This 3D CT study characterizes the Walch B3 glenoid, a recent addition to the Walch classification for primary glenohumeral osteoarthritis. The B3 is theorized to be end-stage progression of the biconcave B2, in which posterior wear consumes the entire paleoglenoid to leave a single uniconcave surface. The authors measured retroversion, inclination, medialization, and posterior subluxation in 52 patients to define the deformity.
When you look at a B3 glenoid on axial CT and the humeral head appears centered, do not be reassured. That concentricity is acquired: the head has carved out its own retroverted socket, so it looks reduced against the glenoid but is actually 80% posteriorly subluxated against the scapula.
Measure version and subluxation against the scapular plane, which is independent of the erosion and reflects true glenohumeral alignment. This matters at the time of arthroplasty. Retroversion above 10° increases cement-interface micromotion, 15° produces eccentric loading, and severely retroverted glenoids risk peg perforation with asymmetric reaming.
A mean 24° of retroversion often exceeds what simple corrective reaming can safely fix, so a B3 should trigger 3D planning and consideration of augmented components or bone grafting rather than a standard anatomic glenoid.
This 3D CT study characterizes the Walch B3 glenoid, a recent addition to the Walch classification for primary glenohumeral osteoarthritis. The B3 is theorized to be end-stage progression of the biconcave B2, in which posterior wear consumes the entire paleoglenoid to leave a single uniconcave surface. The authors measured retroversion, inclination, medialization, and posterior subluxation in 52 patients to define the deformity.
When you look at a B3 glenoid on axial CT and the humeral head appears centered, do not be reassured. That concentricity is acquired: the head has carved out its own retroverted socket, so it looks reduced against the glenoid but is actually 80% posteriorly subluxated against the scapula.
Measure version and subluxation against the scapular plane, which is independent of the erosion and reflects true glenohumeral alignment. This matters at the time of arthroplasty. Retroversion above 10° increases cement-interface micromotion, 15° produces eccentric loading, and severely retroverted glenoids risk peg perforation with asymmetric reaming.
A mean 24° of retroversion often exceeds what simple corrective reaming can safely fix, so a B3 should trigger 3D planning and consideration of augmented components or bone grafting rather than a standard anatomic glenoid.