Wednesday, September 8, 2021

Management of the B2 glenoid - standard glenoid, posteriorly augmented glenoid, bone graft or reverse total shoulder?

Anatomic versus Reverse Shoulder Arthroplasty for the Treatment of Walch B2 Glenoid Morphology: A Systematic Review and Meta-Analysis

These authors point out that the Walch B2 glenoid morphology with glenohumeral osteoarthritis can be a challenging degenerative pattern to manage surgically. While they do not spell out the possible difficulties in this article, we recognize that the B2 carries with it challenges of managing (1) posterior decentering of the head on the glenoid, (2) difficult access to the retroverted glenoid, and (3) diminished posterior bone stock.

Below are a couple of examples from our database:

The authors of the review state that anatomic total shoulder arthroplasty (TSA) in combination with eccentric reaming or bone grafting are the traditional methods of treatment. Newer approaches such as TSA with posteriorly augmented glenoid components and reverse shoulder arthroplasty (RSA) have been proposed as other options

Their aim was to compare mid-term surgical and functional outcomes of Walch B2 glenoids without significant rotator cuff pathology treated with TSA and RSA.

16 articles were included with 414 TSAs and 78 RSAs. 

The TSA group was further subdivided based on the use of eccentric reaming (135 TSAs), an augmented glenoid component (84 TSAs) or bone grafting (11 TSAs) or was unspecified (184 TSAs).

All options resulted in improved average motion and improved average measures of comfort and function. 

The pooled complication rates of 9% for TSA and 6% for RSA and pooled revision rates of 2%  for TSA and 1% (95% CI 0-15%) for RSA. Note, however, the average follow-up was 54.1±14.8 months for TSA patients and 44.8±10.1 months for RSA patients. 

For the TSA+eccentric ream subgroup, the complication rate was 5.6% (5/89 shoulders) and the revision rate was 0.9% (1/116 shoulders). Two shoulders had glenoid component loosening, 3 had failure of the posterior capsule plication (PCP) procedure (1 had both) and 1 had a rotator cuff tear that underwent conversion to RSA. 

For the TSA+posteriorly augmented glenoid component subgroup, the complication rate was 10.5 (4/38 shoulders) and the revision rate was 2.4% (2/84 shoulders). The majority of these complications were glenohumeral subluxation (3 posterior, 1 anterior), of which 1 also demonstrated glenoid component loosening. The 2 revisions were for glenoid component loosening. 

For the TSA+bone graft subgroup, the complication and revision rates were both 18.2% (2/11 shoulders). These 2 shoulders were revised for glenoid component loosening. 

For the TSA+unspecified glenoid arthroplasty subgroup, the complication rate was 20.7% (19/92 shoulders) all from radiographic glenoid component loosening. The revision rate was 16.3% (15/92 shoulders), of which the majority were for glenoid component loosening (6 shoulders) and posterior shoulder dislocations (5 shoulders). 

Four RSA shoulders were noted to have complications. Of these, 3 were nerve palsies (1 axillary, 2 ulnar) and 1 was glenoid component loosening which was revised to hemiarthroplasty.

Comment: This review found that the complication and revision rates for an anatomic total shoulder with eccentric reaming and a reverse total shoulder in the management of the B2 glenoid were essentially equivalent. However, the complication and revision rates were twice as high for TSA with a posteriorly augmented glenoid component and over three times as high for TSA with a bone graft. Anterior and posterior instability were seen with the posteriorly augmented component.

This observation demonstrates that the outcomes of TSA and reverse total shoulder cannot be compared without stratifying the TSA surgeries by the details of glenoid management. 

Some of the failures in the eccentric reaming TSA group were due to failure of a posterior capsular plication. If there is excess posterior translation at the time of TSA, we prefer to use an anteriorly eccentric glenoid component and / or rotator interval plication rather than the more fragile posterior capsular plication (see this link). 

One final point is that while the technique of total shoulder arthroplasty is often described as including "eccentric reaming", suggesting that version is corrected. As indicated below, we have found that "correction" of glenoid retroversion is much less important than achieving centering of the humeral head on the prosthetic glenoid.

