title: Radiologic bone adaptations on a cementless short-stem shoulder prosthesis.
abstract: BACKGROUND
  This study evaluated the timing and location of radiologic bone adaptations related to shoulder arthroplasty using a single type of cementless short-stem shoulder prosthesis.
  
  
  METHODS
  Uncemented short-stem shoulder arthroplasties were evaluated in 52 patients at a mean age of 71.6 years (range, 58.1-86.6) with a minimum clinical and radiologic follow-up of 2 years (mean, 32 months; range, 23-52 months). All radiographs were analyzed for inclination of the stem, filling ratio of metaphysis and diaphysis, bone remodeling around the stem, radiolucent lines around the glenoid, and subsidence of the humeral stem. Finally, the radiographic and clinical findings were compared between patients with low and high bone adaptations.
  
  
  RESULTS
  At final follow-up, no loosening, subsidence, or osteolysis was seen. High bone adaptations were present in 27 patients (51.9%). Cortical thinning and osteopenia in the medial cortex (82.7%) and spot welds in the lateral cortex (78.6%) were the most frequently occurring bone adaptations. Patients with high bone adaptations had significantly higher metaphyseal (0.60 ± 0.05 vs. 0.56 ± 0.06; P = .024) and diaphyseal filling ratio (0.66 ± 0.04 vs. 0.61 ± 0.06; P = .019) at 2-year follow-up than patients with low bone adaptations. Clinical outcome was not influenced by the radiographic changes.
  
  
  CONCLUSIONS
  The clinical and radiologic results of the short-stem shoulder arthroplasty are comparable to those with the third and fourth generations of standard stem arthroplasty. Higher filling ratios in the metaphysis and the diaphysis were significantly associated with the occurrence of high bone adaptations.
authors.affiliation: BG Trauma Center Ludwigshafen at the University of Heidelberg, Heidelberg, Germany. Electronic address: marcschnetzke@gmx.de.
authors.forename: Marc
authors.initials: M
authors.lastname: Schnetzke
authors.affiliation: Hospital Dipreca, Santiago, Chile.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Coda
authors.affiliation: Clinic for Orthopedics and Trauma Surgery, University of Heidelberg, Heidelberg, Germany.
authors.forename: Patric
authors.initials: P
authors.lastname: Raiss
authors.affiliation: Centre Orthopédique Santy, Lyon, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Walch
authors.affiliation: ATOS Clinic Heidelberg, German Joint Center, Shoulder and Elbow Surgery, Heidelberg, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Loew
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019643:Arthroplasty, Replacement; D016723:Bone Remodeling; D001862:Bone Resorption / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D006811:Humerus / Q000503:physiopathology* / Q000601:surgery; D007595:Joint Prosthesis; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000601:surgery*; D011474:Prosthesis Design; D011859:Radiography; D012785:Shoulder Joint / Q000601:surgery*; D016896:Treatment Outcome
keywords: Total shoulder arthroplasty; bone adaptations; bone resorption; filling ratio; metaphyseal fixation; short stem; stress shielding