UW Shoulder and Elbow Academy: The biconcave glenoid

Early Clinical and Radiographic Outcomes of Anatomic Total Shoulder Arthroplasty with a Bi-convex Posterior Augmented Glenoid for Patients with Posterior Glenoid Erosion: Minimum 2-Year Follow-Up

These authors report minimum two-year follow-up for all- polyethylene, biconvex augmented anatomic glenoid component for the management of shoulders with posterior glenoid erosion.

According the the user guide (see this link), this procedure requires removal of bone by reaming to convert the variable anatomy of a B2 glenoid to a standardized biconcavity that fits the back of the implant. This is accomplished by using one reamer system for the anterior concavity

and a second reamer system to shape the posterior concavity

The authors emphasize several additional characteristics of this system: "This implant is available in four sizes, with 3 different amounts of augmentation. Also, given laterality-specific orientation of the pegs/augment it has right and left options. It also has two anchor options, a fluted peg design and a keeled option, with availability dependent on geographic regulatory clearance." and when this implant is used for a B3 or C (monoconcave) glenoid, removal of anterior bone is required to create the biconcavity to match the back of the component.

They conducted a retrospective review of patients having an anatomic total shoulder (aTSA) from 7 clinical sites using this biconvex posterior augmented glenoid (PAG).

86 of 110 consecutive patients during the study period (78% follow-up) met the inclusion criteria and were included in their analysis. Of the 86, 33 had a B1 glenoid, 43 had a B2 glenoid, 5 had a B3 glenoid, and 5 had a C glenoid.

Mean follow-up was 35 ± 10 months. There was one patient with both a prosthetic joint infection and radiographic glenoid loosening that required revision. 79/86 had a Lazarus score of 0 (no radiolucency seen about peg or keel) at final follow-up. The clinical results are shown below.

Comment: For many years many surgeons have successfully treated many patients with the full range of glenoid pathologies using a standard all-polyethylene glenoid (for the technique see this link).

See for example One and two-year clinical outcomes for a polyethylene glenoid

with a fluted peg: one thousand two hundred seventy individual patients from eleven centers.

The goal of Early Clinical and Radiographic Outcomes of Anatomic Total Shoulder Arthroplasty with a Bi-convex Posterior Augmented Glenoid for Patients with Posterior Glenoid Erosion: Minimum 2-Year Follow-Up was to present an experience with a more complex approach to managing arthritic shoulder with posterior glenoid bone loss using a glenoid component with a bi-convex backside and a sequence of specialized instrument as shown below and in this link

While a goal of this implant system is to modify glenoid retroversion, version change may not be necessary as pointed out in articles such as Does Postoperative Glenoid Retroversion Affect the 2-Year Clinical and Radiographic Outcomes for Total Shoulder Arthroplasty?, which concluded that "postoperative glenoid retroversion was not associated with inferior clinical results at two years after surgery."

While a goal of this special glenoid component is to improve the management of patients with posterior glenoid bone deficiencies, it remains to be seen whether this approach is superior to managing these deficiencies with a standard glenoid component as reported in articles such as Anatomic Total Shoulder Arthroplasty with All Polyethylene Glenoid Component for Primary Osteoarthritis with Glenoid Deficiencies, which concluded that "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.

This article does not present data on the increase in cost or surgical time for this implant in comparison to a standard polyethylene component, so the value of this technology (benefit to the patient / cost) cannot be evaluated at this point.

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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)

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).