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Primary stability of two uncementedacetabular components of different geometry: hemispherical or peripherallyenhanced?

Antoniades G, Smith EJ, Deakin AH, Wearing SC, Sarungi M - Bone Joint Res (2013)

Bottom Line: The objective was to determine whether altered geometry resulted in better primary stability.However, the PSL component required a significantly higher seating force than the hemispherical cup in the high-density bone analogue (p = 0.006).Our results, if translated clinically, suggest that a purely hemispherical geometry may have an advantage over a peripherally enhanced geometry in high density bone stock.

View Article: PubMed Central - PubMed

Affiliation: Golden Jubilee National Hospital, Departmentof Orthopaedics, Agamemnon Street, Clydebank, WestDunbartonshire G81 4DY, UK.

ABSTRACT

Objective: This study compared the primary stability of two commercially available acetabular components from the same manufacturer, which differ only in geometry; a hemispherical and a peripherally enhanced design (peripheral self-locking (PSL)). The objective was to determine whether altered geometry resulted in better primary stability.

Methods: Acetabular components were seated with 0.8 mm to 2 mm interference fits in reamed polyethylene bone substrate of two different densities (0.22 g/cm(3) and 0.45 g/cm(3)). The primary stability of each component design was investigated by measuring the peak failure load during uniaxial pull-out and tangential lever-out tests.

Results: There was no statistically significant difference in seating force (p = 0.104) or primary stability (pull-out p = 0.171, lever-out p = 0.087) of the two components in the low-density substrate. Similarly, in the high-density substrate, there was no statistically significant difference in the peak pull-out force (p = 0.154) or lever-out moment (p = 0.574) between the designs. However, the PSL component required a significantly higher seating force than the hemispherical cup in the high-density bone analogue (p = 0.006).

Conclusions: Higher seating forces associated with the PSL design may result in inadequate seating and increased risk of component malpositioning or acetabular fracture in the intra-operative setting in high-density bone stock. Our results, if translated clinically, suggest that a purely hemispherical geometry may have an advantage over a peripherally enhanced geometry in high density bone stock. Cite this article: Bone Joint Res 2013;2:264-9.

No MeSH data available.


Related in: MedlinePlus

Diagrammatic illustration of the momentarm determined for ‘lever-out’ testing. A steel cable, low frictionpulley and universal connection are used to apply a lever-out momentto the introducing assembly. The moment arm was defined by the distance ofthe universal joint from the surface of the synthetic block.
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f2: Diagrammatic illustration of the momentarm determined for ‘lever-out’ testing. A steel cable, low frictionpulley and universal connection are used to apply a lever-out momentto the introducing assembly. The moment arm was defined by the distance ofthe universal joint from the surface of the synthetic block.


Primary stability of two uncementedacetabular components of different geometry: hemispherical or peripherallyenhanced?

Antoniades G, Smith EJ, Deakin AH, Wearing SC, Sarungi M - Bone Joint Res (2013)

Diagrammatic illustration of the momentarm determined for ‘lever-out’ testing. A steel cable, low frictionpulley and universal connection are used to apply a lever-out momentto the introducing assembly. The moment arm was defined by the distance ofthe universal joint from the surface of the synthetic block.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3860168&req=5

f2: Diagrammatic illustration of the momentarm determined for ‘lever-out’ testing. A steel cable, low frictionpulley and universal connection are used to apply a lever-out momentto the introducing assembly. The moment arm was defined by the distance ofthe universal joint from the surface of the synthetic block.
Bottom Line: The objective was to determine whether altered geometry resulted in better primary stability.However, the PSL component required a significantly higher seating force than the hemispherical cup in the high-density bone analogue (p = 0.006).Our results, if translated clinically, suggest that a purely hemispherical geometry may have an advantage over a peripherally enhanced geometry in high density bone stock.

View Article: PubMed Central - PubMed

Affiliation: Golden Jubilee National Hospital, Departmentof Orthopaedics, Agamemnon Street, Clydebank, WestDunbartonshire G81 4DY, UK.

ABSTRACT

Objective: This study compared the primary stability of two commercially available acetabular components from the same manufacturer, which differ only in geometry; a hemispherical and a peripherally enhanced design (peripheral self-locking (PSL)). The objective was to determine whether altered geometry resulted in better primary stability.

Methods: Acetabular components were seated with 0.8 mm to 2 mm interference fits in reamed polyethylene bone substrate of two different densities (0.22 g/cm(3) and 0.45 g/cm(3)). The primary stability of each component design was investigated by measuring the peak failure load during uniaxial pull-out and tangential lever-out tests.

Results: There was no statistically significant difference in seating force (p = 0.104) or primary stability (pull-out p = 0.171, lever-out p = 0.087) of the two components in the low-density substrate. Similarly, in the high-density substrate, there was no statistically significant difference in the peak pull-out force (p = 0.154) or lever-out moment (p = 0.574) between the designs. However, the PSL component required a significantly higher seating force than the hemispherical cup in the high-density bone analogue (p = 0.006).

Conclusions: Higher seating forces associated with the PSL design may result in inadequate seating and increased risk of component malpositioning or acetabular fracture in the intra-operative setting in high-density bone stock. Our results, if translated clinically, suggest that a purely hemispherical geometry may have an advantage over a peripherally enhanced geometry in high density bone stock. Cite this article: Bone Joint Res 2013;2:264-9.

No MeSH data available.


Related in: MedlinePlus