Dai Zhen-Zhen, Sha Lin, Zhang Zi-Ming, Liang Zhen-Peng, Li Hao, Li Hai
Department of Pediatric Orthopedics, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Yangpu District, Shanghai, China.
Orthop J Sports Med. 2021 Jan 27;9(1):2325967120973665. doi: 10.1177/2325967120973665. eCollection 2021 Jan.
The tibial tubercle-trochlear groove (TT-TG) distance was originally described for computed tomography (CT), but it has been measured on magnetic resonance imaging (MRI) in patients with patellar instability (PI). Whether the TT-TG measured on CT versus MRI can be considered equivalent in skeletally immature children remains unclear.
To investigate in skeletally immature patients (1) the effects of CT versus MRI imaging modality and cartilage versus bony landmarks on consistency of TT-TG measurement, (2) the difference between CT and MRI measurements of the TT-TG, and (3) the difference in TT-TG between patients with and without PI.
Cross-sectional study; Level of evidence, 3.
We retrospectively identified 24 skeletally immature patients with PI and 24 patients with other knee disorders or injury but without PI. The bony and cartilaginous TT-TG distances on CT and MRI were measured by 2 researchers, and related clinical data were collected. The interrater, interperiod (bony vs cartilaginous), and intermethod (CT vs MRI) reliabilities of TT-TG measurement were assessed with intraclass correlation coefficients.
The 48 study patients (19 boys, 29 girls) had a mean age of 11.3 years (range, 7-14 years). TT-TG measurements had excellent interrater reliability and good or excellent interperiod reliability but fair or poor intermethod reliability. TT-TG distance was greater on CT versus MRI (mean difference, 4.07 mm; 95% CI, 2.6-5.5 mm), and cartilaginous distance was greater than bony distance (mean difference, 2.3 mm; 95% CI, 0.79-3.8 mm). The TT-TG measured on CT was found to increase with the femoral width. Patients in the PI group had increased TT-TG distance compared with those in the control group, regardless of landmarks or modality used ( > .05 for all).
For skeletally immature patients, the TT-TG distance could be evaluated on MRI, regardless of whether cartilage or bony landmarks were used. Its value could not be interchanged with CT according to our results; however, further research on this topic is needed.
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，但在髌骨不稳定（PI）患者中已通过磁共振成像（MRI）进行测量。在骨骼未成熟儿童中，CT测量的TT-TG与MRI测量的TT-TG是否可视为等效尚不清楚。
在骨骼未成熟患者中研究（1）CT与MRI成像方式以及软骨与骨性标志对TT-TG测量一致性的影响，（2）CT与MRI测量TT-TG的差异，以及（3）有PI与无PI患者之间TT-TG的差异。
横断面研究；证据等级，3级。
我们回顾性确定了24例骨骼未成熟的PI患者和24例患有其他膝关节疾病或损伤但无PI的患者。由2名研究人员测量CT和MRI上的骨性和软骨性TT-TG距离，并收集相关临床数据。使用组内相关系数评估TT-TG测量的评分者间、测量间期（骨性与软骨性）和测量方法间（CT与MRI）的可靠性。
48例研究患者（19例男孩，29例女孩）的平均年龄为11.3岁（范围7-14岁）。TT-TG测量具有出色的评分者间可靠性和良好或出色的测量间期可靠性，但测量方法间可靠性一般或较差。CT测量的TT-TG距离大于MRI测量的（平均差异4.07 mm；95%CI，2.6-5.5 mm），软骨性距离大于骨性距离（平均差异2.3 mm；95%CI，0.79-3.8 mm）。发现CT测量的TT-TG随股骨宽度增加。PI组患者的TT-TG距离高于对照组，无论使用何种标志或成像方式（所有均P>0.05）。
对于骨骼未成熟患者，无论使用软骨还是骨性标志，均可在MRI上评估TT-TG距离。根据我们的结果，其值不能与CT互换；然而，需要对该主题进行进一步研究。
