Stemless or stemmed total shoulder arthroplasty?

 An active man in his mid 50s presented with pain and stiffness in his left shoulder and these x-rays. The axillary "truth" view showed the humeral head centered on an A2 glenoid.

Without preoperative CT or 3D planning, he underwent an anatomic total shoulder arthroplasty with a stemless humeral component (diameter of curvature 50, thickness 18 mm). A standard glenoid component was inserted without attempting to change glenoid version. The shoulder was stable on the "shake and bake" test.

He regained excellent comfort and function. 6 months later he presented with pain and stiffness in the right shoulder and the x-rays below. The axillary "truth" view showed the humeral head posteriorly decentered on a retroverted B2 glenoid.

 

Without preoperative CT or 3D planning, he underwent an anatomic total shoulder arthroplasty. A standard glenoid component was inserted without attempting to "correct" glenoid version. While many shoulders with this amount of posterior decentering are stable with standard humeral head components, on trialing a stemless humeral component (diameter of curvature 50, thickness 18 mm and then a diameter of curvature 50, thickness 20 mm ) this shoulder was posteriorly unstable on the "shake and bake" test. The arthroplasty was quickly and easily converted to a short stemmed implant using an anteriorly eccentric humeral head with a diameter of curvature 50, thickness 18 mm. 

 

This provided excellent posterior stability without excessively tightening the shoulder. 

For anatomic total shoulder arthroplasty, our default option is the stemless humeral implant because of the efficiency of the procedure and the ability to position the humeral head without being concerned about the stem. Our two indications for a stemmed implant are (1) the need for an eccentric humeral head component and (2) soft bone in the proximal humerus. Neither of these can be reliably determined prior to surgery. 

In performing an anatomic total shoulder, the proximal humerus is lateralized from its preoperative position by the addition of the thickness of a prosthetic glenoid component. See Seven ways to Overstuff and Anatomic Arthroplasty.

Thus, especially in shoulders that are tight preoperatively, a humeral implant with less than "anatomic" height may be needed to avoid over tightening the joint (see this link). Surgeons should be aware of the available head geometries of the implant system they are using.

That's our approach. Let's take a look at what the 2023 and 2024 literature has to say about stemless anatomic arthroplasty.

Stemless anatomic total shoulder arthroplasty is associated with less early postoperative pain "there were no differences in pain, patient-reported outcomes, range of motion or strength measures between stemless and short-stem aTSA at 2 years postoperatively."

Radiographic comparison of eccentric stemmed vs. concentric stemless prosthetic humeral head positioning after anatomic total shoulder arthroplasty "Stemless and stemmed aTSA implants have similar rates of reproducing satisfactory postoperative humeral head center of rotation (COR) with both producing COR deviation most commonly in the superomedial direction. Deviation in humeral head height above the greater tuberosity (HHH) contributes to overstuffing in both stemmed and stemless implants, COR deviation contributes to overstuffing in stemmed implants, while radius of curvature (RoC) is not associated with overstuffing."

Stemmed VS stemless total shoulder arthroplasty: a systematic review and meta-analysis "stemmed and stemless TSA provided good clinical results, with similar benefits in terms of clinical outcomes and complications."

A stemless anatomic shoulder arthroplasty design provides increased cortical medial calcar bone loading in variable bone densities compared to a short stem implant "A cortical rim-supported stemless implant maintained proximally improved dynamic bone loading compared to a press-fit short stem implant. Biomechanical time-zero implant micromotion in lower bone densities was comparable between short stem and stemless implants at rehabilitation load levels (220 N, 520 N), but there was higher cyclic stability and reduced variability for stemmed implantation at peak loads (820 N)."

Comparable low revision rates of stemmed and stemless total anatomic shoulder arthroplasties after exclusion of metal-backed glenoid components: a collaboration between the Australian and Danish national shoulder arthroplasty registries "Based on data from 2 national shoulder arthroplasty registries, we found no significant difference in risk of revision between stemmed and stemless total shoulder arthroplasties after adjusting for the type of glenoid component. We advocate that metal-backed glenoid components should be used with caution and not on a routine basis." see also High revision rate of metal-backed glenoid component and impact on the overall revision rate of stemless total shoulder arthroplasty: a cohort study from the Danish Shoulder Arthroplasty Registry. and Complications and revisions in metal-backed anatomic total shoulder arthroplasty: a comparative study of revision rates between stemless and stemmed humeral components

Stemless anatomic and reverse shoulder arthroplasty in patients under 55 years of age with primary glenohumeral osteoarthritis: an analysis of the Australian Orthopedic Association National Joint Replacement Registry at 5 years "In the predominantly male patient population below the age of 55, stemless aTSA had a lower short-term revision risk than stemmed aTSA."

