Baseplate version in reverse total shoulder arthroplasty - does it matter?

Surgeons often strive to correct glenoid retroversion in performing reverse total shoulder arthroplasty. Some have suggested that glenoid version should be corrected so that glenoid component is within 10 degrees of neutral glenoid version as measured on axillary lateral radiographs relative to the plane of the scapula. A computer model suggested that an optimal range of motion would be achieved with neutral to 5° of retroversion.

Version correction techniques may be associated with increased complication rates. In one series, bone grafting had an increased risk of baseplate loosening.

In another series, the use of augmented base plates had an increased risk of acromial stress fractures.

Other surgeons have accepted deviations from "normal" glenoid version to optimize baseplate fixation, using, for example, the alternative center line. 

The authors of Baseplate version in reverse shoulder arthroplasty: does excessive retroversion or anteversion affect functional activities of daily living? sought to determine whether patients with reverse total shoulders inserted with high degrees of baseplate anteversion or retroversion demonstrated poorer clinical outcomes than those inserted in more neutral glenoid version.

All patients underwent RSA with a monoblock baseplate with a 6.5 mm central screw and four peripheral locking screws. 

The goal of glenoid reaming was to achieve at least 80% backside contact of the baseplate with glenoid bone while minimizing bone removal. There was no specific attempt to change glenoid version to neutral. The humeral implant was an “inlay” design with a 135 degree neck shaft angle.

Because CT scans are impractical for assessing postoperative version in patients having RSA, version was assessed using standardized axillary "truth" views

Patients were grouped into four categories: those with baseplates in ≥ 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).

They found 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.

There were no differences in rates of complications and revisions across the four groups.

These results are consistent with other studies, such as 

Mid-term outcomes of reverse shoulder arthroplasty using the alternative center line for glenoid baseplate fixation: a case-controlled study,       

Baseplate retroversion does not affect postoperative outcomes after reverse shoulder arthroplasty.  and 

Do preoperative and postoperative glenoid retroversion influence outcomes after reverse total shoulder arthroplasty? 

Comment: This study suggests that baseplate version is not a major derminant of patient outcome for RSA component designs similar to those used in this study.

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 important in anatomic total shoulder arthroplasty?

Anatomic total shoulder arthroplasty reliably provides long term comfort and function for patients with osteoarthritis and an intact rotator cuff, even in patients with deficiencies in glenoid bone (see Anatomic Total Shoulder Arthroplasty with All-Polyethylene Glenoid Component for Primary Osteoarthritis with Glenoid Deficiencies). While some surgeons attempt to "correct" the patient's glenoid version, others "accept" it (see Glenoid Version, Acceptors and Correctors). It either case, one of the most important technical goals of anatomic total shoulder arthroplasty is excellent seating of the glenoid component (see Edge displacement and deformation of glenoid components in response to eccentric loading. The effect of preparation of the glenoid bone).

Good seating is achieved by reaming the glenoid bone to a single concavity

that matches the backside of the glenoid component

so that no cement is placed between the bone and the backside of the prosthesis to fill in the gaps,

backside cement indicates poor seating and risks cement failure

below is an example of a well-seated glenoid component. The only cement visible is in the peg holes.

To further investigate the technical factors associated with anatomic total shoulder (aTSA) outcomes, the authors of Anatomic total shoulder arthroplasty for posteriorly eccentric and concentric osteoarthritis: a comparison at a minimum 5-year follow-up evaluated 210 patients at a minimum of five years after aTSAs performed with conservative glenoid reaming with no attempt at version correction. 

Preoperatively, 98 (47%) had posteriorly decentered humeral heads and 108 (51%) had centered humeral heads. There were 77 shoulders with Walch type A glenoids and 122 with Walch type B glenoids. 

At a mean 8-year follow-up, the final SST score, change in SST score, and percentage of maximal improvement were not correlated with preoperative or postoperative humeral head centering, Walch classification, or glenoid version. 

Two patients (1%) underwent open reoperations during the study period. 

In patients with Walch B1 and B2 glenoids (n = 110), there were no differences in outcome measures between patients that had postoperative retroversion of more or less than 15°. 

Although 15 of 51 patients (29%) with minimum 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.

Careful preparation of the glenoid bone. 

