Quantitative Variable Assessment of Patellar Instability: An MRI-Based Study

Feng

Yin

et al. 2022

Preprint

purpose: To (1) verify the reliability of the tibial tubercle-trochlear groove (TT-TG) distance measured by posterior condylar reference line (PCRL), surgical and anatomical transepicondylar axis (SEA and AEA) on MRI (TT-TGp, TT-TGs, and TT-TGa, respectively), (2) validate the diagnostic capacity of each parameter, (3) define the pathological threshold value of each TT-TG distance for tibial tubercle osteotomy (TTO).Methods: 86 patients with patellar dislocation (PD) and 86 healthy individuals were included. The intraclass correlation coefficient (ICC) was calculated to assess inter-observer reliability of each parameter. Unpaired t-test and Pearson correlation analysis were conducted. Receiver operating characteristic curves (ROC) and the areas under the curves (AUC) were analyzed to evaluate the diagnostic capacity of the parameters. The data of the control group was used to identify the pathological value of the parameters and Binary logistic regression model was established.Results: The TT-TGp, TT-TGs, and TT-TGa distance were greater in the study group (12.7±4.0, 12.0±4.1, and 11.9±4.2, respectively) than in the control group (8.2±2.9, 8.1±3.0, and 8.0±3.0, respectively) (P<0.001) and were correlated with trochlear dysplasia with a ρ of 0.47, 0.46, and 0.50, respectively (P<0.001). In the study group, the TT-TGp distance was greater than TT-TGs and TT-TGa distance (P<0.001). The ICC of each TT-TG distance was more than 0.85 in any degree of trochlear dysplasia. The AUC of the TT-TGp distance (0.811) was higher than the TT-TGs (0.777) and TT-TGa (0.768) distance. The pathological value of each TT-TG distance was 13.0mm. And the TT-TGp revealed a significant OR of 18.68 (95% CI [6.28, 55.50]) with regard to PD.Conclusion: Each TT-TG distance can be measured reliably by MRI and has a good diagnostic capacity for PD. TTO should be considered when a pathological TT-TG distance (>13.0 mm) is presented.Level of Evidence: Retrospective cohort study (diagnosis); Level of evidence, I.

Section: Discussionmentioning

confidence: 92%

Section: Tt-tg Distancementioning

confidence: 99%

Tibial Tubercle to Trochlear Groove Distance Measured by Transepicondylar Axis on MRI is a Reliable Parameter in Tibial Tuberosity Osteotomy Decision Making in Patients with Recurrent Patellar Dislocation

Feng

Yin

et al. 2022

Preprint

“…The TT-TG distance measured by CT images was unreliable, because the measurement was greatly affected by dysplastic femoral trochlea [ 12 ]. On the other hand, previous literature suggested that the TT-TG distance can be reliably measured by MRI, because the cartilage of femoral trochlea can be clearly visualized and the entry of the trochlea can be accurately located by MRI [ 14 , 25 ]. The results of our study showed that all the three TT-TG distances measured by MRI had excellent interobserver agreements, even in patients with severe trochlear dysplasia.…”

Section: Discussionmentioning

confidence: 99%

“…The TT-TG distance using PCRL as the reference line was measured on the MRI scan according to the method described by Friedman et al [ 25 ]. The most proximal axial slice showing the complete femoral trochlea with cartilage and intact posterior femoral condyles was identified to define the following marks: the deepest portion of the cartilaginous trochlear groove, the tangent line from the posterior cartilaginous edge of the medial to the lateral condyle (posterior condylar reference line, PCRL), the line through the sulcus of the medial epicondyle and the prominence of the lateral epicondyle (SEA) [ 26 ], and the line through the prominence of the medial and lateral epicondyles (AEA) [ 27 ] ( Figure 1 A).…”

Section: Methodsmentioning

confidence: 99%

Tibial Tubercle to Trochlear Groove Distance Measured by Posterior Condylar Reference Line on MRI Can Over-Evaluate Lateralization Deformity of Tibial Tubercle in Patients with Recurrent Patellar Dislocation

Chen

Feng

et al. 2022

JCM

Background: The tibial tubercle to trochlear groove (TT-TG) distance is currently considered as an indication for tibial tubercle osteotomy. While the influence of femoral condylar morphology on such measurement remains unclear. Methods: A total of 86 patients with patellar dislocation (PD) and 86 healthy individuals were enrolled. Femoral condylar morphology and the TT-TG distance measured by anatomical transepicondylar axis (TT-TGa), by surgical transepicondylar axis (TT-TGs), and by posterior condylar reference line (TT-TGp) were assessed by MRI. Unpaired t-test, Spearman, and Pearson correlation analysis were conducted. We determined the pathological value of the parameters and established a binary regression model. Results: The interclass correlation coefficients of all the TT-TG distances were greater than 0.75 in all types of trochlear dysplasia. The lateral/posterior femoral condyle was shorter and the medial/posterior condyle was longer in the study group (28.5 ± 3.3 and 35.2 ± 2.8, respectively) than in the control group (30.9 ± 2.7 and 33.5 ± 2.3, respectively). In the study group, the TT-TGp distance was greater than TT-TGs and TT-TGa distance (p < 0.001). The pathological value of the TT-TG distance was 13.0 mm. Each TT-TG distance revealed a significant OR with regard to PD. Conclusion: The TT-TGa, TT-TGs, and TT-TGp distance can be reliably measured by MRI even in patients with trochlear dysplasia. While the TT-TGp distance may overestimate the lateralization deformity of the tibial tubercle. Posterior femoral condylar dysplasia may be a reason for such overestimating. These findings have not been correlated to clinical outcomes and further studies are required.

“…Although the TT–posterior cruciate ligament (TT-PCL) distance can supplement the deficiency of the TT-TG distance to some extent, the clinical value of the TT-PCL distance has not yet been fully validated. 1 , 6 , 8 , 22 , 32 These facts limit the clinical application of these imaging measurements.…”

mentioning

confidence: 99%

Reliability of the Tibial Tubercle–Roman Arch Distance for Evaluating Tibial Tubercle Malposition and Predicting Patellar Dislocation via Magnetic Resonance Imaging

Orthopaedic Journal of Sports Medicine

Song

et al. 2022

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.