Table 2.

Difference in complication rates depending on specific RSA design

Implant design type		Effect on the complication rate
Glenoid	Lateral offset	Lateralization of glenosphere with metal or bone augment decreases scapular notching,50 increases ROM,17 increases soft tissue tensioning and acromial stress.72 Eccentric glenosphere might decrease scapular notching,54 or at least decrease its severity.55 Glenoid lateralization may be a risk factor for acromial or scapular spine fractures.66,72
	Inferior overhang	Inferior overhang of more than > 3.5 mm decreases/minimizes scapular notching56,57 and improves range of motion.17
	Inferior tilt	Placing the glenoid baseplate in 10 degrees of inferior inclination in order to avoid superior inclination might increase shear forces on the glenosphere,110 decrease the likelihood of instability83 scapular notching50,111 and loosening.43,112
	Large diameter	Larger glenospheres have greater incidence of dissociation,31,84 decrease scapular notching51,52 and improve range of motion especially in external rotation and adduction.17
Humerus	Varus neck-shaft angle	The use of 135 degree neck-shaft angle decreases scapular notching50 compared to 155 degrees. Grammont-style RSA. No difference in dislocation rates between a 135 and 155 degree humeral inclination.78 Use of the 135 or 145 degree humeral neck inclination could contribute to increase in ROM.17
	Grammont-style 155 degree neck-shaft angle	Subscapularis integrity proves to be most effective.76,77
	Retrotorsion	Excessive retrotorsion leads to decreased internal and increased external rotation.60 The best compromise between anterior and posterior notching to favour a functional arc of motion seems to be 20 to 40 degrees of humeral retrotorsion.61
	Short stem	Risk factor for intraoperative fractures.94
	Stemless	Risk factor for intraoperative and postoperative fractures.95
	Onlay stem vs. inlay stem	Onlay stem increases distalization, which leads to increased risk of scapular spine fracture compared to inlay stem.33,73,74
Different combinations	Medial glenoid/medial humerus	Increases risk of scapular notching.41
	Medial glenoid/lateral humerus	Decreases risk of scapular notching and instability significantly more than combination of medial glenoid/medial humerus or lateral glenoid/medial humerus.41
	Lateral glenoid/medial humerus	Decreases risk for scapular notching and instability compared to combination of medial glenoid/medial humerus.41

Note. RSA, reverse shoulder arthroplasty; ROM, range of motion; M, medialized; L lateralized.