The diagnostic potential of low-field MRI in problematic total knee arthroplasties - a feasibility study

Femke F Schröder,Nico Verdonschot,Frank-Christiaan B M Wagenaar,Sjoerd M Van Raak,Frank F J Simonis,Rianne M H A Huis In’T Veld,Corine E Post

doi:10.1186/s40634-020-00274-2

Abstract

PurposeLow-field MRI, allowing imaging in supine and weight-bearing position, may be utilized as a non-invasive and affordable tool to differentiate between causes of dissatisfaction after TKA (‘problematic TKA’). However, it remains unclear whether low-field MRI results in sufficient image quality with limited metal artefacts. Therefore, this feasibility study explored the diagnostic value of low-field MRI concerning pathologies associated with problematic TKA’s’ by comparing low-field MRI findings with CT and surgical findings. Secondly, differences in patellofemoral parameters between supine and weight-bearing low-field MRI were evaluated.MethodsEight patients with a problematic TKA were scanned using low-field MRI in weight-bearing and supine conditions. Six of these patients underwent revision surgery. Scans were analysed by a radiologist for pathologies associated with a problematic TKA. Additional patellofemoral and alignment parameters were measured by an imaging expert. MRI observations were compared to those obtained with CT, the diagnosis based on the clinical work-up, and findings during revision surgery.ResultsMRI observations of rotational malalignment, component loosening and patellofemoral arthrosis were comparable with the clinical diagnosis (six out of eight) and were confirmed during surgery (four out of six). All MRI observations were in line with CT findings (seven out of seven). Clinical diagnosis and surgical findings of collateral excessive laxity could not be confirmed with MRI (two out of eight).ConclusionLow-field MRI shows comparable diagnostic value as CT and might be a future low cost and ionizing radiation free alternative. Differences between supine and weight-bearing MRI did not yield clinically relevant information.The study was approved by the Medical Research Ethics Committees of Twente (Netherlands Trial Register: Trial NL7009 (NTR7207). Registered 5 March 2018, https://www.trialregister.nl/trial/7009).

Highlights

Total knee arthroplasty (TKA) is a highly successful procedure usually performed on patients with end-stage osteoarthritis to improve long-term function and reduce pain [1]
In all six patients who underwent revision surgery, the diagnosis based on the clinical work-up was comparable with the findings during surgery
In six out of the eight cases included in this study, the MRI observations were in line with the diagnosis based on the clinical work-up, and in four out of six cases, the MRI observations of malalignment, suspected loosening, and patellofemoral arthrosis were confirmed with findings during revision surgery

Summary

Introduction

Total knee arthroplasty (TKA) is a highly successful procedure usually performed on patients with end-stage osteoarthritis to improve long-term function and reduce pain [1]. Approximately 20% of the patients are dissatisfied after TKA; these patients’ cases are referred to as the problematic TKA [1] Pathologies related to this dissatisfaction include intra-articular, peri-articular and extra-articular causes. Several differential diagnostic algorithms for the problematic TKA have been developed as a result of a multitude of studies [3, 7,8,9]. In all these differential diagnostic algorithms several additional imaging investigations such as CT, SPECT-CT, stress radiographs or other are used. None of these imaging techniques are solely able to diagnose all probable causes of the problematic TKA simultaneously

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Discussion

Conclusion