Comparing optimum prosthesis combinations of total stemmed, stemless and reverse shoulder arthroplasty revision rates for men and women with glenohumeral osteoarthritis "In a subanalysis of procedures in males since 2017 with additional adjustments,stemless (slTSA) shoulder arthroplasty with cemented polyethylene glenoids had a lower revision rate than stemmed (stTSA) shoulder arthroplasty with modified central peg polyethylene glenoids" The same authors came to a slightly different set of conclusions in A comparison of revision rates for stemmed and stemless primary anatomic shoulder arthroplasty with all-polyethylene glenoid components: analysis from the Australian Orthopaedic Association National Joint Replacement Registry "Revision rates of stTSA and slTSA did not significantly differ and were associated with humeral head size but not patient characteristics. Surgeon inexperience of anatomic shoulder arthroplasty and non-XLPE glenoids were risk factors for stTSA revision but not slTSA.  Revision for instability/dislocation was more common for slTSA."

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

Stemless components lead to improved radiographic restoration of humeral head anatomy compared with short-stemmed components in total shoulder arthroplasty "Stemless prostheses placed during TSA achieved improved restoration of humeral head COR and were less likely to have significant COR outliers compared with short-stem implants."

Short-term radiographic analysis of a stemless humeral component for anatomic total shoulder arthroplasty "This study demonstrates a low rate of stress shielding for a stemless design humeral implant at short-term follow-up without any revision surgery due to humeral component complications."

Preoperative metaphyseal cancellous bone density is associated with intraoperative conversion to stemmed total shoulder arthroplasty "Metaphyseal cancellous bone density can be calculated on preoperative CT scans and is associated with intraoperative conversion to a stemmed humeral component in anatomic shoulder arthroplasty. A threshold of 20 HU can be used to predict which patients are more likely to require stemmed components."

Is stemless total shoulder arthroplasty indicated in elderly patients? "Age >/=70 years does not appear to be a contraindication to stemless anatomic total shoulder arthroplasty. Postoperative improvements in outcome scores were similar between patients aged <70 yr and those aged >/=70 years. There was no difference between the groups regarding the patients who required intraoperative deviation from the preoperatively planned stemless prosthesis to a stemmed prosthesis."  

Comment: As with all of orthopedics, experience is the great teacher for stemless arthroplasty. Be ready.

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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). 

Stemmed versus stemmless total shoulder arthroplasty

Stemmed versus stemmed total shoulder arthroplasty: A comparison of operative times: Stemmed vs stemless TSA operative time

These authors reviewed their master sample of 154 consecutive patients who underwent stemmed and stemless humeral implants.  Only primary TSA without augmented glenoid components were included, given the increased operative time for cases with augmented implants. This brought their final sample to 80. Of the included patients, 40 patients (50.0%) underwent stemless TSA and 40 patients (50.0%) underwent stemmed TSA. A stemmed implant was used if a patient exhibited contraindications to stemless TSA, including severe osteoporosis or evidence of poor cancellous bone in the operating room based upon thumb test (pressing into the bone with the thumb to assess rigidity and bone density). 

The stemmed cohort included 15 males and 25 females and the stemless cohort had 18 males and 22 females.

Patients in the stemless group were younger with a mean age of 61 compared to 68 in the stem group (P<0.01).

Operative time for the stemmed humeral implants was 100 minutes vs 87 minutes for the stemless implants (p=0.04).

This study did not compare the clinical outcomes or adverse outcomes for the two types of implants. 

Comment: The authors point out that a stemless component depends on metaphyseal bone quality for fixation. Apparently, half of their patients were deemed inappropriate for the stemless implant based on "contraindications to stemless TSA, including severe osteoporosis or evidence of poor cancellous bone"; therefore it would seem necessary to have both stemmed and stemless implants available so that the decision between implants could be made based on the intraoperative "thumb test". 

They also point out that stemless implants may be associated with increased cost, so that the savings resulting from a shorter operative time may be offset by the expense of the implant.

Our practice is to maximize our skill using a single versatile method for total shoulder arthroplasty with a standard stemmed implant inserted with impaction autografting; this is an approach that works for osteoporotic bone as well as for more normal bone.

Our method is shown in this link.

How you can support research in shoulder surgery Click on this link.

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 technique is shown in 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).

Follow on twitter: Frederick Matsen (@shoulderarth)

Revision of surface replacement and stemmed arthroplasties

Revision shoulder arthroplasty: does the stem really matter?

These authors reviewed 17 revisions of stemmed arthroplasties (STAs) and 23 revision of surface replacement arthroplasties (SRAs).

