Comparison of Medial and Lateral Meniscus Root Tears.

Ji Hyun Koo,Seung Ah Lee,Sang-Hee Choi,Joon Ho Wang,Bart O Williams

doi:10.1371/journal.pone.0141021

Ji Hyun Koo, Seung Ah Lee + Show 3 more

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https://doi.org/10.1371/journal.pone.0141021

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Abstract

The meniscus root plays an essential role in maintaining the circumferential hoop tension and preventing meniscal displacement. Studies on meniscus root tears have investigated the relationship of osteoarthritis and an anterior cruciate ligament tear. However, few studies have directly compared the medial and lateral root tears. To assess the prevalence of meniscal extrusion and its relationship with clinical features in medial and lateral meniscus root tears, we performed a retrospective review of the magnetic resonance imaging (MRI) results of 42 knee patients who had meniscus posterior horn root tears and who had undergone arthroscopic operations. The presence of meniscal extrusion was evaluated and the exact extent was measured from the tibial margin. The results were correlated with arthroscopic findings. Clinical features including patients’ ages, joint abnormalities, and previous trauma histories were evaluated. Twenty-two patients had medial meniscus root tears (MMRTs) and twenty patients had lateral meniscus root tears (LMRTs). Meniscal extrusion was present in 18 MMRT patients and one LMRT patient. The mean extent of extrusion was 4.2mm (range, 0.6 to 7.8) in the MMRT group and 0.9mm (range, -1.9 to 3.4) in the LMRT group. Five patients with MMRT had a history of trauma, while 19 patients with LMRT had a history of trauma. Three patients with MMRT had anterior cruciate ligament (ACL) tears, while 19 patients with LMRT had ACL tears. The mean age of the patients was 52 years (range: 29–71 years) and 30 years (range: 14–62 years) in the MMRT and LMRT group, respectively. There was a significant correlation between a MMRT and meniscal extrusion (p<0.0001), and between an ACL tear and LMRT (p<0.0001). A history of trauma was significantly common in LMRT (p<0.0001). LMRT patients were significantly younger than MMRT patients (p<0.0001). Kellgren-Lawrence (K-L) grade differed significantly between MMRT and LMRT group (p<0.0001). Meniscal extrusion is common in patients with MMRTs. However, it is rare in patients with LMRTs, which are more commonly associated with a history of trauma and ACL tears.

Highlights

The meniscus is a fibrocartilaginous structure of the knee joint that enables the even distribution of a weight-bearing load across the articular surfaces
Out of 22 patients (10 left knees, 12 right knees) who had medial meniscus posterior horn root tears (MMRTs), meniscal extrusion was present in 18 patients
Out of 20 patients (10 left knees, 10 right knees) who had lateral meniscus posterior horn root tears (LMRTs), meniscal extrusion was present in only one patient

Summary

Introduction

The meniscus is a fibrocartilaginous structure of the knee joint that enables the even distribution of a weight-bearing load across the articular surfaces. The menisci bear between 40 to 70% of the load across the knee, and the rest of the load is transmitted directly to the articular cartilage. The meniscus has several other important biomechanical functions. It keeps the joint lubricated and regulates the joint's movement to prevent over extension. A meniscal tear alters the functioning of the knee joint and may contribute to articular instability [1,2,3,4,5,6,7,8,9,10]

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