| BackgroundAnterior cruciate ligament (ACL) is an important stabilizing structure of the knee, and its basic role is to prevent forward movement of the tibia and some internal rotation movement of the tibia. With the help of posterior cruciate ligament, ACL maintains the normal tibiofemoral joint motion. ACL is composed of collagen fiber bundles in vertical rows, and surrounded by articular synovium, it is the structure in the knee joint but outside the synovial membrane. The main blood supply of ACL comes from the knee middle genicular artery, which passes through the posterior capsule and ends into the femoral intercondylar fossa, near the femoral attachment of ACL; The other blood supplies come from knee medial genicular artery and inferior lateral genicular artery, which are the blood supply of the infrapatellar fat pad. ACL is dominated by a branch of tibial nerve.At present, there is no study of epidemiology and clinical epidemiology of population about ACL injury in our country. There is no exact incidence of ACL injury in the world. In general, the incidence of ACL injury is high, and related with occupation, age and sex.Because of the special circumstances of the knee joint cavity, most of acute ACL complete injuries are hardly repair by conservative treatment except injury within the synovial membrane.Therefore, ACL rupture often requires surgical reconstruction.A successful outcome of ACL reconstruction depends on various factors such as graft materials, graft fixation, and initial graft tensioning, and particularly depends on the tibial and femoral tunnel positions of ACL. However, determination of the proper tunnel positions is difficult in the ACL reconstruction. Many researchers have confirmed that while the tibia and femoral attachment of ACL are important, but the femoral attachment of ACL is more important because of more close to the center of the knee axis. Foreign study reports that the femoral attachment of ACL lay on the end of the medial side of the lateral femoral condyle. It was an oval concave. The average length of it was 18mm, width was 11mm, and area was 113-170mm2. ACL attached to the front of the tibial intercondylar eminence distally on tibial plateau with fan-shaped, the shape of ACL tibial footprints included reversed triangle and oval. The average sagittal diameter of it was 17mm, coronal diameter was 11mm, and area was 136-150 mm2. The long axis along the femoral footprints paralleled to the direction of femoral shaft and the long axis along the tibial footprints paralleled to the direction of anteroposterior diameter of the tibial plateau, which made ACL reverse around itself. In the tibial attachment, ACL formed a "foot"-like structure, not only increased the insertion area, but also formed a bended fold under the front wall of the femoral intercondylar fossa. In the knee extension position, the front fibers of ACL are close to the femoral intercondylar fossa like a ring package as a "physiological friction", to avoid ACL impact intercondylar notch when the knee in extension position.According to domestic report, the diameter of the major axis and minor axis of ACL was 19.32±2.42mm and 10.52±2.24mm respectively, and the area of AMB bundles and PLB bundles was 69.37±20.2mm2 and 86.60±30.22 mm2 respectively. The distance between the attachment center of AMB and PLB was 9.42±1.51mm, the angle formed by the long axis of the femoral shaft and the line through the attachment center of AMB and PLB was 26.90±8.56°. The distance between the attachment center of PLB and over-the-top was 11.8±1.60mm, and the angle formed by the long axis of femoral shaft and the line through the attachment center of PLB and over-the-top position was 26.26±7.78±. The least distance from the attachment center of PLB to the cartilage border of lateral femoral condyle was 6.16±1.00mm. The attachment center of the AMB was located at 10:10±7'(right knee) or 1:49±5'(left knee), the over-the-top position was located at 10:45±8'(right knee) or 1:08±9'(left knee). The data provided clinical anatomy references of femoral attachment for the reconstruction of ACL.The study of ACL femoral attachment is important, but the study of ACL tibial insertion is also necessary. By measuring 101 pairs of dry Chinese skeleton-specimens, width of ACL tibial attachment was 9.38±1.51mm, the largest vertical diameter was 15.93±2.52mm. the distance from front margin of ACL adherent area in tibial eminence to front margin of tibial eminence was 7.85±1.52mm, the angle from axis of adherent area to median sagittal axis was 21.54±4.6°.The majority in the profile of ACL adherent area in tibial eminence was likely a inverted triangle. But more detailed