Anterior Cruciate Ligament Length Research Articles

2D and 3D PVA electrospun scaffold evaluation for ligament implant replacement: A mechanical testing, modelling and experimental biomechanics approach

The gold standard to characterise anterior cruciate ligament (ACL) implants is through the evaluation of mechanical properties such as Young's modulus or ultimate tensile stress. Currently, no studies have been performed to relate the in-vivo hyper-elastic behaviour of the ACL with the design of tissue engineered ligaments. The aim of this work is to determine the most comparable 2D/3D polyvinyl alcohol (PVA) electrospun structure to the in-vivo mechanical behaviour of the natural ligament. Biomechanics of 12 young participants were captured while daily and high impact activities were performed. A musculoskeletal knee model and kinematic data were used to estimate the in-vivo ACL length and strain. The in-vivo ACL tensile forces were determined with a non-linear force/strain relationship. 2D scaffolds, 1 twisted filament scaffolds, 3 twisted filaments scaffolds and 3 twisted/braided filaments scaffolds were fabricated using electrospinning and characterised morphologically and mechanically using scanning electron microscopy and tensile testing respectively. Cyclic tensile and shear tests were performed in dry and wet conditions to crosslinked and non-crosslinked samples. The hyper-elastic behaviour of our PVA scaffolds was characterised with the Mooney Rivlin model and a non-linear string-based model, and both models compared with the in-vivo mechanical behaviour of the native ACL. Crosslinked 3 twisted/braided filaments scaffolds faithfully mimicked the morphology and the hyper-elastic behaviour of the natural ACL, showed a good resistance to shear loading and remained undegraded in phosphate-buffer saline solution. This study demonstrated, for the first time, that 3 twisted/braided filaments PVA electrospun scaffolds have an excellent potential for ACL replacements.

A Novel Predictor of the Length and Size of ACL Grafts in Chinese Han Adults for ACL Reconstruction: An MRI Study.

Currently, there is no simple and valid method to predict the length and size of the native anterior cruciate ligament (ACL) in each adult patient who will undergo ACL reconstruction. This study aimed to develop an imaging prediction method that can predict the length and size of ACL grafts using the intact posterior cruciate ligament (PCL), in order to enhance the graft preparation individualized sizing. Three hundred and nineteen patients aged 18 years or older who underwent magnetic resonance imaging (MRI) of the knee at an orthopaedic clinic between September 9, 2021, and February 5, 2023, were included. The length, sagittal diameter, and coronal diameter of the ACL and PCL were measured in all patients, and F-test were performed to explore linear relationship between ligament measurements. Equations were established to predict a variable of the native ACL for the corresponding variable of the intact PCL (i.e., sagittal diameter of the ACL = 4.32 + 1.08 × sagittal diameter of the PCL, and coronal diameter of the ACL = 2.45 + 0.59 × coronal diameter of the PCL, length of the male ACL = 10.92 + 0.64 × length of the male PCL, length of the female ACL = 11.76 + 0.58 × length of the female PCL) (R2 = 0.532; R2 = 0.417; R2 = 0.488; R2 = 0.509; respectively). The length and size of the intact PCL in cases without PCL buckling are predictors of the length and size of the native ACL in adults, respectively. The use of this information to optimize graft diameter may lower the rates of ACL graft failure in the future.

Tibial Spine Avulsion Repair With FiberRing Suture and Anterior Cruciate Ligament Repair TightRope

Tibial spine avulsion fractures occur predominantly in children and young adults and are an uncommon type of knee injury. To ensure knee stability and preserve range of motion with minimal knee laxity, it is essential to restore anterior cruciate ligament length through surgical reduction and fixation of the fracture. Achieving anatomic reduction of tibial spine avulsion fractures with an arthroscopic approach is a technically complex procedure. In this Technical Note and accompanying video, we describe a unique fixation repair of tibial spine avulsion fractures using Arthrex FiberRing sutures and an Arthrex ACL Repair TightRope. The technique presented is an effective method to reduce tibial spine avulsion fractures to anatomic position with a variable tensioning system that allows for a strong and secure fixation method.

