Muller vs. Virtec straight stem shape comparable for long-term radiological change in THR .
OrthoEvidence Journal (OE Journal) - ACE Report
OE Journal. 2016;4(12):16 Acta Orthop. 2016 Apr;87(2):120-5.646 patients (711 hips) patients undergoing primary total hip replacement with straight femoral stem cement fixation were randomized to receive either a Muller straight stem (MSS) or the Virtec straight stem (VSS) for the purpose of comparing long-term radiographical and survival success ten years post-surgery. Results demonstrated that patients in both groups had comparable implant survival, osteolysis, subsidence, and debonding rates at 10 years.
Was the allocation sequence adequately generated?
Was allocation adequately concealed?
Blinding Treatment Providers: Was knowledge of the allocated interventions adequately prevented?
Blinding Outcome Assessors: Was knowledge of the allocated interventions adequately prevented?
Blinding Patients: Was knowledge of the allocated interventions adequately prevented?
Was loss to follow-up (missing outcome data) infrequent?
Are reports of the study free of suggestion of selective outcome reporting?
Were outcomes objective, patient-important and assessed in a manner to limit bias (ie. duplicate assessors, Independent assessors)?
Was the sample size sufficiently large to assure a balance of prognosis and sufficiently large number of outcome events?
Was investigator expertise/experience with both treatment and control techniques likely the same (ie.were criteria for surgeon participation/expertise provided)?
Ja = 1
Ungewiss = 0.5
Nicht relevant = 0
Nein = 0
Die Bewertung der Berichtskriterien bewertet die Transparenz, mit der die Autoren die methodischen und studienspezifischen Merkmale der Studie in der Veröffentlichung angeben. Die Bewertung ist in fünf Kategorien unterteilt, die im Folgenden vorgestellt werden.
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Randomization
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Outcome Measurements
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Inclusion / Exclusion
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Therapy Description
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Statistics
Detsky AS, Naylor CD, O'Rourke K, McGeer AJ, L'Abbé KA. J Clin Epidemiol. 1992;45:255-65
Der Fragilitätsindex ist ein Instrument, das bei der Interpretation signifikanter Ergebnisse hilft und ein Maß für die Stärke eines Ergebnisses liefert. Der Fragilitätsindex gibt die Anzahl der aufeinanderfolgenden Ereignisse an, die zu einem dichotomen Ergebnis hinzugefügt werden müssen, damit das Ergebnis nicht mehr signifikant ist. Eine kleine Zahl steht für ein schwächeres Ergebnis und eine große Zahl für ein stärkeres Ergebnis.
Warum wurde diese Studie jetzt benötigt?
There are two major femoral stem fixation methods that are regularly used in total hip replacement: shape-closed or force-closed stems. In shape-closed fixation, stems are surrounded by a thin cement mantle and are enhanced with an additional press-fit fixation against the cortical bone. Furthermore, shape-closed fixation can use varying stem shapes, including the Muller straight stem (which has a rectangular cross section) and the Virtec straight stem (which has a wider cross section with rounder edges). Due to the lack of conclusive evidence supporting a significant long-term benefit of one stem shape over the other, the current study was conducted.
Was war die wichtigste Forschungsfrage?
For patients undergoing cemented shape-closed fixation during total hip replacement, did either the Muller straight stem (MSS) or the Virtec straight stem (VSS) result in significant radiographical improvement in osteolysis, radiolucency, and distal migration when compared at least ten years post-surgery?
- When compared at 10 years, Kaplan-Meier (KM) survival after "revision of component for any reason" was observed to be 92% (95% CI 88-95) in the MSS group and 95% (95% CI 92-97) in the VSS group; the difference was not significant (p=0.1)
- KM survival after revision for "aseptic loosening of the stem", specifically was 96% (95% CK 94-99) in the MSS group and 98% (95% CI 97-100) in the VSS group; the difference was also not significant (p=0.2).
- 399 hips (196 in the MSS group and 203 in the VSS group) were radiologically assessed at a mean follow-up of 11 (10 to 16) years for unrevised hips and 6.85 (1 to 16) years for revised hips.
- In the stems that were revised for aseptic loosening (n=22), 17 of them displayed radiological osteolysis on the final radiograph before revision; osteolysis was found to be more common in the MSS groups in Gruen zones 2, 6, and 7 (p=0.06, p=0.07, and p=0.04 respectively).
- Subsidence was found in 5 MSS stems and 4 VSS stems; debonding at the cement-prosthesis interface was found in 6 MSS stems and 4 VSS stems (all 10 cases of debonding were observed in Gruen zone 1).
Was sollte ich mir besonders merken?
For patients undergoing cemented shape-closed fixation during total hip replacement, both the Muller straight stem (MSS) and the Virtec straight stem (VSS) resulted in adequate long-term survival with minimal aseptic loosening, incidence of osteolysis, subsidence and debonding.
Wie wird sich dies auf die Behandlung meiner Patienten auswirken?
The results of this study suggest that Muller and Virtec stems offer excellent survival over a 10 year period. Further randomized trials should be undertaken to evaluate the effect of stem geometry on radiographic changes and survival in different implants.
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