. "When compared to stemmed-implants, stemless aTSA has demonstrated similar outcomes and complication rates."

Surgical time and outcomes of stemmed versus stemless total shoulder arthroplasty 2022 Stemless TSA had equivalent functional outcomes at a minimum 2-year follow-up.

Stemless components lead to improved radiographic restoration of humeral head anatomy compared with short-stemmed components in total shoulder arthroplasty 2023 did not report clinical outcomes for stemless or short-stemmed components. 

Medium-term results of stemless, short, and conventional stem humeral components in anatomic total shoulder arthroplasty: a New Zealand Joint Registry study 2023 "The medium-term survival of stemless implants for anatomic total shoulder arthroplasty appears comparable to short-stem and conventional stemmed implants."

Impact of Humeral Stem Length on Calcar Resorption in Anatomic Total Shoulder Arthroplasty. 2023  "Clinical outcomes were similar amongst all three stem designs in this study, suggesting that the boney adaptive changes observed do not influence clinical outcomes."

Comment: As pointed out in Stemless and stemmed humeral components in anatomic total shoulder arthroplasty. the value (benefit to the patient divided by cost) of stemless humeral components needs to be clarified by further clinical research - including the two randomized clinical trials that are hopefully still underway: 

Patient-reported outcome after stemmed versus stemless total shoulder arthroplasty for glenohumeral osteoarthritis: a patient-blinded randomized clinical trial 

and

Early migration of stemless and stemmed humeral components after total shoulder arthroplasty for osteoarthritis-study protocol for a randomized controlled trial 

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Here are some videos that are of shoulder interest
Shoulder arthritis - what you need to know (see this link).
How to x-ray the shoulder (see this link).
The ream and run procedure (see this link).
The total shoulder arthroplasty (see this link).
The cuff tear arthropathy arthroplasty (see this link).
The reverse total shoulder arthroplasty (see this link).
The smooth and move procedure for irreparable rotator cuff tears (see this link).
Shoulder rehabilitation exercises (see this link).