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J Orthop Surg Res. 2019 Jul 19;14(1):225. doi: 10.1186/s13018-019-1271-1.

Mid-term progressive loosening of hydroxyapatite-coated femoral stems paired with a metal-on-metal bearing.

Author information

1
Orthopaedic Innovation Centre, 320-1155 Concordia Avenue, Winnipeg, R2K2M9, Manitoba, Canada.
2
Concordia Joint Replacement Group, 310-1155 Concordia Avenue, Winnipeg, Manitoba, R2K 2M9, Canada.
3
Department of Surgery, University of Manitoba, Winnipeg, Manitoba, Canada.
4
Concordia Joint Replacement Group, 310-1155 Concordia Avenue, Winnipeg, Manitoba, R2K 2M9, Canada. cburnell@cjrg.ca.
5
Department of Surgery, University of Manitoba, Winnipeg, Manitoba, Canada. cburnell@cjrg.ca.

Abstract

BACKGROUND:

Several hydroxyapatite (HA)-coated femoral stems from a single manufacturer were identified to have aseptically loosened at mid-term follow-up despite prior radiographic appearance of osseointegration. Possible causes and associated risk factors for stem loosening were explored through radiographic review and implant retrieval analysis.

METHODS:

Forty-six retrieved hip stems (Corail, DePuy-Synthes) were identified and grouped by bearing type: metal-on-metal (MoM), metal-on-polyethylene, and ceramic-on-ceramic. Stem lucency was graded on post-operative radiographs up to the time of revision. Stems were examined for stripping of the HA coating, taper corrosion, and bearing wear in metal-on-metal cases. Patient demographics, implant design features, and perioperative data were collected from electronic databases and patient charts.

RESULTS:

Aseptic loosening occurred in 37% of cases examined. MoM bearings were associated with 7.25 times greater risk of loosening compared to other bearing types. Stem radiolucency was more prevalent for MoM cases and, although not statistically significant, demonstrated progressive lucency. Taper corrosion appeared more severe for MoM cases and correlated with proximal stem radiolucency. Removal of the HA coating from the stems was associated with both taper corrosion and MoM bearing wear. Length of implantation was a confounding factor for the MoM cases.

CONCLUSION:

This study has demonstrated a high risk of mid-term loosening of previously osseointegrated HA-coated femoral stems when paired with a MoM bearing. The mechanism of loosening appears progressive in nature and related to the MoM bearing, possibly interacting with the HA coating. If such loosening is recognized early, rapid revision may allow for retention of the femoral stem.

KEYWORDS:

Aseptic loosening; Hip arthroplasty; Hydroxyapatite; Metal-on-metal; Radiolucency; Wear

PMID:
31324195
PMCID:
PMC6642514
DOI:
10.1186/s13018-019-1271-1
[Indexed for MEDLINE]
Free PMC Article

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