title: Histological evaluation of two designs of shoulder surface replacement implants.
abstract: OBJECTIVE
  To assess the extent of osteointegration in two designs of shoulder resurfacing implants. Bony integration to the Copeland cylindrical central stem design and the Epoca RH conical-crown design were compared.
  
  
  METHODS
  Implants retrieved from six patients in each group were pair-matched. Mean time to revision surgery of Copeland implants was 37 months (standard deviation (sd) 23; 14 to 72) and Epoca RH 38 months (sd 28; 12 to 84). The mean age of patients investigated was 66 years (sd 4; 59 to 71) and 58 years (sd 17; 31 to 73) in the Copeland and Epoca RH groups respectively. None of these implants were revised for loosening.
  
  
  RESULTS
  Increased osteointegration was measured under the cup in the Copeland implant group with limited bone seen in direct contact with the central stem. Bone adjacent to the Epoca RH implants was more uniform.
  
  
  CONCLUSIONS
  This difference in the distribution of bone-implant contact and bone formation was attributed to the Epoca implant's conical crown, which is positioned in more dense peripheral bone. The use of a central stem may not be necessary provided there is adequate peripheral fixation within good quality humeral bone.
  
  
  CONCLUSIONS
  Poor osteointegration of cementless surface replacement shoulder prosthesis may be improved by implant design.
authors.affiliation: University College London, John Scales Centre for Biomedical Engineering, Institute of Orthopaedics and Musculoskeletal Science, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex HA7 4LP, UK.
authors.forename: S
authors.initials: S
authors.lastname: Ajami
authors.affiliation: University College London, John Scales Centre for Biomedical Engineering, Institute of Orthopaedics and Musculoskeletal Science, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex HA7 4LP, UK.
authors.forename: G W
authors.initials: GW
authors.lastname: Blunn
authors.affiliation: University College London, John Scales Centre for Biomedical Engineering, Institute of Orthopaedics and Musculoskeletal Science, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex HA7 4LP, UK.
authors.forename: S
authors.initials: S
authors.lastname: Lambert
authors.affiliation: University College London, John Scales Centre for Biomedical Engineering, Institute of Orthopaedics and Musculoskeletal Science, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex HA7 4LP, UK.
authors.forename: S
authors.initials: S
authors.lastname: Alexander
authors.affiliation: University College London, John Scales Centre for Biomedical Engineering, Institute of Orthopaedics and Musculoskeletal Science, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex HA7 4LP, UK.
authors.forename: M
authors.initials: M
authors.lastname: Foxall Smith
authors.affiliation: University College London, John Scales Centre for Biomedical Engineering, Institute of Orthopaedics and Musculoskeletal Science, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex HA7 4LP, UK.
authors.forename: M J
authors.initials: MJ
authors.lastname: Coathup
mesh_terms: D000368:Aged; D019643:Arthroplasty, Replacement; D015519:Bone Density; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D016348:Osseointegration; D011474:Prosthesis Design; D012086:Reoperation; D012189:Retrospective Studies; D012785:Shoulder Joint / Q000473:pathology / Q000601:surgery*; D013997:Time Factors
keywords: Shoulder; Resurfacing; Bone regeneration ;Uncemented Implant; Revision surgery