Diagnostic value of the lateral femoral notch sign and kissing contusion in patients with anterior cruciate ligament injuries: a case-control study.

INTRODUCTION: The lateral femoral notch sign (LFNS) and the kissing contusion (KC) are two indirect signs of anterior cruciate ligament (ACL) injuries. They can be used to diagnose ACL injuries. MATERIALS AND METHODS: A total of 1000 patients were enrolled in this study, including 500 patients with ACL injuries who assigned to experimental group and 500 patients with meniscal tear (MT) who allocated to control group. All the patients underwent magnetic resonance imaging (MRI) preoperatively, and the diagnosis was confirmed with the aid of arthroscopy. The depth of LFNS and the presence of KC were determined on MRI findings. The relationship and characteristics between these two indicators was explored. RESULTS: The notch depth of lateral femoral condyle in the experimental group (0.99 ± 0.56 mm) was significantly greater than that in the control group (0.49 ± 0.28 mm) (P < 0.05). The positive rate of KC in the experimental group (183/500) was markedly higher than that in the control group (3/500) (P < 0.05). The values of notch depth in patients who had ACL rupture concomitant lateral MT injuries and medial collateral ligament (MCL) injuries were 1.12 ± 0.64 and 1.23 ± 0.74 mm, respectively, which were significantly higher than those in patients with only ACL injury (0.89 ± 0.49 mm) (P < 0.05). It also was revealed that when the optimal cut-off point of LFNS was 0.72 mm (area under the curve (AUC) = 81%), the values of specificity and sensitivity were 67% and 84%, respectively. For KC, the corresponding values were 36.6% and 99.4%, respectively. The diagnostic outcome of LFNS was not in agreement with that of KC, as there was a poor coincidence according to the Kappa coefficient (Kappa = 0.155 < 0.4, P = 0.035). CONCLUSION: The LFNS and KC have strong clinical significance in the diagnosis of ACL injuries. A deeper notch often indicates a more complex knee injury. Notch depth equal to 0.72 mm can be basically considered as the optimal cut-off point for LFNS in statistics.

The deep lateral femoral notch sign: a reliable diagnostic tool in identifying a concomitant anterior cruciate and anterolateral ligament injury.

PURPOSE: The aim of the present study was to investigate the validity and reliability of the deep lateral femoral notch sign (DLFNS) in identifying a concomitant anterior cruciate ligament (ACL)/anterolateral ligament (ALL) rupture and predicting the clinical outcomes following an anatomical single-bundle ACL reconstruction. It was hypothesized that patients with a concomitant ACL/ALL rupture would have an increased DLFNS compared to patients without a concomitant ACL/ALL rupture. METHODS: The lateral preoperative radiographs and MRI images of 100 patients with an ACL rupture and 100 control subjects were evaluated for the presence of a DLFNS and ACL/ALL rupture, respectively. The patients were evaluated clinically preoperatively and at a minimum 1 year following the ACL reconstruction. A receiver operator curve (ROC) analysis was performed to define the optimal cut-off value of the DLFNS for identifying a concomitant ACL/ALL injury. The relative risk (RR) was also calculated to determine whether the presence of the DLFNS was a risk factor for residual instability or ACL graft rupture following an ACL reconstruction. RESULTS: The prevalence of DLFNS was 52% in the ACL-ruptured patients and 15% in the control group. At a minimum 1-year follow-up, 35% (6/17) of the patients with DLFNS > 1.8 mm complained of persistent instability, and an MRI evaluation demonstrated a graft re-rupture rate of 12% (2/17). In patients with a DLFNS < 1.8 mm, 8% (7/83) reported a residual instability, and the graft rupture rate was 2.4% (2/83). A DLFNS > 1.8 mm demonstrated a sensitivity of 89%, a specificity of 95%, a negative predictive value of 98%, and a positive predictive value of 89% in identifying a concomitant ACL/ALL rupture. Patients with a DLFNS > 1.8 mm had 4.2 times increased risk for residual instability and graft rupture compared to patients with a DLFNS ≤ 1.8 mm. CONCLUSIONS: A DLFNS > 1.8 mm could be a clinically relevant diagnostic tool for identifying a concomitant ACL/ALL rupture with high sensitivity and PPV. Patients with a DLFNS > 1.8 mm should be carefully evaluated for clinical and radiological signs of a concomitant ACL/ALL rupture and treated when needed with a combined intra-articular ACL reconstruction and extra-articular tenodesis to avoid a residual rotational instability and ACL graft rupture. LEVEL OF EVIDENCE: III.

