New York, NY: MRI shows higher sensitivity and substantial to excellent interreader reproducibility than X-ray for identifying patellar component loosening following total knee arthroplasty (TKA), states a recent study in the journal Radiology.
Due to poor osseous integration at component-bone interfaces loosening of total knee arthroplasty occur, interface assessment may be utilized for the diagnosis of loosening at MRI. Considering this, Yoshimi Endo, Hospital for Special Surgery, New York, NY, and colleagues aimed to determine interreader reproducibility for characterizing component interfaces and diagnosing loosening and to evaluate the diagnostic performance of MRI for diagnosing loosening after TKA versus radiography.
The retrospective study included consecutive knees with TKA that underwent revision between July 2018 and June 2019 and were imaged at MRI and radiography. Assessment of interface type (normal, fibrous membrane, fluid, or osteolysis), presence of bone marrow edema pattern, and percent integration (<33%, 33%–66%, or >66%) was done. Loosening diagnosis was done at MRI if no or almost no normal interface was present. Using surgical findings as a reference, sensitivity and specificity were compared with radiographs. Interreader reproducibility between two readers was evaluated by Gwet agreement coefficient and risk factors for loosening were assessed using multivariable logistic regression.
The study revealed the following findings:
· Among 116 knees in 114 patients (mean age, 63 years ± 10; 59 women), 61 of 116 knees (52.6%) had at least one loose component.
· Interreader reproducibility of MRI was substantial to excellent (Gwet agreement coefficient, 0.67–0.96).
· Loosening was associated with fluid interface (odds ratio [OR], 20.1) or osteolysis (OR, 3.1), absence of any normal interface (OR, 11.8), poor (<33%) osseous integration (OR, 20.4), and bone marrow edema pattern (OR, 4.7).
· Sensitivity and specificity of MRI for loosening were 84% (27 of 32) and 85% (71 of 84) for the patellar, 31% (eight of 26) and 100% (90 of 90) for the femoral, and 81% (22 of 27) and 98% (87 of 89) for the tibial component, respectively.
· MRI had higher sensitivity (84% vs 31%) but lower specificity (85% vs 96%) for patellar component loosening than did radiography, respectively, whereas no evidence of a difference was found for femoral (sensitivity and specificity, MRI vs radiography: 31% vs 46% and 100% vs 99%, respectively) or tibial (sensitivity and specificity, MRI vs radiography: 81% vs 70% and 98% vs 97% respectively) component loosening.
The researchers concluded, "MRI showed substantial to excellent interreader reproducibility and higher sensitivity than did radiography for diagnosing patellar component loosening after total knee arthroplasty."
Reference:
The study titled, "Diagnostic Performance of MRI for Component Loosening in Total Knee Arthroplasty Compared with Radiography," was published in the journal Radiology.
DOI: https://doi.org/10.1148/radiol.204458
KEYWORDS: Radiology journal, MRI, total knee arthroplasty, knee surgery, magnetic resonance imaging, diagnosis, patellar component,radiography, X-ray, Yoshimi Endo, sensitivity, specificity, interreader reproducibility