Anley Cameron Michael, Morris Guy Vernon, Saithna Adnan, James Steven Laurence, Snow Martyn
Arthroscopy Division, The Royal Orthopaedic Hospital, Birmingham, UK
Arthroscopy Division, The Royal Orthopaedic Hospital, Birmingham, UK.
Am J Sports Med. 2015 Jun;43(6):1348-53. doi: 10.1177/0363546515576128. Epub 2015 Mar 26.
The radiological work-up of patients with patellofemoral disorders continues to be debated. The interchangeability of the tibial tubercle-trochlear groove (TT-TG) distance between computed tomography (CT) and magnetic resonance imaging (MRI) has recently been questioned. In addition, a new measurement-the tibial tubercle-posterior cruciate ligament (TT-PCL) distance-has shown that not all patients with a pathological TT-TG distance (>20 mm) have lateralization of the tibial tubercle. Another factor to consider when looking at the position of the tibial tubercle is the knee joint rotation, defined as the angle between the femoral dorsal condylar line and the tibial dorsal condylar line.
To determine, with a larger population, if the TT-TG measurements can be used interchangeably between CT and MRI and to confirm the correlation between the TT-PCL and TT-TG distances in determining tibial tubercle lateralization.
Cohort study (diagnosis); Level of evidence, 2.
Patients with patellofemoral disorders and MRI and CT scans of the same knee (n = 141) were identified. The TT-PCL, the knee joint rotation, and TT-TG were measured independently by 2 fellowship-trained orthopaedic surgeons. Thirty measurements were repeated on a separate occasion to allow for an assessment of the intrarater reliability. The intraclass correlation coefficient (ICC) was used to assess reliability of the measurements.
The mean TT-TG was 4.16 mm less on MRI (P < .05), with the mean TT-TG ± SD being 17.72 ± 5.15 mm on CT (range, 6.97-31.33 mm) and 13.56 ± 6.07 mm on MRI (range, 2-30.04 mm). The ICC for each rater comparing the 2 imaging modalities was only fair (0.54 and 0.48). The mean TT-PCL measurement was 20.32 ± 3.45 mm (range, 10.11-32.01 mm) with excellent interobserver and intraobserver reliability (>0.75). Based on the TT-TG and TT-PCL measurements, 4 groups of patients can be established. When knee joint rotation is compared among groups, an increased TT-TG may result from true lateralization of the tibial tubercle, an increased knee joint rotation, or both.
Based on a statistically significant mean difference (4.11 mm) and only a fair ICC (0.54 and 0.48) for raters comparing the 2 modalities, the measurements for the TT-TG cannot be used interchangeably between CT and MRI. Therefore, currently accepted values for TT-TG based on CT scans should not be applied to an MRI scan. The TT-PCL measurement is a measure of true lateralization of the tibial tubercle, while the TT-TG is an amalgamated measure of true lateralization and knee joint rotation.
髌股关节疾病患者的影像学检查方法仍存在争议。计算机断层扫描（CT）和磁共振成像（MRI）测量的胫骨结节 - 滑车沟（TT - TG）距离的互换性最近受到质疑。此外，一种新的测量方法——胫骨结节 - 后交叉韧带（TT - PCL）距离——表明并非所有TT - TG距离病理性增大（>20 mm）的患者都存在胫骨结节外侧移位。在观察胫骨结节位置时，另一个需要考虑的因素是膝关节旋转，定义为股骨后髁线与胫骨后髁线之间的夹角。
在更大的人群中确定CT和MRI测量的TT - TG值是否可互换使用，并证实TT - PCL与TT - TG距离在确定胫骨结节外侧移位中的相关性。
队列研究（诊断）；证据等级，2级。
纳入患有髌股关节疾病且同一膝关节同时有MRI和CT扫描的患者（n = 141）。由2名经过专科培训的骨科医生独立测量TT - PCL、膝关节旋转角度和TT - TG。在另一个时间重复测量30次，以评估测量者内部的可靠性。组内相关系数（ICC）用于评估测量的可靠性。
MRI测量的平均TT - TG比CT测量的平均TT - TG小4.16 mm（P <.05），CT测量的平均TT - TG ± SD为17.72 ± 5.15 mm（范围6.97 - 31.33 mm），MRI测量的平均TT - TG ± SD为13.56 ± 6.07 mm（范围2 - 30.04 mm）。比较两种成像方式时，每位测量者的ICC仅为中等（分别为0.54和0.48）。TT - PCL的平均测量值为20.32 ± 3.45 mm（范围10.11 - 32.01 mm），观察者间和观察者内可靠性极佳（>0.75）。基于TT - TG和TT - PCL测量值，可将患者分为4组。比较各组间的膝关节旋转角度时，TT - TG增大可能是由于胫骨结节真正的外侧移位、膝关节旋转角度增大或两者共同导致。
基于统计学上显著的平均差异（4.11 mm）以及比较两种成像方式时测量者仅为中等的ICC（0.54和0.48），CT和MRI测量的TT - TG值不可互换使用。因此，目前基于CT扫描的TT - TG公认值不适用于MRI扫描。TT - PCL测量是胫骨结节真正外侧移位的指标，而TT - TG是真正外侧移位和膝关节旋转的综合指标。
