The lateral femoral notch sign and coronal lateral collateral ligament sign in magnetic resonance imaging failed to predict dynamic anterior tibial laxity

Association of the Coronal Lateral Collateral Ligament Sign in ACL-Deficient Knees With Greater Anterior Tibial Translation and Femorotibial Rotation in Adults and Adolescents

Background

The coronal lateral collateral ligament (LCL) sign (the entire LCL being seen in 1 coronal slice on a magnetic resonance imaging [MRI] scan), is a new secondary sign of anterior cruciate ligament (ACL) tear.

Purpose

To (1) evaluate the coronal LCL sign in adults with ACL tears and (2) compare the magnitude of the MRI scan parameters between adolescent and adult ACL-deficient knees with positive coronal LCL signs.

Study Design

Cross-sectional study; Level of evidence: 3.

Methods

We retrospectively reviewed patients who underwent ACL reconstruction between February 1, 2013, and May 31, 2021, and divided them into adolescent (10-18 years) and adult (>18 years) groups. Tibial translation, femorotibial rotation, and presence of the coronal LCL sign were evaluated using MRI. The static femorotibial position parameters were also compared between positive and negative coronal LCL sign groups. Independent Student t tests were used to identify statistically significant differences for continuous variables, whereas the categorical variables were compared using the chi-square test.

Results

A total of 65 adolescents and 300 adults with ACL tears were identified. The coronal LCL sign was present in a similar percentage of adolescents and adults with ACL tears (57% vs 58%; P = .873). The anterior tibial translation (ATT) in patients with positive coronal LCL signs (adolescents, 7.9 ± 3.4 mm; adults, 6.6 ± 3.5 mm) was significantly greater compared with those with negative signs (adolescents, 1.5 ± 2.6 mm, P < .001; adults, 2.3 ± 4.2 mm, P < .001). Femorotibial rotation was also statistically greater in positive coronal LCL sign groups (adolescents, 6.4°± 5.6°; adults, 7.0°± 5.0°) compared with negative sign groups (adolescents, 0.7°± 4.7°, P < .001; adults, 3.5°± 4.2°, P < .001).

Conclusion

The occurrence of the coronal LCL sign on MRI scans was comparable between adolescents and adults with ACL-deficient knees. The presence of the LCL sign was associated with a greater ATT and femorotibial rotation in both adolescents and adults with ACL tears.

The posterior cruciate ligament-posterior femoral cortex angle (PCL-PCA) and the lateral collateral ligament (LCL) sign are useful parameters to indicate the progression of knee decompensation over time after an ACL injury

PURPOSE

The posterior cruciate ligament-posterior cortex angle (angle between the most vertical part of the anterolateral PCL bundle and the posterior diaphyseal cortex of the femur; PCL-PCA) is the most accurate approach to describe the PCL buckling phenomenon observed in anterior cruciate ligament (ACL)-deficient knees. The aim of this study was to determine whether the PCL-PCA is associated with chronicity of the ACL rupture, the meniscal status, preoperative knee laxity or imaging signs such as the lateral collateral ligament (LCL) sign or the posterior tibial slope (PTS) in ACL-injured knees.

METHODS

Patients with a primary ACL reconstruction (ACLR) after physeal closure were selected retrospectively from a hospital-based ACL registry from 2015 to 2021. Exclusion criteria were: previous ipsilateral/contralateral knee surgery, previous ipsilateral ACL or meniscal tear, ipsilateral PCL and/or collateral ligament injuries or tibial plateau fracture. The ACL deficiency was defined as chronic if time from injury to MRI was > 6 months. The meniscal status was assessed during ACLR, separately for the medial and lateral meniscus, and classified into no tear, minor or major unstable tear. The MRI analyses included the assessment of the PCL-PCA and the LCL sign. PTS was assessed from the lateral plain radiographs of the injured knee. The side-to-side difference in anterior tibial translation (ATT) at 200N was obtained with the GNRB.

RESULTS

Eighty-two patients (forty-eight males/thirty-four females) were included in this study. The median PCL-PCA was 16.2° (Q1-Q3: 10.6-24.7) and differed between acute (18.4°) and chronic (10.7°) injuries (p < 0.01). The median PCL-PCA was significantly lower (- 4.6°) in patients with a positive LCL sign (p = 0.03) No significant association could be found between PCL-PCA and meniscal status, PTS or preoperative anterior knee laxity (Lachman, pivot shift and ATT in millimetres).

CONCLUSION

The PCL-PCA was significantly lower in chronic ACL injuries and in patients with a positive LCL sign, indicating a higher buckling phenomenon of the PCL in these patients. These results support the fact that PCL-PCA and the LCL sign may be useful parameters to indicate the progression of knee decompensation over time after an ACL injury, and therefore may constitute a helpful tool to optimise treatment choice and timing of ACL reconstruction if necessary.

LEVEL OF EVIDENCE

III.

