These authors examined the effects of lateralization and distalization on scapular spine fracture (SSF) after reverse shoulder arthroplasty (RSA).
We have previously pointed out that some designs of RSA create a major disruption of the normal anatomic relationships of the shoulder while others do not (see this link). One way to look at this is to consider the arch created by the medial aspect of the humerus and the lateral aspect of the scapula. This arch can be referred to as "Bani's line", described in 1981 (Bandi W Die Läsion der Rotatorenmanschette. Helv Chir Acta 48:537-549).
Some approaches create minimal disruption of the arch (i.e. a more "anatomic" reverse)
If the arch is disrupted, several things happen: (1) increased stress is put on the acromion and scapular spine leading to an increased risk of acromial and scapular spine fractures (SSF), (2) increase stress is placed on the brachial plexus, and (3) the normal alignment of residual infraspinus and subscapularis is disrupted.
The authors of this article hypthesized that postoperative distalization would increase the risk of SSF. They conducted a multicenter retrospective review was performed at a minimum of 1 year postoperatively on primary RSAs with an inlay design (n=342)
The incidence of SSF in the onlay group (11.9%) was significantly higher compared with the inlay group (4.7%).
The onlay stem resulted in a 10 mm increase in distalization compared with an inlay stem, and a 2.5 times increased risk of SSF.
Higher return to activity (92.1% vs. 71.4%) as well as postoperative forward flexion was observed in the group without fracture (135 vs. 120).
To see our technique for reverse total shoulder, click on this link.
To support our research to improve outcomes for patients with shoulder problems, click here.
How you can support research in shoulder surgery Click on this link.
To see our new series of youtube videos on important shoulder surgeries and how they are done, click here.
