屈膝90°MRI对内侧半月板Ramp损伤临床诊断价值的研究

Clinical diagnostic study of Ramp lesion of medial meniscus based on knee MRI at 90°flexed position

目的评价屈膝90°MRI对内侧半月板Ramp损伤的临床诊断价值。方法以2021年9月—2023年9月以膝关节疼痛为主诉收治的228例患者作为研究对象,其中51例患者符合选择标准纳入研究。男31例,女20例;年龄15~67岁,平均38.6岁。身体质量指数17.2~28.7 kg/m^(2),平均23.9 kg/m^(2)。左膝25例,右膝36例。受伤至入院时间0.1~14.3周,平均2.1周。术前均行伸膝0°(伸膝位)、屈膝90°(屈膝位)MRI检查,判断是否存在内侧半月板后缘不规则以及PHMM液体高信号[即内侧半月板后角(posterior horn of the medial meniscus,PHMM)与后囊之间充盈液体]征象。以关节镜探查结果为“金标准”,分别评估伸膝、屈膝位MRI对Ramp损伤两种特异征象的敏感度、特异度、准确度、阳性预测值及阴性预测值。结果经关节镜检查,21例(41.2%)确诊Ramp损伤,其中ThaunatⅠ型1例、Ⅱ型2例、Ⅲ型6例、Ⅳ型7例、Ⅴ型5例。伸膝位、屈膝位MRI示内侧半月板后缘不规则征象阳性率与关节镜下诊断Ramp损伤结果比较,差异均有统计学意义(P<0.05)。伸膝位MRI检查敏感度76.1%、特异度60.0%、准确度66.7%、阳性预测值57.1%、阴性预测值78.3%,屈膝位分别为85.7%、73.3%、78.4%、69.2%、88.0%。伸膝位、屈膝位MRI示PHMM液体高信号征象阳性率与关节镜下诊断Ramp损伤结果比较,差异亦有统计学意义(P<0.05);伸膝位MRI检查敏感度38.1%、特异度100%、准确度74.5%、阳性预测值100%、阴性预测值69.8%,屈膝位分别为85.7%、100%、94.1%、100%、90.9%。结论与传统伸膝0°MRI相比,基于屈膝90°MRI诊断内侧半月板Ramp损伤的敏感度、特异度和准确度均更高。

Objective To evaluate the clinical diagnostic value of knee MRI at 90°flexed position for Ramp lesions of medial meniscus.Methods A total of 228 patients with knee pain as the main complaint who were admitted between September 2021 and September 2023 was selected as the research subjects,of which 51 patients met the selection criteria and were enrolled in the study.There were 31 males and 20 females with an average age of 38.6 years(range,15-67 years).Body mass index was 17.2-28.7 kg/m^(2)(mean,23.9 kg/m^(2)).There were 25 cases of left knee and 36 cases of right knee.The time from injury to admission was 0.1-14.3 weeks(mean,2.1 weeks).Preoperative knee MRI at fully extended position(knee extension position)and 90°flexed position(knee flexion position)were performed to determine the presence of irregular signs at the posterior edge of the medial meniscus,and PHMM fluid high signal[i.e.complete fluid filling between the posterior horn of the medial meniscus(PHMM)and the capsule margin].Findings obtained under arthroscopy served as the“gold standard”to analyze the sensitivity,specificity,accuracy,positive predictive value(PPV),and negative predictive value(NPV)of MRI at knee extension and flexion positions for the two specific signs of Ramp lesion.Results Twenty-one patients(41.2%)were diagnosed with Ramp lesions by using arthroscopy,including 1 case of Thaunat typeⅠ,2 cases of typeⅡ,6 cases of typeⅢ,7 cases of typeⅣ,and 5 cases of typeⅤ.The positive rates of irregular signs at the posterior edge of the medial meniscus on MRI at knee extension and flexion positions were significantly different from the diagnosis of Ramp injury under arthroscopy(P<0.05).The sensitivity,specificity,accuracy,PPV,and NPV of MRI in the diagnosis of irregular signs were 76.1%,60.0%,66.7%,57.1%,and 78.3%respectively at knee extension position,and 85.7%,73.3%,78.4%,69.2%,and 88.0%respectively at knee flexion position.The positive rates of PHMM fluid high signal on MRI at knee extension and flexion positions were significantly different from the diagnosis of Ramp injury under arthroscopy(P<0.05).The sensitivity,specificity,accuracy,PPV,and NPV of MRI in diagnosing PHMM fluid high signal were 38.1%,100%,74.5%,100%,and 69.8%respectively at knee extension position,and 85.7%,100%,94.1%,100%,and 90.9%respectively at knee flexion position.Conclusion Knee MRI at 90°flexed position improves the diagnostic performance of the detection of medial meniscal Ramp lesions compared with MRI at fully extended position.