title: How reverse shoulder arthroplasty works.
abstract: BACKGROUND
  The reverse total shoulder arthroplasty was introduced to treat the rotator cuff-deficient shoulder. Since its introduction, an improved understanding of the biomechanics of rotator cuff deficiency and reverse shoulder arthroplasty has facilitated the development of modern reverse arthroplasty designs.
  
  
  OBJECTIVE
  We review (1) the basic biomechanical challenges associated with the rotator cuff-deficient shoulder; (2) the biomechanical rationale for newer reverse shoulder arthroplasty designs; (3) the current scientific evidence related to the function and performance of reverse shoulder arthroplasty; and (4) specific technical aspects of reverse shoulder arthroplasty.
  
  
  METHODS
  A PubMed search of the English language literature was conducted using the key words reverse shoulder arthroplasty, rotator cuff arthropathy, and biomechanics of reverse shoulder arthroplasty. Articles were excluded if the content fell outside of the biomechanics of these topics, leaving the 66 articles included in this review.
  
  
  RESULTS
  Various implant design factors as well as various surgical implantation techniques affect stability of reverse shoulder arthroplasty and patient function. To understand the implications of individual design factors, one must understand the function of the normal and the cuff-deficient shoulder and coalesce this understanding with the pathology presented by each patient to choose the proper surgical technique for reconstruction.
  
  
  CONCLUSIONS
  Several basic science and clinical studies improve our understanding of various design factors in reverse shoulder arthroplasty. However, much work remains to further elucidate the performance of newer designs and to evaluate patient outcomes using validated instruments such as the American Society for Elbow Surgery, simple shoulder test, and the Constant-Murley scores.
authors.affiliation: Florida Orthopaedic Institute, 13020 Telecom Parkway North, Tampa, FL 33637, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Walker
authors.forename: Jordan
authors.initials: J
authors.lastname: Brooks
authors.forename: Matthew
authors.initials: M
authors.lastname: Willis
authors.forename: Mark
authors.initials: M
authors.lastname: Frankle
mesh_terms: D019643:Arthroplasty, Replacement / Q000295:instrumentation; D001696:Biomechanical Phenomena; D004185:Disability Evaluation; D006801:Humans; D007595:Joint Prosthesis; D053580:Muscle Strength; D011474:Prosthesis Design; D011859:Radiography; D016059:Range of Motion, Articular; D020127:Recovery of Function; D017006:Rotator Cuff / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D000070636:Rotator Cuff Injuries; D012421:Rupture; D012785:Shoulder Joint / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D013708:Tendon Injuries / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D016896:Treatment Outcome