Do lateralization and distalization after reverse total shoulder have a clinically significant relationship with patient outcome?

There are a host of variables that may affect the clinical outcome of reverse total shoulder arthroplasty. A number of authors have attempted to relate distalization and lateralization to outcome scores. For example in Managing rotator cuff tear arthropathy: a role for cuff tear arthropathy hemiarthroplasty as well as reverse total shoulder arthroplasty, the authors found that the postoperative position of the center of rotation and greater tuberosity on anteroposterior radiographs did not correlate with the clinical outcomes for either procedure.

The authors of How To Choose The Best Lateralization And Distalization Of The Reverse Shoulder Arthroplasty To Optimize The Clinical Outcome In Cuff Tear Arthropathy investigated the effect on the 1 year ASES score of combinations of lateralization and distalization of 62 patients having reverse total shoulder arthroplasty performed for cuff tear arthropathy. They measured lateralization by the LSA as shown below





and distalization by the DSA as shown below.







They found the correlation between ASES score and LSA to be = -0.43 and the correlation between ASES score and DSA to be 0.39; both values lying in the "moderate" range.


The accepted value for minimal clinically important difference for the ASES score in total shoulder arthroplasty is 20.9


The DSA of patients with ASES scores > 76 was 48.55 while the DSA of patients with ASES scores < 76. was 37.82, a difference of 10.7.


The LSA of patients with ASES > 76 was 86.43 while the LSA of patients with ASES scores <76 was 100.09, a difference of 13.7.


Thus neither measurement exceeded the threshold for clinical significance.


The authors suggest that optimal LSA should be no more than 90.5° yet of the 24 patients with LSA > 90.5 degrees 75% had ASES scores >76. Furthermore, what should be the lower limit of the LSA?







The authors also suggest that the optimal DSA should be no less than 37.5°, yet of the 17 with DSA less than 37.5, 65% had ASES scores >76. Furthermore, what should be the upper limit of the DSA?




Comment: This is a well done study that effectively uses scatter plots to show all their data. This type of presentation lends itself to an understanding of the variability in the studied relationships.


As the authors point out in their discussion, prior authors have come to varying conclusion about the clinical (rather than statistical) significance of the relationships between distalization angles and lateralization angles.


It seems curious that distalization (a linear dimension) is being measured as an angle, rather than as a linear dimension (see yellow line) and






that laterialization (a linear dimension) is being measured as an angle, rather than as a linear dimension (see yellow line).




Both lateralization and distalization affect deltoid tension, moment arms, center of rotation, stretch on the brachial plexus, the stabilizing compressive force across the articulation, the function of the remaining cuff muscles, the ability to repair the subscapularis and more. We need to know what is the "sweet spot" when the effects of these two variables are considered together?

Finally, distalization and lateralization do not reflect other clinically important variables, such as glenoid tilt, baseplate seating, baseplate fixation, as well as baseplate-bone contact. To determine the relationship of ASES score to the geometry of the reverse total shoulder arthroplasty, a multivariable analysis would be required.

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
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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).

What type of rTSA should I use and how should I position it? Insights from 13 Recent Studies On Prosthesis and Position

Surgeons continue to debate the optimal approach to reverse total shoulder arthroplasty (rTSA) implant selection and position: Should we maximize lateralization? Is a stemless implant viable? How critical is glenosphere position, or humeral version?

Here's a review of 13 recent articles exploring component geometry, implant design, biomechanics, and clinical outcomes in rTSA. 

Readers will come to their own conclusions; mine are that it’s not the implant company that defines the outcome—rather it is the positioning of components to provide the best range of motion and optimal muscle tension. 

Remember this book?

My takeaways

Don't overlateralize the humerus much beyond its preoperative position (don't worry too much about version). Short humeral stems may be associated with component malalignment. Tight fitting short stems may be associated with stress shielding. The value of stemless rTSA has yet to be demonstrated.

Place the glenosphere low on the prepared glenoid (don't worry too much about version except avoid excess ante version) and tilt it inferiorly (correcting the reverse shoulder angle) to reduce the risk of greater tuberosity collision with the acromion. Increasing the size of and lateralizing the glenosphere may increase impingement-free motion, while smaller, lateralized glenospheres may optimize deltoid and rotator cuff muscle-tendon lengths. 

The lateralization shoulder angle (LSA) and distalization shoulder angle (DSA) may not correlate with clinical outcome.

Here are the articles. I have colored the number before the clinical studies in green and the number before ex vivo models in red.

(1) Eccentricity and greater size of the glenosphere increase impingement-free range of motion in glenoid lateralized reverse shoulder arthroplasty: A computational study Increasing the impingement-free range of motion (ROM) can optimize the patient’s functional outcome and reduce the rate of scapular notching. This study used a virtual model of reverse shoulder arthroplasty with glenoid lateralization (L-RSA) to compare (1) the impingement-free range of movement (ROM) between 155◦ Grammont-style inlay stem and 135◦ flushlay stems (i.e. the polyethylene cup located “flush” with the plane of the humeral bone cut and 135◦ neck shaft angle (NSA)); 2) the effect of glenosphere size and type (centered vs eccentric) on impingement-free range of movement (ROM) using a 135◦ NSA flushlay stem. They analyzed 200 CT-scans of patients undergoing shoulder replacement for cuff tear arthropathy, virtually implanting different humeral components using the same glenoid implant.