From the authors of Edge displacement and deformation of glenoid components in response to eccentric loading. The effect of preparation of the glenoid bone we learn that the wobble and warp of the polyethylene component is minimized by spherically reaming the bone to precisely match the back of the component.

Glenoid bone stock is preserved by reaming only enough to create a single concavity, rather than trying to "correct" glenoid version.

The adequacy of glenoid reaming can be evaluated by using a pegless trial with the same backside curvature as the actual component and assuring that there is no rocking with eccentric loading. The goal is complete congruency.

Assuring optimal seating and cementing of the component. 

From the authors of The radiographic evaluation of keeled and pegged glenoid component insertion we learn that poor seating and poor cement technique contribute to poor fixation as evidenced by radiolucent lines on the immediate postoperative x-rays. 

Poor seating is evidenced by the presence of cement between the glenoid bone and the backside of the component. 

Good seating is indicated by the absence of cement between the component and bone (below top), rather than using cement as putty in an attempt to compensate for inadequate reaming.

A thin layer of cement between the bone and component is brittle and subject to cracking, displacement and loss of support for the glenoid implant.

Optimal cementing is reflected by the absence of radiolucent lines on postoperative radiographs.

We have learned that this can be achieved by drying each fixation hole with a CO2 spray

Immediately before pressurizing the cement into the hole

Comment: The survivorship of cemented, pegged, all-polyethylene glenoid components has yet to be surpassed by other types of glenoid implants (see Total shoulder replacement stems in osteoarthritis-short, long, or reverse? An analysis of the impact of crosslinked polyethylene). Attention to the details of bone-preserving bone preparation, complete seating of the component and modern cement technique may further improve the clinical outcomes of anatomic total shoulder arthroplasty. Our technique for this procedure is shown in this link.

B3 glenoid in a 73 year old woman, 12 year followup

A 73 year old woman presented with pain and stiffness of the left shoulder. Her radiographs showed glenohumeral arthritis with a retroverted monoconcave (B3) glenoid. Her Simple Shoulder Test indicated that she could not sleep comfortably, reach the small of her back, lift eight pounds, toss, throw, wash back of her opposite shoulder or do her usual work. She had 120 degrees of active elevation with grade 5 strength.

       

After a discussion of the surgical options, she elected an anatomic total shoulder. This was performed without preoperative MRI, CT scan, 3D planning or brachial plexus block. The long head tendon of the biceps was preserved. Conservative glenoid reaming was performed with no attempt to alter glenoid version. A standard (non-augmented) glenoid component was used. A standard length smooth humeral stem was impaction-grafted into the humeral canal.

At 12 years after her arthroplasty at the age of 85, she reported being able to perform 8 of the 12 functions of the Simple Shoulder Test and was pleased with the outcome of her surgery.

Her x-rays at that time show secure fixation of the humeral and glenoid components with bony ingrowth between the fins of the central glenoid peg. Penetration of the anterior glenoid vault by the central peg is seen on the axillary view.

Comment: As pointed out by the authors of Anatomic Total Shoulder Arthroplasty with All-Polyethylene Glenoid Component for Primary Osteoarthritis with Glenoid Deficiencies, this standardized economical approach (minimal reaming, standard, non augmented, glenoid component) is effective across the range of glenoid types:

Humeral centering on the glenoid can be achieved

without change in glenoid version.

Comments welcome at shoulderarthritis@uw.edu

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). 

The relationship of glenoid version and glenohumeral centering to clinical outcome in a series of 210 patients having anatomic arthroplasty followed for a mean of eight years.

Some shoulder surgeons devote substantial resources to correcting preoperative glenohumeral pathoantomy, while others are inclined to accepting features such as glenoid retroversion (see Glenoid version: acceptors and correctors). 

Recognizing that the surgeon is the method, it is interest to view the outcomes of different  approaches to anatomic total shoulder arthroplasty (ATSA).

The authors of Anatomic total shoulder arthroplasty for posteriorly eccentric and concentric osteoarthritis: a comparison at minimum 5-year follow-up present the average 8 year outcomes for a single-center series of 210 patients with refractory primary osteoarthritis treated with ATSA without attempt to correct glenoid version.

