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The 2012 Otto Aufranc Award : The Interpretation of Metal Ion Levels in Unilateral and Bilateral Hip Resurfacing


Reference:

Van Der Straeten, C., Grammatopoulos, G., Gill, H. S., Calistri, A., Campbell, P. and De Smet, K. A., 2013. The 2012 Otto Aufranc Award : The Interpretation of Metal Ion Levels in Unilateral and Bilateral Hip Resurfacing. Clinical Orthopaedics and Related Research, 471 (2), pp. 377-385.

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Official URL:

http://dx.doi.org/10.1007/s11999-012-2526-x

Abstract

BACKGROUND: The interpretation of metal ion concentrations and their role in clinical management of patients with metal-on-metal implants is still controversial. QUESTIONS/PURPOSES: We questioned whether patients undergoing hip resurfacing with no clinical problems could be differentiated from those with clinical (pain, loss of function) and/or radiographic (component malpositioning, migration, bone loss), problems based on metal ion levels, and if there was a threshold metal level that predicted the need for clinical intervention. Furthermore, we asked if patient and implant factors differed between these functional groups. METHODS: We retrospectively identified 453 unilateral and 139 bilateral patients with ion measurements at minimum followup of 12 months (mean, 4.3 years; range, 1-12.9 years). Patients were designated as well functioning or poorly functioning based on strict criteria. The acceptable upper levels within the well-functioning group were determined from the 75th percentile plus 1.5× interquartile range. The sensitivity and specificity of these levels to predict clinical problems were calculated. RESULTS: Well-functioning group ions were lower than the poorly functioning group ion levels. The acceptable upper levels were: chromium (Cr) 4.6 μg/L, cobalt (Co) 4.0 μg/L unilateral and Cr 7.4 μg/L, Co 5.0 μg/L bilateral. The specificity of these levels in predicting poor function was high (95%) and sensitivity was low (25%). There were more males in the well-functioning group and more females and smaller femoral components in the poorly functioning group. CONCLUSIONS: Metal levels higher than these proposed safe upper limits can predict problems with metal-on-metal resurfacings and are important parameters in the management of at-risk patients. LEVEL OF EVIDENCE: Level II, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

Details

Item Type Articles
CreatorsVan Der Straeten, C., Grammatopoulos, G., Gill, H. S., Calistri, A., Campbell, P. and De Smet, K. A.
DOI10.1007/s11999-012-2526-x
DepartmentsFaculty of Engineering & Design > Mechanical Engineering
Research CentresCentre for Orthopaedic Biomechanics
RefereedYes
StatusPublished
ID Code31358

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