When comparing inlay and flushlay designs, flushlay showed greater impingement-free ROM in all movements except for abduction.They found that increasing the glenosphere size resulted in an increase in impingement-free ROM. Improved impingement-free ROM was found when using eccentric glenoid components





(2) The authors of Humeral Component Version Has No Effect on Outcomes Following Reverse Total Shoulder Arthroplasty conducted a double-blinded, randomized controlled trial to examine the relationship of humeral component version (neutral or 30° of retroversion) to humeral rotation and two-year patient outcomes in reverse total shoulder arthroplasty (rTSA).

The 2 groups did not differ significantly in terms of improvement at 2 years in active shoulder abduction, forward elevation, internal rotation measured as the highest spinal level reached, internal rotation with the arm abducted 90°, external rotation, or muscle strength. The 2 groups did not differ significantly in terms of improvement in postoperative ASES, PROMIS-10 physical, or VAS pain scores at the time of final follow-up. Similar rates of scapular notching were observed between the two groups (21% of the patients in neutral version group and 15 % of the patients in the 30° retroversion group).

(3) The authors of Greater distance from the glenosphere center to the acromion reduces risk of acromial impingement in semi-inlay reverse shoulder arthroplasty assessed the relationship of differences in the distance between the glenosphere center and the greater tuberosity (DGT) and the distance between the glenosphere center and the acromion (DA) to the closest distance between the greater tuberosity and the acromion during active abduction in shoulders with reverse total shoulder arthroplasty. They used models created from computed tomography of the shoulders and fluoroscopic images to examine 3D kinematics of the implants. DA and DGT were measured from 3D surface models.



There were 7 shoulders with DA ≥ DGT, and 4 shoulders with DA < DGT. Although DA was significantly greater in shoulders with DA ≥ DGT than in those with DA < DGT there was no significant difference in DGT between the two groups.

When DA < DGT, contact between acromion and the greater tuberosity is predicted to occur when the arm is abducted. However, in this series there were no significant differences in maximum abduction between the two groups.

(4) Shoulder Geometry After Reverse Total Shoulder Arthroplasty with a Medialized Glenoid and a Lateralized Humerus Predicts Subacromial Notching and Acromial or Scapular Spine Fractures found that implanting components such that DA is greater than DGT in rTSA is associated with a lower incidence of subacromial notching and acromion or scapular spine fractures.

In a prior post, we noted that DGT (yellow) and DA (green) could be determined on plain films (Grashey view), avoiding the need for and cost of postoperative CT scans.

(5) While a number of papers have studied the theoretical effects of humeral lateralization and distalization, the most important thing (MIT) is exploring the effects of humeral position on the patient's clinical outcome. The authors of Lateralization and Distalization Shoulder Angles May Not Predict Clinical Outcomes in Reverse Total Shoulder Arthroplasty: A Systematic Review and Meta-Analysis performed a literature review to assess the evidence supporting the prognostic value of the lateralization shoulder angle (LSA) and distalization shoulder angle (DSA) following reverse total shoulder arthroplasty (rTSA).






4 studies met inclusion criteria, representing a total of 974 shoulders with a minimum follow-up of 24 months with functional outcomes (American Shoulder and Elbow Surgeons score, Constant score) or range of motion (ROM) (active anterior elevation [AAE] and active external rotation).

The overall correlation coefficient for LSA and DSA with postoperative outcomes was only 0.023. Similarly, no significant correlations were found between LSA or DSA and AAE or active external rotation, with the random effects model showing an effect size of −0.097 for AAE and DSA and 0.056 for AAE and LSA.

A prior blog post provides further analysis of LSA and DSA, pointing out that it seems unusual to use angles in an attempt to reflect the linear dimensions of distalization and lateralization, especially when these linear dimensions can be measured directly and normalized to the known dimensions of the implant.




(6) The function of a rTSA depends in large part on getting the most out of the muscles remaining in the shoulder. Optimizing Muscle-Tendon Lengths in Reverse Total Shoulder Arthroplasty used a geometric model of the shoulder to systematically examine surgical placement and implant-design parameters to determine which RTSA configuration most closely reproduces native muscle-tendon lengths of the deltoid and rotator cuff.




The configuration that most closely restored anatomic muscle- tendon lengths in a small shoulder was a 30-mm glenosphere with a centered position, 5 mm of glenoid lateralization, 0 mm of humeral offset, and a 135° neck-shaft angle. For a medium shoulder, the corresponding parameters were 36 mm, centered, 5 mm, 0 mm, and 135°. For a large shoulder, the parameters were 30 mm, centered, 10 mm, 0 mm, and 135°. When only inferior glenoid component placement was considered, the configuration that most closely restored anatomic muscle-tendon lengths in a small shoulder was 36 mm, inferior, 5 mm, 0 mm, and 135°. For a medium shoulder, it was 30 mm, inferior, 10 mm, 0 mm, and 135°. For a large shoulder, it was 36 mm, inferior, 10 mm, 0 mm, and 135°.

