Acromial fractures after reverse total shoulder - current thoughts

Acromial stress fractures (ASFs) and scapular spine stress fractures (SSFs) are important complications of reverse total shoulder arthroplasty, limiting patient comfort and function and creating difficult surgical challenges for open reduction and internal fixation. 

Acromial stress fractures and scapular spine stress fractures are related primarily to unmodifiable patient risk factors: (1) poor bone density (osteoporosis, female sex, older age, and inflammatory arthritis) and (2) diagnoses of rotator cuff deficiency (cuff tear arthropathy and massive rotator cuff tear). These factors need to be identified preoperatively and discussed with the patient with respect to the decision to proceed with RSA, the postoperative progression of rehabilitation and monitoring for unexpected pain and loss of function, as well the consideration of more conservative surgical options for appropriately selected patients at risk (see Managing rotator cuff tear arthropathy: a role for cuff tear arthropathy hemiarthroplasty as well as reverse total shoulder arthroplasty).

Although patient factors are the primary determinant of the risk of ASF and SSF, implant selection and positioning are less important but modifiable risk factors for the surgeon to consider.  Notably the important measures of the final reconstructed geometry are (1) the location of the center of rotation with respect to the scapula and (2) the location of the proximal humerus in relation to the scapula (not whether the implant is “onlay or inlay” or how the implants are classified (GM/HL, GM/HM, GL/HL, GL/HL)).

These surgeon-controlled variables need to be considered not only with respect to their effect on the risk of stress fractures but also with respect to their effect on patient comfort and function. For example, increased glenoid lateralization appears to be associated with a greater risk of ASFs, but it also is associated with improved rotation and lower rates of scapular notching and impingement.  As another example, increased humeral lateralization appears to be associated with lower risk of stress fractures, but may also give rise to an increased risk of unwanted contact between the abducted arm and the acromion. 

Additional elements deserve consideration. 

(1)  Are we using the best method for determining the location of the center of rotation with respect to the scapula and the location of the proximal humerus in relation to the scapula (see figure above)? For example, the use of angles, such as the "lateralization shoulder angle" (LSA) and the "distalization shoulder angle" (DSA) to characterize linear measures of lateralization and distalization may be suboptimal for documenting the proximal/distal and medial/lateral position of the center of rotation and the proximal humerus. 

(2) Should we be focusing only on the postoperative geometrical relationships, or should we also be paying attention to the preoperative to postoperative changes in these relationships, recognizing that the magnitude and direction of these changes may also influence the loads on the acromion and scapular spine? See A method for documenting the change in center of rotation with reverse total shoulder arthroplasty and its application to a consecutive series of 68 shoulders having reconstruction with one of two different reverse prostheses

Here are some recent relevant references.

Robert H. Cofield, MD, Award for Best Oral Presentation 2023: Up to 8 mm of glenoid-sided lateralization does not increase the risk of acromial or scapular spine stress fracture following reverse shoulder arthroplasty with a 135 degrees inlay humeral component Glenoid-sided lateralization in reverse shoulder arthroplasty (RSA) decreases bony impingement and improves rotational range of motion, but has been theorized to increase the risk of acromial or scapular spine fractures (ASFs).  Up to 8 mm of glenoid-sided metallic lateralization did not appear to increase the risk of ASF when combined with a 135 degrees inlay humeral implant. Humeral distalization increased the risk of ASF, particularly when there is a larger change between pre- and postoperative AHD or higher inferior glenosphere overhang. In cases of pronounced preoperative superior humeral migration, it may be a consideration to avoid excessive postoperative distalization, but minimizing bony impingement via glenoid-sided lateralization appears to be safe.

Implant-Positioning and Patient Factors Associated with Acromial and Scapular Spine Fractures After Reverse Shoulder Arthroplasty  Patient factors associated with poor bone density (inflammatory arthritis, osteoporosis, prior shoulder surgery, female sex, older age) and rotator cuff deficiency (massive rotator cuff tear, cuff tear arthropathy) appear to be the strongest predictors of ASFs and SSFs after RSA. To a lesser degree, final implant positioning may also affect ASF and SSF prevalence; increased humeral lateralization was found to be associated with lower fracture rates whereas excessive glenoid-sided and global lateralization were associated with higher fracture rates.

Predictive factors of acromial fractures following reverse total shoulder arthroplasty: a subgroup analysis of 860 shoulders This analysis showed that higher postoperative LSA, lower DSA and a lower ACHD (acromial/humeral distance) were predictive factors only for Levy type III fractures, but not for types I or II. 

