Background/Purpose

Meniscal body extrusion on knee MRI is strongly associated with the development and progression of knee osteoarthritis (OA). However, there is very limited evidence of risk factors for the development of meniscal extrusion.

Thus, our objective was to determine risk factors associated with increased meniscal body extrusion using quantitative measurements from knee MRIs in subjects free of radiographic OA at baseline. We hypothesized that body mass index (BMI), sex, age, and incident ipsilateral meniscal tear are possible risk factors.

Methods

Data for these analyses are from the OAI public use data. A cohort of 340 subjects with age between 45 and 55 (mean age 50 years, 51% women, mean BMI 26.7) with bilateral knee MRIs available at the baseline, 24 months, 48 months, and 72 month exam and no radiological signs of knee OA (both knees’ KL grade = 0 at baseline) were selected. We assessed mid-coronal IW 3-Tesla MR images from baseline and the 72 month follow-up visit. One observer measured widths of the tibia plateau and meniscal body extrusion to the closest 0.1 mm using Sante DICOM Editor (64-bit) software (intraobserver ICC ranging from 0.75 to 0.99). One reader assessed meniscal integrity (presence of tear) at all four time points. To take into account knee size, we calculated an extrusion index as ([meniscal body extrusion]/[tibia width]*100). We evaluated risk factors for increased meniscal body extrusion index from baseline to the 72-month exam by a multivariable linear regression mixed model for medial and lateral compartment, respectively, adjusting for the fact that the same person contributed with two knees and with the covariates: clinical site, age, sex, baseline BMI, baseline extrusion index, and incident meniscal tear.

Results

Mean (SD) medial extrusion index in the right knee at baseline and 72-month follow-up was 3.43 (1.23) and 3.32 (1.30), respectively (similar values in the left knee). The corresponding values for lateral compartment were 1.54 (1.31) and 1.13 (1.52). In the medial compartment we found that female sex (0.35; 95% confidence interval [CI] 0.16-0.53), incident meniscal tear (0.29; 95% CI 0.22-0.55), and the baseline value of the extrusion index (0.63; 95% CI 0.56-0.70) were associated with increased extrusion index by the 72 month follow-up. Results were similar for the lateral compartment (data not shown).

Conclusion

We found female sex, incident meniscal tear, and higher baseline value of extrusion to be risk factors for increased meniscal body extrusion in middle-aged subjects free of radiographic OA. Findings provide new evidence of the causal chain of events in the “meniscal pathway” to knee OA.

---

« Back to 2014 ACR/ARHP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/risk-factors-for-increased-extrusion-of-the-meniscus-body-in-subjects-free-of-radiographic-knee-osteoarthritis-6-year-mri-data-from-the-osteoarthritis-initiative/