Tibial Insertion Of Anterior Cruciate Ligament Research Articles

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.

Comparison of the morphology of the anterior cruciate ligament and related bony structures between pigs and humans.

Pigs are widely used for clinical research on the anterior cruciate ligament (ACL) because of the similarity of the knee structure to the human knee. But evidence to support the suitability of using porcine samples to guide clinical practices is limited. This study aims to explore the qualitative and quantitative morphological features of the porcine knee and ACL, and to compare these with data on humans reported in literature. Nineteen porcine knees were used for this study. The bone structures were measured on coronal X-ray images. The length of the ACL was measured using a caliper. The ACL bone insertion sites were marked and measured on a digital photograph. The lengths of the long and short axis of the ACL isthmus were measured on the X-ray microscopy reconstructed images. The outcomes were compared with previously reported data on humans using an abstract independent-samples T test. Qualitative observation indicated a similar location, orientation and general morphology of the porcine ACL to human ACLs. The major difference was the location of the ACL tibial insertion with respect to the anterior horn of the lateral meniscus (AHLM). The porcine ACL was split into AM and PL bundles by the AHLM, while the AHLM was adjacent to the anterolateral border of the ACL tibial insertion in human knees. The quantitative comparison showed no significant difference between the human and porcine ACL in terms of the length of the ACL, the width of the femoral condyle and tibial plateau, and the tibial interspinal width. However, the CSA, the lengths of the long and short axis of the ACL isthmus, and the femoral and tibial insertion areas of the porcine ACL were all significantly larger than the reported features in human knees. The location, orientation and basic morphology of the porcine ACL and knee are similar to humans. However, the two-bundle structure is more distinct in a porcine ACL, and the dimensions of the porcine ACL are generally larger. This study may provide useful information to researchers when assessing the feasibility and limitations of using porcine samples for research on the human ACL and knee.

Type I Tibial Spine Fractures: Not So Simple to Classify, Not So Easy to Treat; A Multicenter Study

Background:Type I tibial spine fractures are non-displaced or minimally displaced (≤ 2mm displacement) fractures of the tibial eminence and ACL insertion traditionally managed nonoperatively with immobilization.Hypothesis/Purpose:We hypothesized that type I fractures do not carry significant risk of associated injuries and therefore do not require additional interventions aside from immobilization.Methods:We reviewed 52 patients classified by their treating institution with type I tibial spine fractures presenting between January 1, 2000 and January 31, 2019 at 10 institutions. Patients of age ≤ 18 years with pre-treatment plain radiographs and at least one year of follow-up were included. Data was collected on patient demographics, injury mechanism, treatment details, presence of concomitant injuries, range of motion (ROM) at final follow-up, treatment complications, and any return to the operating room for the injured knee. Pre-treatment imaging was reviewed by four authors to assess agreement of classification among the treating institutions. Patients were subclassified into two groups to ensure outcomes represented classic type I fracture patterns. Any patient with universal agreement among the four authors that the fracture did not appear consistent with a type I classification were assigned to Type 1+ Group (T1+). All other patients were assigned to the True Type I Group (TT1). We evaluated concomitant injury, need for operative intervention, and treatment outcomes overall and for each group independently.Results:48 patients met inclusion criteria. 40/48 were TT1 fractures, while 8/48 were T1+ fractures, indicating less than universal agreement among sports specialists in classification of these fractures. Among TT1 patients, 7 of 40 (18.4%) underwent surgical treatment, though this represented 35.7% (5/14) of those who had undergone pretreatment advanced imaging. In the T1+ group, 6 of 8 (75%) underwent surgical treatment, 50% of whom (3/6) had pretreatment advanced imaging. Overall, twelve of 48 patients (25%) had concomitant injuries, nine TT1 patients and three T1+ patients (p=0.77), with 7 concomitant injuries requiring additional surgical management.Conclusions:Classification of type I fractures can be challenging. Nonetheless, a substantial percentage of patients with these fractures (>20%) were found to have concomitant injuries by advanced pretreatment imaging, with surgical management indicated in 58.3% of these patients. Contrary to traditional thought, type I tibial spine fractures do carry a risk of associated injuries. Simple cast immobilization may not be the ideal treatment in all cases. Advanced imaging would be beneficial for those whose plan of care may initially be non-operative treatment.

