Friday, March 15, 2024

Risk of acromial fractures after reverse total shoulder arthroplasty - what can we control?



Acromial fractures are an important cause of poor outcome after reverse total shoulder arthroplasty (RSA). These fractures can cause pain, deltoid weakness because of loss of a secure muscle origin, and restricted range of motion due to unwanted contact between the inferiorly displaced lateral acromion and the humeral tuberosity. They can be associated with scapular notching, which may further compromise shoulder comfort and function.

These fractures are of the "stress" or "fatigue" type, meaning that they result from the repeated application of loads that were unknown to the acromion prior to the reverse total shoulder arthroplasty. This change in loading occurs abruptly - immediately post op -  without the bone having time to remodel. As suggested by the direction of the deformity, repeated downward loading of the lateral acromion from the pull of the acromion is a likely culprit. Conversely, upward loading from contact between the tuberosity and the undersurface of the acromion may also be a contributing factor. 

The risk of acromial fractures is increased by a number of factors that cannot be modified by the surgeon, such as advanced age, female sex,  higher ASA score, poor nutritional status, osteoporosis/osteopenia, inflammatory arthropathy (e.g. rheumatoid arthritis), corticosteroid medication, diabetes, smoking, thinning of the acromion from wear, a diagnosis of cuff tear arthropathy (CTA), diagnosis of massive irreparable cuff tear, prior trauma, prior surgery on the acromion, and prior sectioning of the coracoacromial ligament. 

While the surgeon does determine the implant selection, sizing, positioning, insertion, fixation, distalization, and lateralization, the optimal reverse total shoulder technique remains to be determined because of the myriad of other variables that affect the risk of fracture; analysis of the importance of surgeon-determined variables requires that the study controls for many important variables such as those identified in the previous paragraph.

Here are a few recent articles that are of interest regarding these fractures.

Risk factors of acromial and scapular spine stress fractures differ by indication: a study by the ASES Complications of Reverse Shoulder Arthroplasty Multicenter Research Group found that 1 in 25 patients having RSA sustained an acromial fracture at a minimum of 3 months after surgery. For patients with osteoarthritis the rate was 1 out of 50; for patients with CTA or massive cuff tears that rate was 1 out of 20. While inflammatory arthritis, female sex, and osteoporosis increased the risk, these authors did not identify surgeon-controlled risk factors for acromial fracture.

Acromial Bony Adaptations in Rotator Cuff Tear Arthropathy Facilitates Acromial Stress Fracture Following Reverse Total Shoulder Arthroplasty suggests that (1) cuff tear arthropathy results in adaptive changes in the acromion and (2) the change in acromial loading is more radical when a reverse total shoulder is performed for cuff tear arthropathy than when a RSA is performed for osteoarthritis.

Up to 8mm of Glenoid-Sided Lateralization Does Not Increase the Risk of Acromial or Scapular Spine Stress Fracture Following Reverse Shoulder Arthroplasty With a 135° Inlay Humeral Component looked for surgeon controlled risk fractures for acromial/spine fractures after RSA, which occurred in just over 1 of 20 cases. For the 135 degree inlay component used, glenoid-sided lateralization was not associated with fracture risk. In contrast too other studies, these authors found no relationship between patient age, sex, preoperative acromial thinning, or diagnosis and risk of fracture. They did note that greater preoperative to postoperative change in acromiohumeral distance increased the fracture risk: for every centimeter increase, there was a 121% increased risk for fracture.

See also Acromial stress fracture after reverse total shoulder - does component geometry matter?


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

Follow on twitter: https://twitter.com/RickMatsen or https://twitter.com/shoulderarth
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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).


Sunday, March 10, 2024

Total shoulder arthroplasty: tipping points, prognostic factors and outcomes

Surgeons and patients are interested in the factors predictive of outcome after total shoulder arthroplasty. The authors of Disease diagnosis and arthroplasty type are strongly associated with short-term postoperative patient reported outcomes in patients undergoing primary total shoulder arthroplasty conducted a large observational study of 1,042 patients having primary TSA at a major academic center with one-year follow-up documented by patient reported outcome measures (PROMS).  30% had reverse total shoulders (rTSAs) for cuff tear arthropathy (CTA), 26% had rTSAs for osteoarthritis (OA), and 44% had anatomic total shoulders (aTSAs) for OA. The decision to perform aTSA or rTSA for OA was apparently left to discretion of the individual surgeon. No patient in this study had an aTSA for CTA. 


