ARRS 2022 Abstracts

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1111. Correlation of Quantitative Measurements of Meniscal Extrusion on Knee Radiographs with Meniscal Extrusion on MRI
Authors * Denotes Presenting Author
  1. Arshan Dehbozorgi *; University of Kansas Medical Center
  2. Nebiyu Beteselassie; University of Kansas Medical Center
  3. Jayden Spencer; University of Kansas Medical Center
  4. Carissa Walter; University of Kansas Medical Center
  5. Jordan Baker; University of Kansas Medical Center
  6. Gary Hinson; University of Kansas Medical Center
Objective:
The medial and lateral menisci are vital structures in the knee responsible for axial load transmission and shock absorption. Meniscal extrusion can be a sign of compromised function, which predisposes the knee to articular cartilage damage and joint disease. Magnetic resonance imaging (MRI) is a highly sensitive tool for evaluating meniscal pathology; however, radiographs are usually the initial study ordered for knee pain or suspected joint disease. Golshani et al. demonstrated meniscal extrusion can be detected radiographically with high specificity; however they did not separately analyze weight-bearing (WB) and non-weight-bearing (NWB) radiographs. Our single institution study measured meniscal extrusion on standard NWB MRI and WB radiographs to identify any correlation across these modalities, and particularly the degree of extrusion on WB radiographs versus the standard NWB MRI in the same patient.

Materials and Methods:
A single institution retrospective review was performed. Three readers (two subspecialty-trained musculoskeletal radiologists and a fourth year radiology resident) interpreted the images in random order measuring medial and lateral meniscal extrusion on both modalities. To assess the inter-rater reliability, two-way random-effects intraclass correlation (ICC) was used. Pearson’s correlation coefficient was used to assess the correlation between the radiographs and MRI. Paired t-tests were also used to determine if there was a difference in the amount of meniscal extrusion detected between radiographs and MRI. All analyses were done using SAS software (SAS Institute). A p<0.05 was considered significant.

Results:
There were 143 total patients in the study: 43% men and 57% women. One hundred fourteen patients had WB radiographs and 29 had NWB radiographs. All three modalities showed good agreement between the readers: MRI (ICC=0.541, 95% CI=[0.380, 0.665]), WB radiograph (ICC=0.445, 95% CI=[0.242, 0.605]), and NWB radiograph (ICC=0.458, 95% CI=[0.234, 0.663]). Both WB and NWB radiographs showed good correlation with MRI: WB radiographs (r=0.717, 95% CI=[0.614, 0.796], p<0.001) and NWB radiographs (r=0.860, 95% CI=[0.721, 0.933], p<0.001). There was no significant difference between MRI and NWB radiographs in the amount of meniscal extrusion (0.077 mm, 95% CI=[-0.355, 0.509]), p =0.718); however, WB radiographs had a statistically significant greater degree of meniscal extrusion than MRI (0.347 mm, 95% CI=[0.105, 0.590], p=0.005).

Conclusion:
Our results show a close correlation of meniscal extrusion measurements on radiographs and MRI. There was no significant change in the degree of meniscal extrusion between NWB radiographs and standard NWB MRI in the absence of axial loading. However, the WB radiographs showed greater meniscal extrusion compared to MRI. These results demonstrate that imaging under axial load correlates with greater meniscal extrusion. This study also supports that radiographs (WB and NWB) can serve as a readily available tool in detection of meniscal pathology through evaluation of meniscal extrusion.