Arthroscopic anatomy and pathoanatomy of anterior cruciate ligament ruptures: clinical study with 94 patients

Purpose: To arthroscopically evaluate the size variability of the Anterior cruciate ligament (ACL) insertion sites and to determine whether there are variations in rupture patterns of the two ACL bundles.&#x0D; Material and Methods: Ninetyfour patients undergoing ACL reconstruction between June 2008 and June 2009 were included inour study. The average age of the patients was 26.7 ± 8.3 years (range, 16–48 years). Only patients with an ACL rupture less than 120 days old were included as unpublished data revealed difficulty in distinguishing between AM and PL bundles in older ACL ruptures.&#x0D; Results: The femoral ACL insertion site length ranged from 11 to 20 mm (15.9 ± 2.2). On the tibial side, the length of the tibial ACL insertion site ranged from 9 to 20 mm (16.0 ± 2.1). On the femoral side, the width of the ACL insertion site ranged from 6 to 11 mm (8.3 ± 1.2). On the tibial side, the width of the entire ACL insertion site ranged from 6 to 12 mm (8.7 ± 1.1). The most frequent injury pattern was found to be the proximal rupture of both bundles; seen in 74 patients (78.7%).&#x0D; Conclusion: Both hypotheses were confirmed, and this may be clinically relevant in anatomic ACL reconstruction.

Effect of Percentage of Femoral Anterior Cruciate Ligament Insertion Site Reconstructed With Hamstring Tendon on Knee Kinematics and Graft Force

Background: Previous studies have stated that closely matching the size of the anterior cruciate ligament (ACL) insertion site footprint is important for biomechanical function and clinical stability after ACL reconstruction. However, the ACL varies widely regarding the area of femoral insertion, tibial insertion, and midsubstance of ACL, and reconstructing the insertion site area with a uniform diameter graft can result in a cross-sectional area that is greater than that of the midsubstance of the native ACL. Therefore, understanding the effect of relative graft size in ACL reconstruction on knee biomechanics is important for surgical planning. Purpose: To assess how the percentage of femoral insertion site affects knee biomechanics in single- and double-bundle ACL reconstruction. Study Design: Controlled laboratory study. Methods: A total of 14 human cadaveric knees were scanned with magnetic resonance imaging and tested using a robotic system under an anterior tibial load and a combined rotational load. In total, 7 knee states were evaluated: intact ACL; deficient ACL; single-bundle ACL reconstruction with approximate graft sizes 25% (small), 50% (medium), and 75% (large) of the femoral insertion site; and double-bundle reconstruction of approximately 50% (medium) and 75% (large) of the femoral insertion site, based on the ratio of the cross-sectional area of the graft to the area of the femoral ACL insertion site determined by magnetic resonance imaging. Results: Anterior tibial translation was not significantly larger than the intact state in single-bundle and double-bundle medium graft reconstructions (P > .05) and was significantly greater in the single-bundle small graft reconstruction (P < .05). Anterior knee translation in single-bundle medium graft and large graft reconstructions was not statistically different (P > .05). In contrast, the anterior tibial translation for double-bundle large graft reconstruction was significantly smaller than for double-bundle medium graft reconstruction at low flexion angles (P < .05). The single-bundle small graft force was significantly different from the intact ACL in situ force (P < .05). The graft force with double-bundle large reconstruction was significantly greater than that with the double-bundle medium reconstruction (P < .05) but was not significantly different from that of the intact ACL (P > .05). Conclusion: Knee biomechanics with a single-bundle small graft tended to be significantly different from those of the intact knee. In the kinematic and kinetic data for the single- and double-bundle medium graft reconstruction, only the anterior translation at full extension for the single-bundle reconstruction was significantly different (lower) from that of intact knee. This was a time zero study. Clinical Relevance: This study can provide surgeons with guidance in selecting the graft size for ACL reconstruction.

Assessment of Anterior Cruciate Ligament Tibial Footprint Sagittal Diameter and Orientation of the Ligament in the Intercondylar Notch in Indian Population: A Magnetic Resonance Imaging (MRI) Analysis.