A combination of a smaller, lateralized glenosphere, a humeral socket placed at the anatomic neck plane, and an anatomic 135° neck-shaft angle best restored native deltoid and rotator cuff muscle-tendon lengths in RTSA.


(7) Lack of internal rotation limits important functions after rTSA. Preoperative Planning and Inferior Glenosphere Overhang Increases the Odds of Achieving High Internal Rotation After Univers Reverse Total Shoulder Arthroplasty sought to compare patient characteristics, use of 3-dimensional computed tomography (3D CT)-based preoperative planning, and postoperative implant position between patients with high IR (T12 or better, n=98) or low IR (below the hip, n=50) two years after primary rTSA.

Decreased body mass index, high preoperative IR, and arthroplasty on the dominant arm correlated with an increased odds of high IR. Increased DSA and increased inferior glenoid overhang were associated with a greater chance of being in the high-IR group. However, the standard deviations were larger than the differences (effect sizes), indicating substantial overlap between the two groups:

High IR DSA 48.3±8.9 degrees, Inferior overhang 3.7±2.3 mm.

Low IR DSA 43.6±9.6 degrees, Inferior overhang 2.3±3.0 mm.





(8) While prosthetic design might correlate with outcomes of rTSA, ultimately the position of the component may be more important. Variability in Ultimate Humeral Height of an Inlay Humeral Stem Does Not Impact Outcomes Following Reverse Shoulder Arthroplasty. analyzed radiographic and clinical data from 194 reverse shoulder arthroplasties performed with a 135° humeral component. The distance from the anatomical neck of the humerus to the glenosphere was measured to categorize the implantation as inlay or onlay.


Postoperative humeral position was classified as a true inlay in 25.3% and some degree of onlay in 74.7%. At 2-year follow-up, most of the patient reported outcomes (ASES, Constant, SANE, VAS pain) were not significantly different for the two groups.

(9) The authors of Optimizing range of motion in reverse shoulder arthroplasty used planning software to model the rTSA glenosphere positioning to provide the best theoretical impingement-free ROM for a 3 mm symmetric 135° inclined polyethylene liner: 1) no correction of the RSA angle and no lateralization (C-L-); 2) correction of the RSA angle with medialization by inferior reaming (C+M+); 3) correction of the RSA angle without lateralization by superior compensation (C+L-); and 4) correction of the RSA angle and additional lateralization (C+L+).










The configuration with lateralization and correction of the RSA angle (C+L+) led to better ROM in flexion, extension, adduction, and external rotation. The configuration where correction of the inclination was done by medialization (C+M+) led to the worst ROM. They concluded that with a 135° inlay reversed humeral implant, correcting glenoid inclination (to a RSA angle of 0°) and lateralizing the glenoid component by using an angled bony or metallic augment of 8 to 10 mm provides optimal impingement-free ROM.


(10) Anatomic restoration of lateral humeral offset and humeral retroversion optimizes functional outcomes following reverse total shoulder arthroplasty point out that cadaveric and computer simulations suggest lateral humeral offset (LHO) and humeral retroversion (HR) are associated with strength and range of motion (ROM) after reverse total shoulder arthroplasty (rTSA), but in vivo data is lacking. This study aimed to evaluate the effects of implant parameters (i.e. LHO and HR) on strength and ROM in 30 rTSA patients at an average follow-up of 2.4 years. LHO was measured on two-dimensional axial CT images as the distance between the medial edge of the base of the coracoid process and the most lateral point of the humerus. Humeral retroversion was calculated using the humeral angle derived from subject-specific three-dimensional bone/implant models relative to the epicondylar axis

Higher post-op LHO values were predictive of greater postoperative strength across all movements. However, lateralization of the implant beyond pre-op values (i.e. post-op LHO > pre-op LHO) was associated with poorer strength performance across all ranges of motion and poorer IR ROM.

Patients with minimal deviations in HR (post-op HR within 10◦ of pre-op HR) and minimal deviations in LHO (post-op LHO ≤ pre-op LHO) displayed the greatest postoperative ER ROM.

The authors concluded that anatomic restoration of LHO combined with anatomic restoration of HR may be ideal for maximizing strength and ROM following rTSA.

Overlateralization beyond anatomic may have negative consequences.

(11) Baseplate version in reverse shoulder arthroplasty: does excessive retroversion or anteversion affect functional activities of daily living? While bone grafting and augmented components can help restore reverse shoulder arthroplasty (RSA) baseplate version close to neutral, the indication for version correction in RSA is unclear. The purpose of this study was to compare the clinical outcomes of RSA baseplates in high degrees of retroversion and anteversion to components in more neutral version.





