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In vitro comparison of the effects of rough and polished stem surface finish on pressure generation in cemented hip arthroplasty.

Bartlett GE, Beard DJ, Murray DW, Gill HS - Acta Orthop (2009)

Bottom Line: We compared the pressures generated by rough and polished tapered stems at their cement interfaces, in an in vitro model, before and after 1 million load cycles.At the start of the study, the loading of both polished and rough stems generated interface pressures that were not statistically significantly different.The rough stems also migrated distally and wore the cement mantle, leading to increased rotational instability.

View Article: PubMed Central - PubMed

Affiliation: OOEC, Nuffield Department of Orthopaedic Surgery, University of Oxford, Oxford, UK.

ABSTRACT

Background and purpose: High pressures around implants can cause bone lysis and loosening. We investigated how pressures are generated around cemented femoral stems.

Method: We compared the pressures generated by rough and polished tapered stems at their cement interfaces, in an in vitro model, before and after 1 million load cycles.

Results: At the start of the study, the loading of both polished and rough stems generated interface pressures that were not statistically significantly different. After 1 million load cycles, the rough stems generated greater interface pressures than at the start (p = 0.03), with maximum pressure wave amplitudes of 450,000 Pa or 3,375 mm Hg. The pressures generated by polished stems were similar before and after 1 million load cycles, and were lower than the pressures generated by the rough stems (p = 0.01). Stem loading caused micromotion between the stem and cement. Polished stems migrated distally in the cement but retained rotational and axial stability. The rough stems also migrated distally and wore the cement mantle, leading to increased rotational instability.

Interpretation: The change in the rotational micromotion of the rough stem is likely to be the principal cause of the increased stem pump output and to be a key factor in the longevity of cemented femoral implants.

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Related in: MedlinePlus

Average of median ΔPmax recorded at the start of the study and after completing 1 million cycles with both polished (A) and rough (B) stems (3 mantles were studied in each group).
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Figure 0004: Average of median ΔPmax recorded at the start of the study and after completing 1 million cycles with both polished (A) and rough (B) stems (3 mantles were studied in each group).

Mentions: The results are presented in 2 main forms: as illustrative examples of pressure waveforms generated during single load cycles (Figures 2 and 3) and as a summary of ΔPmax values generated by both stem surface finishes across all the mantles tested (Figure 4).


In vitro comparison of the effects of rough and polished stem surface finish on pressure generation in cemented hip arthroplasty.

Bartlett GE, Beard DJ, Murray DW, Gill HS - Acta Orthop (2009)

Average of median ΔPmax recorded at the start of the study and after completing 1 million cycles with both polished (A) and rough (B) stems (3 mantles were studied in each group).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2823172&req=5

Figure 0004: Average of median ΔPmax recorded at the start of the study and after completing 1 million cycles with both polished (A) and rough (B) stems (3 mantles were studied in each group).
Mentions: The results are presented in 2 main forms: as illustrative examples of pressure waveforms generated during single load cycles (Figures 2 and 3) and as a summary of ΔPmax values generated by both stem surface finishes across all the mantles tested (Figure 4).

Bottom Line: We compared the pressures generated by rough and polished tapered stems at their cement interfaces, in an in vitro model, before and after 1 million load cycles.At the start of the study, the loading of both polished and rough stems generated interface pressures that were not statistically significantly different.The rough stems also migrated distally and wore the cement mantle, leading to increased rotational instability.

View Article: PubMed Central - PubMed

Affiliation: OOEC, Nuffield Department of Orthopaedic Surgery, University of Oxford, Oxford, UK.

ABSTRACT

Background and purpose: High pressures around implants can cause bone lysis and loosening. We investigated how pressures are generated around cemented femoral stems.

Method: We compared the pressures generated by rough and polished tapered stems at their cement interfaces, in an in vitro model, before and after 1 million load cycles.

Results: At the start of the study, the loading of both polished and rough stems generated interface pressures that were not statistically significantly different. After 1 million load cycles, the rough stems generated greater interface pressures than at the start (p = 0.03), with maximum pressure wave amplitudes of 450,000 Pa or 3,375 mm Hg. The pressures generated by polished stems were similar before and after 1 million load cycles, and were lower than the pressures generated by the rough stems (p = 0.01). Stem loading caused micromotion between the stem and cement. Polished stems migrated distally in the cement but retained rotational and axial stability. The rough stems also migrated distally and wore the cement mantle, leading to increased rotational instability.

Interpretation: The change in the rotational micromotion of the rough stem is likely to be the principal cause of the increased stem pump output and to be a key factor in the longevity of cemented femoral implants.

Show MeSH
Related in: MedlinePlus