Aim: To study the relevant anatomy of anterior cruciate ligament tibial footprint and orientation of the ligament in the intercondylar roof in Indian population the using MRI.Methods: A total of 70 knee MRI with intact anterior cruciate ligament (ACL) was assessed for intercondylar roof angle, ACL inclination angle, ACL-bluemensaat angle, ACL sagittal center, and tibial insertion size.Results: The ACL tibial sagittal center was found to be at 43.5% of the anteroposterior tibial length. Tibial insertion size averaged 15.40 (±1.29) mm with no significant difference in males and females (p > 0.05). The roof angle was 36.29 (± 4.02) ˚ and the ACL inclination angle and ACL-bluemensaat angle were 51.22 (± 3.39) ˚ and 4.70 (±3.35) ˚ respectively with no significant sex difference (p > 0.05).Conclusion: The ACL tibial insertion size averaged 15.40 mm and its center was at 43.51% along the Staubli and Rauschning line. The mean roof angle was 36.29 degrees and the ACL-bluemensaat angle was 4.70 degrees. Understanding of the tibial footprint morphology and the relation of the ligament to the roof of the intercondylar notch helps in anatomical graft placement during reconstruction.

The interrelationship between anterior cruciate ligament tibial footprint and anterolateral meniscal root insertions: Quantitative, morphological and positional analyses using three-dimensional computed tomography images

BackgroundThe purpose of this study was to evaluate quantitative, morphological and positional differences between the anterior cruciate ligament (ACL) tibial footprint and anterolateral meniscal root (ALMR) insertion and investigate an intraoperative landmark to estimate their boundaries. MethodsThirty-three fixed human cadaveric knees were evaluated. After resecting the components, the anterior fiber (AF) and posterior fiber (PF) of ALMR, the tibial center of ACL bundles (anteromedial (AM) and posterolateral (PL) bundles) and ACL were marked. Insertion morphology was classified into three categories, and the distance and relative positional relationship between AF/PF insertions and the center of each attachment were measured on three-dimensional computed tomography images. ResultsThere was no significant difference between the AF of AM and ACL (P = 0.16), but both were significantly shorter than the AF of PL (both P < 0.001). There was no significant difference between the PF of ACL and PL (P = 0.99), which were significantly shorter than PF of AM (both P < 0.001). Morphology of the ACL tibial insertion was classified as follows: triangular, 15 knees (45.5%); oval, 18 knees (54.5%); none, C-shape. Quantitative and positional analyses showed that the AF insertion was significantly closer to AM and ACL centers in the oval type than in the triangular type. Excluding two cases, the AF/PF insertion was located laterally to the ML center of the medial and lateral intercondylar tubercles. ConclusionProximity of ACL tibial footprint and ALMR varies by their footprint morphology. The medial and lateral intercondylar tubercles were useful landmarks for ALMR injury prevention.

Anatomical and finite element analysis of anterior cruciate ligament reconstruction within biomechanical insertion

To provide new concepts of anterior cruciate ligament (ACL) reconstruction by anatomical gross observation of ACL tibial insertion and finite element analysis of distribution of ACL mechanical insertion. In the anatomical study, ten fresh adult cadaveric knees were dissected, including 6 males and 4 females, all knees were generally observed through standard medial parapatellar approaches, paying attention to the close anatomical relationship of tibial insertion and anterior horn of lateral meniscus, and ACL was exposed and gradually removed from the inside. The shape of tibial insertion of ACL was observed and recorded, and anterior-posterior diameters and left-right diameters of tibial insertion were measured with vernier caliper. For the study of finite element analysis, three-dimensional thin-layer magnetic resonance imaging of normal knee joint was used to establish knee joint model. Three-dimensional reconstruction software MIMICS and finite element analysis software ANSYS were used to establish knee joint model, subsequently, clinical physical examination Lachman test and pivot-shift test were simulated to observe the force distribution of ACL tibial insertion and femoral insertion. The ACL tibial mechanical insertion was rather flat and long similar as an arc shape without a clear separation between anterior medial bundle (AMB) and posterolateral bundle (PLB) in gross observation. The dense fibers lies belonged to the medial intercondylar ridge and ended up anterior with the osseous landmark of anterior ridge. Its average anterior-posterior diameter was (13.8±2.0) mm, the average left-right diameter of midsubstance was (5.3±0.6) mm, and the average left-right diameter of anterior margin was (11.5±1.2) mm. The finite element analysis showed that distribution on the femoral side was oval shape mainly below the residents' ridge, while the tibial side was rather flat mainly along the medial intercondylar ridge, which was consistent with the anatomical observation. The biomechanical characteristics of ACL attachments were verified theoretically. Anatomical study and finite element analysis have confirmed the flat arc shape of ACL tibial insertion. The ideal reconstruction technique of ACL should be based on its biomechanical insertion. Based on anatomical study and biomechanical analysis, we have proposed the idea of ACL biomechanical insertion reconstruction (BIR) and established a surgical model with oval femoral tunnel and rounded-rectangle tibial tunnel.

