Evaluation of Posterior Cruciate Ligament and Intercondylar Notch in Subjects With Anterior Cruciate Ligament Tear: A Comparative Flexed-Knee 3D Magnetic Resonance Imaging Study

Knee anatomic geometry accurately predicts risk of anterior cruciate ligament rupture

BACKGROUND

Certain anatomical characteristics of the knee have potential relationships with the risk of anterior cruciate ligament (ACL) rupture. There remains a need for stronger evidence using arthroscopy as well as radiological imaging to accurately clarify these relationships.

PURPOSE

To compare the anatomic geometry of the knee joint between patients with and without ACL ruptures.

MATERIAL AND METHODS

Case-controlled study of patients with arthroscopically confirmed ACL ruptures (ACL group) compared to patients with arthroscopically confirmed normal ACLs (control group). Magnetic resonance imaging scans were assessed for a total of 14 quantitative radiological variables including medial and lateral tibial slope angles (bone and cartilage measurements), meniscal height, femoral width, intercondylar notch width and tibial depth.

RESULTS

A total of 105 patients were included in the study, 55 in the ACL group and 50 in the control group. There was a significant difference (P < 0.05) of most of the radiological measurements between the two groups. There was also a significant difference (P < 0.05) when comparing the variables between sexes. Multiple logistic regression analysis produced a mathematical model utilizing all the radiological measurements with 92.6% classification accuracy in predicating an ACL rupture with the medial tibial slope angle being the strongest predicator variable (odds ratio = 8.97, P = 0.011).

CONCLUSION

Greater postero-inferior directed slope measurements of bone and cartilage in both the lateral and medial compartments with a narrower intercondylar notch width increase the risk of ACL rupture. Mathematical modelling can accurately predict the risk of ACL rupture.

Exploring Anatomo-Morphometric Characteristics of Infrapatellar, Suprapatellar Fat Pad, and Knee Ligaments in Osteoarthritis Compared to Post-Traumatic Lesions

Several studies have investigated cartilage degeneration and inflammatory subchondral bone and synovial membrane changes using magnetic resonance (MR) in osteoarthritis (OA) patients. Conversely, there is a paucity of data exploring the role of knee ligaments, infrapatellar fat pad (IFP), and suprapatellar fat pad (SFP) in knee OA compared to post-traumatic cohorts of patients. Therefore, the aim of this study was to analyze the volumetric and morphometric characteristics of the following joint tissues: IFP (volume, surface, depth, femoral and tibial arch lengths), SFP (volume, surface, oblique, antero−posterior, and cranio−caudal lengths), anterior (ACL) and posterior cruciate ligament (PCL) (volume, surface, and length), and patellar ligament (PL) (volume, surface, arc, depth, and length). Eighty-nine MR images were collected in the following three groups: (a) 32 patients with meniscal tears, (b) 29 patients with ACL rupture (ACLR), and (c) 28 patients affected by end-stage OA. Volume, surface, and length of both ACL and PCL were determined in groups a and c. A statistical decrease of IFP volume, surface, depth, femoral and tibial arch lengths was found in end-stage OA compared to patients with meniscal tear (p = 0.002, p = 0.008, p < 0.0001, p = 0.028 and p < 0.001, respectively) and patients with ACLR (p < 0.0001, p < 0.0001, p = 0.008 and p = 0.011, respectively). An increment of volume and surface SFP was observed in group b compared to both groups a and c, while no differences were found in oblique, antero−posterior, and cranio−caudal lengths of SFP among the groups. No statistical differences were highlighted comparing volume, surface, arc, and length of PL between the groups, while PL depth was observed to be decreased in end-OA patients compared with meniscal tear patients (p = 0.023). No statistical differences were observed comparing ACL and PCL lengths between patients undergoing meniscectomy and TKR. Our study confirms that IFP MR morphometric characteristics are different between controls and OA, supporting an important role of IFP in OA pathology and progression in accordance with previously published studies. In addition, PL depth changes seem to be associated with OA pathology. Multivariate analysis confirmed that OA patients had a smaller IFP compared to patients with meniscal tears, confirming its involvement in OA.

Patients with isolated posterior cruciate ligament rupture had a higher posterior intercondylar eminence

Background

To evaluate the anatomic geometry of the posterior intercondylar eminence and its association with PCL injury risk.

Methods

Patients who underwent primary PCL reconstruction from 2015 to 2018 were retrospectively analyzed. The control group included inpatients diagnosed with ACL rupture because of a sports-related accident during the same period, matched by age, gender, height, weight, and side of injury. Measurements of the height of the apex of the posterior intercondylar eminence (HPIE), the slope length (SLPIE) and the slope angle (SAPIE) of the posterior intercondylar eminence were performed using conventional MRI scans assessed by 2 blinded, independent raters. Intraclass correlation coefficients (ICCs) was used to evaluate the consistency of measurement results. Independent sample t tests, Chi-square tests, and logistic analyses were used to compare the two group, with P < 0.05 considered statistically significant.

