Severe B2 glenoid in a 40 year old active man

An active man in his 40s presented with pain and stiffness in the left shoulder after a remote childhood injury. X-rays at the time of presentation demonstrated glenohumeral arthritis with severe posterior decentering of the humeral head on a retroverted, biconcave type B2 glenoid as shown below.

After discussion of the options, including anatomic total shoulder arthroplasty and reverse total shoulder arthroplasty, he elected to proceed with a ream run procedure (see this link).

At four years after surgery, he reported essentially full and comfortable function of his shoulder with improved active elevation from 90 degrees before surgery to 160 degrees. His radiographs at 4 years (below) show an anteriorly eccentric humeral head centered on a remodeled glenoid with radiographic space between the humeral prosthesis and the mature glenoid bone surface.

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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).

Management if the B2 and B3 glenoid types with an augmented glenoid component

Stepped Augmented Glenoid Component in Anatomic Total Shoulder Arthroplasty for B2 and B3 Glenoid Pathology A Study of Early Outcomes

These authors studied the use of a stepped augmented glenoid component for management of Walch B2 (n=29) and B3 (n=21) glenoids and compared the radiographic and clinical outcomes at short-term follow-up with those achieved with a non-augmented component of the same design in Walch A1 glenoids (n=42).

Sequential 3-dimensional (3D) computed tomography (CT) imaging was performed preoperatively, within 3 months postoperatively with metal artifact reduction (MAR) to define implant position, and at a minimum of 2 years postoperatively with MAR. 

Preoperatively, these images showed that the alignment of the humeral head to the glenoid (HGA - represented by the circles in the graph below) was independent of glenoid version. Type B3 (yellow symbols) showed centering of the humeral head on the glenoid that was comparable to type A1 (blue symbols). On the other hand, the alignment of the humeral head to the scapular body (HSA - represented by the triangles) was strongly related to glenoid version. 

Similarly at two years after surgery the humeroscapular alignment (but not the humeroglenoid alignment) was closely related to glenoid version.

The desired implant placement was achieved in all (100%) of the 42 A1 glenoids, 27 (93%) of the 29 B2 glenoids, and 15 (71%) of the 21 B3 glenoids.

Radiographic followup at two years showed:

A1 glenoids: Central peg osteolysis (CPO) was present in 5% of the A1 glenoids. 40% had glenoid component shift.

B2 glenoids: There was only a small difference in the frequency of CPO between B2 glenoids with the augmented component (10%) and A1 glenoids (5%) with the standard component. The short-term clinical and radiographic results were equivalent to those for patients without glenoid bone loss (Walch A1) treated with a non-augmented component. 55% had glenoid component shift.

B3 glenoids: Central peg osteolysis (CPO) with or without implant shift occurred in a higher percentage of B3 glenoids treated with the augmented glenoid component (29%) than A1 glenoids treated with a standard component (5%) B3 glenoids were associated with more component medialization relative to the premorbid joint line compared with A1 and B2 glenoids. 62% had glenoid component shift.

The two year clinical outcome scores were not different for the three glenoid types.

Comment: This authors have continued their careful and thoughtful analysis of arthritic glenohumeral anatomy. Their observations on glenoid component shift and central peg osteolysis obtained with metal subtraction imaging provide knowledge that informs our understanding and management of shoulder arthritis.

They point out both the severity and the shape of glenoid bone loss are important when considering the type of glenoid component to use and its location in aTSA. Use of the stepped augmented glenoid component requires more anterior glenoid reaming to correct pathologic glenoid retroversion in moderate-to-severe B3 glenoids, resulting in implant medialization. These B3 glenoids had a higher rate of central peg osteolysis and persistent postoperative joint-line medialization relative to the premorbid joint line. They do  not recommend use of the stepped augmented glenoid component for correction of severe B3 glenoid retroversion that requires excessive anterior glenoid reaming.

Recognizing that high degrees of retroversion, bone loss and humeral head decentering on the glenoid are indicators of worse pathoanatomy and that each of these - separately or in combination - can negatively affect the durability of the arthroplasty, several questions arise:

(1) How important is it to re-establish the premorbid joint line; how much medialization of the the joint line be compensated for by modification of the prosthetic head curvature and thickness?

(2) How important is it to re-establish the premorbid version in the B2 glenoid at the expense of removing sclerotic glenoid bone; how much abnormal glenoid retroversion be compensated for by using soft tissue balancing and anteriorly eccentric humeral components to center the humeral head?

(3) How important is it to re-establish the premorbid version in the B3 glenoid at the expense of removing sclerotic glenoid bone; since the humeral head is centered in the glenoid is it necessary to change the version?

(4) How important is it to avoid peg perforation; might perforation of the glenoid neck by the central peg actually enhance fixation as it appears to do with many designs of reverse total shoulder?

In sum, what is the best way to balance bone preservation vs "correction" of the pathoanatomy?

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).

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).

Posteriorly augmented glenoid components - an update

Radiographic results of augmented all polyethylene glenoids in the presence of posterior glenoid bone loss during total shoulder arthroplasty

These authors evaluated the clinical and radiographic results of an augmented all-polyethylene glenoid used in 21 patients for the treatment of glenoid osteoarthritis with an average posterior glenoid bone loss of 4.7 mm.

Inclusion criteria: any patient undergoing total shoulder arthroplasty for a diagnosis of glenohumeral osteoarthritis with a Walch B2 or C type glenoid morphology, glenoid retroversion of a minimum of 12°, presence of humeral head subluxation greater than 10%, posterior glenoid bone loss, intact rotator cuff and implantation of an augmented glenoid with minimum of 2-year follow- up.