Anatomical anterior cruciate ligament reconstruction with a flat graft using a new tunnel creation technique

Anterior cruciate ligament (ACL) reconstruction is well established in a single bundle or double bundle technique using hamstrings, quadriceps tendon or patellar tendon. Based on new anatomical findings from the authors about flat ACL and c-shaped tibial insertion, a novel concept was developed to reconstruct the ACL in a more anatomical way. This article describes the new technique of flat ACL reconstruction with graft preparation and creation of flat femoral and tibial bone slits.

The Chinese ACL injury population has a higher proportion of small ACL tibial insertion sizes than Western patients

PurposeThe study purpose is to characterize the sizes of the anterior cruciate ligament (ACL) insertion site and intercondylar notch in Chinese patients undergoing ACL surgery. The findings will provide a reference for individualized clinical treatment of ACL rupture.MethodsFor this study, 137 patients (102 males, 35 females) with an average age of 30.3 ± 9.5 years (range 14–52 years) undergoing ACL reconstruction were included. The tibial ACL insertion site length and width and the intercondylar notch width were measured on MRI and arthroscopically using a ruler. Descriptive statistics of the patients, the distribution of the measurements and the differences between males and females were calculated.ResultsThe ACL tibial insertion size and intercondylar notch width in Chinese patients with ACL injuries, as obtained by MRI and intra-operatively, exhibited significant individual variability. The tibial ACL insertion site had a mean length of 13.5 ± 2.1 mm and width of 10.9 ± 1.5 mm as measured on MRI and a mean length of 13.3 ± 2.1 mm and width of 11.0 ± 1.6 mm as measured intra-operatively. The mean intercondylar notch width was 15.2 ± 2.4 mm on MRI and the mean length was 15.0 ± 2.5 mm intra-operatively. The inter-rater reliability between MRI and intra-operative measurements confirmed that the two methods were consistent. In 65.7% of individuals, the ACL tibial insertion length was < 14 mm.ConclusionThe distribution of tibial footprint size in Chinese patients is different from that in Western populations. There is a higher proportion of subjects with a tibial footprint size < 14 mm among Chinese patients with ACL injury. Therefore, great care should be taken when treating this population with the double-bundle technique or larger graft options.Level of evidence IV.

Development of fibrocartilage layers in the anterior cruciate ligament insertion in rabbits

BackgroundA detailed evaluation focusing on the fibrocartilage layers in the anterior cruciate ligament (ACL) insertion is necessary to consider regeneration of the insertion. This study examined the development of the fibrocartilage layers in the ACL tibial insertion in rabbits by quantitative morphometric evaluations based on histological and immunohistochemical analyses.MethodsMale Japanese white rabbits were used because of their history of use for histomorphometric analyses of the ACL insertion and to eliminate the influence of female hormones on the ACL. Six animals were euthanized at each age (1 day and 1, 2, 4, 6, 8, 12, and 24 weeks); in total, 48 animals were used. Proliferation rate, apoptosis rate, Sox9-positive rate, and chondrocyte number were evaluated. Safranin O-stained glycosaminoglycan (GAG) areas, tidemark length, ACL insertion width, and ACL length were also evaluated. All parameters were compared with those at age 24 weeks of age.ResultsHigh levels of chondrocyte proliferation and Sox9 expression continued until 4 and 8 weeks of age, respectively, and then gradually decreased. Chondrocyte apoptosis increased up to 8 weeks. The chondrocyte number, ACL insertion width, ACL length, safranin O-stained GAG areas, and tidemark length gradually increased up to 12 weeks.ConclusionChondrocytes that displayed chondrocyte proliferation and Sox9 expression increased until 12 weeks of age, in accordance with development of the ACL length and its insertion width. The GAG production and tidemark length also increased until 12 weeks of age. The development of fibrocartilage layers in the ACL insertion was complete at 12 weeks of age.