All cases were performed by one of three fellowship-trained shoulder surgeons. Preoperative 3D planning was not used for any of these cases. 

The shoulder was approached through the deltopectoral interval with a subscapularis peel. In cases with posteriorly eccentric wear, the humeral and glenoid sided capsular release during exposure was limited to the mid- sagittal plane (i.e. “6 o’clock”) to preserve posterior capsular tension. Glenoid reaming was limited to that necessary to create a single concavity, preserving bone stock without attempting to correct retroversion. 

Sufficient reaming was indicated by the absence of tipping when a pegless, round-backed trial component was loaded eccentrically. 

The glenoid component in the majority of cases utilized a fluted central peg for bone ingrowth with cemented peripheral pegs (Depuy-Synthes Anchor Peg; n = 204). Cementation technique involved meticulous drying with a pressurized carbon-dioxide spray

Particular attention was given to avoid cement on the backside of the implant.

A standard anatomic humeral arthroplasty was usually performed with conventional length stem (Depuy Global AP or Enovis Turon; n=204).

In cases in which excessive intraoperative posterior translation was identified with trial components in place, an anteriorly eccentric humeral head without or with rotator interval plication was considered to provide stability.

Preoperative and postoperative standardized axillary views were used to determine Walch classification, glenoid component seating, humeroglenoid alignment (HGA-AP) and version. 

The outcome measures included the Simple Shoulder Test, radiolucencies around the glenoid component, and revisions.

98 (47%) of the shoulders had posteriorly decentered humeral heads while 108 (51%) had centered humeral heads. 

77 shoulders had Walch type A glenoids and 122 had Walch type B glenoids. 

35 shoulders had preoperative glenoid retroversion >15 degrees

The mean preoperative SST score of 3.4 improved to a mean of 9.4 at 8 years after surgery. Two patients (1%) underwent re-operations during the study period. 

There was minimal change in glenoid version: the average postoperative retoversion was 7.0 degrees in comparison the preoperative average of 8.8 degrees.

Neither the final SST, change in SST or percentage of maximal improvement were correlated with pre- and postoperative humeral head centering, Walch classification or glenoid version. 

In patients with Walch B1 and B2 glenoids (n=110), there were no differences in outcome measures between patients with postoperative retroversion of more and less than 15 degrees.

While 15 of 51 patients (29%) with minimum 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 (bottom two images below).

Comment: This study indicates that clinically significant and durable outcomes with low revision rates can be accomplished with a straightforward surgical technique in which glenoid bone preservation is prioritized.

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/

Contact: shoulderarthritis@uw.edu

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). 

Does glenoid retroversion matter in reverse total shoulder?

Substantial amounts of time and money are spent in assessing and addressing glenoid retroversion in shoulders having reverse total shoulder arthroplasty. Some authors suggest that failure to restore glenoid component version to ‘‘normal’’ values may lead to suboptimal joint biomechanics and subsequent component failure. This concern has given rise to the use of 3D CT preoperative planning, eccentric reaming of the glenoid bone, bone grafts and augmented baseplates to reduce postoperative glenoid retroversion to 15 degrees or less.

The authors of Baseplate retroversion does not affect postoperative outcomes after reverse shoulder arthroplasty

investigated the relevance of postoperative glenoid version to the functional outcomes, range of motion, and postoperative complications in 271 patients having a 77% 2-year follow-up rate. 

161 patients had postoperative retroversion less than or equal to 15 degrees, and 110 patients had retroversion greater than 15 degrees. 

There were no significant differences between the groups with respect to American Shoulder and Elbow Surgeons scores, visual analog scales, Single Assessment Numeric Evaluation scores, postoperative range of motion, or complication rates.

The authors state that preserving glenoid bone stock may be more important than aiming for a specific degree of glenoid retroversion in reverse total shoulder arthroplasty.

Comment: These results suggest that preoperative 3D CT planning to guide glenoid retroversion, augmented baseplate implants, or bone grafts are not needed for most cases of reverse total shoulder arthroplasty.

Similar concerns can be raised regarding version in anatomic shoulder arthroplasty as discussed in this post:

Arthritic glenoid retroversion: what to do about it, is an augmented glenoid of value?

To add this blog to your reading list in Google Chrome, click on the reading list icon

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).