A recent paper assessed the effects of glenoid retroversion in shoulder arthroplasty: Does Postoperative Glenoid Retroversion Affect the 2-Year Clinical and Radiographic Outcomes for Total Shoulder Arthroplasty?

These authors studied a population of patients undergoing anatomic total shoulder arthroplasty (TSA) stratified into two groups: those with the glenoid implanted in ≥ 15 degrees of retroversion and those with the glenoid implanted in <15 degrees of retroversion.

The mean improvement in the SST (6.7) for the retroverted group was comparable to that for the nonretroverted group (5.8). The percent of maximal possible improvement (%MPI) for the retroverted glenoids (70%) was comparable to that for the nonretroverted glenoids (67%). The 2-year SST scores for the retroverted (9.3) and the nonretroverted glenoid groups (9.4) were similar

The radiographic results for the retroverted glenoid group were similar to those for the nonretroverted group with respect to 

No patient in either group had subluxation or dislocation after surgery.

The results for type B glenoids were comparable for the retroverted and non retroverted components. 

Another recent paper evaluated the ability of shoulder arthroplasty using a standard glenoid component to improve patient self-assessed comfort and function and to correct preoperative humeral-head decentering on the face of the glenoid in patients with primary glenohumeral arthritis and type-B2 or B3 glenoids:

The authors identified 66 shoulders with type-B2 glenoids (n = 40) or type-B3 glenoids (n = 26) undergoing total shoulder arthroplasties with a non-augmented glenoid component inserted without attempting to normalize glenoid version and with clinical and radiographic follow-up that was a minimum of 2 years. The Simple Shoulder Test (SST), the percentage of humeral-head decentering on the glenoid face, and bone ingrowth into the central peg were the main outcome variables of interest. Similar analyses were made for concurrent patients with type-A1, A2, B1, and D glenoid pathoanatomy to determine if the outcomes for type-B2 and B3 glenoids were inferior to those for the other types.

The SST score (and standard deviation) improved from 3.2 ± 2.1 points preoperatively to 9.9 ± 2.4 points postoperatively (p < 0.001) at a mean time of 2.8 ± 1.2 years for type-B2 glenoids and from 3.0 ± 2.5 points preoper- atively to 9.4 ± 2.1 points postoperatively (p < 0.001) at a mean time of 2.9 ± 1.5 years for type-B3 glenoids; these results were not inferior to those for shoulders with other glenoid types. 

Postoperative glenoid version was not significantly different (p > 0.05) from preoperative glenoid version. 

The mean humeral-head decentering on the glenoid face was reduced 

for type-B2 glenoids from 214% ± 7% preoperatively to 21% ± 2% postoperatively (p < 0.001) 

and for type-B3 glenoids from 24% ± 6% preoperatively to 21% ± 3% postoperatively (p = 0.027). 

The rates of bone integration into the central peg for type-B2 glenoids (83%) and type-B3 glenoids (81%) were not inferior to those for other glenoid types.

While anterior penetration of the central peg did occur, it did not ,interfere with osseous integration or the clinical outcome.

The authors concluded that total shoulder arthroplasty with a standard glenoid inserted without changing version can significantly improve patient comfort and function and consistently center the humeral head on the glenoid face in shoulders with type-B2 and B3 glenoids, achieving >80% osseous integration into the central peg. These clinical and radiographic outcomes for type- B2 and B3 glenoids were not inferior to those outcomes for other glenoid types.

There are many strategies for managing the retroverted glenoid: the ream and run without change in version, an anatomic total shoulder without change in glenoid version, an anatomic total shoulder with change in glenoid version by excessive anterior reaming, an anatomic total shoulder with a posteriorly augmented glenoid component and a reverse total shoulder. 