Incidence, risk factors, and complications of acromial stress fractures after reverse total shoulder arthroplasty Patient-specific factors that were independently associated with the occurrence of an ASF included osteoporosis, rheumatologic disease, shoulder corticosteroid injection within 3 months before surgery, and chronic oral corticosteroid use. Among patients with osteoporosis, the initiation of physical therapy within 6 weeks after surgery also increased the risk of ASF.

Acromial stress fractures and reactions after reverse total shoulder arthroplasty: a case-control study two factors were independently associated with the occurrence of an acromial stress fracture/reaction after RTSA: corticosteroids use and previous shoulder surgery.

Does prior rotator cuff surgery influence the outcomes and complications after reverse total shoulder arthroplasty in patients with cuff tear arthropathy or massive rotator cuff tear? A propensity score-matched study a history of prior rotator cuff surgery was associated with a high incidence of acromial stress fracture

Coracoacromial ligament integrity influences scapular spine strain after reverse shoulder arthroplasty This biomechanical study in cadavers examined the effect of coracoacromial (CA) ligament state (intact vs. released) and arm position on acromial and scapular spine strain following reverse total shoulder arthroplasty (rTSA).  Scapular spine strain was quantified via 4 strain gauges placed along anatomic locations on the acromion and scapular spine.  CA ligament release in the setting of rTSA resulted in increased scapular spine and acromial strain with the arm adducted, although these increases in strain were not statistically significant. 

Low acromial insufficiency fracture rate in reverse shoulder arthroplasty with distal clavicle excision This study investigated the rate of acromial insufficiency fractures (AIF) in patients undergoing reverse shoulder arthroplasty (RSA) with concomitant distal clavicle excision (DCE).  There were 3/174 acromial insufficiency fractures (1.7%). Twelve patients had insufficiency reactions (6.9%). Patients with acromial pathology were more likely to be female, and have a diagnosis of osteoporosis, and inflammatory arthritis. Unfortunately, there was no comparison group of RSAs without distal clavicle excision

Do preoperative scapular fractures affect long-term outcomes after reverse shoulder arthroplasty? Fractures identified on preoperative computed tomography scans were divided into 3 groups: (1) os acromiale, (2) multifragments (MFs), and (3) Levy types. Seventy-two shoulders had an occurrence of SSF. The multifragment fracture group has lower functional and satisfaction scores at all postoperative time points compared with both the nonfracture and the Os/Levy fracture group.

Acquired Acromion Compromise, Including Thinning and Fragmentation, Is Not Associated With Poor Outcomes After Reverse Shoulder Arthroplasty Preoperative acromial compromise was defined as follows: (1) thinning of the acromion (< 3 mm), which means a thickness of less than 30% of the normal acromion thickness (8 to 9 mm), and (2) acromial fragmentation.  In patients with acquired acromial compromise-such as thinning or fragmented acromion because of advanced cuff tear arthropathy or previous acromioplasty, primary RSA resulted in no differences in functional outcome score, ROM, shoulder strength, and overall complications compared with patients without acromial compromise.

Variations in the Anatomic Morphology of the Scapular Spine and Implications on Fracture After Reverse Shoulder Arthroplasty This study evaluated the role of anatomic scapular morphology in acromion and scapular spine fracture (SSAF) risk after reverse shoulder arthroplasty (RSA).  Scapular measurements were captured including scapular width measurements at the acromion (Z1), middle of the scapular spine (Z2), and medial to the first major angulation (Z3). 

 Patients with thicker acromions (Z1) and thinner medial scapular spines (Z3) had increased fracture risk. The mean zone 1 and 3 measurements for the control group were 18.6 ± 3.7 mm and 3.2 ± 1 mm, respectively, compared with 22.5 ± 5.9 mm and 2 ± 0.7 mm, respectively, in the SSAF cohort. This trend was also reflected in the calculated scapular spine proportion (SSP),Z1/Z3. A regression analysis was used to quantify the risk for scapular spine fracture after RSA as a function of SSP. Under this calculation, an SSP = 5 represented a <5% fracture risk; SSP = 9.2, 50%; SSP = 10.8, 75%; and SSP = 13.5, 95% risk.

Acromial and scapular fractures after reverse shoulder arthroplasty: comparison of 3018 reverse total shoulders by inlay and onlay humeral component design When comparing by inlay vs. onlay humeral component design, the rates of postoperative acromial or scapular spine fractures were statistically similar.

Reverse shoulder arthroplasty for patients with cuff tear arthropathy: do clinical outcomes differ by inlay vs. onlay design? At 2-year minimum follow-up, the position of the humeral tray in RSA prostheses (either inlay or onlay) for cuff tear arthropathy was not associated with PROs, shoulder ROM, or rates of complications, including baseplate loosening, acromial stress fracture, and scapular notching.

