Shoulder Arthroplasty Failure Research in action

Most patients having primary arthroplasty do well, 

thus we learn most from studying the failures.

Publications of shoulder arthroplasty outcomes usually report the diagnostic categories associated with failure, such as glenoid component loosening, rotator cuff tear, infection, or instability. While such classifications are descriptively useful, they provide little insight into how failures might be prevented for future patients.

As Judea Pearl has emphasized in his must-read book

actionable knowledge is more likely to arise from asking the counterfactual question: “What might have been done differently that could have prevented this complication?” This principle underlies the Shoulder Arthroplasty Failure Research initiative, which seeks to move beyond descriptive epidemiology toward identification of surgeon-controlled, modifiable factors that govern arthroplasty failure.

A recent study exemplifies this approach: “Humeral and glenoid component malposition in patients requiring revision shoulder arthroplasty: a retrospective, cross-sectional study.” In this investigation, failure of a primary arthroplasty was defined as the occurrence of revision. The authors reviewed 234 revision shoulder arthroplasties performed at 3 institutions.

They reported demographic characteristics and frequencies of revision types following hemiarthroplasty, anatomic total shoulder arthroplasty (TSA), and reverse total shoulder arthroplasty (RSA)

While such descriptive information is important, it does not inform strategies for prevention of arthroplasty failure for patients having arthroplasty in the future. 

The study focused on some of the factors under the surgeon’s control, specifically the position of glenoid and humeral components. The findings were striking: glenoid malposition was identified in 51% of anatomic TSA revisions and 93% of RSA revisions. Humeral component malposition was also frequent, present in 57% of anatomic TSA, 62% of RSA, and 54% of hemiarthroplasty cases. These observations support the counterfactual inference that had the components been positioned appropriately, the likelihood of failure requiring revision may well have been substantially reduced. 

Here are a few examples from the article.

Placement of the RSA baseplate in superior tilt.

Superior placement of the RSA baseplate.

Superior placement of the humeral component in anatomic TSA

Inadequate humeral neck cut in hemiarthoplasty resulting in

superior-medial placement of the humeral component and overstuffing of the joint.

In that the surgeon is the method, each of these malpositions could have been avoided by better surgical technique.  The institutions conducting the revisions were usually not involved in the majority of the primary procedures and thus medical records for many of these patients could not be fully reviewed. As a result, the characteristics of the surgeon performing the primary arthroplasty that was revised (age, training, years in practice, arthroplasty experience, etc) were not available, but would be of great interest.

Comment: This is an imporant study in that it identifies actions that shoulder surgeons can take to reduce the risk of arthroplasty failure for their future patients. It provides a model of how clinically meaningful shoulder arthroplasty failure research can be conducted.

This is an uncommon bird, but well worth investigating.

Elegant Trogan

Madera Canyon, Tucson AZ

May, 2022

Follow on twitter/X: https://x.com/RickMatsen
Follow on facebook: https://www.facebook.com/shoulder.arthritis
Follow on LinkedIn: https://www.linkedin.com/in/rick-matsen-88b1a8133/

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).

Recent JBJS article on failures (51%) of anatomic total shoulder arthroplasties

Patients and surgeons are interested in the causes and prevention of shoulder arthroplasty failures. Failures can be viewed in terms of the characteristics of the surgeon, the patient, the shoulder, and type of failure. Regardless of the cause of the failure, it is the patient (not the surgeon or the implant company) that bears the consequences. Thus, in each case we should do our best to determine "what could have been done to prevent the failure experienced by the patient?" In this way, each failure - whether ours or someone else's - becomes a learning opportunity. At an early morning meeting in August 2025, a small group of shoulder surgeons took the first steps in developing a Shoulder Arthroplasty Failure Research (SAFR) program with the goal of learning from individual cases of arthroplasty failure.

The June, 2025 JBJS article, High Failure Rates of Polyethylene Glenoid Components in Stemless Anatomic Total Shoulder Arthroplasty for Primary and Secondary OA, is interesting to consider in this regard.  These components were used in this series

At a mean followup of 72 months, out of 197 patients, over half (101) had failures necessitating surgical revision, 86 because of glenoid component loosening. What might be done to prevent these failures? 

Left:  Intraoperative view following explantation of the polyethylene glenoid with a 4 x 2-cm bone defect. Right: Explanted components with severe glenoid wear and superior glenoid abrasion, with the pegs completely separated from the body of the glenoid component.

Is the problem (as the title might suggest) the use of a stemless humeral component with a polyethylene glenoid component (in which case failures could be avoided by using a stemmed humeral component)? 

