title: Improvement of the shoulder function after large segment resection of the proximal humerus with the use of an inverse tumour prosthesis.
abstract: OBJECTIVE
  Active shoulder function after segmental tumour resection of the proximal humerus and endoprosthetic reconstruction is regularly compromised, while the overall arm function allows a satisfying use in daily activities. The main functional problem remains the loss of huge parts of the shoulder girdle musculature and its bony attachment. In revision arthroplasty inverse shoulder implants can improve the active range of motion significantly in comparison to anatomical shaped prostheses. The aim of this study was to investigate if these promising experiences are transferable to reconstructions after tumour resection of the proximal humerus by using a modular inverse tumour prosthesis.
  
  
  METHODS
  In this study we observed the functional and oncological results of 18 inverse proximal humerus endoprosthetic replacements (IPHP) with the MUTARS system (Implantcast®) after resection of benign (1x giant cell) and malignant (11x primary bone sarcoma, 5x bone metastasis of carcinoma) bone tumours. Mean age at operation was 42 years. The mean postoperative follow-up was 33 months (range ten to 120).
  
  
  RESULTS
  Resection margins were wide in 13 and marginal in five patients. Mean reconstruction length was 15.1 cm (range 6-25 cm). Mean operation time was 191 minutes. The axillary nerve was mostly preserved in 78 % (n = 14). At latest follow-up the patients presented a medium MSTS-score of 24.6/30. The mean active arm abduction in the shoulder joint was 78° and 88° active arm elevation for patients with intact axillary nerve function, but significantly reduced for the four patients with compromised deltoid function. One patient needed a surgical revision due to a deep implant infection.
  
  
  CONCLUSIONS
  The IPHP offers a significant improvement of active shoulder function in patients in whom the axillary nerve can be preserved in comparison to anatomically-shaped implants. However, for patients without any deltoid function there is no benefit regarding an improved active range of motion using an IPHP.
authors.affiliation: Department of Orthopaedics, University Hospital of Münster, Albert-Schweitzer-Campus 1, Münster, Germany, streitb@ukmuenster.de.
authors.forename: Arne
authors.initials: A
authors.lastname: Streitbuerger
authors.forename: Marcel
authors.initials: M
authors.lastname: Henrichs
authors.forename: Georg
authors.initials: G
authors.lastname: Gosheger
authors.forename: Helmut
authors.initials: H
authors.lastname: Ahrens
authors.forename: Markus
authors.initials: M
authors.lastname: Nottrott
authors.forename: Wiebke
authors.initials: W
authors.lastname: Guder
authors.forename: Ralf
authors.initials: R
authors.lastname: Dieckmann
authors.forename: Jendrik
authors.initials: J
authors.lastname: Hardes
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D019643:Arthroplasty, Replacement / Q000379:methods*; D001365:Axilla / Q000294:innervation; D001859:Bone Neoplasms / Q000556:secondary / Q000601:surgery*; D005260:Female; D006801:Humans; D006811:Humerus / Q000601:surgery; D007595:Joint Prosthesis; D008297:Male; D008875:Middle Aged; D012516:Osteosarcoma / Q000556:secondary / Q000601:surgery*; D011474:Prosthesis Design; D012189:Retrospective Studies; D012782:Shoulder / Q000503:physiopathology* / Q000601:surgery; D012785:Shoulder Joint / Q000601:surgery; D055815:Young Adult