Individual and Combined Anatomic Risk Factors for the Development of an Anterior Cruciate Ligament Rupture in Men: A Multiple Factor Analysis Case-Control Study

Background: No comparative studies have evaluated anatomic risk factors in a large cohort including both patients with anterior cruciate ligament (ACL) ruptures and healthy participants. Purpose: To determine which anatomic parameters are independently associated with an ACL rupture and the diagnostic values of the individual and combined anatomic parameters. Study Design: Case-control study; Level of evidence, 3. Methods: A total of 352 male patients who underwent arthroscopic ACL reconstruction because of a primary ACL rupture and 350 age-, sex-, body mass index–, and side dominance–matched healthy participants were included. Measurements of 32 previously determined parameters and 7 calculations were performed. Between-group differences were calculated. Univariate and multivariate logistic regression models and receiver operating characteristic curve analysis were conducted for the individual and combined independently associated factors. Results: The mean age and body mass index of all participants were 29.9 ± 7.7 years and 27.2 ± 3.1, respectively. There were significant differences between the groups regarding the notch width (NW), notch shape index, anterior tibial slope, notch width index, NW–eminence width (NW:EW) ratio, notch height, axial lateral wall angle, medial intercondylar ridge thickness, alpha angle, medial tibial depth (MTD), lateral tibial slope (LTS), coronal tibial plateau width, eminence width index, tibial proximal anteroposterior distance (TPAP), lateral condylar anteroposterior distance (LCAP)/TPAP, ACL cross-sectional area, ACL volume, medial and lateral meniscal cartilage height, medial and lateral meniscal cartilage angle (MCA), and medial and lateral meniscal cartilage bone height. The NW:EW ratio (odds ratio [OR], 4.419; P = .017), MTD (OR, 8.617; P = .001), LTS (OR, 2.254; P = .011), LCAP/TPAP (OR, 2.782; P = .037), and medial MCA (OR, 1.318; P = .010) were independently associated with the development of an ACL rupture. Combining the independently associated factors revealed a sensitivity of 93% and a specificity of 94% (area under the curve, 0.968). Conclusion: Patients with ACL ruptures could be distinguished from uninjured controls with high sensitivity and specificity via the combined use of the NW:EW ratio, MTD, LTS, LCAP/TPAP, and medial MCA. In clinical practice, these findings may contribute to the development of preventive strategies for ACL ruptures.

Risk Factors of ACL Injury

An anterior cruciate ligament(ACL) is one of the major stabilizers of the knee joint, injury to which can be quite dreadful even ending many sports careers if not properly treated. Knowledge of the risk factors contributing to ACL injury will help in identifying at-risk individuals and develop preventive strategies. The factors contributing to ACL injury are multi-factorial involving biomechanical, anatomical, hormonal, neuromuscular factors etc; and can be broadly classified as Intrinsic and Extrinsic factors. Intrinsic factors are mostly non-modifiable risk factors may be subdivided into anatomical, genetic, gender, previous ACL Injuries etc . Whereas Extrinsic factors are mostly modifiable risk factors include environmental factors, characteristic of surface and shoe, BMI and others. Anatomical risk factors can divided into tibial parameters like posterior tibial slope, medial tibial plateau depth etc ; femoral parameters like notch width, notch index etc.

ACL Size, but Not Signal Intensity, Is Influenced by Sex, Body Size, and Knee Anatomy