High prevalence of a deep lateral femoral notch sign in patients with anterior cruciate ligament (ACL) and concomitant posterior root tears of the lateral meniscus.

PURPOSE: To determine the prevalence of a deep lateral femoral notch sign (LFNS) in magnetic resonance imaging (MRI) in patients with anterior cruciate ligament (ACL) and concomitant posterior root tears of the lateral meniscus (PLRT). METHODS: A retrospective chart review was conducted to identify all patients undergoing ACL reconstruction between 2016 and 2018. Based on the arthroscopic appearance of the lateral meniscus, patients were assorted to one of three groups: isolated ACL tear (ACL-Group), ACL tear with concomitant lateral meniscus tear not involving the posterolateral root (Meniscus-Group), and ACL tear with concomitant PLRT (PLRT-Group). Incidence and depth of a LFNS on preoperative MRI was compared between the three cohorts. RESULTS: 115 patients (mean age: 29.5 ± 11.3 years) were included in the study, with 58 patients (50.4%) assorted to the ACL-Group, 24 patients (20.9%) to the Meniscus-Group, and 33 patients (28.7%) to the PLRT-Group. The prevalence of a LFNS was significantly higher in the PLRT-Group (39.4%), when compared to the ACL- (5.2%) or Meniscus-Groups (25.0%; p < 0.001, respectively). Additionally, logistic regression analysis demonstrated that patients with PLRT were 5.3 times more likely to have a LFNS as compared to those without a lateral root tear (p < 0.001). CONCLUSION: In patients with ACL tears, the presence of a LFNS on preoperative MRI may be predictive for a PLRT. As the LFNS occurs in almost 40% of the patients with combined ACL tears and PLRT, the LFNS may be a useful secondary diagnostic finding in early MRI diagnostic. Identifying PLRT on MRI is clinically relevant, as it prevents misdiagnosis and facilitates surgical decision-making, thus avoiding subsequent delayed treatment. LEVEL OF EVIDENCE: Level IV.

Lateral femoral notch depth is not associated with increased rotatory instability in ACL-injured knees: a quantitative pivot shift analysis.

PURPOSE: A deep lateral femoral notch (LFN) on lateral radiographs is indicative of ACL injury. Prior studies have suggested that a deep LFN may also be a sign of persistent rotatory instability and a concomitant lateral meniscus tear. Therefore, the purpose of this study was to evaluate the relationship between LFN depth and both quantitative measures of rotatory knee instability and the incidence of lateral meniscus tears. It was hypothesized that greater LFN depth would be correlated with increased rotatory instability, quantified by lateral compartment translation and tibial acceleration during a quantitative pivot shift test, and incidence of lateral meniscus tears. METHODS: ACL-injured patients enrolled in a prospective ACL registry from 2014 to 2016 were analyzed. To limit confounders, patients were only included if they had primary ACL tears, no concurrent ligamentous or bony injuries requiring operative treatment, and no previous knee injuries or surgeries to either knee. Eighty-four patients were included in the final analysis. A standardized quantitative pivot shift test was performed pre-operatively under anesthesia in both knees, and rotatory instability, specifically lateral compartment translation and tibial acceleration, was quantified using tablet image analysis software and accelerometer sensors. Standard lateral radiographs and sagittal magnetic resonance images (MRI) of the injured knee were evaluated for LFN depth. RESULTS: There were no significant correlations between LFN depth on either imaging modality and ipsilateral lateral compartment translation or tibial acceleration during a quantitative pivot shift test or side-to-side differences in these measurements. Patients with lateral meniscus tears were found to have significantly greater LFN depths than those without on conventional radiograph and MRI (1.0 vs. 0.6 mm, p < 0.05; 1.2 vs. 0.8 mm, p < 0.05, respectively). CONCLUSION: There was no correlation between lateral femoral notch depth on conventional radiographs or MRI and quantitative measures of rotatory instability. Concomitant lateral meniscus injury was associated with significantly greater LFN depth. Based on these findings, LFN depth should not be used as an indicator of excessive rotatory instability, but may be an indicator of lateral meniscus injury in ACL-injured patients. LEVEL OF EVIDENCE: Prognostic level IV.

The lateral femoral notch sign decreases in paediatric patients following anterior cruciate ligament reconstruction.

