The relationship between scapular notching and reverse shoulder arthroplasty prosthesis design.

BACKGROUND

Inferior scapular notching is a common radiographic complication of reverse shoulder arthroplasty. The purpose of this study is to determine the impact of prosthesis design on the incidence and severity of notching.

MATERIALS AND

METHODS

Eighty-eight patients (mean age, 72 years) who underwent reverse shoulder arthroplasty with a minimum of 12 months' follow-up (mean, 31 months) were retrospectively reviewed. Patients were grouped based on prosthesis design: Tornier (Stafford, TX, USA) (45%), Zimmer (Warsaw, IN, USA) with a nonretentive liner (35%), and Zimmer with a retentive liner (19%). Notching on final radiographs was graded by use of the Sirveaux classification system and a novel classification system.

RESULTS

The incidence of notching was significantly higher with the Tornier prosthesis (92%) compared with the Zimmer prosthesis with nonretentive liners (58%) and retentive liners (71%) (P < .05). The incidence of high-grade notching and the median grade were significantly higher with the Tornier prosthesis compared with the Zimmer prosthesis (P < .05). By use of the novel grading system, there was a higher incidence of notching involving the baseplate with the Tornier prosthesis (68%) compared with the Zimmer prosthesis (33%) (P < .05). The addition of a retentive liner was not associated with greater notching than a nonretentive liner for the Zimmer implant. Diagnosis had no significant influence on notching.

CONCLUSIONS

A higher incidence and severity of notching were observed with the Tornier reverse arthroplasty compared with the Zimmer reverse arthroplasty at short-term follow-up. These findings may be because of the different morphology of the polyethylene component and/or differences in glenosphere offset between the prosthetic systems. In addition to surgical technique, consideration should be given to prosthesis design in mitigating the risk of scapular notching.