Periprosthetic infection: what does my patient care about?

As surgeons we tend to prioritize "eradication" of bacteria as the top priority in the management of our patient with an infected joint replacement. 

Because the functional outcomes of revision arthroplasty are rarely perfect, it's tough knowing if the bugs are gone unless we do yet another operation and find that multiple tissue cultures are negative.  

The patient, however may have a different priority: preserving function of their joint. 

I learned this lesson the hard way 25 years ago. One of my patients with rheumatoid arthritis of the elbow had a good functional result from a cemented total elbow arthroplasty. Unfortunately, she sustained a cat scratch on the ipsilateral forearm. This led to a sinus draining from her elbow that did not resolve with a washout and antibiotics. I convinced her that the best treatment of her infection would be complete component and cement removal. Her soft bone made this procedure difficult and resulted in fragmentation of her remaining bone. 

While this procedure resolved her drainage, she had a virtually complete loss of function of her arm. She declined further surgery. She said she would have rather lived with the drainage than living with a flail elbow.

The authors of Successful Management of Periprosthetic Joint Infection Following Total Joint Arthroplasty, as Defined by the Patient have noted that the literature on the subjective experience of patients undergoing treatment for periprosthetic joint infection (PJI) following total joint arthroplasty (TJA) is scarce, and treatment success is defined without consideration of patient values.

They undertook a study to characterize the experience of 27 patients undergoing PJI management, to identify factors that patients associate with successful treatment and to assess alignment with a 2019 outcome-reporting tool (ORT) by the Musculoskeletal Infection Society (MSIS). Included patients had 1 to 5 year followup after their most recent revision surgery.

Patients participated in interviews that documented their experiences with primary TJA, PJI diagnosis and management, and patient perceptions of the success of their PJI management.

21 (78%) reported considerable mental health impacts during the period from PJI onset to treatment conclusion. In defining successful PJI management, patients consistently emphasized the importance of function, pain relief, mobility, and independence. Nine (33%) of the patients did not agree with their MSIS ORT classification of success versus failure.

Patients endorsed feelings of invalidation and a delay to diagnosis during PJI onset. They described a lack of understanding and preparedness for PJI, which contributed to negative emotions such as sadness, anger, and surprise at the time of PJI diagnosis. During the operative course and rehabilitation, patients struggled with physical limitations; this was especially noted among patients who underwent 2-stage revision. A common theme was the negative impact on patient mental health. 

The authors concluded that success in treating PJI as defined by patients does not align with success as defined by clinicians. They advocate providing comprehensive support to patients throughout the PJI management process. They also encouraged improved patient education at the time of initial consent for arthroplasty surgery regarding the risk and clinical manifestations of PJI, allowing for earlier detection of symptoms and setting realistic expectations about the possible outcomes and the potential need for additional surgeries.

Finally, consideration of the patient's functional outcome from treatment for PJI plays into the surgeon's decision regarding how much bone integrity to risk in attempting to remove implants and cement at the time of revision of an infected arthroplasty.

And the decision to use a single or two stage revision, recognizing the potential downsides of a spacer.

All of this is to support reasonable efforts to minimize the risk of PJI including optimization of health and nutrition, smoking cessation, and avoiding recent cortisone injections as stressed in this post and to consider the information in the slide below from a recent presentation on the topic.

Infection is a risk with all surgeries, particularly ones in which implants are inserted - it merits our best efforts in prevention and thoughtful treatment.

Clear and Present Danger

Cooper's hawk waiting for prey in our backyard 

June 2021

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 outcomes - how are they measured and with what are they associated?

In followup to the previous post, What type of rTSA should I use and how should I position it? Insights from 13 Recent Studies On Prosthesis and Position, we now take a look at some recent publications regarding rTSA outcomes and the factors that may be associated with them. My summary is (1) that it is important to define the outcome measure of interest clearly and in quantitative terms, (2) some of the proposed predictors of of outcome show statistical significance, but not clinically important significance, and (3) the geometries of the rTSA have important effects on both its stability and range of motion and vary widely among different implants.

How are we measuring outcomes?

There are many methods for documenting the results of rTSA, including pain relief, function, patient reported scores, quality of life, satisfaction, range of motion, strength, return to sport, return to work, complication rate, revision rate, and radiographic measurements. Notably there is surprisingly little correlation among these different measures. In evaluating the outcomes of different approaches to rTSA, surgeon scientists choose a primary outcome variable and seek clinically significant (rather than only statistically significant) results.

