Intercondylar area

Abstract: The anterior cruciate ligament originates at the medial wall of the lateral femoral condyle and inserts into the middle of the intercondylar area. It contributes significantly to the stabilization and kinematics of the knee joint. The femoral origin is oval and is located in the posterior aspect of the lateral femoral condyle. Therefore, it is difficult to visualize the femoral origin arthroscopically. This might be one reason for anterior malpositioning of the femoral bone tunnel during anterior cruciate ligament reconstruction. The position of the femoral origin is behind the center of rotation of the knee joint; therefore, it becomes tense when the knee is extended. The tibial insertion is oval and its center is nearly in the middle of the tibial plateau. Definite landmarks for tibial tunnel placement in anterior cruciate ligament reconstruction are the distance between the central insertion point at the intercondylar floor and the posterior cruciate ligament (7-8 mm) and the anterior horn of the lateral meniscus. The anterior cruciate ligament consists of multiple small fiber bundles. From a functional point of view, one can differentiate the anteromedial and posterolateral fiber bundles. The anteromedial fibers are tense during a greater range of motion than the posterolateral fibers. The main part of the anterior cruciate ligament consists of type I collagen-positive dense connective tissue. The longitudinal fibrils of type I collagen are divided into small bundles by thin type III collagen-positive fibrils. In the distal third, the structure of the tissue varies from the typical structure of a ligament. In this region, the structure of the tissue resembles fibrocartilage. Oval-shaped cells surrounded by a metachromatic extracellular matrix lie between the longitudinal collagen fibrils. The femoral origin and the tibial insertion have the structure of a chondral apophyseal enthesis. Near the anchoring region at the femur and tibia, there should be various mechanoreceptors, which might have an important function for the kinematics of the knee joint. The blood supply of the anterior cruciate ligament arises from the middle geniculate artery. The ligament is covered by a synovial fold where the terminal branches of the middle and the inferior geniculate artery form a periligamentous network. From the synovial sheath, the blood vessels penetrate the ligament in a horizontal direction and anastomose with a longitudinally orientated intraligamentous network. The distribution of blood vessels within the anterior cruciate ligament is not homogeneous. We detected three avascular areas within the ligament: Both fibrocartilaginous entheses of the anterior cruciate ligament are devoid of blood vessels. A third avascular zone is located in the distal zone of fibrocartilage adjacent to the roof of the intercondylar fossa.

Abstract: We assessed the anatomy of the anterior cruciate ligament (ACL) and femoral intercondylar notch on cryosections from one cadaveric knee specimen in the coronal oblique plane oriented parallel to the intercondylar roof We determined the course of the ACL, the widths of the cruciate ligaments at intersection, and the intercondylar notch configuration on coronal oblique plane magnetic resonance images in 51 adult cruciate ligament-intact knees (25 women, 26 men; age range, 16 to 47 years) The intercondylar notch widths were measured at the notch entrance, at the intersection of the ACL and posterior cruciate ligament (PCL), and at the notch outlet In the coronal oblique plane, the ACL exhibited a diagonal course from the central and medial part of the anterior intercondylar area of the tibia distally, across the lateral third of the intercondylar notch, to the intercondylar surface of the lateral femoral condyle proximally At the cruciate ligament intersection, the absolute widths of the ACLs measured on average 61+/-11 mm in men and 52+/-10 mm in women representing 319% and 311% of the ACL/central intercondylar notch width ratios The absolute widths of the PCLs measured on average 96+/-13 mm in men and 85+/-13 mm in women representing 504% and 514% of PCL/central intercondylar notch width ratios On average for both groups, men and women, the absolute widths of the PCLs were significantly larger than the absolute widths of the ACLs However, the relative widths of the cruciate ligaments with respect to corresponding intercondylar notch widths were not significantly different In the coronal oblique plane, the intercondylar notch widths showed on average a significant decrease from posterior to intersection and from intersection to anterior At notch outlet, the mean notch width measured 214 mm in men and 185 mm in women At intersection, the mean notch width measured 191 mm in men and 166 mm in women At notch entrance, the notch width measured 146+/-18 mm in men and 127+/-21 mm in women We recommend magnetic resonance tomography of the knee in the coronal oblique plane oriented parallel to the intercondylar roof as the imaging modality of choice to visualize accurately the anatomic diagonal course of the ACL and its relation to the intercondylar notch and posterior cruciate ligament complex

Abstract: A knee distraction device is provided for use in knee arthroplasty. A mechanism applies an adjustable distraction force between the tibial surface and a point on the distal femur of the flexed knee. The spatial relationship of tibia and femur is allowed to change by rotation of the femur around an axis between the center of the hip and the intercondylar area of the distal femur. As the distraction force is applied, relative tensions in the medial and lateral ligamentous structures of the knee are equalized by changes in the spatial relationship of the femur and tibia. During maintenance of distraction, the posterior femoral bone cut may be positioned at a predetermined distance from the cut tibial surface. The use of this mechanism facilitates accurate sizing of the flexion gap and optimal positioning of knee arthroplasty components.

Abstract: We compared the validity of the sonographic longitudinal sagittal image with the suprapatellar transverse axial image for assessment of thickness of femoral cartilage in osteoarthritis (OA) patients. Fifty-one patients with knee OA were enrolled in this study. Cartilage thicknesses of medial and lateral femoral condyles were measured with longitudinal sagittal and suprapatellar transverse axial image using sonography. Fat-suppressed 3D spoiled gradient-echo magnetic resonance imaging (MRI) was also used to get the reference value. The joint space width (JSW) and Kellgren and Lawrence (K-L) grade were measured in weight-bearing anteroposterior knee radiograph. The kappa and intraclass correlation coefficient (ICC) were used to determine inter- and intra-observer agreement of the ultrasound sonography (US) measurements. In medial femoral condyle, the opportunity to obtain cartilage thickness was increased significantly using the longitudinal US scan as compared with tansverse scan (48 cases vs. 36 cases, p < 0.05). There was a good correlation between longitudinal US scan and MRI in the maximum and minimum cartilage thicknesses of medial condyle (r = 0.568; r = 0.844, respectively, p < 0.01). However, there was no correlation between suprapatellar transverse US scan and MRI in medial condyle. In lateral condyle, both US scans showed good correlations with MRI. In Bland-Altman analysis, longitudinal US scan showed good agreement with MRI except in the minimal cartilage thickness of lateral condyle. There was high overall intra- and inter-observer agreement in US scan. US scan in the longitudinal plane is a more feasible method than suprapatellar transverse scan for measuring cartilage thickness of medial femoral condyle in knee OA patient.