Tornier Perform Anatomic Augmented Glenoid Implants correct posterior subluxation and maintain active joint reduction...

The Walch type B2 glenoid is characterized by retroversion, posteroinferior erosion and posterior humeral head subluxation. A surgical management option for a B2 glenoid is an anatomic total shoulder arthroplasty (aTSA) with a posteriorly augmented all-posterior augmented glenoid (PAG) implant. However, little is known about what occurs actively at the glenohumeral articulation after aTSA with a PAG. Additionally, most studies on B2 glenoids, whether pre-aTSA or post-aTSA, assess subluxation statically. Presently, it is unknown if subluxation recurs after aTSA with a PAG or if it varies dynamically throughout active motion. Therefore, the primary objective of this study was to determine if Walch type B2 patients managed with an aTSA and a PAG (Tornier Perform Anatomic Augmented Glenoid Implant) would maintain correction of subluxation when examined statically and when stressed with active motion. The secondary objective was to analyze if a patient's range of motion (good or limited), magnitude of B2, or PAG implant size (15° or 25°) affect postoperative correction of subluxation.

Twenty Walch type B2 patients (mean age 68 years, range 54-83) underwent stemless aTSA with a 15° or 25° PAG implant and were assessed at a minimum 2-year follow-up. All patients underwent dynamic four-dimensional computed tomography scanning to actively track glenohumeral implant alignment and subluxation during a provocative active internal rotation (IR) motion protocol. Bone and implant 3D models of the humerus and scapula for each four-dimensional computed tomography scan were created using 3D Slicer. Landmarks were selected on the models to create coordinate systems that were then used in conjunction with a custom program (MATLAB) to determine subluxation preoperatively (statically), and postoperatively (dynamically).

Posterior humeral head subluxation was significantly corrected (P < .001) from an average of 66% (range 51%-98%) preoperatively to 54% (range 41%-77%) postoperatively. Concentric aTSA joint alignment was maintained throughout an active IR motion protocol, as subluxation percentage only varied by 1% throughout IR movement (range 54%-55%). Neither patient IR range of motion (good or limited) nor size of PAG (15° or 25°) had a significant effect (P > .05) on subluxation postoperatively.

At short-term follow-up, aTSA with an all-polyethylene PAG (Tornier Perform Anatomic Augmented Glenoid Implant) was successful at restoring and maintaining glenohumeral alignment with correction of subluxation throughout a provocative active IR motion protocol. As such, recurrence of subluxation does not occur statically or actively in patients who have undergone glenoid reconstruction with correction of posteroinferior erosion with a half-wedge PAG implant. Thus, aTSA with a PAG implant is an acceptable option for patients with mild or moderate B2 glenoids.