Contact Patch to Rim Distance Predicts Metal Ion Levels in Hip Resurfacing

Yoon, James P.; Duff, Michel J. Le; Johnson, Alicia J.; Takamura, Karren M.; Ebramzadeh, Edward; Amstutz, Harlan C.

doi:10.1007/s11999-012-2711-y

Cited by 38 publications

(32 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, when we stratified the groups by contact patch to rim distance (low, B 10 mm), we noticed that radiographic signs of impingement only resulted in higher ion levels in patients with low contact patch to rim distance. It has been previously observed that a low contact patch to rim distance is a strong predictor of high ion levels [16,31], and this was once again reaffirmed in our study. It appears that, with a well-positioned acetabular cup, impingement does not affect CoS or CrS.…”

Section: Discussionsupporting

confidence: 92%

“…The two groups showed similar characteristics in male to female ratio, height, weight, BMI, femoral component size, percentage of hips with a low contact patch to rim distance (\ 10 mm) [16,31], and postoperative UCLA pain and activity score. The mean age of the patients at surgery was lower and the mean time between surgery and the last blood draw was longer for the impingement group than for the control group (Table 1).…”

Section: Methodsmentioning

confidence: 92%

“…1). This contact patch to rim distance estimation was computed as previously described in the literature [6,16,31], based on design coverage, component size, and acetabular cup abduction and anteversion angles measured from AP pelvis radiographs with Einzel-Bild-Roentgen-Analyse (EBRA) software (EBRA-CUP; University of Innsbruck, Innsbruck, Austria) [10,17]. The contact patch to rim distance represents the functional coverage of the femoral component by the socket.…”

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Does Femoral Neck to Cup Impingement Affect Metal Ion Levels in Hip Resurfacing?

Duff

Johnson

Wassef

et al. 2013

Clin Orthop Relat Res

Self Cite

View full text Add to dashboard Cite

Background Impingement of the femoral neck with the acetabular component after metal-on-metal hip resurfacing arthroplasty (HRA) is a possible cause of edge loading and accelerated bearing wear. No attempt has been made to correlate radiographic impingement signs and blood metal ion levels. Questions/purposes We (1) compared serum cobalt (CoS) and chromium (CrS) concentrations between patients with and without radiographic impingement signs treated with unilateral HRA, (2) determined whether divot depth on the femoral neck correlated with CoS and CrS, and (3) assessed the predictive value of radiographic impingement signs for high levels of CoS and CrS. Methods A retrospective radiographic review of 141 patients with CoS and CrS analyses yielded 21 patients with and 120 without radiographic impingement signs (controls). Radiographic measurements included divot depth and orientation of the acetabular component to compute the contact patch to rim distance, a measure of functional head coverage. We defined a patient as having radiographic impingement signs if a remodeling of the femoral neck cortex showed a depression matching the predicted path of an impinging acetabular component. CoS and CrS were analyzed by inductively coupled plasma mass spectrometry and the radiographs were taken within 12 months of the last blood draw. Results Median CoS and CrS were greater in the impingement group than in controls in patients with less than 10-mm contact patch to rim distances. Divot depth did not correlate with CoS or CrS. In predicting elevated ion levels (C 7 lg/L), the presence of a radiographic impingement sign showed a sensitivity of 50% for CoS and 33% for CrS and a specificity of 87% for both CoS and CrS. Conclusions Radiographic impingement signs influenced CoS and CrS only when the functional head coverage was insufficient due to poor socket positioning. Radiographic impingement signs alone were not a good predictor of elevated metal ion levels. Level of Evidence Level III, diagnostic study. See Instructions for Authors for a complete description of levels of evidence.

show abstract

Section: Discussionsupporting

confidence: 92%

Section: Methodsmentioning

confidence: 92%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Does Femoral Neck to Cup Impingement Affect Metal Ion Levels in Hip Resurfacing?

Duff

Johnson

Wassef

et al. 2013

Clin Orthop Relat Res

Self Cite

View full text Add to dashboard Cite

show abstract

“…When it comes to determination of risk factors for a procedure, a multivariate model is impractical if the wrong variables are being studied. For hip resurfacing, using gender as one of the variables creates collinearity, and usually precludes the study of variables that are correlated with gender but have a much stronger rationale for affecting the outcome, such as component size [1,5] or an etiology of developmental dysplasia [1,3] (which increases the chances of cup malposition, a variable that can only be studied using a threedimensional (3-D) analysis and calculating the contact patch to rim distance, which has the strongest correlation with elevated wear [4,6]). …”

Section: W E Read the Study Bymentioning

confidence: 99%

“…Recent publications [4,6] have highlighted the importance of proper acetabular component positioning, both in the frontal and sagittal planes for hip resurfacing arthroplasty to be successful, and to avoid edge-loading of the components, leading to abnormal wear patterns of the device [4,6]. Large databases such as registries certainly present the advantage of high statistical power but completely lack the ability to record the variables that truly affect the outcome of hip resurfacing, such as a 3-D assessment of acetabular component positioning.…”

Section: W E Read the Study Bymentioning

confidence: 99%