How to predict the dimensions of anterior cruciate ligament in children based on MRI?

There are many studies examining the dimensions of the anterior cruciate ligament (ACL) in children. The correlations between the ACL size in children and other parameters are not well understood. To detect the correlations between the ACL size in children and other parameters including age, gender, bone and soft tissue parameters through measurements on MRI images, and to establish prediction models for the ACL size. A total of 99 patients who underwent MRI scan were included (39 girls, 60 boys; mean age, 13.01 ± 3.94; range of age, 4 to 18). The following measurements were taken on MRI images by 2 observers: ACL length, ACL width, posterior cruciate ligament (PCL) length, the distance from the most anterior aspect of the tibial epiphysis to the anterior aspect of the ACL tibial insertion (AATI), the distance from the most anterior aspect of the tibial epiphysis to the posterior aspect of the ACL tibial insertion (APTI), and the tibial anteroposterior diameter (AP). Correlations between these measurements and the patients' gender and age were investigated, and univariate and multiple linear regression models were established accordingly. Before 13 years old, the ACL length was significantly correlated with the tibial anteroposterior diameter and age (R2 = 0.872, P < .001), and there were no statistically significant gender differences. After 13 years old, the ACL length was significantly correlated with the PCL length and APTI in males (R2 = 0.443, P < .001), and with the PCL length in females (R2 = 0.443, P < .001). In children under 13 years old, there was no significant gender difference in ACL length, and the tibial anteroposterior diameter and age were found to be important indicators in assessing the ACL size. After 13 years old, a significant gender difference in ACL length was observed, and the ACL length was found to be weakly correlated with age and bone parameters. In order to accurately evaluate the ACL size in children aged 13 years and above, it is necessary to refer to the dimensions of the ACL on the collateral side.

Size and Morphology of the Anterior and Posterior Cruciate Ligaments at Different Pediatric Age Intervals: An MRI Analysis.

The incidence of anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) tears in children and adolescents has increased over the past decade, with increasing numbers of ACL and PCL reconstructions in this patient population. To evaluate the size and morphology of both the ACL and the PCL by magnetic resonance imaging (MRI) in different pediatric age groups. Cross-sectional study; Level of evidence, 3. MRI examinations of 127 knees (67 female, 60 male; aged 0-18 years) were analyzed retrospectively. The cohort was split into 6 age subgroups, 1 subgroup for every 3 years (minimum 8 patients per subgroup). The following parameters were measured by 2 independent raters at 2 different time points: ACL length, anteroposterior and mediolateral ACL width, sagittal and coronal ACL inclination, inclination of the intercondylar notch, bicondylar width, notch width, coronal ACL and PCL width, PCL length, and sagittal width of the lateral femoral condyle. The following indices, areas, and volumes were calculated: sagittal width of the lateral femoral condyle/PCL length, ACL area and volume, notch width index, ACL width/notch width, PCL width/notch width, ACL width/bicondylar width, and PCL width/bicondylar width. A correlation analysis was performed for patient age, height, weight, and body mass index (BMI). ACL length was between 18 and 37 mm, and ACL width was between 4 and 6 mm. PCL length ranged between 27 and 43 mm, while PCL width was between 7 and 9 mm. Growth of the cruciate ligaments was the most pronounced between the ages of 4 and 12 years. Correlations with size and weight were strong, while BMI correlated slightly with the measurements. Measurements in female patients were slightly larger than in their male counterparts between the ages of 0 and 6 years, while male patients tended to have larger values starting from ages 7 to 9 years. These values were significantly larger in male patients from the ages of 16 to 18 years (P < .05). This study provides normative data on the morphology of pediatric anatomic features in the knee as a basis for age-appropriate and individualized surgical care of ACL and PCL injuries in children and adolescents.

Effect of demographic features on morphometric variables of the knee joint: Sample of a 20 to 40-year-old Turkish population.