Increased Deltoid and Acromial Stress with Glenoid Lateralization and Onlay Humeral Stem Constructs in Reverse Shoulder Arthroplasty Finite element analysis was performed using a RSA system with both inlay and onlay configurations.  Increased lateralization of the glenoid component resulted in increased levels of deltoid and acromial stress. For a given amount of glenoid lateralization, utilization of an inlay stem decreased acromial and deltoid stresses compared to onlay constructs. 

High delta angle after reverse total shoulder arthroplasty increases stresses of the acromion: biomechanical study of different implant positions. High delta angle (combination of inferiorization and medialization of the center of rotation [COR]) after RTSA may be a risk factor for acromial fracture.

In a rigid body model of the upper extremity muscle, forces of the deltoid muscle were calculated before and after implanting RTSA in different arm and implant positions.  High delta angles correlated with an increase in acromial stress. Both lateralization of the COR and the humerus decreased the acromial stress in this study. The lateralization of the humerus has the highest impact on acromial stress.These results are contrary to some in the current literature, thus further studies with focus on the acromial stress are needed.

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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).

Anatomic total shoulder - preoperative planning and intraoperative decision making.

 Preoperative planning is helpful in anticipating what might be needed to reconstruct an arthritic shoulder; however the final choice of implants is determined at the time of surgery.

A 43 year old man presented with pain and stiffness of his left shoulder. He had a prior CT scan showing an arthritic humeral head centered on a somewhat retroverted glenoid.

We obtained our standard set of plain radiographs: an AP in the plane of the scapula and an axillary "truth" view taken with the arm in a functional arm position of elevation. The truth view showed posterior decentering of the humeral head that was not evident on the CT scan taken with the patient's arm at his side. No 3D CT planning was used.

At surgery, a standard glenoid component was well seated after conservative glenoid reaming. "Corrective" reaming and a posteriorly augmented glenoid component were not used.

 Trialing with an anatomic humeral head component revealed posterior instability when the arm was flexed forward. As a result, a short stemmed humeral component with an anteriorly eccentric humeral head was selected. 

Postoperatively, his shoulder is clinically and radiographically stable when the arm is elevated to a functional position (as seen on the postoperative "truth" view).

Comment: This case illustrates (1) the value of the "truth" view before and after surgery and (2) the importance of tailoring implant selection based on intraoperative testing of motion and stability. NB: when we do an arthroplasty, the shoulder we have after soft tissue releases and osteophyte resection is different from the shoulder before surgery; that's why intraoperative assessment is more important than preoperative planning.

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).

Happy Valentine's Day

 Owl you need is love. 

Superb owl photo I took during Super Bowl

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).

Anatomic vs reverse total shoulder for cuff intact arthritis - what does the recent literature say?

One of the most frequently debated topics in shoulder surgery is the choice between reverse total shoulder (RSA, below left) and anatomic total shoulder (aTSA below right) for patients having osteoarthritis with an intact rotator cuff.

This is going to be an upside down post. First the conclusions and then the published evidence from 2024-2025.

Conclusions

(1) Patients having either aTSA or RSA have good reported outcomes. While some papers have reported statistically significant benefits of one or the other, most of these differences are not clinically significant (i.e. the difference does not exceed the minimal clinically important difference (MCID)). However, there is evidence that shoulder internal and external rotation is better with aTSA and that rotation matters to the patient. The effect of rotation on patient function may not be noted on ASES, VAS, and SANE scores. In contrast three of the 12 Simple Shoulder Test questions relate to shoulder rotation: (3) Can you reach the small of your back to tuck in your shirt?, (4) Can you place your hand behind your head with your elbow straight out to the side? and (11) Can you wash the back of your opposite shoulder?

(2) The complications for the two procedures are different. For RSA, along with instability, intraoperative and postoperative fractures and infections loom large. These observations suggest the need for RSA techniques and implants that respect the often compromised bone quality coupled along with minimizing procedure time and optimizing infection prophylaxis. For aTSA, rotator cuff tears and glenoid component loosening top the list. This suggests the need for thoughtful patient selection with respect to cuff status and technical attention to achieving excellent glenoid component seating. It is worth noting that complication rate and revision rate are different, in that some complications (e.g. acromial/spine fractures) are often managed without revision.

(3) Preoperative stiffness and preoperative weakness are not strongly associated with bettter outcomes for RSA in comparison to aTSA.