Results

Fifty-five patients with PCL rupture met the inclusion criteria and 55 PCL-intact matched controls were included. There were no significant differences between the groups in gender (P = 1.000), limb side (P = 0.848), age (P = 0.291), BMI (P = 0.444) or height (P = 0.290). Inter-observer reproducibility was excellent agreement in HPIE, SLPIE and SAPIE of case and control groups (ICC: HPIE = 0.81, SLPIE = 0.77, SAPIE = 0.85). Patients with PCL rupture had significantly greater HPIE, SAPIE (both P < 0.001), and SLPIE (P < 0.05) than PCL-intact patients. The multivariable analysis showed that HPIE (OR, 1.62 [95% CI, 1.24–2.11], P < 0.001) and SAPIE (OR, 1.17 [95% CI, 1.05–1.31], P < 0.001) were independent factors associated with PCL rupture.

Conclusion

Through this retrospective observational study, we found that patients with PCL rupture may have a higher posterior intercondylar eminence compared to PCL-intact patients.

Level of evidence

III.

Does Femoral Intercondylar Notch Volume Differ in Anterior Cruciate Ligament-Injured Adult Patients Compared to the Uninjured?: A Meta-Analysis

BACKGROUND

Stenotic femoral intercondylar notch is considered as a risk factor for anterior cruciate ligament (ACL) injury and three-dimensional notch volume is used as a marker for the injury. The primary purpose of this study was to assess the difference in notch volume between the ACL-injured and uninjured in men and women combined or stratified by sex. The secondary purpose was to assess the difference in notch volume between the ACL-intact men and women.

METHODS

A search of PubMed/Medline, Scopus, Google Scholar, and Cochrane databases from inception to December 9, 2020, was conducted without restrictions using the following terms: ACL, notch, volume, notch volume, femoral notch volume, and intercondylar notch volume. Studies that compared the ACL-injured with uninjured controls were included. Independent extraction of articles by two authors using predefined data fields including study quality indicators was done. All pooled analyses were based on the inverse-variance weighted random effects model and mean difference was chosen as the effect measure.

RESULTS

Nine studies (1,169 knees) qualified for overall analysis (both sexes combined) and significant heterogeneity was observed, which disappeared after pooling studies with age-sex matched controls and those without. Notch volume in the ACL-injured was 0.75 cm3 (95% confidence interval [CI], 0.53-0.96 cm3), which was smaller than that in the age- and sex-matched controls. Six studies qualified for analysis in men. Notch volume in the ACL-injured men was smaller, especially when non-contact ACL injury was considered (1.40 cm3; 95% CI, 1.08-1.73 cm3). Five studies qualified for analysis in women and ACL-injured women had smaller notch volume irrespective of the mechanism of injury (0.38 cm3; 95% CI, 0.18-0.59 cm3). Notch volume of the uninjured men was larger than that of the uninjured women (1.86 cm3; 95% CI, 1.54-2.18 cm3).

CONCLUSIONS

ACL-injured adults have smaller notch volume than the age- and sex-matched controls. Non-contact ACL-injured males have smaller notch volume compared to ACL-intact males. ACL-injured females have smaller notch volume irrespective of the nature of injury. Men have higher notch volume than women. The quality of evidence is very low to low.

Meniscal ramp lesions: an illustrated review

The purpose of this review is to describe the anatomy and lesions affecting the peripheral portion of posterior horn of medial menisci (ramp lesions), along with illustrations and MRI cases. We will correlate imaging features with arthroscopic classification of ramp lesions. Also, postoperative and chronic changes related to meniscocapsular tears will be presented, as well as biomechanical consequences and treatment approach.

Notch Volume Measured on Magnetic Resonance Imaging Is Better Than 2-Dimensional Notch Parameters for Predicting Noncontact Anterior Cruciate Ligament Injury in Males

PURPOSE

To evaluate and compare intercondylar notch volume with other 2-dimensional notch parameters (measured on magnetic resonance imaging [MRI]) for prediction of noncontact anterior cruciate ligament (ACL) injury in males.

METHODS

Retrospective case-control study in males based on MRI images. The case group consisted of 80 noncontact ACL-injured males and a control group of 80 age- and height-matched ACL-intact males. Inclusion criteria were 18 to 50 years old, full-thickness tear, MRI obtained within 1 year of injury, and ACL tear visually documented during arthroscopy. Multiligamentous, bilateral, or concomitant bony injuries were excluded. Notch volume and 2D parameters in both planes, including notch depth, notch width, intercondylar notch angle, notch-width index, and notch-shape index, were measured on MRI and compared. Slice interval was included in the formula for notch-volume assessment. Bivariate Pearson correlation between notch volume and 2D parameters was estimated. Multivariate conditional logistic regression analysis was used for predictor model. Receiver operating characteristic (ROC) curves were plotted.

