Tan Si Heng Sharon, Lim Beatrice Ying, Chng Kiat Soon Jason, Doshi Chintan, Wong Francis K L, Lim Andrew Kean Seng, Hui James Hoipo
Department of Orthopaedic Surgery, National University Health System, Singapore, Singapore.
J Knee Surg. 2020 Aug;33(8):768-776. doi: 10.1055/s-0039-1688563. Epub 2019 May 7.
The tibial tubercle-trochlear groove (TT-TG) distance was originally described for computed tomography (CT) but has recently been used on magnetic resonance imaging (MRI) without sufficient evidence demonstrating its validity on MRI. The current review aims to evaluate (1) whether there is a difference in the TT-TG distances measured using CT and MRI, (2) whether both the TT-TG distances measured using CT and MRI could be used to differentiate between patients with or without patellofemoral instability, and (3) whether the same threshold of 15 to 20 mm can be applied for both TT-TG distances measured using CT and MRI. The review was conducted using the preferred reporting items for systematic reviews and meta-analyses (PRSIMA) guidelines. All studies that compared TT-TG distances either (1) between CT and MRI or (2) between patients with and without patellofemoral instability were included. A total of 23 publications were included in the review. These included a total of 3,040 patients. All publications reported the TT-TG distance to be greater in patients with patellofemoral instability as compared to those without patellofemoral instability. This difference was noted for both TT-TG distances measured on CT and on MRI. All publications also reported the TT-TG distance measured on CT to be greater than that measured on MRI (mean difference [MD] = 1.79 mm; 95% confidence interval [CI]: 0.91-2.68). Pooling of the studies revealed that the mean TT-TG distance for the control group was 12.85 mm (95% CI: 11.71-14.01) while the mean TT-TG distance for patients with patellofemoral instability was 18.33 mm (95% CI: 17.04-19.62) when measured on CT. When measured on MRI, the mean TT-TG distance for the control group was 9.83 mm (95% CI: 9.11-10.54), while the mean TT-TG distance for patients with patellofemoral instability was 15.33 mm (95% CI: 14.24-16.42). Both the TTTG distances measured on CT and MRI could be used to differentiate between patients with and without patellofemoral instability. Patients with patellofemoral instability had significantly greater TT-TG distances than those without. However, the TT-TG distances measured on CT were significantly greater than that measured on MRI. Different cut-off values should, therefore, be used for TT-TG distances measured on CT and on MRI in the determination of normal versus abnormal values. Pooling of all the patients included in the review then suggest for 15.5 ± 1.5 mm to be used as the cut off for TT-TG distance measured on CT, and for 12.5 ± 2 mm to be used as the cut-off for TT-TG distance measured on MRI. The Level of evidence for this study is IV.
胫骨结节-滑车沟（TT-TG）距离最初是针对计算机断层扫描（CT）描述的，但最近在磁共振成像（MRI）上也开始使用，却没有足够证据证明其在MRI上的有效性。本综述旨在评估：（1）使用CT和MRI测量的TT-TG距离是否存在差异；（2）使用CT和MRI测量的TT-TG距离是否都可用于区分有无髌股关节不稳的患者；（3）对于使用CT和MRI测量的TT-TG距离，是否都可应用15至20毫米这一相同阈值。本综述按照系统评价和Meta分析的首选报告项目（PRISMA）指南进行。纳入所有比较（1）CT和MRI之间或（2）有无髌股关节不稳患者之间TT-TG距离的研究。本综述共纳入23篇出版物。这些出版物共涉及3040例患者。所有出版物均报告，与无髌股关节不稳的患者相比，有髌股关节不稳的患者TT-TG距离更大。在CT和MRI上测量的TT-TG距离均呈现出这种差异。所有出版物还报告，CT测量的TT-TG距离大于MRI测量的（平均差[MD]=1.79毫米；95%置信区间[CI]：0.91-2.68）。研究汇总显示，对照组患者CT测量的TT-TG平均距离为12.85毫米（95%CI：11.71-14.01），而有髌股关节不稳患者的平均距离为18.33毫米（95%CI：17.04-19.62）。MRI测量时，对照组患者的TT-TG平均距离为9.83毫米（95%CI：9.11-10.54），而有髌股关节不稳患者的平均距离为15.33毫米（95%CI：14.24-16.42）。CT和MRI测量的TT-TG距离均可用于区分有无髌股关节不稳的患者。有髌股关节不稳的患者TT-TG距离显著大于无髌股关节不稳的患者。然而，CT测量的TT-TG距离显著大于MRI测量的。因此，在确定正常值与异常值时，CT和MRI测量的TT-TG距离应使用不同的临界值。对本综述纳入的所有患者进行汇总分析后建议，CT测量的TT-TG距离临界值为15.5±1.5毫米，MRI测量的TT-TG距离临界值为12.5±2毫米。本研究的证据级别为IV级。
