Nerot-Sirveaux classification of scapular notching

The Nerot-Sirveaux classification of scapular notching describes the radiographic extent of bone loss in patients with scapular notching after reverse total shoulder arthroplasty (RTSA).

An AP glenoid view (tangential to baseplate) is needed to assess for scapular notching, which will allow visualization of the glenosphere and scapular neck without humeral prosthesis superimposition ¹.

Classification

The Nerot-Sirveaux system classifies the scapular notch as grades 1 to 4 based on the size of the defect seen on the radiograph ¹:

• grade 1: the defect affected only the inferior pillar of the scapular neck

• grade 2: the notch was in contact with the inferior screw due to erosion of the scapular neck down to the level of the screw

• grade 3: bone erosion creating an extended notch over the inferior screw

• grade 4: the notch extends under the baseplate

Interpretation

Grade 1 and 2 scapular notching are thought to be the result of mechanical impingement between the humeral polyethylene component and glenoid rim ^1,2.

Grade 3 and 4 scapular notching are thought to be result of polyethylene-induced osteolysis as mechanical impingement is unlikely to occur past the inferior screw. If erosion results in prosthesis instability, a revision arthroplasty may be required ^1,2.

History and etymology

Francois Sirveaux and colleagues created a classification system for scapular notching in 2004 as part of their publication of results on this then new phenomenon ³. C Nerot’s group described a not dissimilar classification only a few years earlier ⁴, hence the Nerot-Sirveaux classification system.