Prevalence and effect of medial meniscus tear in elderly persons -the bunkyo health study

Abstract

Purpose: The meniscus has a function of dispersing the mechanical load applied to the knee joint. It has been recently revealed that meniscal tear is frequently observed in middle aged and elderly people with/without knee osteoarthritis (knee OA). Meniscal damage leads to the stress concentration to the joints and is, thus, it is becoming clear that meniscus damage is a risk factor for the onset and progression of knee OA. In resent MRI based cohort data, the prevalence of medial meniscal tear with no symptom in middle-aged and elderly is reported to be 28%. However, there is no similar report from large-scale cohort data for the prevalence of meniscus tear and the effect of meniscus tear for pain and mobility in elderly peoples. The purpose of this cross-sectional study was to examine the prevalence of meniscal tear and the effect of meniscus tear for pain and mobility in elderly people. Methods: A total of 1,630 subjects aged between from 65 to 84 years of age participated in the Bunkyo Health Study during from November 2015 to September 2018. 1,191 subjects underwent both the plain radiograph in the standing position and MRI on knee joint (Hitachi, 0.3T). As 46 among 1,191 subjects who showed lateral type of knee OA (femoro-tibial angle <173) were excluded, the remaining 1145 subjects (55.7% females, 72.9 years of age on average) were analyzed. A radiographic severity of knee OA was classified into four grades using the Kellgren-Lawrence (K/L) classification. The medial meniscal tear was evaluated according to MRI Osteoarthritis Knee Score (MOAKS). The linear lesion, which reached the femoral cartilage and / or the tibial cartilage, the complete root tear, and the empty meniscus were defined as a meniscus tear. The region of the medial meniscal tear was described with each five sections (anterior, body, posterior, posterior horn and root) using coronal and sagittal proton density weighted fat suppression (PDFS) images. A p-value less than 5% was considered to be statistically significant. All analyses were undertaken using the statistical package SPSS. Results: The severity of radiographic medial knee OA of the subjects in the present study was 16 (1.4%) for K/L 1, 986 (86.1%) for K/L 2, 106 (9.3%) for K/L 3, and 37 (3.2%) for K/L 4. Medial meniscus lesions were also detected in almost all cases (1144 cases, 99.8%). The medial meniscus tears were detected 453 persons (39.6%; K/L 1: 31.3%, K/L 2: 35.2%, K/L 3: 65.1%, K/L 4: 86.5%). Prevalence of the medial meniscus tears were increased with each generation (p<0.001): 31.8% for 65∼70 years of age, 40.0% for 70∼75 of age, 47.6% for 75∼80 years of age, 52.2% for >80 years of age. The risk of existing medial meniscus tear was significantly higher in K/L 3 and 4 group compared to K/L 1 and 2 group. (odds ratio: 4.6, 95%CI 3.1-6.8). The region of medial meniscus tear was 11.7% in anterior, 27.4% in body, 25.4% in posterior, 62.7% in posterior horn and root. In comparison between with and without medial meniscus tear, the medial meniscus tear group showed larger FTA, larger pain VAS and lower walk speed (adjusted age, BMI and sex, p<0.001, respectively). Conclusions: In the present population-based study, most of the subjects among the middle aged and elderly populations who did not require the medical treatment for their knee joint showed the K/L grade 2 of radiographic knee OA change. In addition, almost all the subjects had medial meniscus lesion, and nearly half of the subjects had medial meniscus tear. In addition, the probability of medial meniscal tears increased with age. The frequency of pain awareness and walking inability also increased with the prevalence of medial meniscus tear.