Davinci’s Glenoid- Decoding the Arthritic Shoulder

Dr. Spencer and the team at the Shoulder and Elbow Center are thrilled to announce the latest of our research efforts being published in the Journal of Shoulder and Elbow Surgery! Working with Dr. Grant Garrigues at Rush Orthopedics and Dr. Ryan Quigley at Sacramento Medical Center, our team has gathered data on patients who have undergone total shoulder replacement and were noted to have a specific type of arthritis on the cup side of the joint (known as a “B2 glenoid”) requiring a special “augmented” plastic cup (called “posterior augmented glenoid”).

As with all things in medicine, there is a great deal of variation in every case. When looking at an arthritic shoulder, any number of concomitant pathologies or variations of standard anatomy can play a part in the patient’s surgical outcome.

These cases present very unique opportunities for medical research in that they allow us to narrow our focus to a specific deformity or anatomic variant- in this case, the B2 glenoid.

As the chart below shows, glenoid morphology in shoulder arthritis can be evaluated using the Walch method, identified using a letter (A,B,C,D) and a number to define how advanced the arthritis is.

Walch Glenoid Classifications

As you can see, the B2 glenoid actually shows 2 curves within the arc of the native glenoid, known as a biconcavity. These glenoids progress from the B1 shown above it, in which the humeral head begins to sit towards the back of the cup as opposed to the center (A1 vs. B1 in the chart above). This is known as posterior subluxation and is a hallmark of B glenoids.

Due to this biconcavity, standard plastic components (like the one shown below) cannot be used as there will be a gap left between a portion of the glenoid and the plastic component.

DJO shoulder replacement including a STANDARD plastic glenoid component

Instead, a specialized component is used called a posterior augmented glenoid. This component, shown below, has a “wedge” built into the back portion of the component.

Tornier shoulder system featuring a POSTERIOR AUGMENTED GLENOID

This wedge fills the gap left by the standard components very nicely and helps restore anatomic alignment to the glenohumeral joint and increase function.

This study, published in the Journal of Shoulder and Elbow Surgery, sought to define the clinical and radiographic markers of improvement in patients treated with this component.

Patients were evaluated clinically and radiographically (a physical exam and x rays) at least 2 years after their surgery and the data were compiled for statistical analysis.

The results showed that shoulders with this B2 glenoid treated with the augmented plastic component corrected the deformity of the glenoid as well as corrected alignment of the humeral head within the cup in addition to improving pain and function at least 2 years postoperatively.

This data is significant because it gives us a much more defined “plan of action” when faced with pathology like this.

The full study has been included at the bottom of this page and, as always, don’t hesitate to let us know if we can be of any help!

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