Or is it the type of polyethylene glenoid component being used (in which case a different glenoid component design could be used)? 

Or is it the technique by which the glenoid component was inserted (in which case greater attention could be directed at the quality of glenoid component preparation, cementing and seating?). 

These three elements are surgeon-controlled variables (in contrast to patient age, sex, diagnosis, BMI, critical shoulder angle and lateral acromial angle, which were measured in this study but which are of lesser interest in that they are not modifiable by the surgeon). 

So...is the stemless humeral component or the glenoid component the problem? Prior studies of this glenoid component (with either stemless or stemmed humeral components) reported glenoid component loosening rates between 25% and 100% after 5 years when used with either stemless or stemmed humeral components: Univers II shoulder prosthesis: a multicenter, prospective randomized controlled trial and Radiologic midterm results of cemented and uncemented glenoid components in primary osteoarthritis of the shoulder: a matched pair analysis. Perhaps failure could be avoided with a different glenoid component.

Or...might the technique of glenoid component insertion be an issue?

In this 6 week postoperative x-ray from the article there is cement between the back of the glenoid component and the glenoid bone (yellow arrows).  Cement in this location can crack and displace leaving the component unsupported. 

This problem can be avoided by placing the component directly on the properly reamed glenoid bone without interposed cement as shown below.

The other issue shown on this x-ray is the large amount of bone in the glenoid vault surrounding the pegs (red arrow) that prevents bone ingrowth around them.

This problem can be avoided by careful preparation of the glenoid bone with good carpentry so that bone ingrowth is enabled.

Perhaps the risk of failure could be reduced using a different insertion technique

As shown below, this patient experienced glenoid component failure

How could this failure have been prevented?

Comment: This is an example of the type of analysis that we hope to carry out in the Shoulder Arthroplasty Failure Research program. Stay tuned!

Looking to make wise choices

Barred Owl

Union Bay Natural Area

May 2025

Follow on twitter/X: https://x.com/RickMatsen
Follow on facebook: https://www.facebook.com/shoulder.arthritis
Follow on LinkedIn: https://www.linkedin.com/in/rick-matsen-88b1a8133/

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).

Learning from surgical failure

 On 22 October 1895, there was a particularly spectacular railway accident at the Gare de l'Ouest in Paris. The No.56 train arriving from Grandville hurtled into the station at a speed of 40 to 60 kilometres an hour, and, unable to stop, plowed through the buffers at the end of the platform. Its engine crashed through the façade of the station building, and fell down on to the Place de Rennes.

Hopefully the responsible railway system, Chemins de fer de l'Ouest, learned more from studying this failure than from studying all their on time, safe arrivals.

The May 26, 2025 post, "Do higher case volumes make us safer and more effective surgeons?", pointed out that it is not the number of cases we do that make us better, but rather the study of our failures that provide a path to improvement. This post also pointed out that the surgeon performing the procedure is, in many instances, the most important determinant of the outcome: the surgeon is the method. 

I found the recent article: Anatomic Total Shoulder Arthroplasty using a Short Humeral Stem and a Non-Augmented Minimally Cemented All-Polyethylene Glenoid: Minimum 2-Years Outcome and Predictors of Clinical Failure of interest in this regard because - in contrast to most other clinical reports -  it presents the experience of an individual senior shoulder surgeon. In the words of Kahneman, this filters out the pattern noise when multiple surgeons are included in the report (see the striking chart in the May 26 post).

The authors reported excellent average outcomes for 128 consecutive anatomic total shoulder arthroplasty (aTSA) using non-augmented glenoid implants and short humeral stems for glenohumeral arthritis with an intact rotator cuff. In spite of the average success, they sought to identify factors associated with adverse outcomes.

The surgeon's technique included minimal glenoid reaming to achieve >90% backside contact of a pegged, all polyethylene standard glenoid implant, inserted with minimal cement. The surgeon used a subscapularis peel which was repaired after insertion of the components using 6 to10 high-strength #2 braided sutures passed through transosseous drill holes. After the implants were placed, the subscapularis tendon was closed with these sutures and with closure of the distal rotator cuff interval with additional braided sutures to reinforce the repair.

104 of the 128 aTSAs were available for evaluation at minimum 2 years follow-up (range 2-5.6 years) (see the challenge of longer term followup). In comparison to many published reports, this represents a high percent followup. The authors included information on the remaining 24 - a few had passed on or became invalid, a few were revised and only a dozen or so could not be tracked. In clinical studies the denominator counts big and the reasons for loss to followup are important.