Tibial insertion of the anterior cruciate ligament and anterior horn of the lateral meniscus share the lateral slope of the medial intercondylar ridge: A computed tomography study in a young, healthy population

BackgroundThe central intercondylar ridge (CIR) is an anatomical bony landmark that bisects the slope of the medial intercondylar ridge (MIR) between the tibial insertion of the anterior cruciate ligament (ACL) and anterior horn of lateral meniscus (AHLM) and was recently revealed by computed tomography (CT) evaluation corresponding to histologic slices of cadaveric knees. The purpose of this study was to clarify the shape and size of ACL and AHLM tibial insertion in young, healthy knees using the new bony landmark (CIR) and previously reported landmarks. MethodsThe contralateral healthy knees in 34 ACL-reconstructed patients (18 male patients, 16 female patients, mean age: 24.0 years) were scanned by CT. In the reconstructed coronal/sagittal images, bony landmarks of ACL (anterior: anterior ridge, posterior: blood vessel in tubercle fossa, medial: MIR, lateral: CIR) and AHLM (medial: CIR, lateral: bottom of the slope) were plotted for evaluation. The length of sagittal slices and the width in five coronal slices of the insertion were measured. ResultsThe ACL insertion consistently showed a boot-like-shape adjacent to the square shape of AHLM on three-dimensional imaging. The mean ACL sagittal length was 14.5 ± 1.9 mm, while the mean ACL widths (in mm) from anterior to posterior were 12.7 ± 2.7, 8.1 ± 1.9, 7.9 ± 2.0, 7.5 ± 1.5, and 7.2 ± 1.6, which was highly correlated with the tibial plateau size. ConclusionsThe boot-like-shape of the ACL tibial footprint insertion shared the slope of MIR with the rectangular shape of AHLM in young, healthy knees. This study may provide useful information for safe tibial tunnel creation at the time of ACL reconstruction.

Individualized Anterior Cruciate Ligament Graft Matching: In Vivo Comparison of Cross-sectional Areas of Hamstring, Patellar, and Quadriceps Tendon Grafts and ACL Insertion Area

Background: Recent literature correlated anterior cruciate ligament (ACL) reconstruction failure to smaller diameter of the harvested hamstring (HS) autograft. However, this approach may be a simplification, as relation of graft size to native ACL size is not typically assessed and oversized grafts may impart their own complications. Purpose: To evaluate in vivo data to determine if the commonly used autografts reliably restore native ACL size. Study Design: Descriptive laboratory study. Methods: Intraoperative data of the tibial insertion area and HS graft diameter were collected and retrospectively evaluated for 46 patients who underwent ACL reconstruction with HS autografts. Magnetic resonance imaging measurements of the cross-sectional area (CSA) of the possible patellar tendon (PT) and quadriceps tendon (QT) autografts were also done for each patient. The percentages of tibial insertion site area restored by the 3 possible grafts were then calculated and compared for each individual. Results: The mean ACL tibial insertion area was 107.2 mm2 (60.5-155.5 mm2). The mean CSAs of PT, HS, and QT were 33.2, 55.3, and 71.4 mm2, respectively. When all grafts were evaluated, the percentage reconstruction of the insertion area varied from 16.2% to 123.1% on the tibial site and from 25.5% to 176.7% on the femoral site, differing significantly for each graft type (P < .05). On average, 32.8% of the tibial insertion area would have been filled with PT, 53.6% by HS, and 69.5% by QT. Based on previous cadaveric studies indicating that graft size goal should be 50.2% ± 15% of the tibial insertion area, 82.7% of patients in the HS group were within this range (36.9%, QT; 30.5%, PT), while 65.2% in the PT group were below it and 60.9% in the QT group were above it. Conclusion: ACL insertion size and the CSAs of 3 commonly used grafts vary greatly for each patient and are not correlated with one another. Thus, if the reconstructed ACL size is determined by the harvested autograft size alone, native ACL size may not be adequately restored. PT grafts tended to undersize the native ACL, while QT might oversize it. Clinical Relevance: These results may help surgeons in preoperative planning, as magnetic resonance imaging measurements can be helpful in determining individualized graft choice to adequately restore the native ACL.