Does Rotation and Anterior Translation Persist as Residual Instability in the Knee after Anterior Cruciate Ligament Reconstruction? (Evaluation of Coronal Lateral Collateral Ligament Sign, Tibial Rotation, and Translation Measurements in Postoperative MRI)

Purpose: The aim of this study was to evaluate the presence of residual instability in the knee after ACL reconstruction through the analysis of MRI findings. Methods: This study included patients who underwent isolated ACL reconstruction between December 2019 and December 2021, and had preoperative and postoperative MRI, clinical scores, and postoperative isokinetic measurements. The anterior tibial translation (ATT) distance, coronal lateral collateral ligament (LCL) sign, and femorotibial rotation (FTR) angle were compared preoperatively and postoperatively. The correlation between the changes in preoperative-postoperative measurements and postoperative measurements with clinical scores and isokinetic measurements was examined. The clinical outcomes were compared based on the presence of a postoperative coronal LCL sign. Inclusion criteria were set as follows: the time between the ACL rupture and surgery being 6 months, availability of preoperative and postoperative clinical scores, and objective determination of muscle strength using isokinetic dynamometer device measurements. Patients with a history of previous knee surgery, additional ligament injuries other than the ACL, evidence of osteoarthritis on direct radiographs, cartilage injuries lower limb deformities, and contralateral knee injuries were excluded from this study. Results: This study included 32 patients. After ACL reconstruction, there were no significant changes in the ATT distance (preoperatively: 6.5 ± 3.9 mm, postoperatively: 5.7 ± 3.2 mm) and FTR angle (preoperatively: 5.4° ± 2.9, postoperatively: 5.2° ± 3.5) compared to the preoperative measurements (p > 0.05). The clinical measurements were compared based on the presence of a postoperative coronal LCL sign (observed in 17 patients, not observed in 15 patients), and no significant differences were found for all parameters (p > 0.05). There were no observed correlations between postoperative FTR angle, postoperative ATT distance, FTR angle change, and ATT distance change values with postoperative clinical scores (p > 0.05). Significant correlations were observed between the high strength ratios generated at an angular velocity of 60° and a parameters FTR angle and ATT distance (p-values: 0.028, 0.019, and r-values: -0.389, -0.413, respectively). Conclusions: Despite undergoing ACL reconstruction, no significant changes were observed in the indirect MRI findings (ATT distance, coronal LCL sign, and FTR angle). These results suggest that postoperative residual tibiofemoral rotation and tibial anterior translation may persist; however, they do not seem to have a direct impact on clinical scores. Furthermore, the increase in tibial translation and rotation could potentially negatively affect the flexion torque compared to the extension torque in movements requiring high torque at low angular velocities.

The posterior cruciate ligament index as a reliable indirect sign of anterior cruciate ligament rupture is associated with the course of knee joint injury

PURPOSE

The objective of this study was to clarify the clinical value of the posterior cruciate ligament index (PCLI) in anterior cruciate ligament (ACL) rupture, to explore the relationship between the PCLI and course of disease, and to identify the influencing factors of the PCLI.

METHODS

The PCLI was defined a quotient of the X (the tibial and femoral PCL attachments) and the Y (the maximum perpendicular distance from X to the PCL). A total of 858 patients were enrolled in this case-control study, including 433 patients with ACL ruptures who were assigned to the experimental group and 425 patients with meniscal tears (MTs) who were allocated to the control group. Some patients in the experimental group have collateral ligament rupture (CLR). Information, such as the patient's age, sex, and course of disease, was recorded. All patients underwent magnetic resonance imaging (MRI) preoperatively, and the diagnosis was confirmed with the aid of arthroscopy. The PCLI and the depth of the lateral femoral notch sign (LFNS) were calculated based on the MRI findings, and the characteristics of the PCLI were explored.

RESULTS

The PCLI in the experimental group (5.1 ± 1.6) was significantly smaller than that in the control group (5.8 ± 1.6) (P < 0.05). The PCLI gradually decreased with time and was only 4.8 ± 1.4 in patients in the chronic phase (P < 0.05). This change was not due to the decrease in X but rather the increase in Y. The results also showed that the PCLI was not related to the depth of the LFNS or injuries of other structures in the knee joint. Furthermore, when the optimal cut-off point of the PCLI was 5.2 (area under the curve = 71%), the specificity and the sensitivity were 84% and 67%, respectively, but the Youden index was just 0.3 (P < 0.05).

CONCLUSION

The PCLI decreases due to the increase in Y instead of the decrease in X with time, especially in the chronic phase. The change in X in this process may be offset during imaging. In addition, there are fewer influencing factors that lead to changes in the PCLI. Therefore, it can be used as a reliable indirect sign of ACL rupture. However, it is difficult to quantify the diagnostic criteria of the PCLI in clinical practice. Thus, the PCLI as a reliable indirect sign of ACL rupture is associated with the course of knee joint injury, and it can be used to describe the instability of the knee joint.

LEVELS OF EVIDENCE

III.