Lower one-year PROMS scores were most prominently associated with a diagnosis of CTA, lower preoperative mental health and workers compensation insurance. Other negative factors included younger age, female sex, current smoking, chronic pain diagnosis, history of prior surgery, lower baseline PROMS, absence of glenoid bone loss. Of note, none of these factors are modifiable by the surgeon. Surgeon controlled variables, such as the implant selected and operative technique were not presented.

The authors found that patients that had to be excluded from analysis because they failed to provide 1 year PROMs were more likely to have a diagnosis of CTA, to be younger, to have race other than white, to have more comorbidities, to have less education, to inhabit areas of higher area deprivation index, to have lower baseline PROMS, to have more preoperative opioid use, and to have more chronic pain or psychiatric diagnoses. First year complications and revisions were not presented.



Comment: This is a carefully done observational study on a large number of total shoulder arthroplasties performed at a leading academic medical center. The authors provide the classic figure one, showing numbers of patients excluded and the reasons.



Graphical displays of the data from their Table 3 are shown below for both the American Shoulder and Elbow Surgeons score and the Penn Shoulder Score


`Several observations can be made from these charts:
(1) The Penn Shoulder Score data are essentially the same as the ASES data
(2) The tipping point (the average score prior to surgery (see What's the right time to have a shoulder joint replacement arthroplasty? When is it "indicated"? for each of the three groups was the same: 30 points. In other words, patients with OA or CTA turning to arthroplasty typically had only 30% of the patient reported outcome measure.
(3) Both the 1 year score and the percent of maximum possible improvement (see How can we measure whether our patients have benefitted from treatment? Problems with the MCID; benefit of %MPI) were lower for shoulders having cuff tear arthropathy than those having osteoarthritis; whereas the results for patients with OA were essentially the same whether the surgeon chose to perform an aTSA or a rTSA.
(4) No surgeon-controlled variables were identified that correlated with outcome.

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


Follow on twitter: https://twitter.com/RickMatsen or https://twitter.com/shoulderarth
Follow on facebook: click on this link
Follow on facebook: https://www.facebook.com/frederick.matsen
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).


Friday, March 8, 2024

Planning: accuracy, precision, outcome and the goal post.



It goes without saying that preoperative planning coupled with surgical experience, technique, and intraoperative adaptability are key ingredients to the successful outcome of shoulder arthroplasty. Preoperative planning allows the surgical team to grapple - before scrubbing in - with the anticipated pathoanatomy and the decisions that will have to made at surgery .

Traditionally, preoprerative planning was based on the physical examination and standard imaging of the shoulder, including standardized plain films with the addition of CT and MRI as necessary.

Recently introduced innovations in preoperative planning and plan implementation include three-dimensional simulation software, image guided navigation, patient specific instrumentation, virtual reality, and mixed reality.

While the effectiveness of these innovations in improving clinical outcomes for the patient remains to be rigorously demonstrated, the advocates of these innovations point to the improved accuracy and precision of component placement that can be achieved:

Accuracy and Reliability of Computerized Surgical Planning Software in Anatomic Total Shoulder Arthroplasty

Reliability and accuracy of 3D preoperative planning software for glenoid implants in total shoulder arthroplasty


The Value of Computer-Assisted Navigation for Glenoid Baseplate Implantation in Reverse Shoulder Arthroplasty: A Systematic Review and Meta-Analysis

  1. Precision refers to the degree of reproducibility or repeatability of the placement - doing it the same way each time. Accuracy, on the other hand, refers to the degree of closeness between the desired and the actual placement - how close do we need to be to what target?


  2. If we think of the field goal in American football, we note that the ball doesn't need to be accurately positioned in the center of the uprights nor does it need to be reproducibly positioned, it just needs to pass between the uprights to get the team three points.




    With respect to accuracy, the outcome (number of points generated) for each of the two sets of six kicks shown below would be the same.








    We need to learn how much accuracy is needed to get our patients the outcome they want. This is difficult, because we have yet to learn where the goal posts are, for example with respect to version correction and reverse total shoulder component position.


    As shown below, precision in and of itself cannot be the goal.




    As we design studies to determine the clinical value of planning innovations, we need define the degree of accuracy and precision needed to achieve the desired outcome for the patient. Do we know where goalposts are - where is the target - and how wide apart are the uprights? 


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


    Follow on twitter: https://twitter.com/RickMatsen or https://twitter.com/shoulderarth
    Follow on facebook: click on this link
    Follow on facebook: https://www.facebook.com/frederick.matsen
    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).

