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Survival of uncemented acetabular monoblock cups: evaluation of 210 hips in the Swedish Hip Arthroplasty Register.

Weiss RJ, Hailer NP, Stark A, Kärrholm J - Acta Orthop (2012)

Bottom Line: The use of 28-mm prosthesis heads rather than 22-mm heads reduced the risk of cup revision (HR = 0.2, CI: 0.1-0.5; p = 0.001).There was no statistically significant difference in revision risk between the cup designs.Further review of the current patient population is warranted to determine the long-term durability and risk of revision of monoblock cup designs.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Medicine and Surgery, Section of Orthopaedics and Sports Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden. rudiger.weiss@karolinska.se

ABSTRACT

Background and purpose: Monoblock acetabular cups represent a subtype of uncemented cups with the polyethylene liner molded into a metal shell, thus eliminating-or at least minimizing-potential backside wear. We hypothesized that the use of monoblock cups could reduce the incidence of osteolysis and aseptic loosening, and thus improve survival compared to modular designs.

Patients and methods: We identified all 210 primary total hip arthroplasty (THA) procedures in the Swedish Hip Arthroplasty Register that used uncemented monoblock cups during the period 1999-2010. Kaplan-Meier and Cox regression analyses with adjustment for age, sex, and other variables were used to calculate survival rates and adjusted hazard ratios (HRs) of the revision risk for any reason. 1,130 modular cups, inserted during the same time period, were used as a control group.

Results: There was a nearly equal sex distribution in both groups. Median age at the index operation was 47 years in the monoblock group and 56 years in the control group (p < 0.001). The cumulative 5-year survival with any revision as the endpoint was 95% (95% CI: 91-98) for monoblock cups and 97% (CI: 96-98) for modular cups (p = 0.6). The adjusted HR for revision of monoblock cups compared to modular cups was 2 (CI: 0.8-6; p = 0.1). The use of 28-mm prosthesis heads rather than 22-mm heads reduced the risk of cup revision (HR = 0.2, CI: 0.1-0.5; p = 0.001).

Interpretation: Both cups showed good medium-term survival rates. There was no statistically significant difference in revision risk between the cup designs. Further review of the current patient population is warranted to determine the long-term durability and risk of revision of monoblock cup designs.

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Related in: MedlinePlus

Kaplan-Meier analysis (with 95% CI) of monoblock and modular cups with revision for any reason as the endpoint.
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Figure 1: Kaplan-Meier analysis (with 95% CI) of monoblock and modular cups with revision for any reason as the endpoint.


Survival of uncemented acetabular monoblock cups: evaluation of 210 hips in the Swedish Hip Arthroplasty Register.

Weiss RJ, Hailer NP, Stark A, Kärrholm J - Acta Orthop (2012)

Kaplan-Meier analysis (with 95% CI) of monoblock and modular cups with revision for any reason as the endpoint.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3369144&req=5

Figure 1: Kaplan-Meier analysis (with 95% CI) of monoblock and modular cups with revision for any reason as the endpoint.
Bottom Line: The use of 28-mm prosthesis heads rather than 22-mm heads reduced the risk of cup revision (HR = 0.2, CI: 0.1-0.5; p = 0.001).There was no statistically significant difference in revision risk between the cup designs.Further review of the current patient population is warranted to determine the long-term durability and risk of revision of monoblock cup designs.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Medicine and Surgery, Section of Orthopaedics and Sports Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden. rudiger.weiss@karolinska.se

ABSTRACT

Background and purpose: Monoblock acetabular cups represent a subtype of uncemented cups with the polyethylene liner molded into a metal shell, thus eliminating-or at least minimizing-potential backside wear. We hypothesized that the use of monoblock cups could reduce the incidence of osteolysis and aseptic loosening, and thus improve survival compared to modular designs.

Patients and methods: We identified all 210 primary total hip arthroplasty (THA) procedures in the Swedish Hip Arthroplasty Register that used uncemented monoblock cups during the period 1999-2010. Kaplan-Meier and Cox regression analyses with adjustment for age, sex, and other variables were used to calculate survival rates and adjusted hazard ratios (HRs) of the revision risk for any reason. 1,130 modular cups, inserted during the same time period, were used as a control group.

Results: There was a nearly equal sex distribution in both groups. Median age at the index operation was 47 years in the monoblock group and 56 years in the control group (p < 0.001). The cumulative 5-year survival with any revision as the endpoint was 95% (95% CI: 91-98) for monoblock cups and 97% (CI: 96-98) for modular cups (p = 0.6). The adjusted HR for revision of monoblock cups compared to modular cups was 2 (CI: 0.8-6; p = 0.1). The use of 28-mm prosthesis heads rather than 22-mm heads reduced the risk of cup revision (HR = 0.2, CI: 0.1-0.5; p = 0.001).

Interpretation: Both cups showed good medium-term survival rates. There was no statistically significant difference in revision risk between the cup designs. Further review of the current patient population is warranted to determine the long-term durability and risk of revision of monoblock cup designs.

Show MeSH
Related in: MedlinePlus