Why is there a high complication rate of shoulder arthroplasty in young patients?

In a recent post, Learning from Surgical Failure, I presented Codman's argument that in order to improve our own, personal  outcomes for our surgical procedures each of us need to follow each of our patients long enough to learn whether the treatment was a success or not, and, if not, to ask why not? This argument is especially relevant to younger patients who have many years to live with adverse outcomes of surgery should they occur. As an example, I saw a 40 year old patient recently who was requesting a ream and run for complications of a surgery he had 25 years ago. Here are the films we obtained. 

Apparently when the patient developed postoperative pain and stiffness and a grinding sensation in his shoulder, he was treated with physical therapy, a second procedure to drive the anchors in deeper, and then a series of cortisone injections. I don't know if his prior surgeon is aware of the patient's current condition (essentially no glenohumeral motion) so that he could learn from this adverse outcome.

Young patients with shoulder arthritis are not only more active and live longer than their older counterparts, but the distribution of their diagnoses is different as shown by the authors of Comparison of Patients Undergoing Primary Shoulder Arthroplasty Before and After the Age of Fifty. Only 21% of the younger patients had primary degenerative joint disease, whereas 66% of the older patients had that diagnosis.

The authors of Complication Rates after Shoulder Arthroplasty in Patients Ages 45 and Younger point out that while shoulder arthroplasty can be effective for reducing pain and improving shoulder function, younger patients with arthritis appear to have a very high risk of arthroplasty failure and revision. They evaluated the minimum two-year complication rates for 70 patients aged 45 years and younger having anatomic total shoulder arthroplasty (TSA n=35), hemiarthroplasty (HA n=30), and reverse total shoulder arthroplasty (RTSA n=5).

One out of every five patients had a complication and one out of every seven had a reoperation. TSA patients had a 29% complication rate with infection being the most frequent issue. RTSA patients had a complication rate of 20%. HA patients had a complication rate of 7%. These data need to be interpreted with caution because (1) the number of patients in this study was small and (2) the inclusion criterion was 2 or more years of followup; 2 years is a small percentage of the remaining lifetime of 45 year old patients that have many more years to experience complications of the arthroplasty.

Because "the surgeon is the method", we would like to know the relationship of the surgeon to complications and re-operations in  multi-surgeon studies. In the words of Kahneman, we would like to assess the system noise in surgical outcome attributable to the individual surgeon.

To accomplish this goal, we'd need to explore the relationship of the number and type of complications to the individual surgeon performing the procedures, controlling for variables including patient demographics, diagnosis, and type of arthroplasty. This would require a multivariable analysis that would include perhaps thousands of patients.

A metric that is important to the interpretation of studies of this type is the PPPI - the percentage of patients included from those potentially included - i.e. of all the young patients with arthritis having arthroplasty performed by each participating surgeon two or more years ago, what percent were included in this study? Only with this number can the reader assess the "loss of followup" bias for each surgeon. Unfortunately, this metric can only be determined in prospective studies and not in retrospective studies such as this one.

In order to understand the importance of the individual surgeon to the rate of complication, we'd like to know the answer to questions such as

(1) among the patients included for each surgeon, what was the distribution of diagnoses (what was the diagnosis mix for each of the diagnoses included in this study: primary osteoarthritis, capsulorrhaphy arthropathy, avascular necrosis, post-traumatic arthritis, inflammatory arthropathy, fracture, cuff tear arthropathy, tumor)?

(2) among the patients included for each surgeon, what was the complication rate for each of the three types of arthroplasty (TSA, RSA, and HA)?

(3) among the patients included for each surgeon, what was the distribution of the different types of complications (this study included infection, subscapularis failure, glenoid component loosening, humeral component loosening, rotator cuff tear, fracture, instability, revision)?

With analyses such as these we can get closer to identifying the factors associated with the unacceptably high complication rate for shoulder arthroplasty in young patients: what is the relative importance of the surgeon, the patient, the diagnosis, the procedure or other factors? Such an approach holds promise for learning why so many arthroplasty complications occur in young patients and how we might prevent these adverse outcomes in the future.