This study aimed to investigate the relationship between body mass index (BMI), age, and sex and morphological risk factors that may cause internal knee injuries. The magnetic resonance images of 728 participants who met the inclusion criteria and had a mean age of 34.4 ± 6.8 years were analyzed retrospectively. Demographic differences were analyzed by measuring 17 morphological parameters known to be associated with internal knee injuries. Men had a higher anterior cruciate ligament length (ACLL), anterior cruciate ligament width, (ACLW) lateral femoral condylar width (LFCW), medial femoral condylar width (MFCW), lateral femoral condylar depth (LFCD), distal femoral width (DFW), and intercondylar femoral width (IFW) than women (P < .05). By contrast, the medial meniscus bone angle (MMBA) was lower in men than in women (P < .05). Women aged 31 to 40 years had a lower Insall-Salvati index (ISI) and lateral tibial posterior slope (LTPS) than those aged 21 to 30 years (P < .05), whereas men aged 31 to 40 years had a lower ISI than those aged 21 to 30 years (P < .05). Women with BMI ≥ 30 had a higher LFCW and MFCW but a lower ISI than those with BMI < 30 (P < .05). Men with BMI ≥ 30 had a higher LFCW, MFCW, DFW, and MMBA than those with BMI < 30 (P < .05). The use of value ranges structured according to demographic characteristics, rather than a single value range for all patient groups, may contribute to the evaluation and treatment of the morphological features that are thought to be effective in the development of internal knee injuries. These values may also shed light on future radiological risk scoring systems and artificial intelligence applications in medicine.

The patient with patellar instability has a stenotic intercondylar notch and a thin anterior cruciate ligament: a retrospective comparative study

BackgroundPatellar instability (PI) usually combines with morphological abnormalities of femoral condyles that may affect the morphology of the intercondylar notch and anterior cruciate ligament (ACL), which are important in individualized ACL reconstruction. This study aimed to investigate the morphological characteristics of the intercondylar notch and ACL in patients with PI.Methods80 patients with PI and 160 age- and gender-matched controls from January 2014 to June 2022 were studied. Morphological measurements of the femoral condyles included intercondylar notch height, notch width, medial condylar width, lateral condylar width, bicondylar width, notch width index, notch angle, lateral femoral condyle ratio (LFCR), condyle flexion angle, and posterior tibial slope. Morphological measurements of the ACL included ACL length, inclination angle, and ACL size. The measurements were compared between PI and control groups, and between males and females in PI group. The independent samples t-test was performed to examine differences in continuous variables. The chi-square test was used for comparing categorical variables.ResultsThe intercondylar notch width, bicondylar width, notch width index, and notch angle were significantly smaller, while the LFCR was significantly larger in PI group than those of control group (p < 0.05). The ACL thickness (0.70 ± 0.16 cm vs 0.80 ± 0.21 cm, p = 0.023) and width (0.54 ± 0.14 cm vs 0.60 ± 0.13 cm, p = 0.029) were significantly smaller in PI group. The notch width was significantly smaller in female patients than males in PI group, but no significant difference was observed in the notch width index and notch angle (p > 0.05). No sex difference related to the morphology of the ACL was found.ConclusionsThe patient with PI had a stenotic intercondylar notch and a thin ACL. No significant sex difference in the intercondylar notch stenosis and ACL size was observed. The morphology of the intercondylar notch and ACL should be taken into consideration when planning individualized ACL reconstruction in the presence of PI.

Correlation between morphological features of the anterior cruciate ligament: A quantitative study using a porcine model.

