Background:

The tibial tubercle (TT)–trochlear groove (TT-TG) distance has low reproducibility in patients with a dysplastic trochlea, whereas the clinical value of the TT–posterior cruciate ligament (TT-PCL) distance remains controversial.

Purposes:

To establish a method to assess the position of the TT on magnetic resonance imaging (MRI) scans using the TT–Roman arch (TT-RA) distance, compare this method with the TT-TG and TT-PCL distance, and provide the pathological threshold value of the TT-RA distance in patients with patellar dislocation.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

The TT-RA distance, TT-TG distance, and TT-PCL distance were measured on MRI scans in 70 patients with a history of patellar dislocation and 70 healthy individuals. Inter- and intraobserver reliability of each measurement parameter were evaluated. The discriminatory capacity and the interrelationship of the 3 measurement parameters were investigated using Pearson correlation and the receiver operating characteristic curve. The pathological threshold values of these measurements were calculated according to the data of healthy individuals. Finally, logistic regression analysis was performed using these values.

Results:

Patients with patellar dislocation had a greater TT-RA distance compared with healthy individuals (18.05 ± 4.16 vs 13.86 ± 2.90 mm; P < .001). The TT-RA distance had a stronger diagnostic capacity, with an area under the curve of 0.802 compared with 0.625 for TT-PCL distance. Excellent reproducibility was seen for TT-RA distance measurement at any degree of trochlear dysplasia (all intraclass correlation coefficients [ICCs] >0.90). The inter- and intraobserver ICCs of the TT-TG distance measurements were extremely low for Dejour type D dysplasia (ICC, 0.509 and 0.616, respectively). The pathological TT-RA distance threshold was calculated as 19.5 mm. Logistic regression showed that patients with a TT-RA distance >19.5 mm were 11.7 times more likely to sustain patellar dislocation than were those with TT-RA distance less than this value.

Conclusion:

The TT-RA distance was a more reliable parameter with which to evaluate TT position than was TT-TG distance in patients with trochlear dysplasia. The TT-PCL distance was the least reliable among the 3 parameters studied.

中文翻译：

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胫骨结节-罗马弓距离通过磁共振成像评估胫骨结节错位和预测髌骨脱位的可靠性

背景：

胫骨结节 (TT)-滑车沟 (TT-TG) 距离在发育不良滑车患者中的可重复性较低，而 TT-后交叉韧带 (TT-PCL) 距离的临床价值仍存在争议。

目的：

建立使用 TT-罗马弓 (TT-RA) 距离评估磁共振成像 (MRI) 扫描中 TT 位置的方法，将该方法与 TT-TG 和 TT-PCL 距离进行比较，并提供病理髌骨脱位患者TT-RA距离的阈值。

学习规划：

横断面研究；证据水平，3。

方法：

在 70 名有髌骨脱位病史的患者和 70 名健康个体的 MRI 扫描中测量了 TT-RA 距离、TT-TG 距离和 TT-PCL 距离。评估了每个测量参数的观察者间和观察者内的可靠性。使用 Pearson 相关性和受试者工作特征曲线研究了 3 个测量参数的辨别能力和相互关系。这些测量的病理阈值是根据健康个体的数据计算的。最后，使用这些值进行逻辑回归分析。

结果：

与健康个体相比，髌骨脱位患者的 TT-RA 距离更大（18.05 ± 4.16 vs 13.86 ± 2.90 mm；P< .001)。TT-RA距离具有更强的诊断能力，其曲线下面积为0.802，而TT-PCL距离为0.625。在任何程度的滑车发育不良（所有组内相关系数 [ICCs] > 0.90）下，TT-RA 距离测量均具有出色的重现性。对于 Dejour D 型发育不良，TT-TG 距离测量的观察者间和观察者内 ICC 极低（ICC 分别为 0.509 和 0.616）。病理 TT-RA 距离阈值计算为 19.5 mm。Logistic 回归显示，TT-RA 距离 >19.5 mm 的患者发生髌骨脱位的可能性是 TT-RA 距离小于该值的患者的 11.7 倍。

结论：

与滑车发育不良患者的 TT-TG 距离相比，TT-RA 距离是评估 TT 位置的更可靠的参数。在所研究的 3 个参数中，TT-PCL 距离是最不可靠的。