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. 2023 Feb 8;12(2):20584601231152396.
doi: 10.1177/20584601231152396. eCollection 2023 Feb.

Sensitivity and specificity for detecting pseudotumors in patients with hip resurfacing arthroplasty, metal-on-metal or metal-on-polyethylene total hip arthroplasty-MRI versus ultrasonography performed by an orthopedic surgery resident

Rasmus T Mikkelsen  1   2   3 , Martin Schou  4 , Trine Torfing  5 , Ole Graumann  5   6 , Søren Overgaard  3   6   7   8 , Claus Varnum  1   2
Affiliations

Sensitivity and specificity for detecting pseudotumors in patients with hip resurfacing arthroplasty, metal-on-metal or metal-on-polyethylene total hip arthroplasty-MRI versus ultrasonography performed by an orthopedic surgery resident

Rasmus T Mikkelsen et al. Acta Radiol Open. .

Abstract

Background: Metal artifact reduction sequence magnetic resonance imaging (MRI) scan is a common method to detect adverse reaction to metal debris in total hip arthroplasty (THA). It might be quicker and cheaper if ultrasonography (US) could screen for the need for an MRI. However, both require trained personnel.

Purpose: We aimed to investigate the sensitivity and specificity of US for detecting pseudotumors (PT) when performed by an orthopedic surgery resident compared to MRI. We also investigated the sensitivity and specificity of US to detect PTs in obese and non-obese patients.

Material and methods: We examined 205 patients with hip resurfacing arthroplasty, metal-on-metal or metal-on-polyethylene THA with both MRI and US. US was performed by an orthopedic surgery resident who was trained according to a standardized training program in musculoskeletal US. Results from MRI were used as gold standard.

Results: US had a sensitivity of 0.92 (95% CI 0.81-0.98) and specificity of 0.94 (95% CI 0.89-0.97) for detecting PT. It had a positive predictive value of 0.84 (95% CI 0.73-0.91) and a negative predictive value of 0.97 (95% CI 0.93-0.99). US performed similarly in obese and non-obese patients.

Conclusions: US had a high sensitivity and specificity for detecting PT when performed by an orthopedic surgery resident. Trained orthopedic surgeons could screen for the need of an MRI scan when searching PTs.

Keywords: Total hip arthroplasty; adverse reaction to metal debris; magnetic resonance imaging; metal-on-metal; pseudotumor; ultrasonography.

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Conflict of interest statement

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Figures

Figure 1.
Figure 1.
Flowchart of inclusion and exclusion of patients. HRA: Hip resurfacing arthroplasty. MoM: Metal-on-metal. THA: Total hip arthroplasty. MoP: Metal-on-polyethylene.
Figure 2.
Figure 2.
Hauptfleisch Type II PT as seen on MRI and US (red arrows). The patient has a MoP THA. On the left is a MARS-MRI STIR sequence image in coronal plan showing left-sided Type II PT. On the right is a lateral transversal US showing a cystic Type II PT with little solid mass.
Figure 3.
Figure 3.
Small medial PTs of less than 10 mm anterior of the femoral neck/implant only visible on US and not MRI.
See this image and copyright information in PMC

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