Stemless anatomic shoulder arthroplasty - humeral loosening?

The 2023 Australian Orthopaedic Association's National Joint Replacement Registry (a link to the full 2023 report can be found here) reports that in Australia total stemless anatomic shoulder arthroplasties were performed more frequently than total stemmed anatomic shoulder replacements. Excluding revisions for infection, the 10 year revision rate was 3.7% for stemless anatomic total shoulders in comparison to 11.2% for those with stemmed humeral components. The overall seven year revision rate for total stemless anatomic revision was lower for males (3.9%) than females (5.2%), but was not influenced by other prosthetic factors or age. The percentage of these revisions performed for humeral component loosening is not provided. 

So, do we know whether or how often stemless humeral components in anatomic total shoulders loosen?

A PubMed search for humeral component loosening in anatomic stemless shoulder arthroplasty revealed the following reports

2015 Midterm results of stemless shoulder arthroplasty: a prospective study. None of the stemless implants were revised for loosening.

2016 Clinical and Radiographic Outcomes of the Simpliciti Canal-Sparing Shoulder Arthroplasty System: A Prospective Two-Year Multicenter Study There was no evidence of migration, subsidence, osteolysis, or loosening of the humeral components.

2016 Anatomic stemless shoulder arthroplasty and related outcomes: a systematic review. One case of asymptomatic radiographic loosening,

2021 Long-term survival and failure analysis of anatomical stemmed and stemless shoulder arthroplasties. Radiological evaluation showed no loosening of the humeral implants.

2021 Survival of stemless humeral head replacement in anatomic shoulder arthroplasty: a prospective study Clinically and radiologically, the authors observed no loosening of the stemless humeral head component.

2022 Mid-term results of Eclipse total shoulder arthroplasty No humeral components were loose.

2022 Sex-related differences in stemless total shoulder arthroplasty No humeral components were loose.

2023 Midterm results of stemless impaction shoulder arthroplasty for primary osteoarthritis: a prospective, multicenter study. There were no cases of humeral loosening.

2022 Stemless Hemiarthroplasty of the Shoulder Using the SMR(R) System: Summary of Six-Year Experience and Surgical Technique No cases of failure or loosening of the humeral implant.

2022 Early fixation of the humeral component in stemless total shoulder arthroplasty : a radiostereometric and clinical study with 24-month follow-up 20 out of 24 prostheses stabilized within the first 12 months postoperatively. Four prostheses showed continuous migration between 12 and 24 months postoperatively. There were no revisions for loosening.

2022 Short-term results of a new anatomic stemless shoulder arthroplasty - A prospective multicentre study Postoperative radiographs showed no continuous radiolucent lines, subsidence, aseptic loosening or progressive radiolucency.

2023 Short-term radiographic analysis of a stemless humeral component for anatomic total shoulder arthroplasty No humeral component shift or subsidence was observed

2023 Medium-term results of stemless, short, and conventional stem humeral components in anatomic total shoulder arthroplasty: a New Zealand Joint Registry study No patients having stemless arthroplasty were revised for humeral component loosening.

These minimal reported values for loosening of the anatomic stemless humeral component may be due to a combination of several factors:

(1) lack of sufficiently long-term followup - time will tell

(2) surgeons' decision to avoid stemless components in patients suspected of having insufficient bone quality based on preoperative assessment

Simple preoperative radiographic and computed tomography measurements predict adequate bone quality for stemless total shoulder arthroplasty a deltoid tuberosity index of 1.41 on plain films and proximal humeral Hounsfield value of 14.1 units on CT had good sensitivity and specificity for adequate stemless fixation.

Preoperative metaphyseal cancellous bone density is associated with intraoperative conversion to stemmed total shoulder arthroplasty A threshold of 20 Hounsfield can be used to predict which patients are more likely to receive stemmed rather than stemless components.