Knowledge of the morphological features of the anterior cruciate ligament (ACL) is critical for accurate reconstruction of it. This study aimed to explore the quantitative correlations among different morphological features of the ACL, thus to provide useful information for improving anatomical reconstruction techniques and designing artificial ligaments. 19 porcine knees were fixed at full extension using 10% formalin and were dissected to expose the ACL. ACL lengths were measured using a caliper. Mid-substances of the ACL were cut and scanned using X-ray microscopy, and the cross-sectional area (CSA) was measured at the isthmus. Margins of direct and indirect bone insertion sites were distinguished and marked. Measurements were performed on digital photographs to obtain the areas of bone insertions. Statistical analysis using nonlinear regression was used to identify potential correlations among the measurements. The results showed that the CSA at the isthmus was significantly correlated with the total area of the bone insertion sites and the area of tibial insertion. The area of the tibial insertion was significantly correlated with the area of its direct insertion site. In contrast, the area of the femoral insertion was significantly correlated with the area of its indirect insertion site. The area of the indirect tibial insertion showed a weak correlation with the length of ACL, whereas the length of the ACL was not able to predict or be predicted by any other parameters. The CSA at the ACL isthmus is more representative for assessing the size of the ACL. However, ACL length has little correlation with the CSA of the isthmus or bone insertion sites, and thus should be evaluated independently for ACL reconstruction.

Relationship of the Cruciate and Meniscofemoral Ligaments with the Knee Osteology. An Anatomical Study.

Objective To analyze the dimensions of the posterior cruciate ligament (PCL), anterior cruciate ligament (ACL), the presence of meniscus-femoral ligaments MFLs in human knees, and the correlation with the dimensions of the knee skeleton. Methods Anatomical study on 29 specimens of human knees in which we measured the length and width of the cruciate and meniscus-femoral ligaments and the dimensions of femoral and tibia condyles and the femoral notch. The ACL length was calculated with different degrees of knee flexion. The relationship between the ligaments and bone dimensions were analyzed. Results The length of the ACL and the PCL were similar. Posterior MFL was more frequent and longer than the anterior MFL. We found the posterior MFL in the 72.41% of the knees and anterior MFL in 20.69%. The ACL presented 30% of its maximum length up to 60°, approximately half of its length between 90° and 120°, reaching its maximum length at 170°. We found a strong correlation between the length of the ACL and that of the PCL ( p = 0.001). However, the lengths of the ACL and PCL were not related with the bone dimensions. Conclusion We have found no correlations between the cruciate and MFLs and the anatomical dimensions of the intercondylar notch and the proximal tibia and distal femur. The presence of the posterior MFL was more frequent and longer than that of the anterior ligament.

Loaded open-kinetic-chain exercises stretch the anterior cruciate ligament more than closed-kinetic-chain exercises: In-vivo assessment of anterior cruciate ligament length change

BackgroundUsage of open-kinetic-chain (OKC) or closed-kinetic-chain (CKC) exercises during rehabilitation planning after anterior cruciate ligament (ACL) reconstruction has been debated for decades. However, the ACL elongation pattern during different rehabilitation exercises at different loadings remains unclear. ObjectivesThis study aimed to determine the effects of OKC and CKC exercises on the length of ACL anteromedial bundle (AMB) and posterolateral bundle (PLB) to provide biomechanical support for making rehabilitation schedules. DesignLaboratory Descriptive Study. MethodEighteen healthy volunteers were asked to perform two OKC motions, including non-weight-bearing and 10 kg loaded seated knee extension (OKC-0, OKC-10), as well as two CKC motions, including box squat (BS) and deep single-legged lunge (Lunge). Techniques of 2D-to-3D image registration and 3D ligament simulation were used to quantify length changes of ACL. ResultsThe motion which led to the least and most ACL elongation were OKC-0 and OKC-10, respectively. The AMB and PLB were significantly longer in OKC-10 than those in OKC-0 during 0–60° and 0–55° of knee flexion (p < 0.01). Compared with reference length, the AMB and PLB were stretched during 0–30° and 0–10° respectively during OKC-10. During CKC exercises, the AMB and PLB were also stretched from 0 to 25°and 0–5°, respectively. Additionally, no significant difference was found in the length change of ACL bundles between BS and lunge. ConclusionsOKC-0 may be safe for the rehabilitation program after ACL reconstruction, and loaded exercises shall be applied when restricted with >30° in early-stage rehabilitation.