95% of the revisions (38 of 40) were due to rotator cuff failure. In 3 cases in each group (6 cases overall), implant loosening was evident as well.

While the operation time, need for humeral osteotomy, need for structural allograft, and number of intraoperative fractures were significantly higher in the STA group, there were no significant  difference between the Constant scores of the 2 groups preoperatively or postoperatively.

Comment: The results of revision arthroplasies depend on many factors, including the diagnosis for which the original arthroplasty was performed. In this series the two groups were not comparable. As shown below surface replacement arthroplasties were used for the simpler pathologies of OA and RA, while stemmed arthroplasties were used for more complex cases, such as fracture, fracture sequelae, and cuff tear arthropathy.

Revisions are highly individualized and depend on factors other than whether the index surgeon felt the need to use a stemmed component.

It is recognized, however, that stemmed arthroplasties need not be fixed with ingrowth or cement, so that revision, if necessary is facilitated. We find that an impaction-grafted humeral component not only preserves but adds bone to the humerus, enables positioning of the humeral articular surface in the desired location (including an eccentric offset when needed as shown in this link) and is applicable to essentially the full range of shoulder arthroplasty indications, rather than being subject to the anatomical restrictions for a resurfacing or stemless device.

We use a chrome cobalt humeral head prosthesis connected to a stem (titanium alloy) the tapered body of which fits inside the humerus.

We note that the humeral canal may be cylindrical or tapered.

and that the cross sectional geometry varies 

We agree that trying to fit a prosthesis by reaming the inside of the bone may substantially weaken it.

and that trying to force a tight fit risks fracture.

Our preferred method for securing the stem within the humeral canal is to use impaction grafting with bone harvested from the arthritic humeral head to conform the inner surface of the bone to the prosthesis. Some have likened this fitting of the patient's bone the prosthesis to the fitting of the traveler to the bed by the inn keeper Procrustes.

As a result, the tapered stem is securely fixed with a biological press fit that safely distributes the load from the prosthesis to the humerus, avoiding stress shielding which has been noted with short stem prostheses (see this link).

The amount of bone removed with an impaction grafted stem is minimal, leaving ample bone stock for revision should it become necessary.

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Consultation for those who live a distance away from Seattle.

Click here to see the new Rotator Cuff Book

Check out the new Shoulder Arthritis Book - 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'

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Conversion of anatomic arthroplasty to reverse total shoulder: what is the place for modular stems?

Conversion of Stemmed Hemi- or Total to Reverse Total Shoulder Arthroplasty: Advantages of a Modular Stem Design

These authors point out that revision of a well-fixed humeral stem has the potential risk of loss of humeral bone stock, nerve injury, periprosthetic fracture, and malunion or nonunion of a humeral osteotomy with later humeral component loosening.

They conducted a retrospective study of 48 hemiarthroplasties and eight total shoulder arthroplasties that were converted to a reverse total shoulder arthroplasty system. 19 of the stems were modular and 37 were non-modular. The incremental cost of a modular stem design over a standard implant are not stated.

The commonest reasons for conversion to a reverse shoulder arthroplasty was rotator cuff lesion with instability/loss of function (29), aseptic stem loosening (8), stem malposition with functional deficit (8), failure of glenoid component (6), and glenoid erosion (5). 

In 13 cases (all with modular stems) the surgeon elected to retain the humeral stem and in 43 (6 with modular stems and 37 without modular seems) the surgeon elected to change the stem because of stem loosening in 10 cases, stem malposition in 8, and difficulty in conversion of a non modular stem to a reverse in 25. In 12 cases a longitudinal humeral osteotomy was required for stem removal.

Blood loss, surgical time, the rate of complications (principally fractures) and revision rate were greater in the cases where the surgeon chose to perform a full stem exchange. 

Comment: It is of interest that most of the anatomic hemiarthroplasties and total shoulder arthroplasties in this series that were revised to reverse total shoulders were for diagnoses (proximal humeral fractures, post traumatic arthritis and cuff tear arthropathy) that today may well be treated with primary reverse total shoulders rather than an anatomic arthroplasty with a modular stem.

While the authors conclude that "..modularity of a shoulder arthroplasty system has proven and substantial advantages if conversion to reverse total shoulder arthroplasty becomes necessary and might be considered as prerequisite for stemmed shoulder arthroplasty systems", it is unclear for which patients they recommend the modular stem.  It would be important to know whether the number of cases of primary arthroplasty with modular stems that need revision and which can be successfully revised without stem removal offsets the incremental cost of the general use of modular stem designs.

See related posts here and here.

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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'