Four groups were identified:
≥ 10 degrees (moderate to severe anteversion; n = 14), 

10 to -10 degrees (neutral; n = 69), 

-10 to -20 (moderate retroversion; n = 25), and 

≤ -20 degrees (severe retroversion; n = 7).

There were no differences in final Simple Shoulder Test (SST), final American Shoulder and Elbow Surgeons score (ASES) or change in SST from pre- to post-operative across the four version groups. There was no linear correlation between baseplate version and final SST. There were no statistically significant differences in difficulty performing tasks related to internal rotation, external rotation, and cross-body adduction among the four baseplate version groups; however, patients with moderate to severe anteversion had a greater frequency of difficulty putting on a coat (86%) compared to patients with neutral version (42%), moderate retroversion (45%) and severe retroversion (0%). There were no differences in rates of complications and revisions across the four groups.

This study did not find evidence that high values of baseplate retroversion or anteversion were associated with inferior patient reported outcomes or functional rotation after reverse total shoulder arthroplasty.


(12) Effects of Different Humeral Stem Length on Stem Alignment and Proximal Stress Shielding in Reverse Total Shoulder Arthroplasty This study aimed to investigate the effects of different humeral stem lengths on stem alignment and proximal stress shielding after rTSA in 320 patients who underwent primary rTSA with at least 2 years of follow-up. The participants were classified into 3 groups according to the humeral stem length of different prostheses types: group A (short stem, range: <80 mm, n = 88), group B (medium stem, range: 80-100 mm, n = 155), and group C (standard stem, range: ≥100 mm, n = 77). Filling ratios were assessed.




Humeral stem malalignment was significantly higher in group A (21.6%) than in groups B (11.6%) and C (9.1%).




However, stress shielding at the lateral metaphyses (36.4%) was more frequently observed in group C.


Longer stem, stem malalignment, and higher diaphyseal canal filling ratio were independent risk factors for stress shielding occurrence, with stem malalignment showing the highest odds ratio.

The authors concluded that although shorter stems could be beneficial for bone preservation, they could lead to stem malalignment, resulting in increased humeral stress shielding if the filling ratios were high.

(13) Stemless Reverse Total Shoulder Arthroplasty: A Systematic Review and Meta-analysis. Stemless humeral components in reverse total shoulder arthroplasty are only approved for clinical trials in the United States with an investigational device exception with limited data. A systematic review on stemless reverse total shoulder arthroplasty evaluated 10 studies that used either the Total Evolutive Shoulder System (TESS) or Verso implant. The mean follow-up period ranged from 6.4 to 101.6 months per study. There was an overall trend of improved clinical outcome scores, a 0.2% humeral component loosening rate, and an 11.2% complication rate.

Geometry is important

Black-necked Stilt

Malheur

May 2025

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).

Reverse total shoulder arthroplasty: do lateralization and distalization correlate with clinical outcome?

Surgeons want to know how the postoperative position of the humerus in relation to the scapula relates to the clinical outcome after reverse total shoulder arthroplasty (RSA).

The authors of The lateralization and distalization shoulder angles are important determinants of clinical outcomes in reverse shoulder arthroplasty studied these relationships in 46 patients having RSA for cuff tear arthropathy (CTA) using measurements of the lateralization shoulder angle (LSA) and the distalization shoulder angle (DSA) as shown below. Four different implant combinations were included.

Although they found positive correlations between the LSA and the ADLER score and the Constant score, they found no significant correlations between the LSA and ASES, SST, or SSV scores.

While they found negative correlations between the DSA and the ADLER score, they found no significant correlations between the DSA and the total Constant, ASES, SST, or SSV scores.

 

More recently the authors of Lateralization and distalization shoulder angles do not predict outcome in reverse shoulder arthroplasty for cuff tear arthropathy reviewed a larger series of 630 primary RSAs for patients with CTA. Five different implants were used.  The regression calculations for LSA or DSA did not reveal significant associations with any of the clinical outcomes.

In Influence of humeral lengthening on clinical outcomes in reverse shoulder arthroplasty no clear relationship between humeral lengthening and clinical outcomes was identified. 

In Negligible Correlation between Radiographic Measurements and Clinical Outcomes in Patients Following Primary Reverse Total Shoulder Arthroplasty the importance of radiographic measurements and their correlation with clinical and functional outcomes following rTSA was found to be limited. 

In Does glenohumeral offset affect clinical outcomes in a lateralized reverse total shoulder arthroplasty? the magnitude of lateralization did not significantly affect the clinical outcomes. 

In Medialized vs. lateralized humeral implant in reverse total shoulder arthroplasty: the comparison of outcomes in pseudoparalysis with massive rotator cuff tear  the postoperative active elevation range and functional outcomes were not affected by medialization or lateralization of the humeral implant. 