(4) Older patients can benefit from both aTSA and RSA

(5) The revision rate for stemless aTSA may be comparable to that for RSA and lower than that for stemmed TSA. There is a suggestion that cuff failure may be less common in stemless aTSA in comparison to stemmed aTSA.

(6) The type of fellowship taken by the surgeon appears to influence the type of arthroplasty selected for osteoarthritis.

(7) The cost of RSA is greater than the cost of aTSA

Now here are the articles.

Is There an Association Between Postoperative Internal Rotation and Patient-reported Outcomes After Total Shoulder Arthroplasty? After shoulder arthroplasty, shoulder normalcy was associated with postoperative internal rotation

Comparison of Anterior Shoulder Pain and Internal Rotation Dysfunction after Anatomic and Reverse Shoulder Arthroplasty for Osteoarthritis Using a new anterior shoulder pain and dysfunction survey (ASPDS) the authors classified anterior shoulder dysfunction and use following RSA compared to aTSA when performed for osteoarthritis. At 2 years after surgery, mean ASPDS scores were worse in the RSA group compared to the aTSA group. Mean functional internal rotation scores were also worse in the RSA group compared to the aTSA group. Notably, no differences reaching statistical significance were observed between aTSA and RSA groups for ASES, SANE or VAS  pain scores. 

Internal rotation based activities of daily living show limitations following reverse shoulder arthroplasty versus anatomic shoulder arthroplasty PROMs were mostly similar between aTSA and rTSA, however the Simple shoulder test (SST) did show a difference with better scores in the aTSA cohort. The activities of daily living that showed significant disparity between aTSA and rTSA were toileting, donning a coat, reaching one’s back as well as throwing overhand with rTSA patients reporting more difficulty in all these ADLs after RSA.

A comparative analysis of anatomic total shoulder arthroplasty versus reverse shoulder arthroplasty for posterior glenoid wear patterns considered patients with B2 and B3 glenoid types. At two year followup, TSA patients had better average active external rotation and internal rotation.  There was no significant difference in complication rate. The most common complication was cephalic vein thrombosis. No complication required revision.

Patients undergoing reverse total shoulder arthroplasty have less pain and require fewer opioid pain medications compared to anatomic total shoulder arthroplasty in the early postoperative period: a retrospective review found that while aTSA patients required more opioid medication refills and remained on opioids for a longer duration in the early postoperative period, by 12 weeks there was no difference in the VAS pain score or the percent of patients taking opioids. As shown below, aTSA patients had significantly better rotation than RSA patients at 12 weeks.




Improvement in Sleep Disturbance Following Anatomic and Reverse Shoulder Arthroplasty The ability to sleep comfortably returned faster than the ability to sleep on the affected side, with the ability to sleep comfortably reaching a plateau at 3 months and the ability to sleep on the affected side reaching a plateau at 6 months. 13.2% of patients in the TSA group and 16.0% of those in the RSA group could not sleep comfortably and 31.4% of those in the TSA group and 36.8% of those in the RSA group could not sleep on the operative side.

Reverse versus anatomic total shoulder arthroplasty for glenohumeral osteoarthritis with intact cuff: a meta-analysis of clinical outcomes found no clinically significant differences in patient reported outcomes. The aTSA group had a significantly more external rotation relative to the RSA group. Twelve studies reported adverse outcomes, with the RSA group having a lower rate of complications and reoperations relative to aTSA at an average follow-up of 3.4 years.



Total Shoulder Arthroplasty Versus Reverse Shoulder Arthroplasty in Primary Glenohumeral Osteoarthritis With Intact Rotator Cuffs: A Meta-Analyses found no significant differences in forward elevation, external rotation in adduction, internal rotation, visual analog scale (VAS), American Shoulder and Elbow Surgeons (ASES) score, and Single Assessment Numeric Evaluation (SANE) scores. There were a total of 20 (3.68%) complications in the aTSA group and eight (2.4%) complications in the RSA group. The complications in the aTSA group consisted of seven radiographic failures, six subscapularis failures, three posterior dislocations, two late rotator cuff insufficiencies, one arthrofibrosis, and one wound infection. The complications in the RSA group consisted of four acromial stress fractures, two baseplate fractures, one periprosthetic infection, and one periprosthetic fracture.

Comparison between Anatomic Total Shoulder Arthroplasty and Reverse Shoulder Arthroplasty for Older Adults with Osteoarthritis without Rotator Cuff Tears found that the TSA group demonstrated significantly better postoperative ASES and Constant-Murley scores than the RSA group, but these differences did not exceed the MCID for these measures. The TSA group showed a significantly better postoperative active ROM than the RSA group regarding forward flexion as well as external and internal rotations.