Posterior Cruciate Ligament and Patellar Tendon Can Predict Anterior Cruciate Ligament Size for Planning During ACL Reconstruction in Pediatric Patients

To establish correlations between the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), and patellar tendon in normal pediatric knees to inform surgical planning for ACL reconstruction graft size. Magnetic resonance imaging scans of patients ages 8 to 18 years were assessed. Measurements included ACL and PCL length, thickness, and width, and ACL footprint thickness and width at the tibial insertion. Interrater reliability was assessed with a random set of 25 patients. Pearson correlation coefficients were used to assess the correlation between ACL, PCL, and patellar tendon measurements. Linear regression models were used to test whether the relationships differed by sex or age. Magnetic resonance imaging scans of 540 patients were assessed. Interrater reliability was high for all measurements except PCL thickness at midsubstance. Sample equations for estimating ACL size are as follows: ACL length= 22.61+ 1.55∗PCL origin width (R2= 0.46; 8- to 11-year-old male patients), ACL length= 12.37+ 0.58∗PCL length+ 2.29∗PCL origin thickness - 0.90∗PCL insertion width (R2= 0.68; 8- to 11-year-old female patients), ACL midsubstance thickness= 4.95+ 0.25∗PCL midsubstance thickness+ 0.04∗PCL insertion thickness - 0.08∗PCL insertion width (R2= 0.12; 12- to 18-year-old male patients), and ACL midsubstance width= 0.57+ 0.23∗PCL midsubstance thickness+ 0.07∗PCL midsubstance width+ 0.16∗PCL insertion width (R2= 0.24; 12- to 18-year-old female patients). We found correlations between ACL, PCL, and patellar tendon measurements that can be used to create equations that predict ACL size in various dimensions based on PCL and patellar tendon measurements. There is a lack of consensus on the ideal ACL graft diameter for pediatric ACL reconstruction. The findings from this study can assist orthopaedic surgeons to individualize ACL graft size for specific patients.

Changes in the Cross-Sectional Profile of Treated Anterior Cruciate Ligament Within 2 Years After Surgery.

Background:The cross-sectional area (CSA) of the anterior cruciate ligament (ACL) and reconstructed graft has direct implications on its strength and knee function. Little is known regarding how the CSA changes along the ligament length and how those changes vary between treated and native ligaments over time.Hypothesis:It was hypothesized that (1) the CSA of reconstructed ACLs and restored ACLs via bridge-enhanced ACL restoration (BEAR) is heterogeneous along the length. (2) Differences in CSA between treated and native ACLs decrease over time. (3) CSA of the surgically treated ACLs is correlated significantly with body size (ie, height, weight, body mass index) and knee size (ie, bicondylar and notch width).Study Design:Cohort study; Level of evidence, 2.Methods:Magnetic resonance imaging scans of treated and contralateral knees of 98 patients (n = 33 ACL reconstruction, 65 BEAR) at 6, 12, and 24 months post-operation were used to measure the ligament CSA at 1% increments along the ACL length (tibial insertion, 0%; femoral insertion, 100%). Statistical parametric mapping was used to evaluate the differences in CSA between 6 and 24 months. Correlations between body and knee size and treated ligament CSA along its length were also assessed.Results:Hamstring autografts had larger CSAs than native ACLs at all time points (P < .001), with region of difference decreasing from proximal 95% of length (6 months) to proximal 77% of length (24 months). Restored ACLs had larger CSAs than native ACLs at 6 and 12 months, with larger than native CSA only along a small midsubstance region at 24 months (P < .001). Graft CSA was correlated significantly with weight (6 and 12 months), bicondylar width (all time points), and notch width (24 months). Restored ACL CSA was significantly correlated with bicondylar width (6 months) and notch width (6 and 12 months).Conclusion:Surgically treated ACLs remodel continuously within the first 2 years after surgery, leading to ligaments/grafts with heterogeneous CSAs along the length, similar to the native ACL. While reconstructed ACLs remained significantly larger, the restored ACL had a CSA profile comparable with that of the contralateral native ACL. In addition to size and morphology differences, there were fundamental differences in factors contributing to CSA profile between the ACL reconstruction and BEAR procedures.Registration:NCT 02664545 (ClinicalTrials.gov identifier).

