title: Influence of arm lengthening in reverse shoulder arthroplasty.
abstract: BACKGROUND
  Reverse shoulder arthroplasty (RSA) can improve anterior active elevation (AAE) by lengthening of the deltoid and hence increasing its lever arm. However, evaluations of functional outcomes of RSA have shown variable improvements in the range of motion. The aim of our study was to correlate humeral and arm lengthening to postoperative AAE.
  
  
  METHODS
  We reviewed 183 RSAs with a minimum follow-up of 1 year. Lengthening of the humerus and the arm was evaluated in relation to the contralateral side.
  
  
  RESULTS
  We observed mean humeral lengthening of 0.2 ± 1.4 cm (range, -4.7 to +5.2 cm) and mean arm lengthening of 1.6 ± 1.9 cm (range, -5.1 to +5.4 cm). Postoperative AAE was 140° ± 27° (range, 30° to 180°). We found no significant correlation between lengthening or shortening of the humerus and AAE (P = .169). Shortening of the arm led to a mean AAE value of 122°; lengthening of 0 and 1 cm, mean AAE of 140°; lengthening of greater than 1 cm to 2.5 cm, mean AAE of 144°; and lengthening of greater than 2.5 cm, mean AAE of 147°. When we compared patients with lengthening of the arm and those with shortening, the postoperative AAE was significantly greater after arm lengthening, 145° versus 122°, with a mean difference of 23° (95% confidence interval, 13° to 33°) (P < .001).
  
  
  CONCLUSIONS
  This study shows that shortening of the arm reduced AAE. With respect to arm lengthening, a lengthening threshold was not found. An objective assessment of deltoid lengthening is possible preoperatively, intraoperatively, and postoperatively, and this measure seems to correlate with the functional outcome.
authors.affiliation: Service de Chirurgie Orthopédique et Traumatologie de l'Appareil Moteur, Hôpitaux Universitaires de Genève, Geneva, Switzerland. Alexandre.laedermann@hcuge.ch
authors.forename: Alexandre
authors.initials: A
authors.lastname: Lädermann
authors.forename: Gilles
authors.initials: G
authors.lastname: Walch
authors.forename: Anne
authors.initials: A
authors.lastname: Lubbeke
authors.forename: Gregory N
authors.initials: GN
authors.lastname: Drake
authors.forename: Barbara
authors.initials: B
authors.lastname: Melis
authors.forename: Guillaume
authors.initials: G
authors.lastname: Bacle
authors.forename: Philippe
authors.initials: P
authors.lastname: Collin
authors.forename: T Bradley
authors.initials: TB
authors.lastname: Edwards
authors.forename: François
authors.initials: F
authors.lastname: Sirveaux
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001132:Arm; D019643:Arthroplasty, Replacement / Q000009:adverse effects* / Q000379:methods; D001852:Bone Lengthening / Q000379:methods*; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006811:Humerus / Q000601:surgery*; D007090:Image Interpretation, Computer-Assisted; D007595:Joint Prosthesis; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011182:Postoperative Care / Q000379:methods; D011475:Prosthesis Failure; D016059:Range of Motion, Articular / Q000502:physiology*; D020127:Recovery of Function; D012086:Reoperation / Q000379:methods; D012189:Retrospective Studies; D018570:Risk Assessment; D012782:Shoulder / Q000000981:diagnostic imaging / Q000601:surgery*; D014057:Tomography, X-Ray Computed / Q000379:methods; D016896:Treatment Outcome; D055815:Young Adult