Background: Little is known about sex-based differences in anterior cruciate ligament (ACL) tissue quality in vivo or the association of ACL size (ie, volume) and tissue quality (ie, normalized signal intensity on magnetic resonance imaging [MRI]) with knee anatomy. Hypothesis: We hypothesized that (1) women have smaller ACLs and greater ACL normalized signal intensity compared with men, and (2) ACL size and normalized signal intensity are associated with age, activity levels, body mass index (BMI), bicondylar width, intercondylar notch width, and posterior slope of the lateral tibial plateau. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Knee MRI scans of 108 unique ACL-intact knees (19.7 ± 5.5 years, 62 women) were used to quantify the ACL signal intensity (normalized to cortical bone), ligament volume, mean cross-sectional area, and length. Independent t tests were used to compare the MRI-based ACL parameters between sexes. Univariate and multivariate linear regression analyses were used to investigate the associations between normalized signal intensity and size with age, activity levels, BMI, bicondylar width, notch width, and posterior slope of the lateral tibial plateau. Results: Compared with men, women had significantly smaller mean ACL volume (men vs women: 2028 ± 472 vs 1591 ± 405 mm3), cross-sectional area (49.4 ± 9.6 vs 41.5 ± 8.6 mm2), and length (40.8 ± 2.8 vs 38.1 ± 3.1 mm) ( P < .001 for all), even after adjusting for BMI and bicondylar width. There was no difference in MRI signal intensity between men and women (1.15 ± 0.24 vs 1.12 ± 0.24, respectively; P = .555). BMI, bicondylar width, and intercondylar notch width were independently associated with a larger ACL ( R 2 > 0.16, P < .001). Younger age and steeper lateral tibial slope were independently associated with shorter ACL length ( R 2 > 0.03, P < .04). The combination of BMI and bicondylar width was predictive of ACL volume and mean cross-sectional area ( R 2 < 0.3). The combination of BMI, bicondylar width, and lateral tibial slope was predictive of ACL length ( R 2 = 0.39). Neither quantified patient characteristics nor anatomic variables were associated with signal intensity. Conclusion: Men had larger ACLs compared with women even after adjusting for BMI and knee size (bicondylar width). No sex difference was observed in signal intensity, suggesting no difference in tissue quality. The association of the intercondylar notch width and lateral tibial slope with ACL size suggests that the influence of these anatomic features on ACL injury risk may be partially explained by their effect on ACL size. Registration: NCT02292004 and NCT02664545 ( ClinicalTrials.gov identifier).

Experimental study on flexural properties of timber columns with interior notches in traditional Japanese timber structures

In this study, the columns with interior notches in traditional Japanese timber frames were selected as the research object, and static bending tests were performed to investigate the effect of interior notches on the flexural properties of columns. First, the bending behaviors of columns under three-point and four-point load configurations were compared to obtain a suitable referenced strength of a column without notches. The reduction in the load-bearing capacity of columns with different types of interior notches in traditional Japanese timber structures was determined through experimental tests and statistical analysis. The results indicated that the mean bending strength of columns with three different notch types was consistent with those without notches, the continuous timber on both sides of the notch had a beneficial effect on maintaining a higher strength and reducing the stress intensity around the notch. The fracture position and the standard deviation of the bending strength were affected not only by the notch depth, but also by the notch width on the tensile side of the column.

Femoral and Tibial Bony Risk Factors for Anterior Cruciate Ligament Injuries Are Present in More Than 50% of Healthy Individuals

Background: Anterior cruciate ligament (ACL) injuries are multifactorial events that may be influenced by morphometric parameters. Associations between primary ACL injuries or graft ruptures and both femoral and tibial bony risk factors have been well described in the literature. Purpose: To determine values of femoral and tibial bony morphology that have been associated with ACL injuries in a reference population. Further, to define interindividual variations according to participant demographics and to identify the proportion of participants presenting at least 1 morphological ACL injury risk factor. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Computed tomography scans of 382 healthy participants were examined. The following bony ACL risk factors were analyzed: notch width index (NWI), lateral femoral condylar index (LFCI), medial posterior plateau tibial angle (MPPTA), and lateral posterior plateau tibial angle (LPPTA). The proportion of this healthy population presenting with at least 1 pathological ACL injury risk factor was determined. A multivariable logistic regression model was constructed to determine the influence of demographic characteristics. Results: According to published thresholds for ACL bony risk factors, 12% of the examined knees exhibited an intercondylar notch width <18.9 mm, 25% had NWI <0.292, 62% exhibited LFCI <0.67, 54% had MPPTA <83.6°, and 15% had LPPTA <81.6°. Only 14.4% of participants exhibited no ACL bony risk factors, whereas 84.5% had between 2 and 4 bony risk factors and 1.1% had all bony risk factors. The multivariate analysis demonstrated that only the intercondylar notch width ( P < .0001) was an independent predictor according to both sex and ethnicity; the LFCI ( P = .012) and MMPTA ( P = .02) were independent predictors according to ethnicity. Conclusion: The precise definition of bony anatomic risk factors for ACL injury remains unclear. Based on published thresholds, 15% to 62% of this reference population would have been considered as being at risk. Large cohort analyses are required to confirm the validity of previously described morphological risk factors and to define which participants may be at risk of primary ACL injury and reinjury after surgical reconstruction.