As stated in A Study in Hospital Efficiency (Codman, E.A. 1917). "All patients should be followed long enough to determine whether or not the treatment has been successful, and to ask 'if not, why not?'".

Overall, mean ASES scores improved from 41 to 89, SST from 4.5 to 10, and VAS-pain from 5.5 to 0.7. [Note that these average postoperative scores are within the minimal clinically important differences of perfect scores.  Thus it would be statistically impossible for any change in implant or technique (for example, routine use of preoperative 3D CT planning) to make a clinically significant improvement in the average outcomes.]

Fifty-nine patients had preoperative posterior glenoid wear patterns (Walch B2 or B3) and 47 had concentric or minimal glenoid wear (Walch A1, A2, or B1). The presence of posterior glenoid wear was not found to influence any outcome score

There were three modes of failure identified by the authors

(1) Subscapularis failure: 5 patients underwent revision to reverse shoulder arthroplasty for subscapularis insufficiency and one underwent open subscapularis repair with graft augmentation following traumatic injury. Three of the subscapularis tears arose because of trauma and/or patient reported noncompliance with postoperative immobilization or restrictions. All but one of the subscapularis failures reported here occurred within the first 12 months postoperatively. None of the patients with subscapularis failure requiring surgery had undergone prior open capsulorrhaphy or subscapularis repair

(2) ASES score <70: Ten patients had a final ASES score < 70, which was associated with a history of previous surgery (overall, twenty-four shoulders had undergone previous surgery). 

(3) Glenoid osteolysis: 10 patients (13%) had radiographs  demonstrating glenoid osteolysis (defined as "radiolucency extending at least two mm from the center of peripheral pegs"). Glenoid osteolysis was not found to be associated with preoperative posterior glenoid erosion. The presence of glenoid osteolysis was not found to have an adverse effect on clinical outcome with the period of followup in this study. 

Comment: These authors report overall excellent results with their surgical technique. They have also defined three adverse outcomes that merit further study so that they and we can learn to avoid them.

Subscapularis failure: It would be of interest to know the rehabilitation program used by the surgeon. I am using a "slow roll" approach to range of motion exercises during the first six weeks and spend time cautioning the patient about falls and about avoiding external rotation stretching and active internal rotation during this period. Perhaps this surgeon does the same.

Prior surgery: It's a fact that young patients with arthritis commonly have had prior surgery. While the patient's history is not modifiable, we should try to learn if these patients have particular issues that could be addressed at surgery, such as (a) stiffness that might drive consideration of more aggressive soft tissue releases or smaller components or (b) difficulty in centering the humeral head on the glenoid that may drive use of eccentric humeral head components.

Glenoid osteolysis: While glenoid osteolysis was not noted to have an adverse effect on clinical outcomes in this minimum two year followup study, longer term followup is needed, although such studies are challenging.  These authors took care to optimize glenoid bone preparation. It would be of interest to know how well the components were seated, in that glenoid seating may be a major factor in achieving durable fixation.

This is a fine example of an individual surgeon study that has identified three adverse outcomes from anatomic arthroplasty. While it is unlikely that modifications in the surgical technique will lead to clinically significant improvement in the average outcome scores (because the average scores reported are so good), it is possible that additional study of patients with these failure modes may show us how to lower their frequency. 

The first step is to define the problems.

Fish with a problem

Montake Fill, Seattle June 2019

You can support cutting edge shoulder research that is leading to better care for patients with shoulder problems, click on this link

Follow on twitter/X: https://x.com/RickMatsen
Follow on facebook: https://www.facebook.com/shoulder.arthritis
Follow on LinkedIn: https://www.linkedin.com/in/rick-matsen-88b1a8133/

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).

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Does it matter to the patient whether a rotator cuff repair heals or not?

A bit of context.

In large part, rotator cuff tears are a consequence of aging, increasing in prevalence in older individuals. A high percentage of these tears are asymptomatic (link, link, link). Some studies comparing non-operative and surgical treatment of cuff tears have found similar outcomes for each (link, link, link).

In 1962 McLaughlin wrote about the rotator cuff: “In youth, it is thick, strong, and elastic and can be disrupted only by great force; after middle-age it has worn thin and often becomes so weak and brittle that it ruptures with ease”. On surgical management, he added “The wise surgeon, realising that he may find little but rotten cloth to sew, will operate only by necessity and make a carefully guarded prognosis”. 