Three-dimensionalmagnetic resonance imaging analysis shows sex-specific patterns in changes in anterior cruciate ligament cross-sectional area along its length.

Smaller anterior cruciate ligament (ACL) size in females has been hypothesized to be a key contributor to a higher incidence of ACL tears in that population, as a lower cross-sectional area (CSA) directly corresponds to a larger stress on the ligament for a given load. Prior studies have used a mid-length CSA measurement to quantify ACL size. In this study, we used magnetic resonance imagingto quantify the CSA along the entire length of the intact ACL. We hypothesized that changes in the ACL CSA along its length would have different patterns in males and females. We also hypothesized that changes in ACL CSA along its length would be associated with body size or knee size with different associations in females and males. MR images of contralateral ACL-intact knees of 108 patients (62 females, 13-35 years) undergoing ACL surgery were used to measure the CSA along the ACL length, using a custom program. For both females and males, the largest CSA was located at 37%-39% of ACL length from the tibial insertion. Compared to females, males had a significantly larger CSA only within the distal 41% of the ACL (p < 0.001). ACL CSA was associated with patient height and weight in males (r > 0.3; p < 0.05), whereas it was associated with intercondylar notch width in females (r > 0.3; p < 0.05). These findings highlight the importance of standardizing the location of measurement of ACL CSA.

Medial meniscus posterior root repair influences sagittal length and coronal inclination of the anterior cruciate ligament: a retrospective study.

Medial meniscus (MM) posterior root tears (PRTs) lead to abnormal kinematic changes in the knee and may induce pathological external rotation of the tibia during knee flexion. This study aimed to investigate changes in the length and inclination of the anterior cruciate ligament (ACL) after MM posterior root repair using magnetic resonance imaging (MRI). This retrospective study included 44 patients who underwent MM posterior root repair between 2016 and 2019. Clinical outcomes were evaluated before and after surgery. MRI examinations were performed at 10°/90° of knee flexion preoperatively and 3months postoperatively. The ACL length, proximal angle, and distal angle were determined using the sagittal view. MM extrusion and ACL inclination angle were determined using the coronal view. Clinical outcomes significantly improved 1year after surgery. The postoperative ACL length (29.7 ± 2.4mm) and proximal angle (47.0 ± 7.4°) at 90° of knee flexion decreased relative to the preoperative values (31.5 ± 2.3mm and 51.8 ± 8.7°, P < 0.01). The postoperative ACL inclination (64.9 ± 5.6°) at 10° of knee flexion decreased relative to the preoperative value (69.7 ± 5.6°, P < 0.01). Pathologically-stretched linear ACL at 90° of knee flexion and a steep ACL inclination at 10° of knee flexion could be reduced after MM posterior root repair. This suggests that pullout repair could restore MM function as a secondary stabilizer, thereby preventing meniscal and cartilage degeneration.

Dimensions of the anterior cruciate ligament and thickness of the distal femoral growth plate in children: a MRI-based study.

When determining the dimensions of an anterior cruciate ligament (ACL) graft in children, bone age should be considered in addition to the patient's age, gender, and body height. We aimed to determine the relationship between age, gender, and ACL dimensions as well as thickness of growth plate cartilage of the distal femur during puberty. We retrospectively analyzed MRI scans of the knee in 131 children (82 girls, 49 boys) aged 6-18years (mean age: 14.9 ± 2.6years). ACL length and width as well as thickness of the growth plate cartilage at the distal femoral epiphysis were measured. Mean ACL length increased linearly up to the age of 12years in females and 14years in males; thereafter, mean ACL length remained constant. Mean ACL length was largest at the age of 12 to < 13years (38.18mm) in females and at 15 to < 16years (39.38mm) in males. Mean ACL width increased up to the age of 12years in girls and 13years in boys. After the age of 12years, both the ACL length and width were significantly larger in boys than girls (p = 0.002 and p = 0.045, respectively). Mean thickness of the growth plate cartilage of the distal femur remained stable up to the age of 12years in girls and 14years in boys. Thickness of the growth plate cartilage changed most markedly between the age intervals of 11 to < 12years and 12 to < 13years in girls and between the age intervals of 13 to < 14years and 14 to < 15years in boys. ACL dimensions depended on both age and gender during the growth period. Measurement of cartilage thickness of the femoral distal growth plate proved to be an objective parameter to assess the maturation stage of local bone. This may be useful for the planning and timing of orthopedic ACL procedures. III-retrospective cohort study.

