Summary

Tibial Tubercle–Rotational Angle (TT-RA) and Plateau Axis–Tuberosity Axis (PA-TA) angles, which represent tibial tubercle torsion and which are not affected by tibiofemoral rotation, may serve as novel predictive parameter for Anterior Cruciate Ligament Rupture.

Abstract

Objective

Predictive value of tibiofemoral parameters for Anterior Cruciate Ligament Rupture (ACLR) and their impact on graft failure has been investigated previously. Sagittal malalignment of the knee such as increased Posterior Tibial Slope (PTS), and axial malalignment of the knee such as increased Tibial Tubercle-Trochlear Groove (TT-TG) distance are recognized as biomechanical factors that increase loading on the Anterior Cruciate Ligament (ACL).
Many studies have examined the relationship between Tibial Tubercle (TT) lateralization, rotation, and torsion with patellofemoral instability.However there are few studies examining the relationship between TT morphology and ACLR.They are limited to the relationship between TT-TG distance with ACLR .However, TT-TG gives an idea about the lateralization and axial malalignment of TT, but does not represent the malposition of TT since it is affected by the tibiofemoral rotation.
The aim of this study was to evaluate TT morphology in patients with ACLR, and to examine the relationship between PTS and radiological parameters used to evaluate the position of TT.

Method

Magnetic Resonance Imaging(MRI) and lateral knee X-rays of 100 patients who underwent surgery due to ACL tear between 2016-2022 and a control group of 100 patients without pathology on MRI, were retrospectively analyzed.
In both groups; TTT (Tibial Tubercle Torsion), TT-RA (TT-Rotation Angle), PA-TA (Plateau Axis-Tuberosity Axis), TT-TG , TT-PCL (TT-Posterior Cruciate Ligament) and TT Lateralization distance representing TT position were measured using axial MRI.
TTH (Tibial Tubercle Height) and TTA (Tibial Tubercle Angle) representing the size of TT and PTS were measured on lateral knee X-rays of both groups.
Data were analyzed using IBM-SPSS software 26. Independent t-test was used for comparison of means.The correlations between the parameters themselves were analyzed.The predictive values of parameters for ACLR were assessed using logistic regression analysis.Statistical significance was set as p<0,05.

Results

In the ACLR group, compared to the control group the mean values of TT-RA (7.96ºvs.12.09º,p<0.001), PA-TA (8.41º vs. 11.58º,p<0.001) , TTT (5.68ºvs. 8.34º,p<0.001) were significantly lower.
In the ACLR group, compared to the control group the mean values of TT-TG (10.69mm vs. 8.17mm,p<0.001) ,PTS (12.84º vs. 10.61º,p<0.001) , TTH (11.69mm vs. 10.02mm,p<0.001) were significantly higher.
In the Pearson correlation test, a significant correlation was found between PTS and TT-TG (p<0.001, r=0.344), TT-RA (p=0.004, r=-0.201), PA-TA (p=0.03, r=-0.152) , TTH (p<0.001, r=0.306) ,TTA (p<0.03, r=-0.205).
In logistic regression analysis; TTT (p=0.01,OR=0.849) , TA-RA (p=0.02,OR=0.822) ,TT-TG (p<0.001, OR=1.298) ,PTS (p=0.007, OR=1.177), TTH (p=0.002, OR=1.327) were found to be associated with ACLR, independently of other parameters.

Conclusions

The results of this study demonstrate that TT-RA, PA-TA and TTT are statistically lower in patients with ACLR. In ACLR patients, TT is morphologically less externally rotated than normal. There is a correlation between PTS and some radiological parameters used to evaluate the position of the TT .
TT-RA and PA-TA angles representing torsion of TT may serve as novel predictive parameter for ACLR. Based on the results of this study, further biomechanical and clinical studies are warranted to investigate whether increased TT internal torsion increases ACL strain.