Medial posterior meniscal root tears are associated with development or worsening of medial tibiofemoral cartilage damage: the multicenter osteoarthritis study

Abstract

Purpose: To assess the association of meniscal root tear with the development or worsening of tibiofemoral cartilage damage.

Materials and methods: Institutional review board approval and written informed consent from all subjects were obtained. A total of 596 knees with radiographically depicted osteoarthritis were randomly selected from the Multicenter Osteoarthritis study cohort. Cartilage damage was semiquantitatively assessed by using the Whole-Organ Magnetic Resonance Imaging Score (WORMS) system (grades 0-6). Subjects were separated into three groups: root tear only, meniscal tear without root tear, and neither meniscal nor root tear. A log-binomial regression model was used to calculate the relative risks for knees to develop incident or progressing cartilage damage in the root tear group and the meniscal tear group, with the no tear group serving as a reference.

Results: In the medial tibiofemoral joint, there were 37 knees with isolated medial posterior root tear, 294 with meniscal tear without root tear, and 264 without meniscal or root tear. There were only two lateral posterior root tears, and no anterior root tears were found. Thus, the focus was on the medial posterior root tear. The frequency of severe cartilage damage (WORMS ≥ 5) was higher in the group with root tear than in the group without root or meniscal tear (76.7% vs 19.7%, P < .0001) but not in the group with meniscal but no root tear (76.7% vs 65.2%, P = .055). Longitudinal analyses included 33 knees with isolated medial posterior root tear, 270 with meniscal tear, and 245 with no tear. Adjusted relative risk of cartilage loss was 2.03 (95% confidence interval [CI]: 1.18, 3.48) for the root tear group and 1.84 (95% CI: 1.32, 2.58) for the meniscal tear group.

Conclusion: Isolated medial posterior meniscal root tear is associated with incident and progressive medial tibiofemoral cartilage loss.

Figure 1:

Schematic of meniscal roots. The anterior root of the medial meniscus (MM) inserts broadly into the anterior intercondylar crest. The anterior root of the lateral meniscus (LM) inserts into a portion of the anterior intercondylar crest in front of the lateral tibial tubercle and lateral to the anterior cruciate ligament, with which it partially blends. The posterior root of the medial meniscus inserts into the posterior slope of the medial tibial tubercle. Most of the posterior root of the lateral meniscus inserts into a horizontal part of the posterior intercondylar area, but some fibers attach to the posterior slope of the lateral tubercle.

Figure 2:

Flowchart of the selection criteria for the study.

Figure 3:

This schematic (sagittal section of the knee) helps explain the subregions of the medial tibiofemoral joint defined by the WORMS system. In this study, the central (C) and the posterior (P) femoral subregions, as well as all tibial subregions (anterior [A], central, and posterior), were included, but the anterior femoral subregion, which corresponds to the patellofemoral joint, was not included.

Figure 4:

Coronal short tau inversion recovery image in 57-year-old woman with intact medial posterior meniscal root (arrow) shows a linear band of hypointensity corresponding to the posterior meniscal root, which is attached to the tibial plateau. There is no apparent tibiofemoral cartilage damage.

Figure 5a:

Images in 59-year-old woman. (a) Coronal short tau inversion recovery image shows torn medial posterior meniscal root (*), signified by discontinuity of the bandlike hypointensity between the posterior horn of the medial meniscus and the tibial plateau. Note tibiofemoral cartilage damage (short arrows) and a small subchondral bone marrow edemalike lesion (long arrow). In the lateral compartment, there is no apparent cartilage damage and the root of the lateral meniscus is normal. (b) Axial fat-suppressed proton-density–weighted image confirms medial PMRT (*); lateral meniscus appears normal (arrowheads).

Figure 5b:

Images in 59-year-old woman. (a) Coronal short tau inversion recovery image shows torn medial posterior meniscal root (*), signified by discontinuity of the bandlike hypointensity between the posterior horn of the medial meniscus and the tibial plateau. Note tibiofemoral cartilage damage (short arrows) and a small subchondral bone marrow edemalike lesion (long arrow). In the lateral compartment, there is no apparent cartilage damage and the root of the lateral meniscus is normal. (b) Axial fat-suppressed proton-density–weighted image confirms medial PMRT (*); lateral meniscus appears normal (arrowheads).