Anatomic and Reverse Total Shoulder Arthroplasty for Osteoarthritis: Outcomes in Patients 80 Years Old and Older At most recent follow-up, there were no significant differences in PROMs between cohorts. aTSA patients achieved greater postoperative motion in external rotation and internal rotation. There were six complications amongst aTSA patients (7.8%): four with subscapularis insufficiency, one humeral shaft periprosthetic fracture treated with open reduction and internal fixation, and one with prosthetic joint infection revised to a functional composite spacer. Three rTSA patients (5.6%) sustained complications – all acromion/scapular spine fractures (2 Type 2; 1 Type 3) which were treated non-operatively.

Reverse total shoulder arthroplasty for primary osteoarthritis with restricted preoperative forward elevation demonstrates similar outcomes but faster range of motion recovery compared to anatomic total shoulder arthroplasty Postoperative active flexion and external rotation were similar between RSA and TSA cohorts. Internal rotation was worse in the RSA cohort. RSA led to faster postoperative FF and ER recovery. There was no statistically significant difference in complication rates between cohorts.

Clinical outcomes of anatomic vs. reverse total shoulder arthroplasty in primary osteoarthritis with preoperative external rotation weakness and an intact rotator cuff: a case-control study In preoperatively weak patients with cuff-intact primary osteoarthritis, aTSA leads to similar postoperative strength, range of motion, and outcome scores compared with patients with normal preoperative strength, indicating that preoperative weakness does not preclude aTSA use. Patients who were preoperatively weak in ER demonstrated improved postoperative rotational motion after undergoing aTSA and rTSA, with both groups achieving the minimal clinically important difference and substantial clinical benefit at similar rates.

Does preoperative forward elevation weakness affect clinical outcomes in anatomic or reverse total shoulder arthroplasty patients with glenohumeral osteoarthritis and intact rotator cuff? Patients with cuff intact glenohumeral arthritis and preoperative FE weakness obtain postoperative outcomes similar to patients with normal preoperative strength after either aTSA or rTSA. Preoperatively weak aTSAs achieved greater ER but lower rates of clinically relevant improvement in overhead motion compared to weak rTSAs.

Anatomic Versus Reverse Total Shoulder Arthroplasty for Primary Osteoarthritis With an Intact Rotator Cuff: A Midterm Comparison of Early Top Performers Active external rotation (ER) was greater after aTSA at midterm follow-up in both ASES and SAS score cohorts; however, preoperative to postoperative improvement was equivalent. Postoperative ER and SAS scores were greater after aTSA. No difference was found in the incidence of complications and revision surgeries between top-performing aTSAs and rTSAs. 

Treatment of B2 Type Glenoids with Anatomic versus Reverse Total Shoulder Arthroplasty: A Retrospective Review Postoperatively patients in the aTSA group had significantly better external rotation and internal rotation compared to the rTSA group. There were no differences in patient reported outcomes between the two groups. No patients in the aTSA group had recurrent posterior humeral head subluxation. Eight complications requiring revision occurred, 4 in each group.

The authors of Stemless anatomic and reverse shoulder arthroplasty in patients under 55 years of age with primary glenohumeral osteoarthritis: an analysis of the Australian Orthopedic Association National Joint Replacement Registry at 5 years stated that instability was the predominant cause of revision for reverse total shoulder arthroplasty (rTSA), and stemmed aTSA, while loosening was the predominant cause of revision for stemless aTSA (SLaTSA). The 6-year cumulative percent revision rate was 12.4% for stemmed aTSA (instability, loosening, cuff failure, infection), 7.0% for SLaTSA (instability, loosening, infection) and 6.5% for rTSA (instability, infection) .

Anatomic or reverse total shoulder arthroplasty? How fellowship training affects selection of arthroplasty type Surgeons having completed a Sports Medicine fellowship chose rTSA over ATSA at a higher rate than those who completed a shoulder and elbow fellowship, both for all indications and for a primary diagnosis of glenohumeral osteoarthritis. 

Trends in Total Shoulder Arthroplasty Utilization and Implant Pricing from 2017 to 2022 the inflation-adjusted cost of aTSA decreased from $8055 in 2013 to $6223 in 2022, and RSA from $12,207 to $8882 in 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).