Caring for the young

White headed woodpecker

Leavenworth, Washington 

June 2022

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).

How can we prevent acromial and spine fractures after reverse total shoulder?

As emphasized in a recent post, acromial and scapular spine fractures continue to be a major cause of poor results after reverse total shoulder arthroplasty.

A couple of examples to kick things off.

Case 1: A 78 year old man had recognized risk factors for these fractures: osteoporosis and the diagnosis of cuff tear arthropathy. He has been treated for his osteoporosis with Alendronate.

His preoperative and post reverse total shoulder radiographs are shown below.

.

A month after surgery, while his arm was still in a sling immobilizer, he developed pain in his lateral shoulder. Examination revealed a localized spot of exquisite tenderness on the lateral acromion. On an axillary view a non-displaced crack is seen in his acromion at the site of his tenderness.

Case 2: An 82 year old woman had symptomatic cuff tear arthropathy and this AP radiograph

A reverse total shoulder was performed as shown below

Two months after an uneventful recovery, she developed pain on use of the arm and point tenderness over the acromion posteriorly. While plain x-rays were unremarkable, a CT scan documented her stress fracture at the point of her tenderness

While these patients' age, sex, diagnoses of cuff tear arthropathy and osteoporosis were not modifiable, the question is whether there are modifiable risk factors, such as the geometry of the prosthetic RSA reconstruction.

A review of much of the current literature on this topic can be found in this post.

A recent publication, Shoulder Geometry After Reverse Total Shoulder Arthroplasty with a Medialized Glenoid and a Lateralized Humerus Predicts Subacromial Notching and Acromial or Scapular Spine Fractures, attempted to assess (1) whether the difference between the acromion to glenosphere center of rotation distance (DA) and the greater tuberosity to glenosphere center distance (DGT) influences the incidence of subacromial notching (SaN) in shoulders following reverse total shoulder arthroplasty (rTSA) and (2) whether this relationship is associated with the incidence of acromion or scapular spine fractures.

They  conducted a retrospective cohort study of 526 patients who underwent RSA with a medialized glenoid and a lateralized humerus.

After propensity score matching, 360 shoulders were analyzed (240 in the DA ≥ DGT group and 120 in the DA < DGT group). Both groups showed similar improvements in clinical outcomes postoperatively.

The DA ≥ DGT group exhibited a significantly lower incidence of SaN (0%) compared to the DA < DGT group (10.8%, P < 0.001). Additionally, the DA ≥ DGT group had a lower rate of acromion or scapular spine fractures (0.4%) compared to the DA < DGT group (5.0%, P = 0.006) [although a larger sample size will be necessary to achieve statistical power]. 

If we go back to Case 1, the 78 year old man with the acromial fracture, his distance to acromion (green arrow) was ≥ distance to greater tuberosity (yellow arrow).

5. If we revisit Case 2, the 82 year old lady, her distance to acromion (green arrow) was ≥ the distance to greater tuberosity (yellow arrow).

These cases remind us that age, diagnosis of cuff tear arthropathy and osteoporosis are more strongly associated with the occurrence of acromion/spine fractures than component design or position. That said, patient demographics (female sex, age, rheumatoid arthritis) and shoulder diagnosis (cuff tear arthropathy, massive irreparable cuff tears with pseudoparalysis) are not modifiable, so we need to continue to research modifiable factors that may reduce the rate of these factors especially in high risk patients. 

Possible candidates to be studied are (1) assuring that osteoporosis is under optimal management, (2) minimizing global lateralization of the humerus in RSA, (3) defining the optimal degree of glenosphere tilt and inferior placement, (4) burring down the lateral aspect of the greater tuberosity to make sure that there is no tuberosity/acromial contact when the arm is abducted and rotated, (5) slowing the return to activity after surgery, (6) prophylactic calcitonin, (7) considering a cuff tear arthropathy prosthesis rather than a RSA in high risk patients.

