What Is the Best Option for Addressing Difficult Glenoids with Implants?

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.

Literature Review:

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.

Allred in 2016, showed that there was more backside contact with cortical bone, less bone removed, and longer fatigue life when using the wedge vs. the step design.   I do feel like the overall clinical results that were reported in this study are consistent with my own experience using augmented glenoids. My patients receiving the augmented glenoid seem to have similar results to my patients receiving the traditional glenoid implants. There is an article in New York University’s Bulletin of the Hospital of Joint Diseases Volume 73, Supplement 1 that reports two-year minimum follow up using a wedge design. This study was a comparison of 24 augmented vs. 24 non-augmented total shoulder procedures.  The results were improvements in SPADI, Constant, ASES, UCLA, and SST scores, as well as improvements in external rotation and forward elevation. The conclusion of the study showed similar results between the two groups at two-year follow-up.

Early results of these augmented glenoid implants are promising, but studies by Cofield and Walch have shown us that we need to follow these patients to truly determine their longevity. I think surgeons always need to plan for potential revision of their surgeries. I think revising a step-cut component may be very challenging due to the bone removed during implantation, which in my mind, makes the wedge augmented component a more attractive option at this time. It will be interesting to see if surgeons in the future will choose an anatomic total shoulder with an augmented implant or choose a reverse total shoulder for these challenging glenoids.

Curtis Noel, MD, is a fellowship trained shoulder and elbow surgeon at the Crystal Clinic Orthopaedic Center in Akron, Ohio, and the director of the shoulder and elbow service for Summa Health Orthopaedic residency program. He completed his residency in Akron and his fellowship at the Steadman-Hawkins Clinic of the Carolinas. Dr. Noel, a frequent industry lecturer and author, is an Equinoxe® design team member.