Tibial internal rotation in combined anterior cruciate ligament and high-grade anterolateral ligament injury and its influence on ACL length

BackgroundAssessment of combined anterolateral ligament (ALL) and anterior cruciate ligament (ACL) injury remains challenging but of high importance as the ALL is a contributing stabilizer of tibial internal rotation. The effect of preoperative static tibial internal rotation on ACL -length remains unknown. The aim of the study was analyze the effect of tibial internal rotation on ACL length in single-bundle ACL reconstructions and to quantify tibial internal rotation in combined ACL and ALL injuries.MethodsThe effect of tibial internal rotation on ACL length was computed in a three-dimensional (3D) model of 10 healthy knees with 5° increments of tibial internal rotation from 0 to 30° resulting in 70 simulations. For each step ACL length was measured. ALL injury severity was graded by a blinded musculoskeletal radiologist in a retrospective analysis of 61 patients who underwent single-bundle ACL reconstruction. Preoperative tibial internal rotation was measured in magnetic resonance imaging (MRI) and its diagnostic performance was analyzed.ResultsACL length linearly increased 0.7 ± 0.1 mm (2.1 ± 0.5% of initial length) per 5° of tibial internal rotation from 0 to 30° in each patient.Seventeen patients (27.9%) had an intact ALL (grade 0), 10 (16.4%) a grade 1, 21 (34.4%) a grade 2 and 13 (21.3%) a grade 3 injury of the ALL. Patients with a combined ACL and ALL injury grade 3 had a median static tibial internal rotation of 8.8° (interquartile range (IQR): 8.3) compared to 5.6° (IQR: 6.6) in patients with an ALL injury (grade 0–2) (p = 0.03). A cut-off > 13.3° of tibial internal rotation predicted a high-grade ALL injury with a specificity of 92%, a sensitivity of 30%; area under the curve (AUC) 0.70 (95% CI: 0.54–0.85) (p = 0.03) and an accuracy of 79%.ConclusionACL length linearly increases with tibial internal rotation from 0 to 30°. A combined ACL and high-grade ALL injury was associated with greater preoperative tibial internal rotation. This potentially contributes to unintentional graft laxity in ACL reconstructed patients, in particular with concomitant high-grade ALL tears.Study designCohort study; Level of evidence, 3.