Preoperative 3D Computed Tomography Bone Density Measures Provide Objective Bone Quality Classifications for Stemless Anatomic Total Shoulder Arthroplasty Preoperative CT imaging allows accurate evaluation of the bone densities in the proximal humerus. Three-dimensional regions of interest, rescaling using patient-specific calibration, and a machine learning model resulted in good-to-excellent prediction for objective bone quality classification. 

(3) surgeon decision to avoid stemless component in patients with soft bone as determined by intraoperative assessment

Simple preoperative radiographic and computed tomography measurements predict adequate bone quality for stemless total shoulder arthroplasty

"If bone quality was deemed adequate on inspection, the surgeon would use his thumb to compress the cut surface of the bone. Bone that was compressed with minimal force was deemed insufficient for stemless component fixation, and therefore placement of a short metaphyseal-fitting stem was performed. Once the stemless trial was implanted, rotational stability was assessed by applying manual torque to the implant via the implant inserter handle, and if the component rotated, the bone was deemed inadequate for stemless fixation. This was repeated for the final implant, and if the implant rotated within the bone under minimal torque, the stemless humeral component was revised to a short-stem meta- physeal-fitting humeral component intraoperatively. Sixty-one planned stemless TSAs were included, with 56 (91.8%) undergoing stemless TSA and 5 (8.2%) undergoing short, metaphyseal-fitting humeral stemmed TSA after intraoperative assessment determined that the bone quality was insufficient for stemless fixation."

Clinical and Radiographic Outcomes of the Simpliciti Canal-Sparing Shoulder Arthroplasty System: A Prospective Two-Year Multicenter Study

"Next the surgeon attempted to compress the neck cut surface with his/her thumb. Bone that was easily compressed with minimal force was also considered not sufficient for implantation. If the physician subjectively determined that the bone had sufficient strength to support the press fit of the nucleus, the humerus was pre- pared with the standardized surgical technique outlined in the protocol: a guide- pin was placed in the center of the cut surface of the humeral head, and sequential bone preparation was completed with cannulated instrumentation. With the three-finned blazer in place, the surgeon tested for stability. If the blazer rotated within the bone, the bone was considered inadequate for implantation of the canal-sparing device. If the bone was still considered acceptable, a metallic humeral cut protector was secured to the trial Simpliciti nucleus to prevent proximal humeral bone damage during glenoid exposure and preparation."

Preoperative metaphyseal cancellous bone density is associated with intraoperative conversion to stemmed total shoulder arthroplasty "The decision to convert to a stemmed humeral component was made intraoperatively based on a lack of stability of the trial stemless component. After the humeral cut was performed at the anatomic neck, a stemless anatomic humeral trial component was placed, followed by a head protector. The glenoid was prepared, and a final glenoid component was placed. When attention was turned back to the humerus, the head protector was removed. If the trial component was stable, then a final stemless component was inserted. If the trial component was grossly mobile, then the decision was made to convert to a stemmed humeral component."

Bone quality in total shoulder arthroplasty: a prospective study correlating computed tomography Hounsfield units with thumb test and fracture risk assessment tool score. "Surgeons are poor at identifying suboptimal bone quality at the anatomic neck of the proximal humerus based on intraoperative thumb test when referencing against CT Hounsfield Units and fracture risk scores."

 

Comment: With their short and mid-term follow up, the available publications do not indicate that loosening of stemless humeral components in anatomic total shoulder arthroplasty is substantial clinical problem. Appartently, surgeons are making good choices regarding when to use a stemless implant based on their preoperative and interoperative observations.

 

If, after completing the glenoid arthroplasty, the stemless humeral component is discovered to be unstable on trialing, the surgeon has several options:

    (1) autograft the insertion site with bone from the resected humeral head until the nucleus of the implant is stable; this technique is useful if a cyst is encountered during humeral bone preparation

    (2) increase the size of the nucleus to achieve a more secure fit in the available bone

    (3) convert from a stemless to a stemmed implant that is compatible with the glenoid component.

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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).

Are short stems of value in total shoulder arthroplasty?

