Patient and radiographic factors help to predict metal-on-metal hip resurfacings with evidence of a pseudotumor

Matharu, G; Blanshard, O; Dhaliwal, K; Judge, A; Murray, D; Pandit, H

Journal article

Patient and radiographic factors help to predict metal-on-metal hip resurfacings with evidence of a pseudotumor

Abstract:: Background

The role of radiographs in the follow-up of metal-on-metal hip resurfacing (MoMHR) patients is unclear. We investigated whether a combination of patient and radiological factors predicted MoMHRs with evidence of a pseudotumour.

Methods

We performed a retrospective single-centre case-control study (384 MoMHRs). The pseudotumour group (n=130) all had symptomatic pseudotumours on cross-sectional imaging with the diagnosis confirmed at revision. The non-pseudotumour group (n=254; subgroup previously reported on) had normal cross-sectional imaging. Radiographs immediately prior to revision were assessed in the pseudotumour group and compared with radiographs performed at the time of normal cross-sectional imaging in the non-pseudotumour group. Two blinded independent observers analysed radiographs for signs of failure (excellent interobserver agreement). Logistic regression modeling identified patient and radiological predictors of pseudotumour revision.

Results

Pseudotumour hips more commonly had abnormal radiographs (80.0% vs. 63.4%; p=0.001). Patient and radiological factors predicting pseudotumour revision in the multivariable model were: female gender (odds ratio (OR) 3.14 (95% CI 1.85-5.35); p<0.001), high inclination (OR 1.04 per degree (95% CI 1.01-1.07); p=0.006), acetabular osteolysis (OR 5.06 (95% CI 2.14-12.0); p<0.001), femoral osteolysis (OR 17.8 (95% CI 5.09-62.2); p<0.001), and acetabular loosening (OR 3.35 (95% CI 1.34-8.35); p=0.009). Factors predicting being in the non-pseudotumour group were: anteversion ≥5° (5° to <10°: OR 0.31 (95% CI 0.12-0.77), p=0.012; ≥10°: OR=0.32 (95% CI 0.15-0.70), p=0.004) and heterotopic ossification (OR 0.19 (95% CI 0.05-0.72); p=0.015). The model was well calibrated (p=0.589) with good discriminatory ability (area under the curve (AUC)=0.801; sensitivity=74.4%, specificity=71.7%).

Conclusions

A combination of patient and radiological factors provided useful information for distinguishing between MoMHRs with and without evidence of pseudotumours. Surgeons may wish to consider these specific patient and radiological factors before proceeding with cross-sectional imaging. Radiographs are important when assessing MoMHR patients and should be included in all follow-up protocols.

Publication status:: Published

Peer review status:: Peer reviewed

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APA Style

Matharu, G., Blanshard, O., Dhaliwal, K., Judge, A., Murray, D., & Pandit, H. (2017). Patient and radiographic factors help to predict metal-on-metal hip resurfacings with evidence of a pseudotumor. Journal of Bone and Joint Surgery, 99(3), 214–222.

MLA Style

Matharu, G, et al. “Patient and Radiographic Factors Help to Predict Metal-on-Metal Hip Resurfacings with Evidence of a Pseudotumor.” Journal of Bone and Joint Surgery, vol. 99, no. 3, 2017, pp. 214–22.

Chicago Style

Matharu, G, O Blanshard, K Dhaliwal, A Judge, D Murray, and H Pandit. 2017. “Patient and Radiographic Factors Help to Predict Metal-on-Metal Hip Resurfacings with Evidence of a Pseudotumor.” Journal of Bone and Joint Surgery 99 (3): 214–22.
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