Below is an example of a severely retroverted B2 glenoid in a young active patient managed with a ream and run procedure without attempting to change glenoid version. On the left is the preoperative axillary and the right the axillary at three months after surgery when the patient had 150 degrees of comfortable shoulder elevation. Note the lack of change of glenoid version and the use of an anteriorly eccentric humeral head component.

A second example is a man in his mid 70's presented with a stiff painful shoulder. These x-rays were obtained a the time of office evaluation, showing osteoarthritis

and a B2 glenoid.

He elected a total shoulder arthroplasty with a standard glenoid component and impaction grafting of the humeral component. The arthroplasty was carried out without a specific attempt to change glenoid version.

He returned for routine followup at 2.5 years after surgery with full shoulder function and the x-rays below

His AP view shows bony integration into the central peg and no evidence of lucent lines around his glenoid component.

His axillary view showed centering of an anteriorly eccentric humeral component on a secure glenoid component placed in retroversion with some penetration of the cortex of the glenoid neck. 

He allowed us to take a short movie of his shoulder function two and one half years after surgery.

Another example is this active man who presented with a painful, stiff left shoulder. His plain films are shown below.

 His axillary "truth" view, shows a retroverted type B2 glenoid

This was treated using a total shoulder arthroplasty with the glenoid component inserted without changing the retroversion.

His x-rays at two years after surgery show bone ingrowth into the central peg of the component with no evidence of loosening.

He kindly gave us permission to show a video of his function at two years after surgery.

Two other recent publications support the concept that conventional anatomic total shoulder arthroplasty (TSA) without augmented glenoid components can yield outcomes for type B2, type C and retroverted glenoids that are equivalent to those for type A1 glenoids. 

(1) Outcomes of anatomic shoulder arthroplasty performed on B2 vs. A1 type glenoids

These authors compared outcomes of TSA performed on A1 glenoids (n=178) and B2 glenoids  (n-111) treated with asymmetric glenoid reaming at a minimum of 2-years (mean 40 months). 

More men presented with a B2 glenoid (80 of 111; 72%) compared with A1 (101 of 178; 57%).

Both groups had similar Constant Strength scores preoperatively but the B2 group improved significantly more at final follow-up. 

The Total Constant score was also significantly better at follow-up in the B2 glenoid group. 

All other Constant subscales, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES), and Single Assessment Numerical Evaluation (SANE) measures showed no significant differences between the A1 and B2 glenoid groups. 

A similar proportion of patients rated their satisfaction as either very satisfied or satisfied between the A1 and B2 (glenoid types.

Lazarus scores were also similar between the A1 and B2 groups as were the rates of humeral radiolucent lines and humeral osteolysis.

Postoperative complications occurred in 8 shoulders (7%) in the B2 group and 8 shoulders in the A1 group (5%). The revision rates were also similar between the B2 (6 patients; 5%) and A1 (6 patients; 3%) groups.

(2) Early to midterm outcomes of anatomic shoulder arthroplasty performed on dysplastic (type C)


These authors hypothesized that TSA performed for Walch type C dysplastic glenoids with standard glenoid components can reliably produce successful results at short to midterm follow-up. They identified 29 patients that met inclusion criteria of a preoperative Walch type C dysplastic glenoid, treatment with TSA using standard (non-augmented) glenoid components and a minimum of 2-years clinical. These patients were matched to a cohort of 58 patients with a type A1 glenoid and minimum of 2-years clinical follow-up. The mean follow-up for this study was 4.5 years. 

Baseline measures were not significantly different between the Walch type C dysplastic group and the matched type A1 cohort. 

The Walch type C group had no significant differences in ASES score, ASES pain, or SANE score compared to the matched type A1 cohort. 

The complication rate of patients with a type C glenoid was 14% (4 of 29) with a 7% (2 of 29) revision rate. Similarly,  the complication rate for the A1 matched cohort was 17% (10 of 58) with a 12% (7 of 58) revision rate. 

Both groups had high patient satisfaction without statistical differences. 

There were no differences in the rate of radiographic lucencies or Lazarus scores.

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Here are some videos that are of shoulder interest
Shoulder arthritis - what you need to know (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).