Finally, the authors of Managing rotator cuff tear arthropathy: A role for cuff tear arthropathy hemiarthroplasty as well as reverse total shoulder arthroplasty studied the postoperative relationships in 58 patients having RSA for CTA, including: 

(1) the superior/inferior position of the greater tuberosity in relation to the acromion tip

(2) the medial/lateral position of the greater tuberosity in relation to the acromion  tip

(3) the superior/inferior position of the center of rotation in relation to the bony glenoid center

(4) the medial/lateral position of the center of rotation in relation to the bony glenoid center

(5) the abduction moment 

(6) the distance from the center of rotation to the greater tuberosity

(7) the distance from the center of rotation to the acromion 

As in the prior reports, none of these parameters were significantly associated with clinical outcome.

Comment: Factors other than postoperative radiographic parameters are responsible for the amount of improvement in patient comfort and function following RSA.

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: 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).

Reverse total shoulder - do radiographic measurements relate to the patient outcome?

While reverse total shoulder can be a successful surgery for patients with pseudoparalysis, fracture and failed anatomic arthroplasty, the clinically ideal positioning and type of implant have yet to be determined. For example, while distalization of the glenosphere may lead to an increase in motion and lower risk for scapular notching, it comes with increased risk for neurological injury, acromial/scapular stress fractures and deltoid fatigue. Less distal positioning of the glenosphere may result in collision of the greater tuberosity against the acromion, with risk of loss of range of motion and acromial/spine fracture. 

In an attempt to correlate component type and position with the rate of complications and clinical outcomes, many radiographic measurements have been proposed. 

One example is "arm length" measurement - the distance between the transepicondylar line to the inferior aspect of the acromion. "Humeral lengthening" is the difference between this measurement before and after surgery.

Two other measurements are the lateralization shoulder angle (LSA below left) and the distalization shoulder angle (DSA below right)

It can be seen that these measurements do not directly reflect the position of the center of rotation nor the type or position of the humeral component. A recent article examined the clinical importance of these measurements.

Assessing the validity of the distalization and lateralization shoulder angles following reverse total shoulder arthroplasty

These authors explored the relationship between the distalization shoulder angle (DSA) and lateralization shoulder angle (LSA) and clinical outcome after reverse total shoulder arthroplasty performed in 238 patients by an individual surgeon. 

One group had a 155 degree medialized design  (Anatomical Shoulder Reverse System, Zimmer), 2.5 mm of lateral offset and a 36 mm glenosphere. 

Another group had a 135 degree laterally offset design (AltiVate system from DJO) All females with a lateralized implant had a 32 mm glenosphere with 6 mm of lateral COR offset, while all males had a 32 mm glenosphere with 10 mm of offset.

The reasons for choosing the different prostheses are not provided.

Lateralized prostheses were associated with higher LSAs (88 ± 7) vs. 82 ± 7 for medialized prostheses. While the difference was statistically significant, there was substantial overlap.

The distalization shoulder angle did not correlate with humeral lengthening.

Neither the DSA or the LSA were strongly correlated with 2-year postoperative American Shoulder and Elbow Surgeons score or shoulder range of motion.

Comment: This study did not include a multivariate analysis of the many demographic (e.g. age, sex, diagnosis) and surgical variables (e.g. implant type, size and position) that may influence outcome.  On univariate analysis the authors did not find evidence to support the view that measurements of LSA and DSA have a major influence on the function of a reverse total shoulder. 

Further study, probably using different measurements will be necessary to elucidate the reverse total shoulder geometries that are associated with the best function and the lowest risk of complications. 

Follow on twitter: https://twitter.com/shoulderarth

Follow on facebook: https://www.facebook.com/frederick.matsen

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

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

Here are some videos that are of shoulder interest

Shoulder arthritis - what you need to know (see this link)

Shoulder arthritis - x-ray appearance (see this link)

The smooth and move for irreparable cuff tears (see this link)

The total shoulder arthroplasty (see this link).

The ream and run technique is shown in this link.

The cuff tear arthropathy arthroplasty (see this link).

The reverse total shoulder arthroplasty (see this link).

Shoulder rehabilitation exercises (see this link).

This is a non-commercial site, the purpose of which is education, consistent with "Fair Use" as defined in Title 17 of the U.S. Code.          

Note that author has no financial relationships with any orthopaedic companies.

What is the optimal position of a reverse total shoulder?

The lateralization and distalization shoulder angles are important determinants of clinical outcomes in reverse shoulder arthroplasty. 

These authors sought to determine the effect of reverse total shoulder (RSA) lateralization and distalization on final functional outcomes.

They measured the “distalization shoulder angle” (DSA)

 and the  “lateralization shoulder angle” (LSA).

in 46 patients who underwent RSA. Functional outcome and radiographs were evaluated at a minimum of 2 years postoperatively.

LSA values between 75° and 95° were correlated with better active external rotation. Postoperative active anterior elevation, Constant, and Activities of Daily Living Requiring External Rotation scores had a positive correlation with the LSA.

DSA between 40° and 65° resulted in better active anterior elevation and abduction.

However there was a lot of scatter in the data

They looked at four groups of prosthetic techniques

With the exception of the low active external rotation in Group I, there were no discernible differences in outcome among the groups.