Narrow Notch Width and Low Anterior Cruciate Ligament Volume Are Risk Factors for Anterior Cruciate Ligament Injury: A Magnetic Resonance Imaging-Based Study

Background: The relationship between anterior cruciate ligament (ACL) injury and anatomical structures is still a topic of debate. Purpose: The aim of this study was to compare knee geometry in demographically matched ACL-injured and ACL-intact athletes. Methods: We conducted a case-control study comparing 2 groups, each consisting of 55 professional athletes (44 men and 11 women): 1 group with complete ACL tears (cases) and 1 group with intact ACLs (controls). The groups were compared using magnetic resonance imaging (MRI) in terms of intercondylar notch geometry, tibial plateau characteristics, and ACL volume. Results: Among cases and controls, we found the cases had lower notch width (20.24 ± 2.68 mm vs. 22.04 ± 2.56 mm, respectively) and notch width index (0.29 ± 0.03 vs. 0.31 ± 0.03, respectively). The mean ACL volume in the cases (1181.63 mm3 ± 326 mm3) was also lower than in controls (1352.61 mm3 ± 279.84 mm3). The parameters of tibial slope geometry were comparable between groups. In addition, women had lower ACL volume than men (1254 ± 310 mm3 vs. 890 ± 267 mm3, respectively) and higher medial posterior tibial slope (4.76 ± 2.6 vs. 6.63 ± 1.83, respectively). Among cases, women had narrower notch width than men (16.9 ± 2.42 mm vs. 21.08 ± 2.03 mm). However, notch width index was comparable between male (0.3 ± 0.02) and female (0.28 ± 0.03) cases. Conclusion: Our findings suggest that narrow notch width and low ACL volume may enhance the risk of ACL injury among athletes. There was no association found between posterior tibial slope and ACL injury between athletes with injured ACLs and controls. Further study is indicated.

Stenotic intercondylar notch is not a risk factor for posterior cruciate ligament rupture: a morphological analyses using magnetic resonance imaging

Purpose The present study aimed to examine the factors related to the morphological characteristics of the femoral condyle in posterior cruciate ligament rupture in female and male populations. Methods One hundred and three patients (41 females, 62 males) with posterior cruciate ligament rupture from 2010 to 2020 were included in this retrospective case–control study. The sex and age of the posterior cruciate ligament rupture group were matched to those of the control group (41 females, 62 males; age range 16–69 years). Magnetic resonance imaging was used to measure the intercondylar notch width, femoral condylar width, and intercondylar notch angle in both the axial and coronal images. The ‘α’ angle was also measured using magnetic resonance imaging. The notch width index is the ratio of the intercondylar notch width to the femoral condylar width. Three types of intercondylar notch shapes (types A, U, and W) were evaluated in the axial magnetic resonance imaging images. Results The difference in the mean coronal notch width index between the study groups was statistically significant in the female population. The difference in the mean coronal femoral condylar width between the study groups was statistically significant in the male population. Conclusions A larger coronal notch width index was the greatest risk factor for posterior cruciate ligament rupture in the female population. In the male population, decreased coronal condylar width was the greatest risk factor for posterior cruciate ligament rupture. The results did not indicate that patients with a PCL rupture have a stenotic intercondylar notch. Posterior cruciate ligament injury prevention strategies could be applied to females with a larger coronal notch width index and males with a decreased condylar width. Levels of evidence Level III.