Arthritis in a 37 year old body builder/weight lifter with B2 pathoanatomy

A 37 year old man from a few states South, dedicated to body building, presented with a prior diagnosis of right shoulder arthritis, labral tears, bursitis, biceps tendinitis previously treated elsewhere with "an arthroscopic subacromial decompression, distal clavicle excision, capsular release, chondroplasty, humeral and glenoid osteoplasty, removal of loose bodies, and manipulation under anesthesia" without apparent benefit.

At his initial visit, he was 5ft 10in, very muscular with a body weight of 240lbs. His shoulder motion was very limited: 100 degrees of elevation and no rotation.

His Simple Shoulder Test on presentation is shown below.


His x-rays at presentation are shown below.

Because of his desire to return to heavy weight training, he elected to have a ream and run procedure. No CT scan or three dimensional preoperative planning software was used.

His surgery was performed without a brachial plexus block. An in situ head cut was used because the shoulder's muscularity and capsular tightness. 

His postoperative films are shown below.


One week after surgery, he had regained excellent flexibility



At three months after surgery, he was working on strength of flexion



At seven months post op, he was progressing his exercises.

At a year after surgery he sent this video of his workouts.


Comment: As can be seen, this is no ordinary patient, but rather one who is extremely motivated and who has been committed to stay in close email contact with the surgical team, even though he lives over a thousand miles away. As emphasized in The ream and run: not for every patient, every surgeon or every problem, patient motivation and surgical technique are elements critical to the outcome of the ream and run procedure. All the videos shown here were part of the patient's communication with the ream and run team and are shown with the patient's permission.

While other arthroplasty options - anatomic total shoulder, augmented glenoid components, reverse total shoulder - could have been considered after his failed arthroscopic surgery, none seemed as compatible with his activity goals as the ream and run procedure.

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

Follow on twitter: https://twitter.com/RickMatsen or https://twitter.com/shoulderarth
Follow on facebook: click on this link
Follow on facebook: https://www.facebook.com/frederick.matsen
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).













Thursday, March 7, 2024

Managing cuff tear arthropathy in an active farmer / physician - the simple and safe approach, 11 year followup.

 A 77 year old muscular retired physician, active rancher from the opposite corner of the U.S. presented with pain and loss of function of the left shoulder, thirteen years after a prior rotator cuff procedure. 

His functional deficits at that time are shown on his Simple Shoulder Test 

His x-rays at presentation are shown below.



He did not want a reverse total shoulder because of his active lifestyle caring for his farm and farm animals, clearing fallen trees, and landscaping. Instead he elected a CTA hemiarthroplasty (see this The cuff tear arthropathy arthroplasty). The procedure was performed eleven years ago without preoperative CT or MRI scans, 3D planning or interscalene block. His supraspinatus and infraspinatus tendons were absent. His subscapularis was detached, but reconstructed at the end of the case.

Seven years after surgery he returned for routine followup with these x-rays




and this shoulder function,

Now eleven years after surgery at the age of 88 he reports a mild increase in shoulder discomfort with active use, but that he is still working on his farm, sometimes tripping over tree stumps or falling when stepping in hidden holes

His current x-rays (11 years after his arthroplasty) are show below.



Comment: The CTA hemiarthroplasty is a durable, cost-effective and safer alternative to a reverse total shoulder for patients who have cuff tear arthropathy and retained active elevation (see Managing rotator cuff tear arthropathy: a role for cuff tear arthropathy hemiarthroplasty as well as reverse total shoulder arthroplasty).  

Managing cuff tear arthropathy in the active woman rancher






Unfortunately, in spite of their value to the patient, these implants are becoming less and less available, perhaps related to the fact that their use generates less revenue for the surgeon and for the orthopaedic company vendor than the more complex reverse total shoulder

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

Follow on twitter: https://twitter.com/RickMatsen or https://twitter.com/shoulderarth
Follow on facebook: click on this link
Follow on facebook: https://www.facebook.com/frederick.matsen
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).

Tuesday, March 5, 2024

What happens when glenoid version and inclination are "corrected"?


Posteriorly augmented glenoid components are increasingly being advocated for use in anatomic total shoulder arthroplasty. As pointed out in Augmented anatomic glenoid components - are they necessary? their value in terms of improving clinical patient outcomes is yet to be demonstrated. In addition to their increased cost, their use may be associated with increased loosening moments and difficulty in fitting the component to the glenoid bone.



Furthermore, the use of stepped, wedged, or half wedged glenoid components assumes that the two concavities in an eroded glenoid lie with one anterior and the other posterior. 









However it has become evident that the pathologic concavity need not be confined to the posterior direction and is not infrequently in the posterior superior aspect of the glenoid.


As a result, it may not be well fit by a posteriorly augmented glenoid component.

