Curtis Noel, MD
Read complete study: Total shoulder arthroplasty for glenohumeral arthritis associated with posterior glenoid bone loss: results of an all-polyethylene, posteriorly augmented glenoid component
The authors reported on 19 patients with 20 total shoulders with minimum two-year follow-up using an augmented glenoid component. They hypothesized the need for augmented glenoids as a way to save bone and prevent medializing the joint line. The average follow-up was 36 months, and the average pre-op retroversion to be corrected was 23.5⁰. The study showed significant improvements in forward elevation and external rotation, while also showing improvements in the SF36 physical form. The implant used in this study was an all-polyethylene, step-cut glenoid with an “anchor peg” for bone growth, in which 12 of the 19 patients showed osseus integration. The conclusion of the authors was that the short-term results are promising for these augmented glenoids, but further research needs to be completed.
I agree with these authors, and others, on the need to address retroversion in total shoulder arthroplasty. Treating the retroverted glenoid is challenging. For these B2 and B3 glenoids, surgeons have limited options. We know that implanting the glenoid in retroversion is not a good option as it increases the edge loading and leads to early loosening and failure. Reaming down the high side and placing a ‘standard’ glenoid can medialize the joint line and places the implant on subcortical bone, which is also not ideal. Using an anatomic total shoulder with an augmented glenoid implant is an attractive option, as it allows the placement of the implant on more solid bone and maintains the joint line. A final option is placing a reverse total shoulder, which may be the best option for some patients.
I currently prefer a wedge augmented glenoid component, instead of a step-cut implant. In my hands, the wedge glenoid is easier to implant and is more bone preserving.
Joseph Zuckerman, MD
These authors studied the ability to implant a custom glenoid component in 10 cadaver glenoids with glenoid defects using patient-specific guides and traditional non-guided techniques. The use of the patient-specific guide reduced angular deviations from the plan and significantly improved the position and length of the screw placements when used to implant the custom made glenoid components.
The authors have focused on a well-known challenge in shoulder arthroplasty – treatment of the deformed glenoid during anatomic or reverse shoulder arthroplasty. There is no doubt that two approaches canbe developed to address this issue. The first is the use of patient-specific guides (or intraoperative positioning devices) to improve the accuracy of component placement. We all recognize that a properly placed glenoid component will have longer-term survival than a malpositioned component. The second approach is to have non-standard glenoid components available to address the deformity. These can be either custom-made implants specific for the patient being treated or augmented “off the shelf” implants that address the common deformities encountered.
I have found that using non-custom or “off the shelf” augmented glenoid components have addressed many of the bone-loss issues I have encountered.
The authors actually combine both approaches – they use a custom implant with a specimen-specific guide. This could be perceived as the “best of both” but in actuality it is quite impractical from a cost perspective. The incremental cost of a custom implant combined with a CT-generated, patient-specific guide would add significant incremental cost. In 2016, regardless of where the surgery is being performed in the world, it is a surgeon’s responsibility to consider cost, especially in the context of cost vs. potential benefit. In addition, the FDA has been very strict on the use of custom implant components, which leaves us surgeons limited options for this approach. Continue reading