Primary Cuff Repairs

Surgeons in the United States perform over 400,000 rotator cuff repair surgeries annually, with each procedure costing between $8,400 and $56,200.  Thus the total annual expenditure on rotator cuff repair surgeries in the U.S. ranges from approximately $3.36 billion to $22.48 billion. It is important to note that these figures represent direct surgical costs and do not account for additional expenses such as preoperative evaluations, postoperative rehabilitation, or potential costs associated with surgical complications. Therefore, the overall economic impact of rotator cuff injuries and their treatment is likely higher. The rate of rotator cuff repairs per 100,000 citizens is increasing steadily (link, link, link). Rotator cuff repair remains the most commonly performed shoulder surgery.

As pointed out in Rotator cuff repair: published evidence on factors associated with repair integrity and clinical outcome,  innovations in surgical technique, instrumentation, augmentation or biologics do not appear to be leading to improved clinical outcomes perceived by the patient.

New, more expensive innovations for cuff repair are being used; for some of these there is questionable evidence of improved benefit/cost.

Editorial Commentary: Bioinductive Collagen Implants Reduce Rotator Cuff Retear, yet Cost-Effectiveness and Improvement in Clinical Outcomes Are Unclear"Unfortunately, retear rates do not appear to have improved significantly since the 1980s, despite advances in surgical technology and the biomechanics of repair."

No Short-term Clinical Benefit to Bovine Collagen Implant Augmentation in Primary Rotator Cuff Repair: A Matched Retrospective Study

Ambulatory Surgery Centers Reduce Patient Out-of-Pocket Expenditures for Isolated Arthroscopic Rotator Cuff Repair, but Patient Out-of-Pocket Expenditures Are Increasing at a Faster Rate Than Total Healthcare Utilization Reimbursement From Payers

Subacromial Balloon Spacer Versus Partial Rotator Cuff Repair in the Treatment of Massive Irreparable Rotator Cuff Tears: Facility Personnel Allocation and Procedural Cost Analysis "The facility cost of subacromial balloon spacer was significantly higher than that of partial cuff repair"

Surgeon idiosyncrasy is a key driver of cost in arthroscopic rotator cuff repair: a time-driven activity-based costing analysis "The largest cost drivers of aRCR are the use of biologic adjuncts, augments, the use of multiple suture anchors, and certain anchor brands."

Arthroscopic Transosseous Rotator Cuff Repair may be more cost effective than suture anchor repairs.

Use of intraoperative platelet-rich plasma during rotator cuff repair is correlated with increased patient-level charges across multiple categories

Measurement of value in rotator cuff repair: patient-level value analysis for the 1-year episode of care "There was a poor correlation between the clinical outcome and the cost of care."

The primary cost drivers of arthroscopic rotator cuff repair surgery: a cost-minimization analysis of 40,618 cases"Surgeon-controllable factors significantly increase cost, most notably subacromial decompression, distal clavicle excision, use of regional anesthesia, and the number of suture anchors.

Failed Cuff Repairs 

Healthcare costs of failed rotator cuff repairs are approaching one half billion dollars.

A recent article,The clinical impact of retears after repair of posterosuperior rotator cuff tears: a systematic review and meta-analysis assessed the published data on the consequences for the patient of a retear after surgical repair of a torn rotator cuff. The authors reviewed 43 studies including  3350 patients. The average age of the participants was 62 years (range, 52-78 years). 

At a median of 18 months' follow-up  844 repairs (25%) were described as retorn on imaging. 

The differences in patient assessed outcome between healed repairs and retears at follow-up were statistically significant, but the differences in pain, function, or quality of life were not clinically significantly different for healed and retorn cuff repairs.

In light of the foregoing, there is an opportunity to reconsider the approach to the patients with cuff tears, making sure that they are aware of 

(1) the factors potentially influencing the rate of successful tendon healing such as age, tear size, and severity of muscle degenerative changes as pointed in Degenerative Rotator Cuff Tears: Refining Surgical Indications Based on Natural History Data

(2) the complications that can be associated with cuff repair. The authors of Complications Within 6 Months After Arthroscopic Rotator Cuff Repair: Registry-Based Evaluation According to a Core Event Set and Severity Grading found that the cumulative risk for adverse events at 6 months after rotator cuff repair was 18.5% (21.8% for partial tears, 15.8% for full-thickness single-tendon tears, 18.0% for tears with 2 ruptured tendons, and 25.6% for tears with 3 ruptured tendons). These adverse events included shoulder stiffness, persistent or worsening pain, rotator cuff defects, neurologic lesions, surgical-site infection, device failure, and others.

