Cementless RM Pressfit Cup: a clinical and radiological study of 91 cases with at least four years follow-up.
Cementless metal-back acetabular cups have good long-term results, but some problems have appeared due to the shell's stiffness, modularity and required bearing surfaces. The RM Pressfit Cup is a single-piece polyethylene cementless acetabular cup that is covered by a thin layer of titanium. This allows for bone integration without limitations related to the stiffness of a metal-back shell. There is very little published information about this new, innovative implant design. The purpose of this study was to evaluate the clinical and radiological results from a continuous series of 91 cups (85 patients) with a follow-up of at least 4 years. No patients were lost to follow-up. The Harris Hip Score (HHS) was used to assess the clinical outcome. To assess the radiological outcomes, digital X-rays were used to evaluate the cup position and integration; wear was measured using Livermore's technique. The clinical results were excellent: the mean HHS was 94 and 82% of cases had good or excellent scores. Three of the cups had to be revised because of dislocation brought on by incorrect positioning. X-rays revealed that three implants had shifted during the first 6 weeks, but had stabilized afterwards. Bone integration on X-rays was satisfactory in all cases with no signs of osteolysis. The configuration of the bone trabeculae showed that loads between the implant and peri-acetabular cancellous bone were evenly distributed. The wear of the polyethylene cup-ceramic head bearing was 0.07 mm/year. The results of this series are consistent with recent published studies with the RM Pressfit Cup.


METHODS
IV.
Orthopaedic Surgery Department 2, Tours CHRU, Université François-Rabelais de Tours, PRES Centre-Val de Loire Université, Tours, France.
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L
Lafon
Orthopaedic Surgery Department 2, Tours CHRU, Université François-Rabelais de Tours, PRES Centre-Val de Loire Université, Tours, France.
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H
Moubarak
Orthopaedic Surgery Department 2, Tours CHRU, Université François-Rabelais de Tours, PRES Centre-Val de Loire Université, Tours, France.
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J
Druon
Orthopaedic Surgery Department 2, Tours CHRU, Université François-Rabelais de Tours, PRES Centre-Val de Loire Université, Tours, France. Electronic address: rosset@med.univ-tours.fr.
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P
Rosset
D000077:Acetabulum / Q000000981:diagnostic imaging* / Q000502:physiology / Q000601:surgery*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation*; D019544:Equipment Failure Analysis; D005260:Female; D005500:Follow-Up Studies; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000502:physiology / Q000601:surgery; D006622:Hip Prosthesis; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000601:surgery; D010012:Osteogenesis / Q000502:physiology; D010020:Osteonecrosis / Q000601:surgery; D020959:Polyethylene; D011474:Prosthesis Design; D011859:Radiography; D014025:Titanium; D016896:Treatment Outcome
D020959:Polyethylene; D014025:Titanium
Cementless acetabular cup; Osseointegration; Total hip arthroplasty