MRI as Diagnostic Modality for Analyzing the Problematic Knee Arthroplasty: A Systematic Review

BACKGROUND: Various diagnostic modalities are available to assess the problematic knee arthroplasty. Visualization of soft‐tissue structures in relation to the arthroplasty and bone remains difficult. Recent developments in MRI sequences could make MRI a viable addition to the diagnostic arsenal. PURPOSE: To review the diagnostic properties of MRI, to identify certain causes of complaints that may be directly related to implant failure of total (TKA) or unicompartmental knee arthroplasty (UKA); infection, loosening and wear, instability, malalignment, arthrofibrosis, or patellofemoral problems. STUDY TYPE: Systematic review. POPULATION: Twenty‐three studies were included: 16 TKA, four UKA, and three cadaveric studies. Causes of knee arthroplasty complaints analyzed were; infection (three), loosening and wear (11), malalignment (five) and instability (four). FIELD STRENGTH AND SEQUENCES: No field strength or sequence restrictions. ASSESSMENT: PubMed, SCOPUS, and EMBASE were searched. Risk of bias was assessed using the COnsensus‐based Standards for the selection of health Measurement Instruments (COSMIN) and the QUality Assessment of Diagnostic Accuracy Studies‐2 (QUADAS‐2). STATISTICAL TESTS: The results of the original research articles are stated. RESULTS: Fifteen studies assessed the reproducibility of analyzing infection, loosening and wear, and malalignment. Fourteen of 15 studies were deemed as adequate to good quality. Results showed a moderate to excellent agreement (ICC/K 0.55–0.97). Fourteen studies addressed the accuracy. For infection and loosening and wear the sensitivity and specificity estimates varied between 0.85–0.97 and 0.70–1.00, respectively. The accuracy for malalignment was excellent (r ≥ 0.81). For these studies QUADAS‐2 analysis suggested few risks of bias. A meta‐analysis was not possible due to the heterogeneity of the data. DATA CONCLUSION: This study supports that MRI can be used with overall reproducible and accurate results for diagnosing infection, loosening and wear, and malalignment after knee arthroplasty. Nonetheless, studies regarding the diagnosis of instability, arthrofibrosis or patellofemoral complaints using MRI are limited and inconclusive. Level of Evidence: 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2020;51:446–458.