title: Anterior deltoid deficiency in reverse total shoulder replacement: a biomechanical study with cadavers.
abstract: Reverse total shoulder replacement (RTSR) depends   on adequate deltoid function for a successful outcome. However, the   anterior deltoid and/or axillary nerve may be damaged due to prior   procedures or injury. The purpose of this study was to determine   the compensatory muscle forces required for scapular plane elevation   following RTSR when the anterior deltoid is deficient. The soft   tissues were removed from six cadaver shoulders, except for tendon   attachments. After implantation of the RTSR, the shoulders were   mounted on a custom-made shoulder simulator to determine the mean   force in each muscle required to achieve 30° and 60° of scapular   plane elevation. Two conditions were tested: 1) Control with an   absent supraspinatus and infraspinatus; and 2) Control with anterior   deltoid deficiency. Anterior deltoid deficiency resulted in a mean   increase of 195% in subscapularis force at 30° when compared with   the control (p = 0.02). At 60°, the subscapularis force increased   a mean of 82% (p < 0.001) and the middle deltoid force increased   a mean of 26% (p = 0.04). Scapular plane elevation may still be possible following an RTSR   in the setting of anterior deltoid deficiency. When the anterior   deltoid is deficient, there is a compensatory increase in the force   required by the subscapularis and middle deltoid. Attempts to preserve   the subscapularis, if present, might maximise post-operative function.
authors.affiliation: Hospital For Special Surgery, 535 E 70th Street, New York, New York 10021, USA. gulottal@hss.edu
authors.forename: L V
authors.initials: LV
authors.lastname: Gulotta
authors.forename: D
authors.initials: D
authors.lastname: Choi
authors.forename: P
authors.initials: P
authors.lastname: Marinello
authors.forename: T
authors.initials: T
authors.lastname: Wright
authors.forename: F A
authors.initials: FA
authors.lastname: Cordasco
authors.forename: E V
authors.initials: EV
authors.lastname: Craig
authors.forename: R F
authors.initials: RF
authors.lastname: Warren
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena; D002102:Cadaver; D057645:Deltoid Muscle / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D016059:Range of Motion, Articular / Q000502:physiology*; D012785:Shoulder Joint / Q000503:physiopathology / Q000601:surgery*