Jon Levy kindly responded to this post stating that his big three for minimizing the acromial / spine fracture risk are 

(1) optimizing glenoid component fixation

(2) avoiding early arc abduction impingement (he currently uses 70 degrees as his goal post).

(3) avoiding lateralizing the final humerus position more than the preop position.

We need to continue explore better methods for preventing these fractures: they are disabling for the patients that sustain them; they are too common. 

Common Yellowthroat

Montlake Fill, April 2020

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).

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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How should this irreparable cuff tear be treated? - Revealed

  A 58 year old woman with type II diabetes presented with several year history of pain and weakness of the right shoulder. This started while she wasworking as a stocker grocery distributorship following lifting heavy bins of hominy and other produce. On one occasion she noted an audible pop. At evaluation she had passive elevation of 140 and active elevation of 80 degrees. She had grade three strength of elevation, grade four strength of external rotation and grade 5 strength of internal rotation. There was palpable crepitus on active and passive shoulder movement. 

Her images at the time of presentation are shown below.

Her symptoms did not respond to 2 months of PT.

After discussion of the alternatives, including superior capsular reconstruction, biologic patches, tendon transfers and reverse total shoulder arthroplasty, the patient elected to have smooth and move: an outpatient fifteen minute open procedure performed through an anterior deltoid split without sacrifice of acromial or coracoacromial ligament integrity with excision of the hypertrophic bursa, resection of the ragged ends of the torn tendons, and resection of the prominent aspects of the uncovered greater tuberosity followed by a manipulation to assure full range of passive motion. 

At surgery the findings of the MRI were confirmed. The undersurface of the coracoacromial arch was smooth.  The long head tendon of the biceps and subscapularis were intact; no biceps surgery was performed. 

After surgery she was encouraged to perform range of motion exercises and to return to active use of her shoulder immediately. 

At six weeks after surgery she returned for routine followup, reporting that her preoperative pain was relieved by the afternoon of surgery and had not returned. She was able to return to full use of her shoulder. 

A video of her active motion at her 6 week visit is shown here.

In contrast to the alternatives, this procedure is inexpensive, allows immediate post operative return to function, and does not preclude subsequent procedures in the unusual circumstance of recurrent symptoms. 

For this woman, the smooth and move was a wise choice.

Great horned owl

Ravenna Park, Seattle

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).

How should this irreparable cuff tear be treated?

 A 58 year old woman with type II diabetes presented with several year history of pain and weakness of the right shoulder. This started while she wasworking as a stocker grocery distributorship following lifting heavy bins of hominy and other produce. On one occasion she noted an audible pop. On evaluation she had passive elevation of 140 and active elevation of 80 degrees. She had grade three strength of elevation, grade four strength of external rotation and grade 5 strength of internal rotation. There was palpable crepitus on active and passive shoulder movement. 

Her images at the time of presentation are shown below.

Her symptoms did not respond to 2 months of PT.

What would be your suggested treatment?

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).

Do higher case volumes make us safer and more effective surgeons?

I've always held that "the surgeon is the method", meaning that considering all of the variables that might affect the outcome of a given surgery for a given problem, the most important is the person making the decisions, carrying out the procedure, and analyzing the results = the surgeon. As surgeons we are engaged in the constant pursuit of learning to achieve better outcomes for our patients. We hope, as the saying goes, that experience is the great teacher and that practice makes us better at our art. But as we'll see below, the number of repetitions is not the only thing that matters.

My friend JP Warner pointed to this article, Higher Surgeon Volume is Associated With a Lower Rate of Subsequent Revision Procedures After Total Shoulder Arthroplasty: A National Analysis, the authors of which assessed the association between increasing surgeon volume and decreasing rate of revision for anatomic (aTSA) and reverse (rTSA) shoulder arthroplasty using the Centers for Medicare and Medicaid Services (CMS) fee-for-service inpatient and outpatient claims data from 2015 through 2021. 