Comment: The position of the humerus relative to the scapula after reverse total shoulder arthroplasty is determined by the prosthesis selected and the position in which it is inserted. The classical Grammont approach emphasized medialization and distalization. As shown in the diagrams below by Steve Lippitt, medialization (middle figure below) can slacken the rotators resulting in the loss of active external rotation noted in this study.

More modern approaches emphasize a more anatomic reconstruction with less distalization and more lateralization as shown below.

While the two angles described in this study are of interest, we find it simpler to measure distalization directly as shown here

 and lateralization directly as shown here

Finally, since instability is one of the most common complications of reverse total shoulder arthroplasty,    it is important to prioritize the component geometry and the component position that optimizes the stability for each patient.

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

How you can support progress in shoulder surgery

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

Range of motion after reverse total shoulder - how important is it and what affects it? Lets look at 35 recent publications

Overview of the articles

Functional internal rotation after shoulder arthroplasty is important to the quality of the outcome realized by the patient.

Limitation of functional internal rotation is common after reverse total shoulder arthroplasty. This is especially the case for patients with cuff tear arthropathy, poor preoperative internal rotation, and high body mass index.

Functional internal rotation is better for patients having anatomic total shoulder arthroplasty in comparison to those having reverse total shoulder arthroplasty

Functional internal rotation after reverse total shoulder arthroplasty is optimized by

    Avoiding unwanted contact of the scapula with the humerus and humeral component

    Lateralizing the glenoid center of rotation

    Mildly inferiorly offsetting the glenosphere

    Avoiding a constrained liner

    Successfully repairing the subscapularis

    Anatomically restoring the lateral humeral offset and humeral retroversion

Functional internal rotation is not associated with 

    Lateralization or distalization shoulder angles

    Glenoid retroversion

Here are the articles  

Understanding loss of internal rotation after reverse shoulder arthroplasty: a narrative review of current literature Functional internal rotation after RSA is optimized by maximizing impingement-free arc of motion and subscapularis repair in patients with mobile scapulothoracic joints, adequate preoperative humerothoracic extension, and low body mass index.

Do internal rotation and global range of motion affect patient outcomes?

Internal rotation limitation is prevalent following modern reverse shoulder arthroplasty and negatively affects patients' subjective rating of the procedure 59% of patients having RSA reported subjective internal rotation (IR) limitations, and 41% had objective IR limitations. Comparison of preoperative and postoperative IR showed that 24% had worsened IR, whereas 33% improved. Limited IR was associated with lower patients' subjective rating of RSA and negatively affected PROMs. Regression analysis showed that limited IR was the only independent determining factor that was significantly associated with a lower subjective rating of RSA. "Despite advancements in RSA design, limited IR remains a prevalent issue, significantly affecting patients' satisfaction and clinical outcomes." 

Restoration of internal rotation after reverse shoulder arthroplasty may vary depending on etiology in patients younger than 60 ​years of age: a multicenter retrospective study  "The restoration of active internal rotation with the elbow at the side remains the main functional weak link of RSA" Patients with easy active internal rotation had better Constant scores, as well as improved motion in forward elevation.

Is There an Association Between Postoperative Internal Rotation and Patient-reported Outcomes After Total Shoulder Arthroplasty? An acceptable outcome (SANE score of > 75%) was associated with sufficient internal rotation reach to the midback or higher.

Thresholds for diminishing returns in postoperative range of motion after total shoulder arthroplasty Postoperative range of motion (ROM) of more than 113 degrees of abduction, 162 degrees of FE, 52 degrees of ER, and IR to L1 added only minimal \ improvement in the Simple Shoulder Test, American Shoulder and Elbow Surgeons score, and the Shoulder Pain and Disability Index. 

How do reverse and anatomic total shoulders compare with respect to range of motion?

Evaluation of New Normal After Shoulder Arthroplasty: Comparison of Anatomic versus Reverse Total Shoulder Arthroplasty In comparison to 40% of patients having anatomic total shoulder arthroplasty (aTSA) only 26% of reverse total shoulder arthroplasty  (rTSA) patients (rTSA) reached a SANE score > 95 (100 = "normal" function). aTSA significantly outperformed rTSA in American Shoulder and Elbow Surgeons (ASES) score, ability to reach a high shelf, lift 10 pounds, perform usual work and perform usual sport, Simple Shoulder Test (SST) score, ability to lift 8 pounds and carry 20 pounds, range of motion including clinician measured elevation, abduction, external rotation, and internal rotation.  

Comparison between Anatomic Total Shoulder Arthroplasty and Reverse Shoulder Arthroplasty for Older Adults with Osteoarthritis without Rotator Cuff Tears The aTSA group demonstrated significantly better postoperative ASES and Constant-Murley scores than the RSA group. The TSA group showed a significantly better postoperative active ROM than the RSA group regarding forward flexion as well as external and internal rotations. "Clinical results and ROM were better with TSA than with RSA during the short- and mid-term follow-up periods."

