Magee Thomas, Shapiro Marc, Williams David
Department of Radiology, Neuroimaging Institute, 27 E Hibiscus Blvd., Melbourne, FL 32901, USA.
AJR Am J Roentgenol. 2004 Apr;182(4):931-6. doi: 10.2214/ajr.182.4.1820931.
Meniscal resection decreases the ability of the meniscus to evenly distribute forces placed on it. These forces are oriented centrifugally on the meniscus by normal weight-bearing and are distributed by circumferentially oriented fibers. This alteration may predispose the knee to radial tears after surgery.
One of three musculoskeletal radiologists prospectively interpreted 100 consecutive postoperative MRI examinations of the knee. A prospective MRI report was generated for the referring orthopedic surgeon, and prospective MRI interpretations were correlated with arthroscopic findings (n = 63). MRI examinations on those patients who underwent second-look arthroscopy were retrospectively reviewed by three musculoskeletal radiologists who reached a consensus on the prevalence of new postoperative meniscal radial tears. MRI criteria for radial tear diagnosis were used as outlined by Tuckman et al.: truncation, abnormal morphology, lack of continuity, absence of the meniscus, or any combination of those criteria on one or more MR images. An additional criterion used was abnormal increased signal in that area on T2-weighted images.
Thirty-two of the 100 patients had meniscal radial tears on prospective MRI interpretations. In 29 of these 32 patients, second-look arthroscopy confirmed meniscal radial tears in the areas described on the MRI examinations. Five additional radial tears were shown on second-look arthroscopy that were not seen on prospective MRI interpretations. Two of those additional five radial tears were seen on consensus retrospective MRI review.
In this study, a 32% prevalence of meniscal radial tears in the postoperative knee was present on prospective MRI interpretations as opposed to a reported 14% prevalence in the nonoperated knee. Meniscal resection decreases the ability of the meniscus to evenly distribute forces placed on it. This circumstance may increase the prevalence of meniscal radial tears in the postoperative knee. New meniscal radial tears are common in patients presenting with pain after knee surgery.
半月板切除术会降低半月板均匀分布施加于其上的力的能力。这些力通过正常负重以离心方式作用于半月板，并由周向排列的纤维进行分布。这种改变可能使膝关节在术后易发生放射状撕裂。
三位肌肉骨骼放射科医生中的一位对连续100例膝关节术后MRI检查进行前瞻性解读。为转诊的骨科医生生成一份前瞻性MRI报告，前瞻性MRI解读结果与关节镜检查结果（n = 63）进行关联。对那些接受二次关节镜检查的患者的MRI检查进行回顾性分析，三位肌肉骨骼放射科医生就术后新出现的半月板放射状撕裂的发生率达成共识。采用Tuckman等人概述的MRI诊断放射状撕裂的标准：截断、形态异常、连续性中断、半月板缺失，或在一个或多个MR图像上出现这些标准的任何组合。另一个使用的标准是T2加权图像上该区域信号异常增高。
在100例患者中，有32例在前瞻性MRI解读中存在半月板放射状撕裂。在这32例患者中的29例中，二次关节镜检查证实了MRI检查所描述区域的半月板放射状撕裂。二次关节镜检查还发现了另外5例放射状撕裂，在前瞻性MRI解读中未被发现。在回顾性MRI共识分析中发现了这另外5例放射状撕裂中的2例。
在本研究中，前瞻性MRI解读显示术后膝关节半月板放射状撕裂的发生率为32%，而据报道非手术膝关节的发生率为14%。半月板切除术会降低半月板均匀分布施加于其上的力的能力。这种情况可能会增加术后膝关节半月板放射状撕裂的发生率。新的半月板放射状撕裂在膝关节手术后出现疼痛的患者中很常见。