INTRODUCTION: Anterior cruciate ligament (ACL) ruptures are common amongst paediatric patients, especially those participating in competitive sports. While magnetic resonance imaging (MRI) is typically used to confirm the diagnosis, certain radiologic findings can be indicative of an ACL tear, including a lateral femoral notch sign (LFNS) > 1.5 mm (mm). No study has focussed on understanding the resolution pattern of the LFNS in paediatric patients following ACL reconstruction (ACLR). The aim of this study is to determine whether the depth of the LFNS regresses following ACLR. The authors hypothesize that following ACLR, the LFNS will resolve. METHODS: All patients who were treated for acute ACL rupture by one of two paediatric orthopaedic surgeons between 2015 and 2020 were collected; 321 patients with the age of 5-18 were collected. Patients were excluded if they underwent previous ipsilateral knee surgeries and if they did not have pre-operative knee radiographs; 274 patients met inclusion criteria. LFNS was measured on pre-operative (PreOp) and most recent post-operative (PostOp) radiographs. A comparison cohort of patients with an LFNS <1.5 mm matched by age within 1.5 years, sex, and laterality was also collected. The median difference was calculated by taking the difference between PreOp LFNS and PostOp LFNS of each participant and finding the median of those values. RESULTS: A total of 274 pre-operative radiographs were analysed for an LFNS depth >1.5 mm. Seventeen radiographs met these criteria with a median age of 16.3 years and a median depth of 1.70 mm. Of the 17 radiographs, 8 (47.1%) of participants were skeletally immature. The median LFNS depth at most recent follow-up and median percent decrease were 1.50 mm and 28%, respectively. Only 11.8% of patients demonstrated no change in LFNS depth from PreOp to PostOp imaging. Wilcoxon signed-rank test indicated that the PreOp LFNS was significantly greater than the PostOp LFNS (p < 0.001). Mann-Whitney U tests with cases and the comparison cohort demonstrated no difference in the percent decrease (p = 0.106). CONCLUSION: This study sought to understand the resolution of the LFNS depth following initial ACL rupture. At a median of 7.67 months following ACLR, the LFNS depth decreased significantly by 0.60 mm. These findings suggest that following ACL rupture, the paediatric LFNS has the potential to resolve. Future studies should aim to further assess the resolution pattern of the LFNS with advanced imaging, such as MRI.

[Long-term outcomes of lateral femoral notch after early anterior cruciate ligament reconstruction].

OBJECTIVE: To investigate the outcome of lateral femoral notch (LFN) after early anterior cruciate ligament (ACL) reconstruction and evaluate the recovery of knee joint function after the operation. METHODS: The clinical data of 32 patients who underwent early ACL reconstruction from December 2015 to December 2019 were retrospectively analyzed. The study included 18 males and 14 females, aged 16 to 54 years old, with an average age of (25.39±2.82) years. The body mass index (BMI) of the patients ranged from 20 to 30 kg/cm2, with an average of (26.15±3.09) kg/cm2. Among them, 6 cases were caused by traffic accidents, 19 by exercise, and 7 by the crush of heavy objects. MRI of all patients showed LFN depth was more than 1.5 mm after injury, and no intervention for LFN was performed during surgery. Preoperative and postoperative depth, area, and volume of LFN defects were observed by MRI data. International Cartilage Repair Society (ICRS) score, Lysholm score, Tegner activity levels, and knee injury and osteoarthritis outcome score (KOOS) were analyzed before and after the operation. RESULTS: All patients were followed up from 2 to 6 years with an average of (3.28±1.12) years. There was no significant difference in the defect depth of LFN from (2.31±0.67) mm before the operation to (2.53±0.50) mm at follow-up (P=0.136). The defect area of LFN was decreased from (207.55±81.01)mm2 to (171.36±52.69)mm2 (P=0.038), and the defect volume of LFN was decreased from (426.32±176.54) mm3 to (340.86±151.54)mm3 (P=0.042). The ICRS score increased from (1.51±0.34) to (2.92±0.33) (P<0.001), the Lysholm score increased from (35.37±10.54) to (94.46±8.45) (P<0.001), and the Tegner motor score increased from (3.45±0.94) to (7.56±1.28), which was significantly higher than that of the preoperative data (P<0.001). The KOOS score of the final follow-up was 90.42±16.35. CONCLUSION: With the increase of recovery time after anterior cruciate ligament reconstruction, the defect area and volume of LFN decreased gradually, but the defect depth remained unchanged. The knee joint function of the patients significantly improved. The cartilage of the LFN defect improved, but the repair effect was not good.