Comparison of Anterior Shoulder Pain and Internal Rotation Dysfunction after Anatomic and Reverse Shoulder Arthroplasty for Osteoarthritis used an anterior shoulder pain and dysfunction survey (ASPDS) to classify anterior shoulder dysfunction and used the functional internal rotation (FIR) score, to quantify internal rotation (IR) deficiency following RSA compared to aTSA when performed for osteoarthritis. ASPDS scores were lower in the RSA group  compared to the aTSA group. Mean FIR scores was also worse in the RSA group compared to the aTSA group. "Findings suggest that anterior shoulder pain and dysfunction and decreased internal rotation are more common in RSA compared to aTSA when performed for osteoarthritis, with differences observed at two years postoperatively. These differences in outcomes were not captured by traditional shoulder outcomes questionnaires.

Exactech Equinoxe Anatomic Versus Reverse Total Shoulder Arthroplasty For Primary Osteoarthritis with an Intact Rotator Cuff in Patients with No Glenoid Deformity aTSAs had more favorable abduction, internal rotation, external rotation, Constant score, and SAS score.

What are the factors that affect internal rotation after a reverse total shoulder?

Preoperative diagnosis and rotator cuff status impact functional internal rotation following reverse shoulder arthroplasty Patients who undergo RSA for primary osteoarthritis have a better chance of postoperative improvement in functional internal rotation (fIR). A decrease in fIR is common after RSA for massive irreparable cuff tears.

Predictive factors influencing internal rotation following reverse total shoulder arthroplasty. Poor preoperative functional IR was risk factor for poor postoperative IR.  BMI was inversely correlated with degree of IR after RTSA. Preoperative opioid use was found to negatively affect IR. Glenoid retroversion, glenoid lateralization, and individualized component positioning affected postoperative IR. 

Influence of preoperative rotational shoulder stiffness on rate of motion restoration after anatomic and reverse total shoulder arthroplasty for glenohumeral osteoarthritis with an intact rotator cuff Preoperative stiffness is associated with slower recovery of active ROM over a longer duration in patients undergoing shoulder arthroplasty for RCI-GHOA.

Varus-valgus alignment of humeral short stem in reverse total shoulder arthroplasty: does it really matter? The varus position enhances rotational range of motion (ROM) but increases instability, while the valgus position does not significantly impact ROM or instability compared to the neutral position.

Humeral Component Version Has No Effect on Outcomes Following Reverse Total Shoulder Arthroplasty: A Prospective, Double-Blinded, Randomized Controlled Trial Securing the humeral component at neutral version or 30 degrees of retroversion in rTSA resulted in similar active shoulder external rotation, internal rotation, forward elevation, abduction, and strength measurements, complication rates, and VAS pain, PROMIS-10 physical, and ASES scores at 2 years postoperatively

Analysis of three different reverse shoulder arthroplasty designs for cuff tear arthropathy - the combination of lateralization and distalization provides best mobility  CTA patients with a lateralized and distalized RSA configuration were associated with achieving better flexion and abduction with less scapular notching. A better rotation was associated with either of the lateralized RSA designs in comparison with the classic Grammont prosthesis.

Glenoid lateralization and subscapularis repair are independent predictive factors of improved internal rotation after reverse shoulder arthroplasty After Grammont-style RSA two surgical factors were associated with better AIR after RSA: glenoid lateralization (with BIO-RSA technique) and subscapularis repair. Internal rotation was functional (>/= L3 level) in 67% of operated shoulders.

Lateralization and distalization shoulder angles do not predict outcomes in reverse shoulder arthroplasty for cuff tear arthropathy  There was no association between lateral shoulder angle (LSA) or distal shoulder angle (DSA) measurements and 2-year functional outcomes after RSA.

Modified distalization shoulder angle and lateralization shoulder angle show weakly correlation with clinical outcomes following reverse shoulder arthroplasty DSA and LSA show minimal correlation with postoperative outcomes and have limited predictive value.

Lateralization and Distalization Shoulder Angles in Reverse Shoulder Arthroplasty: Are They Still Reliable and Accurate in All Patients and for All Prosthetic Designs? While prosthetic design and preoperative shoulder anatomy have a significant influence on LSA and DSA measurements in RSA, optimal LSA and DSA values may lack validity and reliability.

Increased glenoid baseplate retroversion improves internal rotation following reverse shoulder arthroplasty With a 135 degree and lateralized glenoid, postoperative baseplate retroversion of >10 degrees was associated with significantly improved internal and external rotation at 90 degrees, Constant-Murley, and Single Assessment Numeric Evaluation scores at 2-year follow-up compared to <10 degrees retroversion. Additionally an increased change in version from preoperative to postoperative appears to improve internal rotation with the arm at 90 degrees without limiting external rotation in adduction or forward flexion. While baseplate retroversion does not improve internal rotation, overall function appears to be improved and therefore consideration may be given to accepting retroversion or intentionally retroverting the baseplate if fixation allows.

Baseplate inferior offset affects shoulder range of motion in reverse shoulder arthroplasty in Asian population The range of motion in abduction, flexion, and internal and external rotations significantly improved with increased inferior baseplate offset.