Anterior Cruciate Ligament Tibial Footprint Size as Measured on Magnetic Resonance Imaging: Does It Reliably Predict Actual Size?

Background: Measuring the size of the anterior cruciate ligament (ACL) tibial footprint on magnetic resonance image (MRI) is common for preoperative planning of ACL reconstruction. However, the accuracy of such measurement has not been well documented. Purpose: To investigate whether the actual size of the ACL tibial footprint could be predicted by its measurement on MRI and to develop equations to improve the accuracy of predicting the actual size based on MRI measurement. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: A total of 164 patients with normal visualized ACL in gross evaluation and MRI were included (mean ± SD age, 67.3 ± 8.3 years). Cases with ACL tear, severe mucoid degeneration, osteophyte around the ACL tibial insertion, or intervals >12 months between MRI and actual measurement were excluded. The ACL tibial footprint was carefully dissected and measured during total knee arthroplasty. The length of the ACL tibial footprint on MRI was measured on a sagittal image, while the width was measured on an oblique coronal image. For the ACL tibial footprint, the association between measurement on MRI and actual measurement of length and width was analyzed via univariable and multivariable regression analyses. Reliability of measurements on MRI was also evaluated. Results: The length and width of the ACL tibial footprint as measured on MRI showed strong correlation with the actual length and width (coefficients: ρ = 0.904 and ρ = 0.808, respectively). There were differences between ACL size on MRI and its actual size: length, 12.4 mm (range, 9.7-15.3 mm) vs 13.8 (10.6-17.8) (P < .001); width, 8.8 mm (range, 7.0-12.1 mm) vs 7.2 (5.8-10.4) (P < .001). Based on sex, there were also differences between the size per MRI and the actual size (P < .001 for all): length in men, 12.6 mm (range, 10.9-15.3 mm) vs 14.2 (12.3-17.8); length in women, 12.4 mm (range, 9.7-14.5 mm) vs 13.7 (10.6-15.8); width in men, 9.3 mm (range, 8.0-12.1 mm) vs 7.6 (5.8-10.4); width in women, 8.7 mm (range, 7.0-10.4 mm) vs 7.2 (5.8-9.7). The actual length of the ACL tibial footprint could be predicted by its length on MRI and sex (R2 = 0.83, P < .001). Similarly, actual width could be predicted by the width on MRI and sex (R2 = 0.75, P < .001). All intraclass correlation coefficients were >0.8, indicating good reliability. Conclusion: Measurements of the size of the ACL tibial footprint on MRI showed strong correlation with its actual size. Prediction equations showed good concordance correlation coefficients.

Mediolateral Differences of Proteoglycans Distribution at the ACL Tibial Footprint: Experimental Study of 16 Cadaveric Knees.