(3) the recovery or "down time" period. In Functional Recovery Period after Arthroscopic Rotator Cuff Repair: Is it Predictable Before Surgery? 31% took less than 3 months, 40% took between 3 and 6 months, and 28% took greater than 6 months to achieve a score greater than 80%. Age, shoulder stiffness, and rotator cuff tear size influenced functional recovery time.

What about non-repair surgery?

The observation in  The clinical impact of retears after repair of posterosuperior rotator cuff tears: a systematic review and meta-analysis that shoulders with anatomically failed (retorn) and anatomically successful cuff (not retorn) repairs both have similar clinical outcomes makes us wonder what leads to the clinical improvement if the repair is retorn. What might happen if patients at high risk for retear, those concerned about complications and those not wishing to experience the protracted period of recovery were treated with a non-repair surgery (that is, a smooth and move / debridement). 

Smooth and Move in the Treatment of Irreparable Cuff Tears - Technique and Case Example

One of the major advantages of the smooth and move is that the patient can go back to active use of their shoulder immediately post surgery - because nothing is repaired there is no repair to protect. This is in marked contrast to the postoperative restrictions on motion during the healing period recommended for the balloon, patches, augments, partial repairs and superior capsular reconstruction. This is illustrated in the examples shown below,

The smooth and move in the management of irreparable tears or failed rotator cuff repairs

Can a subacromial balloon do this?

Massive rotator cuff tear and the smooth and move

Irreparable cuff tear in a 62 year old woman.

A 61 year old women with an irreparable cuff tear

Irreparable rotator cuff tear in an active man

Massive irreparable rotator cuff tears - how to treat them

Irreparable rotator cuff tear after failed rotator cuff repair

The Superior Capsular Reconstruction - what is its place?

Rotator cuff tears - the benefits of non-repair surgery

Treatment of irreparable cuff tears with retained active elevation

Here are some relevant articles from the literature on the effectiveness of the smooth and move

Significant improvement in patient self-assessed comfort and function at six weeks after the smooth and move procedure for shoulders with irreparable rotator cuff tears and retained active elevation.The smooth and move procedure provided clinically significant improvement as early as 6 weeks after surgery.

Treatment of irreparable cuff tears with smoothing of the humeroscapular motion interface without acromioplasty In 77 shoulders with irreparable tears, simple shoulder test (SST) scores improved from an average of 4.6 (range 0-12) to 8.5 (range 1-12) (p < 0.001). Fifty-four patients (70%) improved by at least the minimally clinically important difference (MCID) of 2 SST points.

Partial rotator cuff repair versus debridement for irreparable rotator cuff tears: A systematic review In 153 shoulders treated with debridement, post-operative satisfaction was 80.7 %.

Comparison of Multiple Surgical Treatments for Massive Irreparable Rotator Cuff Tears in Patients Younger Than 70 Years of Age found that most studies did not evaluate treatment with simple debridement in comparison to more complex procedures. However for studies that did, debridement had the highest P-score (probability of achieving the desired outcome), as shown below.

Forrest plot for Constant Score:

Forrest plot for range of active forward flexion:

This network meta-analysis found that simple debridement was the most effective procedure in significantly improving Constant score and active flexion for individuals with massive irreparable cuff tears when it was compared to other more complex surgical modalities. 

Comment

Of course we know that many thousands of patients benefit from rotator cuff repair surgery each year. For the majority, the procedure improves shoulder comfort and function. This is especially the case for acute tears in healthy patients with good quality cuff tendon and muscle.

For chronic cuff tears, a trial of non-operative management, including gentle stretching and strengthening can often be helpful and does not preclude surgical intervention if it becomes necessary.

For patients with large, chronic, atraumatic cuff tears, there may be a downside of attempting a rotator cuff repair with the risks of retear, complications, dissatisfaction, prolonged recovery, and cost. Evidence is currently lacking that these downsides can be eliminated by new innovative surgical approaches. Against this background a non-repair alternative, such as smooth and move/debridement, may be a cost-effective and safe consideration for selected patients with retained preoperative active elevation. Furthermore, the smooth and move does not burn bridges for other more complex procedures should they become indicated.

You can support cutting edge shoulder research that is leading to better care for patients with shoulder problems, click on this link

Follow on twitter/X: https://x.com/RickMatsen

Follow on facebook: https://www.facebook.com/shoulder.arthritis

Follow on LinkedIn: https://www.linkedin.com/in/rick-matsen-88b1a8133/

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).