Baseplate version in reverse shoulder arthroplasty: does excessive retroversion or anteversion affect functional activities of daily living? High values of baseplate retroversion or anteversion were not associated with inferior patient reported outcomes or functional rotation after reverse total shoulder arthroplasty

Virtual assessment of internal rotation in reverse shoulder arthroplasty based on statistical shape models of scapular size. Glenosphere position required to maximize IR varied by scapula size. For smaller scapulae, maximum IR at 0 degrees (IR0) was reached with a combination of 2.5-mm inferior offset and 0-4 mm of lateralization. For larger scapulae, maximum IR0 was reached with a combination of 2.5 mm of inferior offset and 4 mm of lateralization.  Maximum IR in 60 degrees of abduction was reached in smaller scapula with 4-6 mm of lateralization and at least 12 mm of lateralization in larger scapula. 

Functional internal rotation is associated with subscapularis tendon healing and increased scapular tilt after Grammont style bony increased offset reverse shoulder arthroplasty with 155 degrees humeral implant This study revealed that in a Grammont-type RSA, postoperative internal rotation behind the back recovery is first associated with subscapularis tendon healing, followed by passive internal rotation at 90 degrees of abduction and finally the ability to tilt the scapula anteriorly. 

Healed subscapularis and its clinical implications for internal rotation in humeral lateralized reverse shoulder arthroplasty Healed subscapularis (SSC) groups had significantly better IR aROM, and IR strength than both nonhealed and nonrepaired SSC groups.

Comparative Efficacy of Latissimus Dorsi and Teres Major Versus Pectoralis Major Tendon Transfers Combined with Exactech Equinoxe Reverse Total Shoulder Arthroplasty in Improving Internal Rotation: A Preliminary Result Both latissimus dorsi and teres major (LDTM) and pectoralis major (PM)  transfers combined with RTSA significantly improve clinical outcomes in patients with massive cuff tears and cuff tear arthropathy who had a loss of active IR. The LDTM transfer is superior for IR aROM with the arm behind the back, while the PM transfer more effectively improves IR strength in front of body. 

Avoiding unwanted contact.

Optimizing range of motion in reverse shoulder arthroplasty Lateralizing the glenoid component by using an angled bony or metallic augment of 8 to 10 mm provides optimal impingement-free ROM.

Impact of constrained humeral liner on impingement-free range of motion and impingement type in reverse shoulder arthroplasty using a computer simulation This RSA computer simulation model demonstrated that constrained humeral liners led to less impingement-free ROM. A lateralized glenosphere improved abduction ROM.

Reverse shoulder arthroplasty implant design and configuration has a significant effect on conjoint tendon impingement  Conjoint tendon impingement can be associated with larger glenospheres, anterosuperior baseplate and glenosphere positioning, humeral implants or trays positioned medial and posterior, and increased humeral component retroversion. 

Eccentricity and greater size of the glenosphere increase impingement-free range of motion in glenoid lateralized reverse shoulder arthroplasty: A computational study A greater glenoid size and eccentric glenoid type allowed for more mobility. A 135 degrees stem allowed greater mobility in all movements except for abduction than a 155 degree inlay stem.

Preoperative Planning and Inferior Glenosphere Overhang Increases the Odds of Achieving High Internal Rotation After Univers Reverse Total Shoulder Arthroplasty Specific baseline patient characteristics influence the ability to obtain high IR after rTSA including increased preoperative IR, BMI, and surgery on the dominant arm. There are several factors within the surgeon's control: inferior glenosphere overhang and slight distalization increased postoperative IR. 

Preoperative Planning Software Does Not Accurately Predict Range of Motion in Reverse Total Shoulder Arthroplasty The passive glenohumeral impingement-free ROM generated from preoperative planning incompletely predicts clinically measured active humerothoracic ROM, possibly because of the unmeasured factors of soft-tissue tension, muscular strength, humeral torsion, resting scapular posture, and, most importantly, scapulothoracic motion.

Posteroinferior glenosphere positioning is associated with improved range of motion following reverse shoulder arthroplasty with a 135 degrees inlay humeral component and lateralized glenoid posteroinferior glenosphere position may improve ROM when using a 135 degrees inlay humeral component and a lateralized glenoid.

The case for an anatomic reconstruction

Development, Evolution, and Outcomes of More Anatomical Reverse Shoulder Arthroplasty The original Grammont-style RSA revolutionized shoulder arthroplasty but had several limitations, including scapular notching and reduced rotational motion. The development of a lateralized center of rotation construct aimed at addressing the limitations associated with the Grammont-style design and to more closely reproduce the native anatomy in order to improve patient outcomes.

Anatomic restoration of lateral humeral offset and humeral retroversion optimizes functional outcomes following reverse total shoulder arthroplasty. Greater deviations from pre-op lateral humeral offset was predictive of poorer IR ROM. Patients with minimal deviations in humeral retroversion (post-op humeral retroversion (HR) within 10 degrees of pre-op HR) and minimal deviations in lateral humeral offset (LHO) (post-op LHO </= pre-op LHO) displayed the greatest postoperative ER ROM.  

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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).