Does Bone Regrow After Notchplasty in ACL Reconstruction? A Prospective Computed Tomography Study With 2-Year Follow-up

Background: During notchplasty in anterior cruciate ligament (ACL) reconstruction, bone is excised from the lateral and roof area of the notch to widen the intercondylar space and avoid notch-graft impingement in extension. There are concerns that bone regrowth of the area will cause narrowing and increase the risk of complications. Purpose: To determine the possibility of late narrowing of the notch after notchplasty using computed tomography (CT) analysis. Study Design: Case series; Level of evidence, 4. Methods: Measurements were performed on CT scans (axial and sagittal planes with knee in extension) in patients who had undergone single-bundle anatomic ACL reconstruction using hamstring graft. Two axial image levels were used: at the anterior outlet and the anterior one-eighth level of the notch. The maximum notch height and width, the notch width at one-third and two-thirds of the preoperative notch midwidth height, the maximum condylar width, and the surface area of the lateral half of the notch were measured preoperatively and at 1 week and 2 years postoperatively. Results: Included were 20 consecutive patients (mean ± standard deviation age, 28 ± 7.3 years; follow-up, 24.2 ± 3.3 months). At the anterior notch outlet, the maximum notch width increased by 1.9 ± 1.7 mm at 1 week postoperatively and narrowed by 0.3 ± 1.1 mm at the final follow-up, while the maximum notch height increased by 1.7 ± 1.9 mm and narrowed by 0.8 ± 1.8 mm, respectively. At one-eighth of the roof length, the maximum notch width increased by 1.1 ± 1.7 mm at 1 week postoperatively and narrowed by 0.1 ± 1.1 mm at the final follow-up, and the maximum notch height increased by 1.2 ± 1.5 mm and narrowed by 0.5 ± 1.5 mm, respectively. All differences were statistically significant when comparing the pre- to the immediate postoperative measurements, and they were nonsignificant when comparing the immediate postoperative to the final follow-up measurements. The same applied for the ratio of maximum notch width to maximum condylar width, indicating no postoperative narrowing of the notch. Conclusion: Notch size-shape after a 2-mm notchplasty did not change significantly in stable knees during the first 2 years after anatomic ACL reconstruction. Surgeons should consider performing this adjuvant technique when there is notch-graft impingement during surgery.

Association between Intercondylar Notch Dimensions and Morphometry of Anterior Cruciate Ligament – A Cadaveric Study

Introduction: Injuries to the anterior cruciate ligament (ACL) are commonly encountered in day-to-day practice. The morphology of the intercondylar notch (ICN), in particular, the width, and shape of the notch are of anatomic interest predisposing to ligament injuries. The previous literature points to contradicting views on the association between ICN dimensions and cruciate ligament injuries. Aim of the study: This study aims to study the morphometry of the ACL and ICN in 32 prosected lower limbs and to see if any association exists between the two. Objectives The objectives of the study were to estimate the dimensions of ACL (maximum length and width) in 32 prosected lower limbs, estimate the dimensions of ICN (ICN width and depth) along with intercondylar (IC) width in 32 prosected lower limbs, and test the strength of association between the dimensions of ICN with the dimensions of ACL. Materials and Methods: The study was done in the Department of Anatomy of MVJ Medical College and Research Hospital, Bengaluru. Thirty-two prosected lower limbs from the department of anatomy were used for the study. Results: It was observed that IC width correlated positively with ACL length as well as ACL width. A strong positive correlation was also observed between IC width with ICN width. Femoral notch width index also correlated positively with ACL width. Conclusions: The above study provides valuable data on the morphometry of ACL and its association with all dimensions of IC fossa unlike previous studies which have correlated the dimensions of IC fossa only with the thickness of ACL.