| Objective: The aim of this study is to investigate the relationship between the magnetic resonance imaging(MRI)classification of the discoid lateral meniscus,the degree of injury,and the age of onset of clinical symptoms of knee joint.Methods: Patients with symptoms caused by discoid lateral meniscus of knee joint in Department of Pediatric Orthopaedics and Department of Joint Surgery in our hospital from January 2012 to december 2019 were collected retrospectively.A total of 211 patients were included in the study,The 211 patients were grouped by age and divided into juvenile group(under 12 years old),group young adult group(13-40 years old),and elderly group.The knee MRI meniscus classification and meniscus injury classification were observed in each group.At the same time,the lateral discoid meniscus of both knees were divided into symptomatic knee group and asymptomatic knee group,and the differences between the two groups were compared.Discoid meniscus MR typing,using the Wang Shuli typing method,is divided into plate type,wedge type,and thick horn type.Discoid meniscus damage was graded by using Stoller’s method,which was divided into grades I,II,and III.The classification proportions between the groups were compared,and the results were analyzed by chi-square test.Result:A total of 211 cases were included in the study,including 120 females and 91 males.The age of onset was 2-81 years,the Media and IQR was 14(8,33)years.Among the 211 patients,96 were in the juvenile group,67 in the young group,and 48 in the senior group.Among patients with discoid lateral meniscus,there were 0 cases of grade I injury,93 cases of grade II injury,and 118 cases of grade III injury.There were 105 cases of left knee and 106 cases of right knee.Comparing the proportions of various types of discoid meniscus in the juvenile group,young and senior group,there was a statistical difference between the three groups(χ2 = 18.08,P ﹤ 0.05).The proportion of wedge-shaped discoid lateral meniscus in the juvenile group was lower than that of the other two groups,while the proportion of plate type and fat angle type was higher than the other two groups.There was no statistically significant difference in the proportion of different types of discoid meniscus injuries among the three age groups(k = 15.11,P =0.078).However,the proportion of discoid lateral meniscus grade Ⅲ injury in the juvenile group was lower than that in the other two groups.The proportions of discoid meniscus types in symptomatic knee group and asymptomatic knee group were statistically different(χ2 = 27.07,P ﹤ 0.05).The proportion of wedge-shaped discoid lateral meniscus in the asymptomatic knee group was significantly higher than that in the symptomatic knee group.On the contrary,the proportion of fat angle discoid lateral meniscus in the asymptomatic knee group was significantly lower than that in the symptomatic knee group.There was a statistically significant difference in the proportion of discoid lateral meniscus injury classification between the asymptomatic knee group and the symptomatic knee group(χ2= 43.19,P ﹤ 0.05).All of the symptomatic group were grade Ⅱ and Ⅲ injury,while nearly half of the asymptomatic group were grade I injury.Conclusion: The morphology of congenital discoid meniscus is related to the time of occurrence of the clinical symptoms.Generally,the plate type and thick horn type discoid meniscus will show damage symptoms early in adolescence and the damage is serious,while the wedge type discoid meniscus will have clinical symptoms in adulthood in most cases and the degree of damage is slight.Among the asymptomatic discoid meniscus of the knee joint,wedge type discoid meniscus accounts for a relatively high proportion and has a lower damage grade.For bilateral discoid meniscus surgery with unilateral symptoms,if the asymptomatic discoid meniscus is wedge type,simultaneous surgical treatment is not recommended.If the asymptomatic discoid meniscus is thick horn type or plate type,it is recommended that one-stage surgery be performed at the same time. |
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