They found that in comparison to an arthroplasty case volume of <4 per year, an annual surgeon case volume of

 ≥ 10 aTSAs was associated with a 27% decreased odds of a revision within 2 years

≥ 29 aTSAs was associated with a 33% decreased odds of a revision within 2 years

An annual surgeon volume of ≥ 29 rTSAs was associated with a 26% decreased odds of a revision within 2 years.

The figure below shows the trend line for revisions as function of surgeon case volume.

There are several interesting observations to be made on this graph: 

(1) the downward trend appears to continue out to surgeons performing over 100 shoulder arthroplasties per year, No end in sight for the effect.

(2) the effect of case volume on revision rate appears relative continuous: there is no obvious inflection point after which the volume effect starts to level off, 

(3) there is wide scatter in the data, indicating that there are factors other than annual case volume that are driving a surgeon's revision rate (some lower volume surgeons have lower revision rates than some higher volume surgeons).

So questions arise: 

(1) which is more important, the number of cases / year or the lifetime total number of cases ("how many do you do" vs "how many have you done")?

(2) how does a patient learn a surgeon's case volume? 

(3) how important should case volume be in a patient's choice of surgeon (e.g. how far should the patient travel or how much more should they be willing to pay to be cared for by a higher volume surgeon)?  

(4) what factors account for the high variability shown in this chart (note especially the three surgeon outliers at the top with over twice the average revision rate even though they're in the "high volume" category)? Should the patient be more concerned about the volume or the revision rate of their potential surgeon?

(5) if a large percentage of patients select their surgeon on volume, how do low volume surgeons become high volume surgeons? 

(6) is it experience (the number of cases) that is the determinant of revision rate?

In his books Noise a Flaw in Human Judgment and Thinking Fast and Slow Daniel Kahneman emphasized that experience does not automatically improve the outcome.  Over time, experienced surgeons may gain increased confidence but not necessarily increased competence, a phenomenon Kahneman calls the illusion of validity. Instead it is learning that leads to better outcomes. Learning, in turn, comes from quality, timely and accurate feedback. If a surgeon routinely takes and analyzes postoperative x-rays, she or he can learn how well the preoperative plan was executed - becoming smarter with each case. That's pretty easy to do. What's harder is to study each case that required revision to learn what went wrong - this is harder because the revision is delayed and memory fades. 

Each failure is a learning opportunity not to be passed up. Through the experience of studying the factors associated with each revision, the surgeon can reduce the risk of revisions in the future. There is safety in numbers, but its not the only thing that counts.

Dunlins Ocean Shores 2020

While there is safety in numbers, the peregrine falcon can usually cause an adverse event for one of them.

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).

Spinning the data on the value of glenoid augmentation - a guide for authors of systematic reviews and meta-analyses

In the previous post we discussed the challenges in doing clinically significant research on shoulder arthroplasty.

As a follow-on, here we focus on the importance of the way research is presented, with particular reference to spin – defined as bias that overstates efficacy and/or underestimates harms of a treatment. Systematic reviews and meta-analyses are at risk for spin if there was bias in the primary studies on which they were based. 

There is the potential for spin in any presentation of outcomes. Evaluation of spin in reviews of biodegradable balloon spacers for massive irreparable rotator cuff tears found that 93.1% of the 29 included studies had at least one type of spin. See other examples of spin in our literature on this post. 

A recent article provides a useful guide to the elements of spin and how to avoid them.

The authors of Evaluation of Spin in Systematic Reviews and Meta-Analyses Involving Glenoid Augmentation in Total Shoulder Arthroplasty assessed the quantity and types of spin in systematic reviews and meta-analyses of glenoid augmentation in shoulder arthroplasty. They searched for each of 15 types of spin (see A new classification of spin in systematic reviews and meta-analyses was developed and ranked according to the severity). At least one form of spin was identified in 13 (81.3%) of the 16 studies. 