What's new? Anatomic total shoulder arthroplasty for cuff intact arthritis

Stay curious

Anatomic total shoulder arthroplasty - aTSA (rather than reverse total shoulder - RSA) is for many surgeons the "go to" procedure for most patients with cuff-intact shoulder arthritis. While in the past there have been concerns about (1) glenoid component failure and (2) failure of the rotator cuff, modern glenoid implants and improved surgical techniques to assure excellent glenoid component seating along with proper preoperative evaluation of the rotator cuff have greatly reduced these risks. It is well documented that the range of motion is on average better for aTSA than RSA and that in contrast to RSA, aTSA essentially avoids the risks of two serious complications of RSA: dislocation and acromial/spine fractures. While some studies have shown lower revision rates for RSA than aTSA, these studies must be viewed from the perspective that in the uncommon occurrence of aTSA failure, a revision to an RSA is usually successful. However revision for an unstable RSA or an acromial/spine fracture may be avoided by the patient and surgeon because of concerns about complications and effectiveness.

Let's look at a few recent articles an aTSA from the past year. 

An informative study on aTSA in the management of two common forms of osteoarthritis can be found in Anatomic total shoulder arthroplasty for posteriorly eccentric and concentric osteoarthritis: a comparison at minimum 5-year follow-up. This article presents outcomes for aTSA performed using an all-polyethylene glenoid component inserted after conservative glenoid reaming with no attempt at changing glenoid version. Two hundred and ten patients were included of which 98 (47%) had posteriorly decentered humeral heads and 108 (51%) had centered humeral heads.  77 shoulders had Walch type A glenoids; 122 had Walch type B glenoids. At a mean 8-year follow-up, the final SST, change in SST and percentage of maximal improvement were not correlated with pre- or postoperative humeral head centering on the glenoid, Walch classification or glenoid version. Two patients (1%) underwent open re-operations during the study period. In patients with Walch B1 and B2 glenoids (n=110), there were no differences in outcome measures between patients with postoperative glenoid component retroversion of more or less than 15o. While 15 of 51 patients (29%) with 5-year radiographs had glenoid radioluciences, these radiographic findings were not associated with inferior clinical outcomes. On multivariable analysis glenoid component radiolucencies were most strongly associated with incomplete component seating.

Risk of complications: 

Patient, surgeon, indications and implant factors can influence the risk of complications after aTSA. 

A Preoperative Risk Assessment Tool for Predicting Adverse Outcomes among Total Shoulder Arthroplasty Patients studied  208,634 TSAs performed on Medicare-insured patients. More than one in ten (11.2%) had at least one adverse outcome (hospital readmission, postoperative complication, emergency room visit, or mortality during the 90 days post discharge). Patients with an adverse outcome were older, more likely to be female, have a diagnosis of fracture, issues related to social determinants of health, greater healthcare utilization, and comorbidities such as anemia. Notably, this study did not identify surgical technical factors related to adverse outcomes.

Risk factors for rotator cuff tears and aseptic glenoid loosening after anatomic total shoulder arthroplasty reviewed 2699  primary aTSAs (1823F/ 1,922M/27 unspecified; mean age: 65.6 years).  5 different glenoid design types were used (1779 nonaugmented hybrid cage glenoid components, 650 posterior augment cage, 731 nonaugmented peg, 212 posterior augment peg, 369 keel, and 31 unspecified). The indications for the different glenoid types was not specified. 3.2% aTSA shoulders had a cuff tear. The multivariate analysis identified that aTSA patients with cuff failure were more likely to have previous shoulder surgery and small size glenoids. 3.3% of aTSA shoulders had aseptic glenoid loosening; 15.5% loose glenoids also had a rotator cuff tear. 30 of the 123 glenoid failures were cage-glenoid dissociations. The multivariate analysis identified that aTSA patients with aseptic glenoid loosening were more likely to be younger (≤62 years) at the time of surgery, have small size glenoids and have a nonhybrid glenoids.

Glenoid Components: 

As the study above indicates, some glenoid implants use hybrid fixation - often with a metallic central post. 

Ten-Year Implant Survivorship and Performance of Anatomic Total Shoulder Arthroplasty Patients with the Zimmer Biomet Comprehensive® Shoulder System - a Short Stemmed Humeral Implant and Hybrid Glenoid concluded that patients having hybrid glenoid components had comparable long-term clinical results in comparison to the current longitudinal literature regarding survivorship of other implant systems. 

Some authors advocate metal-backed glenoid components; yet a number of studies, point to a higher revision rate for these implants. 

High revision rate of metal-backed glenoid component and impact on the overall revision rate of stemless total shoulder arthroplasty: a cohort study from the Danish Shoulder Arthroplasty Registry found that for the Eclipse stemless TSA system, the adjusted hazard ratio for revision of a metal-backed glenoid component was 8.75 in comparison to stemless Eclipse with an all-polyethylene glenoid component.