The authors of Three-dimensional analysis of biplanar glenoid deformities: What are they and can they be virtually reconstructed with anatomic total shoulder arthroplasty implants? discuss the three dimensional deformity in the arthritic glenoid and its implications for the use of augmented components. They defined "biplanar" glenoid deformities as those with a combined increase in both superior inclination and retroversion and suggest that these deformities are associated with difficulties in glenoid implantation and inferior clinical outcomes.

They analyzed 268 patients with glenohumeral osteoarthritis indicated for total shoulder arthroplasty.  Glenoids with superior inclination ≥10˚ and retroversion ≥20˚ were considered to have biplanar deformity. 49% of these shoulders had type B2 pathoanatomy. The direction of the deformity was directly posterior in 57% and posterior superior in 24%.

Their parameters for acceptable glenoid reconstruction included glenoid polyethylene implant position with  90% seating and less than 20% cancellous bone exposure, no central peg perforation, no more than a single peripheral peg perforation, and maintenance of prosthetic joint line lateral to pathologic joint line. 

Accepting less correction increased the rate of satisfactory reconstruction and decreased the planning system's suggested use of augmented glenoid components:

(1) The shoulders were first virtually planned for anatomic TSA attempting correction to neutral inclination and version.  Virtual aTSA planning indicated that 41% of the shoulders could not be reconstructed to neutral inclination and version using any implant. Of those that could, the system suggested that 94% have augmented implants. 

(2) The shoulders were then virtually planned for anatomic TSA accepting correction to 5˚ superior inclination and 10˚ retroversion. Virtual aTSA planning indicated that 10% could not be reconstructed with any implant.  Of those that could, the system suggested that 58% have augmented implants.

Final implant insertion commonly involved removal of substantial amounts of bone,  unseating in the posterosuperior quadrant, cancellous exposure in the anteroinferior quadrant, and vault perforation.





As the authors point out despite classical recommendations for 80% as the threshold for adequate glenoid implant seating, recent evidence suggests that even with 84% seating, the risk of glenoid loosening increases by up to 28% compared to full backside support. Seating values below 90% are associated with increases in bone stress and critical cement volumes. Furthermore, the importance of subchondral bone preservation is well-established, but specific thresholds for the amount of cancellous bone exposure are not defined. 

Comment: This is an important study. It makes us ask, is it more important to "correct" the glenoid pathoanatomy or to preserve glenoid bone stock and "accept" increased glenoid version and inclination? (see Glenoid version: acceptors and correctors). How should a surgeon optimize version, inclination, cancellous bone exposure, and component seating? Many of the publications attempting to address these questions are based on finite element analysis, simulation modeling, in vitro studies using Sawbones, theory, or studies using outdated components (e.g. those with keels or non-ingrowth pegs).  These studies can create a view of a "correct time zero implant position" or "acceptable resurfacing parameters" that may or may not relate to the outcome of the patients we treat. 

This study points out that correcting a biplane deformity to neutral version and inclination frequently frequently results in peg perforation, exposure of subchondral cancellous bone and inadequate backside support of the implant.

It may be that the most robust approach to glenoid component placement is to conservatively ream the glenoid face to a single concavity, accepting glenoid version and inclination, preserving maximal bone quality and quantity, and completely seating a standard round backed glenoid component that matches the reamed concavity. 

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

Follow on twitter: https://twitter.com/RickMatsen or https://twitter.com/shoulderarth
Follow on facebook: click on this link
Follow on facebook: https://www.facebook.com/frederick.matsen
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).





Sunday, March 3, 2024

Shoulder arthritis in a young weightlifter and firefighter


A 40 year old weightlifter, firefighter and high school football coach from Florida presented with painful glenohumeral arthritis after a prior arthroscopic instability repair. His Simple Shoulder Test responses are shown below.


Physical examination revealed a stiff shoulder.

His preoperative images are shown below





Wishing to avoid the risks and limitations associated with the polyethylene glenoid component used in conventional total shoulder arthroplasty, he proceeded with a ream and run procedure 10 months ago.

His postoperative radiographs are shown below




With a fully dedicated rehab effort he was able to complete a half-marathon in under six and half hours seven months after surgery. 

At ten months after surgery he had returned to work as a firefighter and sent this report and videos






Comment: This is obviously no ordinary patient, no ordinary shoulder arthritis and no ordinary rehab effort. We be informed by the progressive recovery and long term followup.

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

Follow on twitter: https://twitter.com/RickMatsen or https://twitter.com/shoulderarth
Follow on facebook: click on this link
Follow on facebook: https://www.facebook.com/frederick.matsen
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).