Creatively, the authors of Evaluation of New Normal After Shoulder Arthroplasty: Comparison of Anatomic versus Reverse Total Shoulder Arthroplasty introduced the concept of "new normal" after shoulder arthroplasty which they defined as a Single Assessment Numeric Evaluation (SANE) score ≥95 at a minimum 2-year follow-up for  849 aTSA and 745 rTSA patients. The SANE asks patients to rate their shoulder on a scale of 0 to 100, with 100 representing their normal shoulder function

40% of aTSA and 26% of rTSA patients attained this "new normal".

 aTSA significantly outperformed rTSA in total Simple Shoulder Test score (as well as the ability perform individual functions of the SST (reach a high shelf, lift 10 pounds, perform usual work and usual sport), lift 8 pounds, and carry 20 pounds) as well as the American Shoulder and Elbow Surgeons score; and range of motion. A subanalysis among patients treated for osteoarthritis with an intact rotator cuff produced similar results, with aTSA patients outperforming rTSA patients in many higher demand functions.

Defining the Minimal Clinically Important Difference and Patient Acceptable Symptom State Following Reverse Shoulder Arthroplasty for Glenohumeral Arthritis or Cuff Tear Arthropathy at Minimum 5-Year Follow-Up sought to determine the minimal clinically important difference (MCID) and patient acceptable symptomatic state (PASS) at mid-term followup for 80 patients having rTSA

The thresholds for MCID achievement and percentages that reached achievement were as follows: ASES, 11.4 (88.8%); SANE, 14.8 (85.0%); VR 12 Physical, 4.9 (66.3%). 

The thresholds for PASS achievement and percentages that reached achievement were as follows: ASES, 80.8 (65.0%); SANE, 75.9 (66.3%); VR 12 Physical, 44.4 (57.5%). 

Factors associated with failure to achieve these thresholds included worker's compensation coverage, prior ipsilateral shoulder procedure, and tobacco use. Higher preoperative scores were (expectedly) associated with failure to reach MCID levels of improvement.

Radiological Outcome in Reverse Shoulder Arthroplasty does not correlate with patient satisfaction or quality of life correlated radiological findings with clinical outcomes, patient satisfaction, and health-related quality of life (HRQoL) at a minimum of 2 years postoperatively for 49 patients.

Postoperative health-related quality of life (HRQoL) showed strong positive correlations with all clinical scores.

Distalization had a negative impact on external rotation and strength capacity while medialization of the COR showed a contrary relationship to external rotation and strength.

Radiological measurements predicted postoperative ROM and scapular notching yet failed to accurately predict HRQoL or clinical outcome. 

What are some of the patient factors that affect outcome?

Patient Characteristics

Patients and surgeons usually think about shoulder function in terms of the arm position in relation to the body. Yet most of shoulder surgery focuses on the glenohumeral joint. The position of the scapula and the thoracic posture may affect the motion and function of the upper extremity.  Patients posture affects clinical outcomes and range of motion after reverse total shoulder arthroplasty: A clinical study aimed to correlate preoperatively photo-documented posture to scapula orientation using CT and analyze their relation to the functional outcome following rTSA implantation in 360 patients with a minimum follow-up of 2 years. 

Each patient’s posture was analyzed using standardized pre- operative photo and video documentation. The posture was defined following the classification system of Moroder et al as type A (upright posture, retracted scapulae), type B (intermediate), and type C (kyphotic posture with protracted scapulae).

According to the photo-documented posture types, the patients were divided into posture types A (N 59), B (N 253) and C (N 48). The posture types were not strongly associated with the CT measurements of scapular position.

Average absolute Constant-Murley Score differed slightly among the groups (A 69, B 69 and C 64).

In terms of ROM, types A and B exhibited somewhat better flexion and abduction (flexion 124 and 123 vs113; abduction 140 and 137 vs.128). Patients with posture type A demonstrated better internal and external rotation.

The authors concluded that patients with clinical posture types A and B exhibited improved ROM values and clinical outcomes compared to type C postures and that the patient’s posture should be considered in rTSA planning.

However, as can be seen from the charts below, the differences are small and there were quite a few outliers.

So once again we're faced with statistically significant differences that are not clinically significant.

It is unclear how the patients posture should influence the type and position of arthroplasty components used.

Increasing Use of Reverse Total Shoulder Arthroplasty in Younger Adults Despite Higher Complication Rates sought to evaluate the trends of rTSA use in the United States and to evaluate medical and surgical complications in patients under 60 years of age undergoing rTSA using the Premier Healthcare Database. 