This study aimed to identify the staining pattern of ACL attachment blended with cartilage of the medial tibial plateau at the tibial insertion and histologically characterize the tibial footprint. Sixteen fresh frozen cadaveric knees (mean age: 52.0 ± 6.2 years) were used for this study. The specimens were bisected in the coronal plane, in accordance with the fiber orientation of the ACL tibial attachment. Adjacent sections were then stained with hematoxylin and eosin (H&E) to observe the morphology of the ACL insertion and with fast green and Safranin-O protocols to evaluate for collagen and proteoglycans (PG). The insertion area on the tibial footprint was divided into five zones in the medial to lateral direction, which was determined by division of the section from most prominent medial tibial spine to most lateral margin of ACL attachment. Then rectangular area with a vertical length that is twice the width of respective five zones was set. Stained areas of all images were quantified positively by using ImageJ software, and the value for staining area measured was defined in percentage by multiplying whole image area by 100. The mean proportion of Safranin-O staining is significantly greater nearer to the medial tibial spine (59% in zone 1, 32% in zone 2, 13% in zone 3, 13% in zone 4, and 4% in zone 5, P < 0.001). The medial section of the tibial insertion area grew in size and increased in PG staining with more densely organized collagen arrangement with more fibrocartilage cells. The ACL tibial insertion showed a medially eccentric staining pattern by histological evaluation of the ACL attachment to cartilage. Our histological results of the eccentric biomaterial property in the medial tibial spine of ACL insertion area can be considered in making a more functional anatomic tibial tunnel placement.

Anterior cruciate ligament tibial insertion site is elliptical or triangular shaped in healthy young adults: high-resolution 3-T MRI analysis.

To clarify the morphology of anterior cruciate ligament (ACL) tibial insertion site in healthy young knees using high-resolution 3-T MRI. Subjects were 50 ACL-reconstructed patients with a mean age of 21.4±6.8years. The contralateral healthy knees were scanned using high-resolution 3-T MRI. The tibial insertion sites of the anteromedial (AM) and posterolateral (PL) bundle fibres, and the ACL attachment on the anterior horn of lateral meniscus (AHLM) were segmented from the MR images, and 3D models were reconstructed to evaluate the morphology. The shape of ACL footprint was qualitatively analysed, and the size of AM and PL attachments and AHLM overlapped area was measured digitally. Tibial AM and PL bundles were clearly identified in 42 of 50 knees (84.0%). Morphology of the whole ACL tibial insertion site was elliptical in 23 knees (54.8%) and triangular in 19 knees (45.2%), but not classified as C-shape in any knees. However, the AM bundle attachment was of C-shape in 29 knees (69.0%) and band-like in 13 knees (31.0%). Overlap of ACL on AHLM was found in 26 knees (61.9%), and the size of the overlapped area was 4.8±4.7% of the whole ACL insertion site. 3D morphology of the intact ACL tibial insertion site analysed by high-resolution 3-T MRI was elliptical or triangular in healthy young knees. However, the AM bundle insertion site was of C-shape or band-like. A small lateral portion of the ACL was overlapped with the AHLM. As for clinical relevance, these findings should be considered in order to reproduce the native ACL insertion site sufficiently. III.

Tibial insertions of the anterior cruciate ligament and the anterior horn of the lateral meniscus: A histological and computed tomographic study

BackgroundA positional relationship between the anterior cruciate ligament (ACL) and the anterior horn of the lateral meniscus (AHLM) has not previously been a topic of interest in the literature because the AHLM is already known to be obviously adjacent to the ACL and is assumed as a lateral border. The objective of this study was to investigate the positional anatomic relationship between the ACL and AHLM by histological evaluation of sequential slices and computed tomography (CT) of the tibial insertion sites. Hypothesis/purposeThe ACL has a specific positional relationship with the AHLM and there is an identifiable distinct bony border between them. The position of the AHLM could be an important and useful landmark for accurate tibial tunnel positioning in anatomical ACL reconstruction. Study designDescriptive laboratory study. MethodsTwelve ACL-intact knees from embalmed cadavers were used in this study. Six knees were sectioned into four slices for histologic examination in the coronal planes parallel to the AHLM alignment. Before sectioning, these knees were subjected to three-dimensional (3-D) volume-rendering CT. Each of the four slices demonstrated the insertion area of the ACL relative to the position of the AHLM. Each histologic slice was compared with the corresponding CT image. Only histological examination in the sagittal planes was performed in the other six knees. ResultsThe ACL fibres were broadly attached at the region anterior to the AHLM. However, the ACL and AHLM shared a clear border identifiable on the coronal CT images and appeared as a prominence of the bony ridge on the 3-D CT images. No dense ACL fibres were attached to the region posterior to the AHLM. Based on the histological data, the geometry of the ACL tibial insertion was L-shaped along the AHLM. ConclusionThe ACL and AHLM have a specific positional relationship not only in the mediolateral direction but also anteroposteriorly. The AHLM serves not only as a lateral border, but also as a useful reference in an anterioposterior direction for tunnel positioning in ACL reconstruction. Specifically, the ACL fibres were found to be broadly attached onto the bony surface in the region anterior to the AHLM and there was no firm attachment of the ACL in the region posterior to the AHLM on the tibial side, which is useful in avoiding posterior tunnel placement.