anatomic morphological features of the ACL tibial attachment has not been reported.The methods of previous studies measuring the ACL attachment can be divided into two categories:one is measuring directly by using of vernier caliper, the accuracy of vernier caliper is mostly in 0.02mm, the method can still measure the linear distance, but it is difficult when measuring irregular areas. Another method is to take digital photos of objects under test firstly, and then apply professional digital photo analysis software to take measurement. This method can measure the area of various shapes, because of many components, and expensive cost, it can only apply in some professional organizations. Someone has introduced Photoshop software as a clever method of measurement of irregular shapes. Measurements using the software in the anatomy of the ACL attachment have not been reported, its accuracy, advantages and disadvantages need further assessment.Objective1. to observed anatomic morphological features of tibial and femoral attachment of ACL and measure the area, Horizontal diameter and anteroposterior diameter of ACL tibial attachment and the area, width and length of ACL femoral attachment and the distance between the geometric center of AMB and PLB of ACL tibial and femoral attachment;2. To discuss the relationship between ACL reconstruction with the measurements of the tibial and femoral attachment of ACL;3. To assess the accuracy, advantages and disadvantages of measurement of ACL attachment by using Photoshop software.Materials and Methods1 specimen source 10 cases of formalin soaked adult knee specimens (provided by Department of Anatomy of Southern Medical University),5 cases of male and female respectively, including 8 cases of left knee,2 cases of right knee, all of them are from different specimens. the femurol and the tibial side ends of the retention of the stump 10 cm long, excluding the knee structure is not complete, there are obvious anatomical abnormalities or degenerative joint specimens.2 anatomical method Remove the skin muscle, joint capsule and the patella around the knee, and retain the lateral and medial collateral ligament, anterior and posterior cruciate ligament and the lateral and medial meniscus. Saw the femoral condyle into two parts through the top of the intercondylar fossa along the sagittal plane, and remove the part of the medial femoral condyle, medial collateral ligament and posterior cruciate ligament, then fully reveal the inner side of the lateral femoral condyle, remove the synovial tissue around ACL. ACL and its attachment is visible3 observation methods Flex knee joint passively from 0°to 130°, and observe the fiber tension variation of ACL during flexion and extension.4 measurement methods Bend the knee to the angle that the two functional bundles most obvious, and then, separate ACL from the upper of ACL along the fiber bundle to go up and down separately, end on the femoral and tibial attachment. Divide ACL into anteromedial bundle (AMB) and posterolateral bundle (PLB), and cut off AMB and PLB from the tibial and femoral attachment respectively. then trace the contours of tibial and femoral attachment, mark the center according to the outline geometry with pins.And then parallel one edge of the rectangular transparent film Prepared in advance to the line formed by lateral and medial posterior margin of the tibial plateau (in the femoral attachment, parallel one edge of the rectangular transparent film to the long axis of femur shaft), mark the anterior, posterior, lateral and medial side. making rubbings of the AMB and PLB outline of ACL attachment and the center of two bundles with a transparent film, and then imprint rubbings on a standard A4 paper, take photos vertically to paper 90°with a digital camera (Nikon, China). Then, measure ACL tibial insertion of the anteroposterior diameter dl and transverse diameter d2, ABM area s1, PLB area s2, paper size S1 and the distance between the two bundles'centers D1 by using Adobe Photoshop Cs4 (Adobe, China) software coming with tools. The same as measuring ACL femoral attachment of the long diameter d3 and short diameter d4, ABM area s3, PLB area s4, paper size S2 and the distance between the two bundles'centers D2, these values are pixel values that are recorded as Ps value. The area of the standard A4 paper is known. In the same photo of the paper, using "actual area of the paper/paper'Ps value= measured area of the actual size/measurement Ps'value" principle, we can get the conversion values from the size of the various measurements.5 statistical methods With the application of SPSS 13.0 Statistical Package for measurement data processing, all