目的:介绍一种新的磁共振成像(MRI)标志,被称为眼镜蛇标志,并确定其诊断指标。次要目的是证明该体征可能是近端腿筋撕脱伤患者肌腱回缩的错误评估来源。
方法:这项回顾性队列研究针对2019年1月至2023年6月手术治疗近端腿筋撕脱伤的患者。MRI眼镜蛇征被定义为波浪形弯曲的T2-低信号带,其自由端向远端折叠在自身上方,像眼镜蛇的头.主要结果指标是近端腿筋撕脱伤患者的眼镜蛇征特征。次要结果是该体征与肌腱缩回的关联。该研究包括81例近段腿筋撕脱伤患者(平均年龄45.7,SD=13.9),41(50.6%)完全撕脱,33半膜,和7根联合肌腱。
结果:在25例患者中发现了MRI眼镜蛇征(半膜17例,完全8例)。仅在半膜病例中通过手术证实。它对分离的半膜撕脱表现出51.5%的敏感性和83.3%的特异性,显著的正似然比为3.0。MRI回缩10.05cm(±3.0),在手术测量时减少到7.9厘米(±2.5)(平均差=2.0厘米,p<0.001)。回归分析证实MRI回缩对眼镜蛇征的影响,每单位赔率增加1.4(p<0.001)。在线性回归分析中,MRI回缩每增加1个单位对应手术回缩增加79%(系数0.7,t=11.1,p<0.001).
结论:眼镜蛇征对孤立的半膜撕脱的诊断准确性可接受,具有83.3%的高特异性,51.5%的低灵敏度,正似然比为3.0。眼镜蛇征的存在表明MRI退缩高估了约21%。
方法:三级。
OBJECTIVE: To introduce a new magnetic resonance imaging (MRI) sign, termed the Cobra sign, and identify its diagnostic metrics. The secondary aim was to demonstrate that this sign can be a source of false evaluation of tendon retraction in patients with proximal hamstring avulsion injury.
METHODS: This retrospective cohort study targeted patients surgically treated for proximal hamstring avulsion injury from January 2019 to June 2023. The MRI Cobra sign was defined as a wavy curved T2-hypointense band with the free end folding distally over itself, resembling a cobra head. The primary outcome measure was the characterization of the Cobra sign in patients with proximal hamstring avulsion injury. The secondary outcome was the association of this sign with tendon retraction. The study included 81 proximal hamstring avulsion injury patients (mean age of 45.7, SD = 13.9), with 41 (50.6%) complete avulsions, 33
semimembranosus, and 7 conjoint tendons.
RESULTS: The MRI Cobra sign was found in 25 patients (17
semimembranosus and 8 complete). It was confirmed surgically only in
semimembranosus cases. It demonstrated 51.5% sensitivity and 83.3% specificity for isolated
semimembranosus avulsions, with a significant positive likelihood ratio of 3.0. MRI retraction was 10.05 cm (±3.0), reducing to 7.9 cm (±2.5) on surgical measurement (mean difference = 2.0 cm, p < 0.001). The regression analysis confirmed MRI retraction\'s influence on the Cobra sign, with a 1.4 odds increase per unit (p < 0.001). In linear regression analysis, each unit increase in MRI retraction corresponded to a 79% increase in surgical retraction (coefficient 0.7, t = 11.1, p < 0.001).
CONCLUSIONS: The Cobra sign demonstrated acceptable diagnostic accuracy for isolated
semimembranosus avulsion, with a high specificity of 83.3%, a low sensitivity of 51.5%, and a positive likelihood ratio of 3.0. The presence of the Cobra sign indicates an overestimated MRI retraction by approximately 21%.
METHODS: Level III.