Histological Analysis of the Tibial Anterior Cruciate Ligament Insertion

Objective:To describe the morphology of the tibial ACL insertion by histological assessment in the sagittal plane.Methods:For histology the native (undissected) tibial ACL insertion of 6 fresh-frozen cadaveric knees was cut into 4 sagittal sections parallel to the long axis of the medial tibial spine. The slices were stained with hematoxylin and eosin, Safranin O and Russell-Movat pentachrome. All slices were digitalized and analyzed at a magnification of ×20.Results:From medial to lateral the anterior-posterior lengths of the ACL insertion were an average of 10.2, 9.3, 7.6 and 5.8 mm. The anterior margin of the tibial ACL insertion raised from an anterior ridge. The most medial ACL fibers rose along with a peak of the anterior part of the medial tibial spine in which the direct insertion was adjacent to the articular cartilage. Parts of the bony insertions of the anterior and posterior horns of the lateral meniscus were in close contact to the lateral ACL insertion. A small fat pad was located just posterior to the tibial ACL insertion. There were no central or posterolateral inserting ACL fibers in the area intercondylaris anterior.Conclusion:The functional intraligamentous midsubstance ACL fibers arose from the most posterior part of its bony tibial insertion in a flat and “C-shape” way. The anterior border of this functional ACL started from a bony ‘anterior ridge’ and the medial border was along with a peak of the medial tibial spine.

Variations in Anterior Cruciate Ligament Anatomy

The aim of anterior cruciate ligament (ACL) reconstruction is to restore native ligament anatomy to potentially restore function. Morphologic measurements of the native ACL are a valuable asset to effective surgical planning, influencing decisions such as graft choice and single- vs double-bundle reconstruction. Several studies support the existence of high interindividual morphologic variabilities, an important factor that should be taken into account for each patient to ensure native ligament anatomy restoration and function. Anatomical features that can be objectively evaluated before and during ACL reconstruction surgery include the ACL length, tibial and femoral insertion site sizes, inclination angle, and intercondylar notch size.

ASSOCIATION OF ANTERIOR CRUCIATE LIGAMENT DEGENERATION WITH MEDIAL MENISCUS TEAR AND INTERCONDYLAR NOTCH IMPINGEMENT

To explore the association of anterior cruciate ligament (ACL) degeneration with intercondylar notch impingement and the medial meniscus tear in knee osteoarthritis (KOA). Between July 2014 and February 2016, 55 KOA patients (55 knees) with ACL degeneration (degeneration group) and 55 KOA patients (55 knees) without ACL degeneration (control group) were included in the study. No significant difference was found in gender, age, body mass index, and side between 2 groups (P>0.05). The notch width index was measured on preoperative MRI to evaluate whether the intercondylar notch was narrow. The location of the medial and lateral meniscus tear and osteophyte of the ACL tibial insertion were observed under arthroscopy, and the incidences of the meniscus tear and osteophyte were calculated. There was no significant difference in anterior horn and body tear of the medial meniscus and in anterior horn, body, posterior horn, and root tear of the lateral meniscus (P>0.05). Significant difference was found in the posterior horn and root tear of the medial meniscus, osteophyte of the ACL tibial insertion, narrow intercondylar notch, and the notch width index between 2 groups (P<0.05). The incidence of root tear of the medial meniscus was 53.8% (7/13) in 13 knees with osteophyte of the ACL tibial insertion and was 16.5% (16/97) in 97 knees without osteophyte, showing significant difference (χ2=9.671, P=0.002). There is a strong association of ACL degeneration with posterior horn and root tear of the medial meniscus and intercondylar notch impingement in KOA. And the high incidence of root tear of the medial meniscus in knee is correlated with osteophyte of the ACL tibial insertion.