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MRI Differentiates Knee Synovitis Patterns
Radiologists can determine synovial patterns among patients with total knee arthroplasty.
MRI can differentiate synovial patterns in patients with total knee arthroplasty (TKA), according to a study published in Radiology.
Researchers from the Hospital for Special Surgery in New York City, NY, performed a retrospective cross-sectional study to determine the diagnostic accuracy of MRI for differentiating synovial patterns in patients with TKA, whether diagnostic accuracy differs in index versus revision TKA, and interobserver and intraobserver reliability for assessment of synovial patterns at MR imaging.
A total of 108 consecutive patients with TKA participated in the study. They all underwent MR imaging within one year prior to revision surgery from 2012 to 2014. The MR images were reviewed and cases were qualitatively categorized by the appearance of the synovium as one of the following:
• Frondlike and hypertrophied (particle-induced synovitis)
• Lamellated and hyperintense (infection)
• Homogeneous effusion with the signal intensity of fluid (nonspecific synovitis)
The MR imaging appearance was compared with surgical and microbiology reports as the reference standard to determine the sensitivity, specificity, and positive and negative predictive values for the index TKA and revision TKA cohorts.
The results were as follows:
| Sensitivity | Specificity | |
| Surgical diagnosis of complications related to polyethylene wear (including osteolysis and loosening) | 0.907–0.930 | 0.723–0.7383 |
| Infection | 0.652–0.783 | 0.976–0.988 |
| Stiffness, instability, and nonspecific pain | 0.643–0.667 | 0.894–0.939 |
Diagnostic accuracy was higher in the index TKA cohort than in the revision TKA cohort. Interobserver and intraobserver reliabilities were almost perfect (κ = 0.82 and κ = 0.83, respectively).
The researchers concluded that MR imaging can help distinguish qualitative differences in the appearance of the synovium in TKA between particle-induced synovitis, infection, and nonspecific synovitis, with almost perfect interobserver and intraobserver reliability. Diagnostic accuracy is higher for index TKA than for revision TKA.