“The conclusion claims the beneficial effect of the experimental  treatment despite a high risk of bias in primary studies” was the most commonly occurring type of spin in this review; it is found in many previous studies in other orthopaedic literature, ranging from 23.1%-65%. A common weakness contributing to this type spin was drawing conclusions based on primary studies of low levels of evidence

‘‘Conclusion claims the beneficial effect of the experimental treatment despite reporting bias’’ was the next most common; which may mislead readers by the selective inclusion and omission of results in the abstract. Reporting bias results from the tendency to overreport or selectively publish positive results. One example of reporting bias can be seen in a recent article that concluded that the reverse shoulder arthroplasty “provided highly favorable results” but only reported the statistically significant improvement in Constant scores and omitted the lack of statistically significant improvements in VAS, ASES,  SST, and functional range of motion measurements. 

The 15 types of spin are listed here as a heads up for surgeons considering publishing a systematic review. 

The title claims or suggests a beneficial effect of the experimental intervention not supported by the findings 

Authors hide or do not present any conflict of interest 

Selective reporting of or overemphasis on efficacy outcomes or analysis favoring the beneficial effect of the experimental intervention 

Selective reporting of or overemphasis on harm outcomes or analysis favoring the safety of the experimental intervention 

Failure to specify the direction of the effect when it favors the control intervention 

Failure to report a wide confidence interval of estimates 

The conclusion claims the beneficial effect of the experimental treatment despite a high risk of bias in primary studies – Most common 43.8 % of the glenoid augmentation studies.

The conclusion claims the beneficial effect of the experimental treatment despite reporting bias. Second most common (37.5% of the glenoid augmentation studies.).

The conclusion formulates recommendations for clinical practice not supported by the findings 

The conclusion claims safety based on non-statistically significant results with a wide confidence interval 

The conclusion focuses selectively on statistically significant efficacy outcome 

The conclusion claims equivalence or comparable effectiveness for non-statistically significant results with a wide confidence interval 

The conclusion extrapolates the review findings to a different intervention (e.g., claiming efficacy of one specific intervention although the review covered a class of several interventions) 

Conclusion extrapolates the review's findings from a surrogate marker or a specific outcome to the global improvement of the disease 

Conclusion extrapolates the review's findings to a different population or setting 

The authors also applied A Measurement Tool to Assess Systematic Reviews (AMSTAR 2), a questionnaire that quantifies the quality of a systematic  review based on criteria such as whether authors reported presence of bias, impact of bias, the use of a predetermined protocol, funding sources, and conflicts of interest, and/or adequately characterized studies included in the review. Based on this review three (18.8%) of the studies were related as "moderate" quality and the remaining thirteen (81.3%) were rated as "low" quality. None met the criteria for "high" quality.  The elements of the AMSTAR 2 are shown below

Did the research questions and inclusion criteria for the review include the elements of PICO (Patient, Population, or Problem; Intervention; Comparison; Outcome)? 

Did the report of the review contain an explicit statement that the review methods were established before the conduct of the review, and did the report justify any significant deviations from the protocol?
Did the review authors explain their selection of the study designs for inclusion in the review?
Did the review authors use a comprehensive literature search strategy?
Did the review authors perform study selection in duplicate?
Did the review authors perform data extraction in duplicate?
Did the review authors provide a list of excluded studies and justify the exclusions?
Did the review authors describe the included studies in adequate detail?
Did the review authors use a satisfactory technique for assessing the risk of bias in individual studies that were included in the review? 

Did the review authors report on the sources of funding for the studies included in the review?

The authors also found a statistically significant association between the presence of a conflict of interest and the lack of reporting funding sources. These conflicts included examples of all of the following: authors who reported receiving grants, personal fees, royalties, and research fees from orthopedic device manufacturers, as well as authors who were investors, presenters, or consultants for orthopedic device manufacturers.

They concluded  that “Spin is highly prevalent in the abstracts of systematic reviews and meta-analyses studying glenoid augmentation with TSA. Misleading reporting is the most common category of spin.“

 

We want our publications to be as useful and as transparent as possible. Hopefully, this guide will help us avoid spin when we present our work.

Bullock's Oriole

Umtanum Washington, 5/25/25

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Here are some videos that are of shoulder interest
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