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Detection of incorrect manufacturer labelling of hip components

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ABSTRACT

We describe the case of a 53-year-old man who underwent a left metal-on-metal hip resurfacing in 2015. Component size mismatch (CSM) was suspected because of the patient’s immediate post-operative mechanical symptoms and high metal ion levels. Surgical notes indicated the appropriate combinations of implants were used. However, we detected a mismatch using computed tomography. Revision was performed and subsequent measurements of explanted components confirmed the mismatch. To our knowledge, this case is the first report of a CT method being used in a patient to pre-operatively identify CSM.

Electronic supplementary material: The online version of this article (doi:10.1007/s00256-016-2478-4) contains supplementary material, which is available to authorized users

No MeSH data available.


A 2D CT coronal slice of the patient with the mismatched left hip resurfacing (right) and the patient’s previous right hip resurfacing (left) in view. The femoral head of the mismatched component is not sitting centrally in the acetabular component with B being 1.5 times greater than A. On the previous right hip resurfacing, with correctly paired components, the femoral head is centrally placed (C to D)
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Fig3: A 2D CT coronal slice of the patient with the mismatched left hip resurfacing (right) and the patient’s previous right hip resurfacing (left) in view. The femoral head of the mismatched component is not sitting centrally in the acetabular component with B being 1.5 times greater than A. On the previous right hip resurfacing, with correctly paired components, the femoral head is centrally placed (C to D)

Mentions: Consequently, a low-dose CT scan (1.4 mSv) of the patient’s hip was obtained (Fig. 3). The low-dose CT scan was obtained using a SOMATOM Definition AS 128-slice CT scanner (Siemens Heathineers, Erlangen, Germany) using the CT protocol shown in Table 1. Three-dimensional models of the components were produced. The centre of rotation of each component was compared (Fig. 4) and the distance between the edge of the acetabular cup and femoral head surface was measured (Fig. 5). This method works on the premise that a fully engaged head should be equally spaced from the outer surface of the acetabular cup and that the centre of rotation of spheres fitted to the outer surface of the acetabular and femoral head components should overlap, provided that an offset-bore acetabular component has not been used.Fig. 3


Detection of incorrect manufacturer labelling of hip components
A 2D CT coronal slice of the patient with the mismatched left hip resurfacing (right) and the patient’s previous right hip resurfacing (left) in view. The femoral head of the mismatched component is not sitting centrally in the acetabular component with B being 1.5 times greater than A. On the previous right hip resurfacing, with correctly paired components, the femoral head is centrally placed (C to D)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5121176&req=5

Fig3: A 2D CT coronal slice of the patient with the mismatched left hip resurfacing (right) and the patient’s previous right hip resurfacing (left) in view. The femoral head of the mismatched component is not sitting centrally in the acetabular component with B being 1.5 times greater than A. On the previous right hip resurfacing, with correctly paired components, the femoral head is centrally placed (C to D)
Mentions: Consequently, a low-dose CT scan (1.4 mSv) of the patient’s hip was obtained (Fig. 3). The low-dose CT scan was obtained using a SOMATOM Definition AS 128-slice CT scanner (Siemens Heathineers, Erlangen, Germany) using the CT protocol shown in Table 1. Three-dimensional models of the components were produced. The centre of rotation of each component was compared (Fig. 4) and the distance between the edge of the acetabular cup and femoral head surface was measured (Fig. 5). This method works on the premise that a fully engaged head should be equally spaced from the outer surface of the acetabular cup and that the centre of rotation of spheres fitted to the outer surface of the acetabular and femoral head components should overlap, provided that an offset-bore acetabular component has not been used.Fig. 3

View Article: PubMed Central - PubMed

ABSTRACT

We describe the case of a 53-year-old man who underwent a left metal-on-metal hip resurfacing in 2015. Component size mismatch (CSM) was suspected because of the patient’s immediate post-operative mechanical symptoms and high metal ion levels. Surgical notes indicated the appropriate combinations of implants were used. However, we detected a mismatch using computed tomography. Revision was performed and subsequent measurements of explanted components confirmed the mismatch. To our knowledge, this case is the first report of a CT method being used in a patient to pre-operatively identify CSM.

Electronic supplementary material: The online version of this article (doi:10.1007/s00256-016-2478-4) contains supplementary material, which is available to authorized users

No MeSH data available.