There is interest in the effect of the type of polyethylene used: cross linked, XLPE or non cross linked, non-XLPE. While many favor XLPE the article below emphasized the importance of controlling for other variables that can affect component longevity

Modelling XLPE vs non-XLPE glenoid revision rates for anatomic shoulder arthroplasty in osteoarthritis including differing polyethylene glenoid fixation designs. found that when restricted to procedures performed since 2017 there was no significant association between polyethylene type and revision rates after adjustment for patient age, sex, humeral head size, humeral fixation, stemmed or stemless and glenoid component type (metal backed, cemented polythylene, or all polyethylene with a modified central peg).

Keeled components are going out of favor, yet this 10 year followup of young patients is of interest. 

Anatomical Total Shoulder Arthroplasty with Keeled glenoids in Patients under 60 years at 10 years minimum: which risk factors of failure are still valid at long term follow-up? 87 shoulders in 82 patients 36 to 60 yo were included at a mean follow-up of 14 years. Revision-free survivorship was 81% at 10 years and 65% at 15 years. Among the 28 revised shoulders, 19 were for glenoid loosening. Heavy labor was a risk factor for glenoid component loosening. While Walch type did not influence revision rate, flat backed components and glenoids prepared with curettage (rather than reaming) were risk factors for glenoid. This reinforces the concept that glenoid component seating is an essential element for preventing loosening.

Some authors advocate for posteriorly augmented glenoid components in shoulders with posterior bone loss.

Total shoulder arthroplasty for glenohumeral arthritis associated with posterior glenoid bone loss: midterm results of an all-polyethylene, posteriorly augmented, stepped glenoid component. presents the use of a stepped glenoid component which requires the removal of some posterior glenoid bone as shown here.

Thirty-five shoulders with minimum 5-year follow-up underwent aTSA using a posteriorly augmented glenoid component for the treatment of glenohumeral osteoarthritis with posterior glenoid bone loss. Postoperative Grashey and axillary radiographs were reviewed to record the degree of radiolucency surrounding glenoid pegs on a scale of 0 (no radiolucency) to 5 (gross loosening), as described by Lazarus et al. The degree of central peg osseous integration was classified via x-ray on a scale of 1 to 3, as described by Wirth et al, with 3 representing complete integration and 1 indicating surrounding osteolysis. Survivorship free from revision was 92% at 8.8 years postoperatively.  Two patients experienced prosthetic instability requiring revision, leaving 33 shoulders with an average follow-up of 6.6 years. There was a progressive increase in Lazarus score and a decrease in Wirth score between 2- and 5-year follow-up. A significant correlation was identified between VAS pain scores and both Lazarus and Wirth scores, i.e. the severity of radiographic loosening correlated with subjective pain levels. The authors concluded that these outcomes were comparable ("noninferior") to those for patients undergoing TSA with a nonaugmented glenoid component for the treatment of posterior glenoid bone loss as reported in the literature.

Humeral Components:

What is the clinical importance of radiographic changes around the humeral component in anatomic shoulder arthroplasty?, investigated the frequency, patterns and clinical significance of radiographic findings around the humeral component of total shoulder arthroplasty (TSA n=91) and hemiarthroplasty (HA n=79) at minimum 4-year follow-up. The mean radiographic and clinical follow-up was 7.0 years. No patients were revised for loose humeral components during the study period. For both HA and TSA, the most common zones of cortical thinning or resorption involved the medial calcar, greater tuberosity and lateral humerus diaphysis. The mean metaphyseal filling ratio (MFR) was higher in patients with bone changes in ≥3 zones and resorption of the calcar. The frequency and degree of bone changes around the humeral component were higher in TSA patients with high-grade radiolucencies around the glenoid component. Patients with high-grade radiolucencies around the glenoid component had inferior SST scores in comparison to patients who did not have a high-grade radiolucencies around the glenoid component. This finding may represent the effects of other processes - such as osteolytic reaction to particulate debris - in addition to stress shielding.

There is increasing interest in stemless humeral components

Influence of humeral position of the Affinis short® stemless shoulder arthroplasty system on long-term survival and clinical outcome reviewed 80 patients treated with a stemless shoulder arthroplasty for OA of the shoulder at a mean follow-up of 92 months. Range of motion and outcome scores were improved. The center of rotation restoration was anatomical in 75 %  of all implants and in non-anatomical in 25 %. The humeral component position did not affect the functional outcome whereas the ten-year cumulative survival rate for the anatomic group was higher in comparison with the non-anatomical group (96.7 % vs. 75 %). 

