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Fixed or loose? Dic...
Fixed or loose? Dichotomy in RSA data for cemented cups
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- Aspenberg, Per, 1949- (författare)
- Östergötlands Läns Landsting,Linköpings universitet,Hälsouniversitetet,Ortopedi och idrottsmedicin,Ortopedkliniken Linköping,Department of Orthopaedics, IKE, Faculty of Health Sciences, Linköping
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- Wagner, Philippe (författare)
- Swedish National Competence Center for Musculoskeletal Disorders Lund University Hospital
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- Nilsson, Kjell G. (författare)
- Umeå universitet,Ortopedi
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- Ranstam, Jonas (författare)
- Lund University,Lunds universitet,Ortopedi, Lund,Sektion III,Institutionen för kliniska vetenskaper, Lund,Medicinska fakulteten,Orthopaedics (Lund),Section III,Department of Clinical Sciences, Lund,Faculty of Medicine,Swedish National Competence Center for Musculoskeletal Disorders Lund University Hospital
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(creator_code:org_t)
- 2009-07-08
- 2008
- Engelska.
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Ingår i: Acta Orthopaedica. - Basingstoke : Medical Journals Sweden AB. - 1745-3674 .- 1745-3682. ; 79:4, s. 467-473
- Relaterad länk:
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http://www.ncbi.nlm....
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https://doi.org/10.1...
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http://dx.doi.org/10...
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https://urn.kb.se/re...
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https://doi.org/10.1...
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https://lup.lub.lu.s...
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https://urn.kb.se/re...
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Abstract
Ämnesord
Stäng
- BACKGROUND AND PURPOSE: Roentgen stereometric analysis (RSA) cannot discern whether a single prosthesis is fixed or migrating below the detection level. Samples of patients usually show migration values that appear to be continuously distributed. Is there such continuity, or is there a dichotomy between stable and migrating prostheses? The hypothesis of a dichotomy has, to our knowledge, not been tested. We present an exploratory evaluation of such a dichotomy using a mixture distribution algorithm. METHODS: We analyzed the migration (as determined by RSA) of 147 cemented acetabular cups of 7 different designs by using a new set of algorithms for frequency distribution analysis called Rmix. RESULTS: We first analyzed a migration vector, regardless of direction. After 2 years there was a significant dichotomy between 2 lognormal subgroups within the sample. Although some types of cups were over-represented in one of the subgroups, neither cup design, sex, nor operating department could explain the dichotomy into two groups, which appears to reflect the existence of two basically different types of behavior of the cups. We next analyzed the migration along the 3 axes in space, and found a similar dichotomy. During the second year, around 80% of the patients belonged to a distinct, normally distributed subgroup with a mean not different from 0 mm and a small variation. The remainder differed significantly from this subgroup and showed migration. INTERPRETATION: There is a dichotomy in migration pattern. During the second postoperative year, most cups belonged to a subpopulation that appeared stable. The remainder is probably at risk of loosening. For a single type of prosthesis, the relative size of the stable subgroup may be a good index of the expected performance. The possibility of detecting subgroups within a seemingly continuous sample might be useful in many fields of medicine.
Ämnesord
- MEDICIN OCH HÄLSOVETENSKAP -- Klinisk medicin -- Ortopedi (hsv//swe)
- MEDICAL AND HEALTH SCIENCES -- Clinical Medicine -- Orthopaedics (hsv//eng)
Nyckelord
- Acetabulum/*radiography Aged Aged
- 80 and over Algorithms Arthroplasty
- Replacement
- Hip/*adverse effects/methods Cementation Female Hip Prosthesis/adverse effects Humans Male Middle Aged Photogrammetry Prosthesis Design *Prosthesis Failure
- MEDICINE
- MEDICIN
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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