measurements are recorded as Mean±Standard Deviation.Using "men or women", "left or right" as the grouping variable, the data about ACL tibial and femoral attachment were statistically tested with the independent sample t tests. The differences between the two groups were checked whether they were statistically significant. The d3, d4, s1 and s2 of ACL femoral attachment were statistically tested with measurements of previous literature data using single-sample t tests, The differences between the two experiments were checked whether they were statistically significant, the accuracy, advantages and disadvantages of using Photoshop software for measurement of ACL were assessed. P<0.05, the differences were statistically significant.Result1. The anatomical features of ACL and its attachment:10 cases of ACL of all specimens could be divided into AMB and PLB two function bundles. When the knee was extended, the fibers of ACL were parallel in sagittal plane, as a flat ribbon. The distal and posterior part of fibers of ACL on the femoral attachment loosed gradually with the increasing of bending Angle, and rotated forward. When the knee was bended to 90°, the distal and posterior part of fibers of ACL on the femoral attachment began to lie distal and anterior to the ligament. the proximal and anterior fibers loosed a little at the same time. When the knee was bended over 90°to 130°, the distal and posterior part of fibers of ACL lay in the front of the ligament completely. All fibers of ACL were tight. ACL rotated along the sagittal plane from the side view as knee was flexing and extending. There were always two different function bundles. At about 60°, the two function bundles of ACL were most obvious in the middle-upper section of the ligament. The tibial insertion of ACL located at the side of the medial intercondylar ridge, and the posterior margin of it did not exceed the highest place of intercondylar ridge. AMB located on the anteromedial side of footprint, and PLB located on the posterolateral side of footprint. The irregular shape of tibial attachment could be divided into reversed triangle, oval and quadrilateral. The femoral attachment of ACL located on the posterior part of the inside of lateral femoral condyle. The edges of it were near the distal and rear edge of cartilage. AMB located on the anteromedial side of footprint, and PLB located on the posterolateral side of footprint. The shapes of the femoral attachment were oval primarily.2. measurements of ACL attachmentIn the 10 cases of specimens, the anteroposterior length and breadth of the ACL tibial attachment footprints were (17.89±2.44)mm and (13.85±1.79)mm respectively. The area of the tibial attachment of the AMB and the PLB were (101.18±32.28) mm2 and (77.61±19.86)mm respectively, and the distance of between the geometric centre of the AMB and the PLB was (8.03±1.51)mm. the major axis and minor axis of the ACL femoral attachment footprints were (16.65±1.70) mm and (10.23±1.22) mm respectively. The area of the femoral attachment of the AMB and the PLB were (61.38±12.34) mm2 and (67.95±7.90) mm2 respectively, and the distance between the geometric centre of the AMB and the PLB was (8.63±0.77) mm.The AMB, PLB attachment area of ACL of woman was smaller than the man and the same as the major axis of the ACL femoral attachment footprints and the distance between the geometric centre of the AMB and the PLB by statistical analysis.3. The evaluation of measurement method of ACL attachment on the application of Photoshop softwareThe research data compared to the past domestic data made by Jianquan Wang et.al. The AMB area and the minor axis of femoral attachment had no significant difference between the two studies. The PLB area, major axis and distance between the geometric centre of AMB and PLB of femoral attachment were less than Wang's research data.The measurements of ACL attachment were accurate with the application of Photoshop software. The experimental method could not only overcome the problem of measuring an area of irregular shapes, and get more reliable measurement data, but also save the cost of the study. It was both a practical and inexpensive method of measurement.Conclution1. ACL could be divided into AMB and PLB functional bundles according to different fibers of ACL in knee flexion and extension. It was accepted widely in the world.2. The measurements of ACL attachment footprints could be used as the reference in ACL reconstruction.3. The measurements of ACL attachment were accurate with the application of Photoshop software. It was both a practical and inexpensive method of measurement... |
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