Analysis of Factors Influencing Optimal humeral sided Reconstruction in Anatomic Total Shoulder Arthroplasty reviewed 298 patients who underwent anatomic total shoulder arthroplasty (aTSA) utilizing three stem types: 145 long stem,  102 short stem, and 51 stemless implants. The stemless implant was more replicable in recreating the anatomic shape with a mean COR shift of 3.0 mm and neck shaft angle of 137. Stemless arthroplasty was also quicker to master compared to standard or short stemmed implants but did have a greater initial operative time.

The Effect of Lateralization on Clinical Outcomes after Anatomic Total Shoulder Arthroplasty found that the shift in center of rotation from the  position determined by the "perfect circle" was the radiographic measure most closely associated with the ASES score, the WOOS score, and forward flexion. 

Stemmed VS stemless total shoulder arthroplasty: a systematic review was a review and metaanalysis of 14 articles (1496 patients). 792 had stemless humeral components and  704 had stemmed humeral implants. The Constant score,  elevation and abduction were similar in both groups, while external rotation was 4° higher in the stemless group. No differences were found in operating time and overall complications. However, deep infections were higher in the stemless group (2.2% vs. 0.8%) 

Preoperative Planning for the Humeral Component 

The Impact of Three-Dimensional Humeral Planning and Standard Transfer Instrumentation on Reconstruction of Native Humeral Anatomy for Anatomic Total Shoulder Arthroplasty To explore the utility of planning and transfer instrumentation in inserting a stemless component, three surgeons used 3D-printed humeri based on CTs of existing patients. Humeral neck cuts were performed on all specimens (phase 1) without any preoperative humeral planning; (phase 2) with 3D planning, and (phase 3) with a neck-shaft angle (NSA) guide and digital calipers used to measure humeral osteotomy thickness to aid in the desired humeral cut. For both 3D change in center of rotation (COR) and medial to lateral change in COR, use of preoperative planning alone and with standard transfer instrumentation resulted in a more anatomic restoration of ideal COR. The deviations from planned cut thickness decreased with each phase: phase 1: 2.6 ± 1.9 mm, phase 2: 2.0 ± 1.3 mm, phase 3: 1.4 ± 0.9 mm (P = .041 for phase 3 vs. phase 1). For neck shaft angle, in phase 1, 7 of 15 (47%) cases were in varus; in phase 2, 5 of 15 (33%) were in varus; and in phase 3, 1 of 15 (7%) cases was in varus.

Preoperative planning is always a good thing, however equivalent planning can be achieved quickly and more cheaply without 3D CT scans using a plain AP x-ray and PACS software

 

Biceps Tendon  

While some surgeons proclaim that they are "biceps killers", others retain the biceps because of its stabilizing function (unless it is frayed or unstable in its groove). The study Biceps Tenodesis in the Setting of Total Shoulder Arthroplasty: A Matched Cohort Analysis included 88 shoulders, half of which had and half of which did not have biceps temodesis. The authors found no significant differences between cohorts in postoperative forward elevation, external/internal rotation, VAS, ASES, or SST score.

Rotator Cuff

Preoperative Rotator Cuff Fatty Infiltration and Muscle Atrophy Do Not Negatively Influence Outcomes Following Anatomic Total Shoulder Arthroplasty sought to determine the effects of rotator cuff fatty infiltration (FI) and muscle atrophy (MA) on clinical outcomes following TSA. There were 163 shoulders from 154 patients with a mean age of 62.5 and a mean follow-up of 2.9 years that met inclusion criteria. Rotator cuff muscle area was not correlated with any preoperative or postoperative range of motion or patient reported outcome measures. No significant differences in preoperative ROM or PROMs were found between patients with minimal-to-mild and moderate-to-severe FI (P > .05).

Pain Management

Methylprednisolone taper is an effective addition to multimodal pain regimens after total shoulder arthroplasty: results of a randomized controlled trial: 2022 Neer Award winner Patients were randomly assigned to receive intraoperative dexamethasone only (control group n=32) or intraoperative dexamethasone followed by a 6-day oral methylprednisolone (Medrol) taper course (treatment group n=35). The treatment group demonstrated a reduction in mean VAS pain scores over the first 7 postoperative days (POD). Between POD 1 and POD 7, patients in the control group consumed an average of 17.6 oxycodone tablets while those in the treatment group consumed an average of 5.5 tablets. This equated to oral morphine equivalents of 132.1 and 41.1 for the control and treatment groups, respectively. There were fewer opioid-related side effects during the first postoperative week in the treatment group. The treatment group reported improved VAS pain scores at 2-week, 6-week, and 12-week postoperatively.  At follow-up there was 1 infection in the control group and 1 postoperative cubital tunnel syndrome in the treatment group. 

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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).

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