[Research progress of lateral femoral notch sign in diagnosis of anterior cruciate ligament rupture].

OBJECTIVE: To summarize the relationship between lateral femoral notch sign (LFNS) and anterior cruciate ligament (ACL) rupture. METHODS: The relevant literature of LFNS at home and abroad in recent years was retrospectively reviewed, and its mechanism, diagnostic criteria and influencing factors in diagnosis of ACL rupture were summarized and analyzed. RESULTS: The LFNS is associated with rotational stability of the knee. As an indirect sign of ACL rupture, the LFNS has high clinical diagnostic value, especially the diagnosis of ACL rupture with lateral meniscus injury. CONCLUSION: The diagnostic criteria and influencing factors of LFNS in diagnosis of ACL rupture are still unclear and controversial, which needs further study.

Fate of the lateral femoral notch following early anterior cruciate ligament reconstruction.

BACKGROUND: The goal of this longitudinal study was to investigate the fate of the lateral femoral notch (LFN), which is frequently seen as an impaction fracture of the lateral femoral condyle in patients with anterior cruciate ligament (ACL) tears. METHODS: Patients who underwent early ACL reconstruction between 2006 and 2010 were reviewed. If post-injury magnetic resonance images showed an LFN greater than 1.5 mm in depth, patients with untreated LFN were followed. Two blinded observers performed quantitative and qualitative imaging analysis. RESULTS: Sixteen patients (five women, 11 men) were available for follow-up nine years (six to 10 years) post-injury. The median defect area of the LFN significantly decreased from 2.3 cm2 (range: 0.9-3.8 cm2) to 1.6 cm2 (range: 0.4-3.2 cm2) (P < .001). The defect depth did not significantly change from 2.3 mm (range: 2.0-3.6 mm) to 2.5 mm (range: 1.3-3.6 mm) (P > .05). The International Cartilage Repair Society (ICRS) score increased from 1.5 (range: 0-3) post-injury to 2.0 (range: 0-4) at follow-up (P < .01). The Lysholm score was 93 (72-100), the Tegner activity level was 6 (3-9) and the knee injury and osteoarthritis outcome score (KOOS) score was 97 (91-100). CONCLUSIONS: The defect area of the LFN decreased overtime, whereas the depth of the impression remained. Focal cartilage lesions were found in all except two patients post-injury and progressed during follow-up. However, patient-reported outcome scores were satisfying.

T2 relaxation times of the anterolateral femoral cartilage in patients after ACL-reconstruction with and without a deep lateral femoral notch sign.

PURPOSE: To quantitatively assess T2 relaxation times of the anterolateral femoral cartilage following anterior cruciate ligament (ACL)-reconstruction with and without a positive deep lateral femoral notch sign (DLNS) at post-traumatic MRI. MATERIALS AND METHODS: In 52 patients post-traumatic MRI as well as 12 months after ACL-rupture (ACLR) and surgical treatment were analysed. In 28 patients a positive DLNS was present at post-traumatic MRI. For quantitative analysis, T2 relaxation time measurements (7 TE: 10-70 ms) were performed at time of re-evaluation. Three polygonal ROIs encompassing the full cartilage layer were placed in the anterolateral femoral cartilage. Clinical assessment included Lysholm-Tegner-Activity-Score, Rasmussen's clinical score and modified Cincinnati-Rating-System-Questionnaire. Description and differences were calculated as means and confidence intervals of means, controlled for the cluster effect of person, if appropriate. RESULTS: In patients with a positive DLNS after ACLR, relaxation times in the notch region were significantly prolonged compared to patients without a positive DLNS (Δ 7.4 ms, CI: 5.6-9.2; p-value <0.001) as well as to the adjacent anterior (Δ 5.7 ms, CI: 4.7-6.7; p-value <0.001) and central femoral cartilage (Δ 6.6 ms, CI: 5.7-7.6; p-value <0.001). Solely insignificant differences were noticed in the performed clinical scores comparing the two groups (p > 0.05). CONCLUSION: Significantly prolonged T2 relaxation times of the anterolateral femoral cartilage were found in patients with a positive DLNS following ACL-reconstruction compared to patients without a DLNS. Based on these results, it has to be assumed that a positive DLNS is associated with higher cartilage degradation.