Evaluation of the role of glenosphere design and humeral component retroversion in avoiding scapular notching during reverse shoulder arthroplasty

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• 作者：Julien Berhouet ; Pascal Garaud ; Luc Favard
• 关键词：Basic Science Study ; Biomechanics ; Cadaver Model
• 刊名：Journal of Shoulder and Elbow Surgery
• 出版年：February, 2014
• 年：2014
• 卷：23
• 期：2
• 页码：151-158
• 全文大小：1105 K

文摘

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Background

Scapular notching is a common observation during radiological follow-up of reverse shoulder arthroplasty. The purpose of this study was to evaluate the effect of glenosphere design and humeral component retroversion on movement amplitude in the scapular plane and inferior scapular impingement.

Materials and methods

The Aequalis Reversed Shoulder Prosthesis (Tornier) was implanted into 40聽cadaver shoulders. On the glenoid side, 8 different combinations were tested:

36-mm glenosphere: centered (standard), eccentric, with an inferior tilt, or with the center of rotation (COR) lateralized by 5 or 7 mm; and

42-mm centered glenosphere: used alone or with the COR lateralized by 7 or 10 mm.

The humeral component was positioned in 0掳, 10掳, 20掳, 30掳, and 40掳 of retroversion. Maximum adduction and abduction were measured when inferior impingement and superior impingement, respectively, were detected.

Results

The average increase in abduction amplitude was 10掳 and inferior impingement occurred 18掳 later with a 42-mm glenosphere, especially when it was lateralized by 10 mm, relative to a 36-mm centered glenosphere (P < .05). These 2 combinations provided a 28掳 increase in the movement amplitude in the scapular plane. Positioning of the humeral component in 10掳 or 20掳 of retroversion or in anatomical retroversion was most effective at avoiding inferior impingement but had less effect on abduction range of motion (except with the 42-mm glenosphere).

Conclusion

Our study confirmed published results with various glenosphere designs but was unique in describing the effect of humeral retroversion on scapular impingement. Inferior scapular notching can be most effectively prevented by using large-diameter glenospheres with lateralized COR and by making sure to replicate the patient's native humeral retroversion.