 Symptomatic Aseptic Loosening of a Short Humeral Stem Following Anatomic Total Shoulder Arthroplasty

These authors point out that the reported rate of aseptic humeral component loosening with standard-length stems is low (0.3%).

They reviewed 184 shoulders that received TSA with a grit-blasted, rectangular short humeral stem without ingrowth coating (Univers Apex; Arthrex; Naples, FL). 

The average patient age was 62.1 years old and 57.1% were male. 

65% had followup x-rays at one year after surgery. Twenty-three (12.5%) patients had a painful shoulder and radiographic concern for potential humeral loosening at a mean follow-up of 1.5 years. 

At the time of publication, 13(7.1%) of these had undergone revision shoulder arthroplasty where a loose stem was confirmed. 

All revisions underwent tissue culture; three cases were consistent with probable or possible periprosthetic infection at the time of revision arthroplasty. 

The rate of symptomatic aseptic humeral loosening in this series was 10.9% with 5.4% undergoing revision surgery. Patients with symptomatic aseptic humeral loosening were more likely to be male (90.5%) than those patients without symptoms (52.8%; p<0.001). There were no differences in canal fit between patients with concern for symptomatic loosening and those with pain-free, stable implants.

These authors concluded that "the early humeral loosening rate for this stem design far outpaces previously reported rates and this study likely under-reports the true incidence of clinically-significant loosening as it only contains limited short-term follow-up."

Comment: This study does not provide evidence of the clinical value of this short stemmed humeral prosthesis in comparison to a standard length stem.

We have found that loose short stemmed humeral components can be successfully revised to an impaction allografted standard stem.

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 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).

Humeral component loosening and radiolucent lines.

Humeral stem lucencies correlate with clinical outcomes in anatomic total shoulder arthroplasty

These authors compared clinical outcomes of 288 anatomical total shoulders (aTSA) with and without radiolucencies around an uncemented grit-blasted metaphyseal-fit humeral stems at a minimum of 5-years after surgery.

The operations were performed by fellowship trained surgeons from 14 different centers across the world.  Exclusion criteria included revision shoulder arthroplasty, rheumatoid arthritis, and post-traumatic arthritis. The article does not provide details of surgical technique, for example how the humerus was prepared, how the size of the implant was selected and whether impaction grafting was used.

Two-hundred forty-three humeral stems showed no radiolucent lines. Among the 37 humeral stems with lucent lines, lines were most common in zones 8, 4, 7, and 3. 

The clinical outcomes were inferior for those shoulders with humeral component loosening

Gross humeral loosening was noted in 4 of the 37 patients in the humeral lucent line group (11%). Other complications besides humeral loosening were more common in the humeral lucent line group.

Comment: This minimum 5 year follow up is informative. 13% of these stems had either gross humeral loosening or showed humeral radiolucent lines. These findings were associated with inferior clinical outcomes.

The association of humeral loosening or lucency with glenoid loosening brings up the possibility that a low grade infection might be at play in these cases. Alternatively, cement or polyethylene debris from glenoid failure might have contributed to the humeral changes.

The results of this study can be compared to those in a recent publication using a smooth humeral stem inserted with impaction autographing (see this link)

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To see a YouTube of how we do total shoulder arthroplasty, click on this link.

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

To see our new series of youtube videos on important shoulder surgeries and how they are done, 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  arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'

Total shoulder - failure at 10 years

A 60 year old active patient presented to an outside medical center with pain, stiffness and x-rays showing degenerative joint disease.

A total shoulder replacement was performed. Note the white area of cement inserted underneath the face of the glenoid implant (arrow)

After surgery she developed progressive pain and loss of function. Eight years later x-rays of the shoulder showed loosening of the glenoid component (upper arrow) and loosening of the humeral component with a shift in position of the humeral component (lower arrow). Of note is the degradation of the cement originally placed beneath the glenoid component. It is possible that cement debris contributed to the failure of her joint replacement.

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

How you can support progress in shoulder surgery

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