The augmented glenoid component 

was inserted after posterior preparation by removing sclerotic bone with a high-speed bur and then placing a corresponding sized rasp guide. An oscillating rasp was used to finalize preparation of the posterior glenoid surface.

Significant improvements were demonstrated for American Shoulder and Elbow Surgeons Shoulder Assessment (52.3), Simple Shoulder Test (8.1), forward flexion (50°), external rotation (32°), and pain.

Preoperative retroversion averaged 20.8° (range, 12°-37°), humeral scapular alignment averaged 30% (range, 15%-50%), and humeral glenoid alignment averaged 8% (range, 0%-23.0%.). 

Postoperative retroversion averaged 9° (range, 0°-32°), humeral scapular alignment averaged 6.98% (range, 0%-23%), and humeral glenoid alignment averaged − 0.24% (range, − 8% to 3.5%). 

Central peg ingrowth was demonstrated in all patients, and complete component seating was achieved in 19 patients. No complications were encountered, and no clinical or radiographic failures were identified.

Comment: This is a well done study. As the authors point out and as pointed out in this post, Failure of a total shoulder glenoid component occurs after two years, longer term followup of these implants will be of great interest.

This study can be compared to other recent studies with two year followup on posteriorly augmented glenoid components as presented below.

First

Augmented glenoid component for bone deficiency in shoulder arthroplasty.

These authors report on 14 shoulders having shoulder arthroplasty with an augmented glenoid component to treat posterior glenoid bone deficiency associated with advanced osteoarthritis.

According to a modified Neer result rating system, 36% of patients had an excellent result, 50% a satisfactory result, and 14% an unsatisfactory result.

At the most recent radiographs, four of the 12 shoulders that could be evaluated radiographically had more than mild glenohumeral subluxation. Three shoulders had moderate posterior subluxation, one shoulder had severe anterior subluxation. All of the shoulders with postoperative subluxation had some degree of subluxation present prior to surgery. 

The shoulder with severe anterior subluxation postoperatively had moderate posterior subluxation prior to surgery. This patient had Parkinsonism and sustained anterior instability resulting in dislocation, treated with closed reduction, followed by immobilization and physical therapy. 

There was no periprosthetic lucency in four shoulders, periprosthetic lucency was grade 1 in seven shoulders and grade 5 in one shoulder, and the glenoid component had shifted in position. This shoulder also had moderate posterior subluxation, and this glenoid component was considered radiographically loose.

The authors concluded, "Our results suggest patients undergoing total shoulder arthroplasty with an asymmetric glenoid component for osteoarthritis achieve satisfactory mid-term pain relief and improvement in function; however, instability is not always corrected. The advantage of this component seems marginal, and its use has been discontinued."


Second
Preliminary Results of a Posterior Augmented Glenoid Compared to an all Polyethylene Standard Glenoid in Anatomic Total Shoulder Arthroplasty

These authors report on 24 patients having total shoulder arthroplasty using a posteriorly augmented glenoid for arthritis with posterior glenoid wear. The degree of posterior wear and retroversion before surgery are not presented.

At two years after surgery, 60% of the shoulders had a periglenoid radiolucent line with an average radiographic line score of 1.10.

One glenoid was radiographically loose. 

Two shoulders demonstrated superior subluxation. 

Three were anteriorly subluxated.

Comment: These results speak to the challenges inherent in the use of posteriorly augmented components.

One of the rarely discussed concerns is the effects of using thick posterior polyethylene to manage the   posteriorly directed loads applied when the arm is elevated to the functional position of forward elevation, which is known to create the risk of functional decentering.

This is best explained by noting that when the arm is at the side with a posteriorly augmented glenoid, the net humeral joint reaction force (red arrow) is centered.

However, when the arm is elevated to a functional position, the net humeral joint reaction force (red arrow) is directed posteriorly against the posteriorly augmented polyethylene, subjecting it to the risk of cold flow.

 Furthermore, the point of application of the net humeral joint reaction force of the elevated arm creates an increased glenoid loosening moment (blue line), when the posterior polyethylene is thick.

It is possible that these mechanisms contributed to the development of lucent lines and instability with posteriorly augmented glenoid components in the series presented.

Another concern with removal of the posterior sclerotic glenoid bone for the insertion of an augmented component (as shown below)

 is that should the augmented component fail, the amount of posterior bone loss may compromise revision surgery.

Our approach to the retroverted glenoid is simple - see this link..

(1) We do not rely on preoperative CT scans because they cannot image the shoulder in the functional  position of forward elevation. Instead we prefer the simple standardized axillary view taken with the arm elevated 90 degrees in the plane of the scapula as shown below (this shoulder demonstrates the bad arthritic triad).

(2) We do not use preoperative planning software or patient specific drill guides, but rather ream the glenoid conservatively without trying to 'normalize' glenoid version as shown in this link.

(3) Finally, in a total shoulder arthroplasty for a retroverted glenoid, we place a standard glenoid component on the conservatively reamed glenoid, using an anteriorly eccentric humeral humeral head component if necessary to achieve centering of the articulation. 

This type of reconstruction is shown below on an axillary view taken with the arm in the functional position of forward elevation. Note the centered humeral head and the lack of glenoid lucent lines after two years of implantation.

This approach preserves the maximal amount of glenoid bone in contrast to what is required to fit the bone to a more complex back side geometry as explained in this link.

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