title: The RM Pressfit vitamys: 5-year Swiss experience of the first 100 cups.
abstract: BACKGROUND
  The RM Pressfit vitamys is a titanium particle-coated monoblock cup with vitamin E stabilised highly cross-linked polyethylene. Initial fixation is achieved via press-fit with subsequent stability by bone on-growth. This is the first study to report the 5-year results of this design.
  
  
  METHODS
  We performed a prospective cohort study according to STROBE guidelines of 100 consecutive total hip replacements (THRs) in 92 patients all with ceramic heads. Demographic data, pre/postoperative visual analogue scale (VAS) for pain and satisfaction, Harris Hip Scores (HHS) and complications were recorded. Radiographic analysis of osteolysis and loosening was complemented by EBRA (Einzel-Bild-Röntgen-Analyse) evaluation of cup movement.
  
  
  RESULTS
  Our cohort comprised 48 women (mean age 67; SD 10.4) and 44 men (mean age 69; SD 7.8). The mean body mass index was 27 kg/m2 (SD 4.6). Surgical indications were osteoarthritis 96%, avascular necrosis 3% and fracture 1%. 82% had a direct anterior approach, 15% anterolateral and 3% trans-gluteal. 4 surgeons were involved. 1 cup was repositioned and fixed with screws within a week of index surgery. There were 2 intraoperative femoral fractures, 3 haematomata with 1 requiring drainage and 1 deep infection settling with an open washout and modular exchange. Mean VAS satisfaction increased from 3.8 (SD 2.0) to 8.8 at 6 weeks (SD 1.4) and 9.5 (SD 1.3) at 5 years. The HHS functional scores were 58.9 (SD 13.2) preoperatively and 94.6 (SD 6.6) at 5 years. Radiographic analysis showed neither progressive radiolucency nor osteolysis. Mean migration was 1.5 mm after 5 years.
  
  
  CONCLUSIONS
  Mid-term results of the RM Pressfit vitamys cup are encouraging.
authors.affiliation: Clinic for Orthopaedic and Trauma Surgery, Luzerner Kantonsspital, Luzern - Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: Wyatt
authors.affiliation: Clinic for Orthopaedic and Trauma Surgery, Luzerner Kantonsspital, Luzern - Switzerland.
authors.forename: Jan
authors.initials: J
authors.lastname: Weidner
authors.affiliation: Clinic for Orthopaedic and Trauma Surgery, Luzerner Kantonsspital, Luzern - Switzerland.
authors.forename: Dominik
authors.initials: D
authors.lastname: Pfluger
authors.affiliation: Clinic for Orthopaedic and Trauma Surgery, Luzerner Kantonsspital, Luzern - Switzerland.
authors.forename: Martin
authors.initials: M
authors.lastname: Beck
mesh_terms: D000077:Acetabulum / Q000601:surgery; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D020099:Coated Materials, Biocompatible; D015331:Cohort Studies; D005260:Female; D005271:Femur Head Necrosis / Q000000981:diagnostic imaging / Q000601:surgery; D005500:Follow-Up Studies; D006620:Hip Fractures / Q000000981:diagnostic imaging / Q000601:surgery; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging / Q000601:surgery; D011446:Prospective Studies; D011474:Prosthesis Design / Q000379:methods*; D011475:Prosthesis Failure; D018570:Risk Assessment; D013557:Switzerland; D013997:Time Factors; D014025:Titanium; D014810:Vitamin E / Q000494:pharmacology*
chemical_list: D020099:Coated Materials, Biocompatible; D014810:Vitamin E; D014025:Titanium