The diagnoses treated were similar for the two groups: osteoarthritis ~75% and rotator cuff tear ~25%

From 2016 to 2020, there was a substantial increase in the proportion of reverse TSAs used, with rTSA comprising 49% of all TSA in patients <60 years old in 2016 and rising to 59% by 2020. After propensity score matching, 3,087 patients <60 years old and 9,261 patients ≥60 years old remained.  The authors observed 1.53  times greater odds of 90-day surgical complications in patients <60 years old, without a difference in odds of medical complications.

Of note, the differences between these arbitrarily delineated age groups are not large, suggesting that factors other than age may be driving the rate of complications in these patients having rTSA. Age "cutoffs" may not be clinically useful.

The influence of sex: A Deep Dive into Reverse Total Shoulder Arthroplasty Outcomes found that out of 2,747 RTSA cases, 1,804 (65%) were performed on female patients. The preoperative diagnoses were similar

While some statistically signficant differences were noted between males and females, none of the 24 month follow-up values were clinically significant (i.e. they did not differ by an amount exceeding the minimal clinically important difference) The MCID for the SPADI is 8-13, for the QuickDASH is 12, and for the Constant score is 10 points. 

No differences were noted in any of the radiological outcomes over time. 

Implant Characteristics

Concavity compression is the mechanism by which the rTSA is stabilized as explained in detail here: Understanding the dislocating reverse total shoulder: concavity compression. The concavity is characterized by its diameter of curvature (DOC) and the ratio of its depth to the radius of curvature (D/r or "percent capture" (D/r X 100%). As explained by the authors of Reverse total shoulder arthroplasty polyethylene percentage capture: a descriptive analysis of commercially available reverse shoulder arthroplasty systems the geometry of the humeral liner is best described by these numbers rather than by names such as "retentive" or "constrained". Surgeons should understand the geometry of the systems they are considering for the patient at hand.

These authors collected implant design data from the most commonly used rTSA systems. They found that the mean percentage capture of standard polyethene inserts was 48% (range, 35%-63%), which was significantly less than the retentive insert group with a mean percentage capture of 61% (range, 45%-81%).

Large variability in degree of constraint of reverse total shoulder arthroplasty liners between different implant systems confirmed the large variations in the degree of constraint of rTSA liners between different implant systems, and in many cases even within the same implant systems. While greater D/r ratios (percentage capture) is expected to confer greater stability to the rTSA, it also increases the risk of limitation of range of motion from unwanted contact between the liner and the scapula.

D/r ratio is but one of elements determining rTSA stability from concavity compression. Others include the size  of the glenosphere, and factors that affect the magnitude and direction of the compressive force, such as strength of the deltoid and remaining cuff muscles, baseplate position and inclination, humeral neck-shaft angle, and impingement as well as humeral and glenoid lateralization .

The influence of glenosphere size and glenoid-sided offset on shoulder stability following reverse total shoulder arthroplasty using the Zimmer Trabecular Metal Reverse Plus Shoulder System found that in a position of combined abduction and internal rotation (45° of scapular plane abduction with (1) neutral rotation and (2) 90° internal rotation), use of a larger glenosphere results in greater joint stability than that of a smaller glenosphere. Lateralization of a smaller glenosphere increases joint stability to equivalent levels of that associated with the neutral-offset larger glenosphere. 

My observation is that the positions tested in this study do not represent the common position of rTSA instability, which is combined shoulder adduction, internal rotation, and extension (as in pushing up from a toilet, chair or bed or tucking in a shirt)

From Grammont to a New 135° Short-Stem Design: Two-Hand Lever Test and Early Superior-Lateral Dislocations Reveal Critical Role of Liner Stability Ratio and Stem Alignment pointed out that in rTSA the neck-shaft angle (NSA) has trended downward from 155° to 135° to reduce scapular notching, but concerns about instability persist. 

 The authors also pointed to the importance of the liner stability ratio. The liner stability ratio is the force needed to dislocate the shoulder divided by the compressive load across the joint.

They calculated the liner stability ratios of common implants from the formula LSR = (square root (1 − (r − d/r)2)) / (r − d/r)

To assess superior-lateral stability, the authors developed the intraoperative two-hand lever test (2HLT)

In 63% (31/49) of their cases, the 2HLT detected superior-lateral instability with standard liners, leading to the use of a retentive 135° liner.

Lots of things we need to think about.

Yellow headed blackbird considering which fly to go after

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).

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).