Correlation between ACL size and dimensions of bony structures in the knee joint

It is difficult to measure the dimensions of the anterior cruciate ligament (ACL) in vivo, which makes choosing an individualized graft size for ACL reconstruction particularly troublesome. The morphology and function of porcine ACL have been reported to be similar to the native human ACL. This study aimed to identify bony morphological parameters on X-ray images that were significantly correlated with features of the native ACL. Anteroposterior X-ray images of 19 porcine knees were obtained. The width, height and area of the femoral notch, the widths of the femoral and tibial condyles and the width and area of the interspinal fossa of the tibia were measured. ACL length was measured using a caliper. The ACL was then resected and the outline of the bone insertion sites were marked and photographed for measuring the areas of the insertion sites. The excised ACL substance was scanned using X-ray microscopy and reconstructed to measure the medial-lateral (ML) and anterior-posterior (AP) widths, the long and short axes and cross-sectional area of the ACL isthmus. Linear regression analyses showed that the area of the interspinal fossa of the tibia was significantly correlated with the long axis and ML width of the ACL, and with the AP / ML width (p value = 0.038, 0.032 and 0.016 respectively). The width of the femoral condyle was significantly correlated with the area of the tibial insertion and the length and ML width of the ACL (p value = 0.013, 0.000 and 0.038 respectively). The area of the interspinal fossa of the tibia / notch width index (NWI) was significantly correlated with the long axis / short axis of the ACL (p value = 0.016). The width of the interspinal fossa of tibia / NWI was significantly correlated with the short axis of the ACL isthmus (p value = 0.009). However, the dimensions of the femoral intercondylar notch and the width of the interspinal fossa of the tibia were not significantly correlated with any of the ACL parameters. In conclusion, the dimension of the interspinal fossa of the tibia and the width of the femoral condyle measured from X-ray images might be used to estimate the shape and size of the ACL, which might be helpful for choosing a suitable graft size for ACL reconstruction. Data statementAll data relevant to the study are included in the article.

Long-term outcomes of arthroscopic suture fixation for anterior cruciate ligament tibial avulsion fracture

Introduction: Anterior cruciate ligament (ACL) tibial avulsion fracture is one of the most common knee injury. There are many classical procedures to be available for fixation ACL tibial avulsion fracture. Nowaday, arthroscopic suture fixation for ACL tibial avulsion fracture has many advantages and limits complications effecting knee joint. Objective: To evaluate long-term outcomes of arthroscopic suture fixation for anterior cruciate ligament tibial avulsion fracture. Subject and method: Thirty six patients with ACL tibial avulsion fracture (types II, III, IV), mean age of 33.8 years (range from 22 to 46 years) were prospectively followed up after arthroscopic suture fixation for anterior cruciate ligament tibial avulsion. Along with clinical examination, radiographs, Lysholm score, IKDC classification were used to evaluate the patients. Anteroposterior knee laxity was measured with a KT-1000. Result: Patients were followed up for a mean of 14.46 months (range, 6 to 24 months). At final follow-up, the mean Lysholm score was 92 (range, 81 to 100). 34 patients (94.5%) were classified by IKDC score as normal or nearly normal (grade A or B). The IKDC classification was abnormal (grade C) in 2 patients (5.6%). Anterior translation of the tibia, measured with the KT-1000, was 1.69mm on average (range, 0 to 6mm) compared to the healthy side. All 36 fractures achieved union within 3 months. Conclusion: Treating ACL avulsion fracture with arthroscopic suture fixation can restore ACL length, stabilize fragments, promote early motion.

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).

Age- and sex-specific differences in ACL and ACL bundle size during adolescent growth.

Anterior cruciate ligament (ACL) injuries are increasingly common in adolescents, and injuries in this age-group are associated with many unique challenges. Recent large animal studies suggest that the size and function of the major bundles of the ACL change differently throughout skeletal growth. To better aid clinical treatment of pediatric partial ACL tears and better predict outcomes from age-specific treatments, there is a need to measure changes in ACL bundle size in humans during growth. As such, the objective of this study was to compare changes in the length and cross-sectional area (CSA) of the ACL and its primary bundles in adolescent human subjects. Magnetic resonance imaging (MRI) scans were analyzed to determine the visibility and integrity of the ACL and its anteromedial and posterolateral bundles. MRI scans were considered from a retrospective database of subjects ranging from 10 to 18 years of age. The ACL and its anteromedial and posterolateral bundles were segmented and reconstructed into 3D models, and length and CSA were calculated. Total ACL length and CSA were greater in males compared with females, with a statistically significant interaction between age and sex for CSA. Sex had a significant effect on the CSA of both bundles. These sex-dependent differences emerge with moderate to large effect sizes (range: d = 0.50 to d = 1.23) beginning around 13 years of age. Along with ACL bundle structure-function relationships previously established in preclinical animal models, these findings may point toward biomechanical changes in the adolescent human ACL.