ARTHROPLASTY
Metal ion levels and functional results after either resurfacing hip arthroplasty or conventional metal-on-metal hip arthroplasty
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by one or more authors of the
original publication.
OrthoEvidence Journal (OE Journal) - ACE Report
OE Journal. 2013;1(8):3 Acta Orthop. 2011 Oct;82(5):559-66Exclusive Author Interview
Dr. Van Susante discusses metal ion concentrations following hip resurfacing and conventional metal-on-metal arthroplasty
82 patients requiring a total hip replacement were randomized to receive a resurfacing hip arthroplasty or a conventional uncemented metal-on-metal total hip arthroplasty. The objective of this trial was to compare both functional outcomes and cobalt and chromium blood levels. The results indicate that patients who underwent resurfacing arthroplasty had higher chromium concentrations for up to 24 months post-surgery. Additionally, cobalt concentrations were higher in the blood for 6 months. Both groups demonstrated improvements in functional outcome measurements 24 month postoperatively.
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)?
はい = 1
不確実＝0.5
無関係 = 0
いいえ = 0
報告基準評価では、著者が出版物内で試験の方法論的特徴や試験特性を報告する際の透明性を評価します。評価は以下の5つのカテゴリーに分類されます。
3/4
Randomization
2/4
Outcome Measurements
4/4
Inclusion / Exclusion
4/4
Therapy Description
3/4
Statistics
Detsky AS, Naylor CD, O'Rourke K, McGeer AJ, L'Abbé KA. J Clin Epidemiol. 1992;45:255-65
Fragility Indexは、重要な所見の解釈を助けるツールで、結果の強さの尺度を提供します。Fragility Indexは、その所見が有意でなくなるために、二項対立の結果に追加する必要がある連続した事象の数を表します。数値が小さいほど弱い所見を表し、数値が大きいほど強い所見を表します。
なぜ今この研究が必要なのですか？
In the treatment of advanced hip osteoarthritis, hip resurfacing arthroplasty is considered the best option. Although this procedure is hypothesized to have several advantages in comparison to conventional total hip arthroplasty; these benefits have not been confirmed by scientific evidence. Only one RCT evaluated the clinical outcomes observed with resurfacing arthroplasty compared to metal-on-metal hip arthroplasty. Results from this study demonstrate improvements in functional outcomes with the resurfacing procedure; however, confounding factors may be affecting the result. In addition, there is also concern regarding toxic effects from increased metal ions (cobalt and chromium) in the blood. The previous RCT only examined functional outcomes; therefore, a trial evaluating blood levels of cobalt and chromium was merited.
主な研究課題は何ですか？
What are the effects of a resurfacing total hip arthroplasty on functional outcomes and cobalt and chromium blood levels when compared to a conventional uncemented metal-on-metal total hip arthroplasty, measured over a 24 month period?
重要な知見は？
- All functional outcome measures (HHS, OHS, UCLA, SF-12) improved following surgery and was maintained up until 24 months, in both treatment groups (p<0.001).
- At 12 and 24 months, those in the resurfacing group had a median UCLA activity score of 8, compared to a score of 7 in the conventional group (p<0.05). Despite the randomization, patients in the resurfacing group had higher UCLA scores at baseline.
- At 24 months, the OHS was a median 13 in resurfacing patients compared to 16 in the conventional group (p<0.05).
- There was no statistically significant difference in patient satisfaction between the groups, at the 24 month follow up. However, patients in the resurfacing group were more satisfied than those in the conventional group, at 12 months (p=0.01, r=-0.30).
- Cobalt concentrations were higher in the patients undergoing resurfacing arthroplasty compared to those in the conventional arthroplasty group at both 3 months (p<0.001, r=-0.50) and 6 months (p=0.006, r=-0.35).
- Chromium concentrations were significantly higher in the resurfacing arthroplasty group, and this trend was observed for all time points up until 24 months (p<0.001, r=-0.50).
- Two patients in the conventional arthroplasty group had an insert exchange for recurrent dislocation. One patient in the resurfacing group had a femoral component revision due to early aseptic loosening. No pseudotumors were encountered in either group.
最も覚えておくべきことは？
The levels of chromium and cobalt in the blood were greater in the resurfacing group at the 6 month follow-up, The increase concentration of chromium was maintained for all follow-ups, where as the increase concentration of cobalt diminished. Patients in the resurfacing group had superior UCLA, OHS scores, and satisfaction at some follow-up periods.
それが私の患者ケアにどのように影響するか？
Studies with longer follow-up periods are required to more accurately determine the benefits and risks associated with the resurfacing arthroplasty compared to the conventional arthroplasty.
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