RESULTS

All MRIs had a standard slice thickness of 3 mm and slice interval of 0.3 mm. Notch volume (P < .001), notch angle in the axial plane (P = .001), and notch width in the coronal plane (P = .009) were significantly smaller in the ACL-injured group. Notch volume had inconsistent and negligible to low correlation with 2D parameters. Notch volume was the only significant contributor in the predictor model (P < .001). ROC curve showed that notch volume had highest area under the curve of 84.1% and optimal cutoff at 7.1550 cm³ (specificity, 88.7%; sensitivity, 65%).

CONCLUSION

Significantly smaller intercondylar notch volume is associated with noncontact ACL injury in men and is the most important predictor for such an injury (optimal cutoff of 7.1550 cm³). Two-dimensional notch parameters are inconsistently associated with noncontact ACL injury in men, and none of the 2D parameters can be used as a surrogate for notch volume. Two-dimensional notch parameters fare poorly in predicting noncontact ACL injury in males. Notch volume measurement should include slice interval as a factor.

LEVEL OF EVIDENCE

III, retrospective case-control study.

The space available for the anterior cruciate ligament in the intercondylar notch is less in patients with ACL injury

PURPOSE

The aim of this study was to determine if a difference exists in the relationship between the femoral intercondylar notch volume, and the volumes of anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) in ACL injured patients and healthy subjects.

METHODS

Intact knees of 19 healthy subjects and bilateral knees of 18 ipsilateral ACL reconstructed patients were scanned using 3-tesla high-resolution magnetic resonance imaging. The intercondylar notch, ACL, PCL and hamstring graft were segmented using three-dimensional (3D) processing software. The native intercondylar notch, ACL, and PCL volumes were compared between both groups. The volumes of native ACL and graft were compared in ACL injured patients.

RESULTS

The following volumes showed no significant differences between the ACL injured group and control group; intercondylar notch (9.9 ± 2.3 vs 9.6 ± 1.7 cm³), ACL (2.4 ± 0.7 vs 2.4 ± 0.6 cm³) and PCL (3.9 ± 1.0 vs 3.4 ± 0.8 cm³), and the ratio of the ACL to the intercondylar notch (24.6 ± 5.0 vs 25.4 ± 2.9%). There was a significant difference in the ratio of PCL to the intercondylar notch (39.1 ± 4.3 vs 35.9 ± 4.9%, p = 0.023). The graft was significantly larger than native ACL volume (3.0 ± 0.7 vs 2.4 ± 0.7 cm³, p = 0.012).

CONCLUSIONS

The ratio of the PCL volume in the femoral intercondylar notch was higher in the ACL injured group compared to the healthy control group, despite the ratio of ACL volume in the femoral intercondylar notch being similar in both groups. A greater awareness of the potentially limited space for the graft alongside the PCL within the femoral intercondylar notch may allow surgeons a more informed choice of graft type and size.

LEVEL OF EVIDENCE

IV.

Correlation between notch width index assessed via magnetic resonance imaging and risk of anterior cruciate ligament injury: an updated meta-analysis

PURPOSE

To analyze the correlation between notch width index (NWI) and/or femoral intercondylar notch width (NW) assessed by magnetic resonance imaging (MRI) and risk of anterior cruciate ligament (ACL) injury.

METHODS

We searched the PubMed, Embase, China National Knowledge Infrastructure and Wanfang databases for literature reporting a correlation between ACL injury and NWI and/or NW. Subgroup analyses were stratified by ethnicity, sex and control source. The weighted mean difference (WMD) and 95% confidence intervals (95% CIs) were calculated for the ACL injury cases and controls using random- or fixed-effects models. Begg's test and sensitivity analyses were applied to assess publication bias and stability of the results, respectively.

RESULTS

Twenty-eight eligible studies were finally enrolled. The NW was significantly narrowerin the ACL injury cases than in the control cases (pooled WMD, - 1.88 [95% CI, - 2.43 to - 1.32]). The results were similar when stratified by ethnicity and sex. Similarly, the NWI was lower in ACL injury cases than in the controls. Asian populations presented similar results when stratified by ethnicity, among the self-control group when stratified by control source, and among men when stratified by sex. No publication bias was identified; however, the sensitivity analysis suggested unstable results in the NWI subgroup analysis.

CONCLUSIONS

The current meta-analysis evidenced that the NW assessed via MRI was significantly smaller in ACL injury cases than in the controls. The NWI was lower in ACL injury cases among men. Prevention strategies for ACL injury could be applied for people with intercondylar notch stenosis.