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BACKGROUND: The anterolateral ligament (ALL) of the knee has recently been described in detail. Most studies of the ALL have been conducted in adults; therefore, little is known about the anatomy and histology of the ALL in younger patients, and nothing is known about the fetal presence of the ALL. PURPOSE: To evaluate the ALL in human fetuses to determine its presence or absence and to describe its microscopic anatomy and histological features compared with the findings of studies conducted in adults. STUDY DESIGN: Descriptive laboratory study. METHODS: Twenty human fetal cadaveric specimens were used. The mean age of the fetuses was 28.64 ± 3.20 weeks. The ALL was dissected in the anterolateral region of the knee, and its anatomic parameters, including its origin, insertion, and path in relation to known adjacent anatomic landmarks, in addition to its length, width, and thickness over the path toward the tibia, were measured. After dissection, the ALL was removed en bloc with a portion of the lateral meniscus for histological analysis of 4-µm sections, hematoxylin and eosin staining, and immunohistochemical staining for type I collagen. RESULTS: The ALL was located in all dissected knees. Its origin was located at a mean distance of 1.87 mm from the origin of the lateral collateral ligament, with variations from the center of the lateral epicondyle to posterior and proximal to it, and it exhibited an anterior-inferior path toward the tibia, an insertion in the lateral meniscus approximately 2.08 mm anterior to the popliteal tendon, and another insertion in the tibia between the Gerdy tubercle and the fibular head at 2.46 mm below the articular cartilage. The histological sections of the ALL showed well-organized, dense collagenous tissue fibers with elongated fibroblasts (mean, 1631 fibroblasts/mm2) and a predominance of type I collagen. CONCLUSION: The ALL is present during fetal development, with anatomic and histological features similar to those of the adult ALL. CLINICAL RELEVANCE: The findings of this study help to better understand the ALL's anatomy and histology from the fetal period to adulthood. The study presents the existence of the ALL since fetal development, emphasizes the characterization of the ALL, and brings important information to future pediatric ALL lesion studies.

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The aim of this study was to examine and compare fetal and adult knee and elbow joint ligaments and determine histologically how these ligaments change over time. In addition, the images of fetal and adult joint ligaments were examined with magnetic resonance imaging (MRI). This study was conducted on 10 male fetus ranging from ages 14 to 17.5 weeks, two adult male cadavers obtained from Gazi University Faculty of Medicine Department of Anatomy and MR images of the knee and elbow regions of 10 male adults obtained from Atatürk Educational and Research Hospital between 2009 and 2011. In the present study, the sections taken from knee and elbow of ten 14­17.5 week old fetuses and the ligaments of tissue taken from the knee and elbow of two male cadavers using the same method of dissection were monitored. After monitoring tissue, microtome sections taken from paraffin-embedded structures were stained using the Masson-Trichrom and Orcein-Picroindigocarmine staining method. These sections were examined under a microscope and photographed. The images of 17 week old fetuses and the knee and elbow of the adults were obtained with MRI. The differences detected between adult and fetus ligaments consisted of fibroblast density and collagen thickness, density and waves. Although the fetus ligaments were not seen sufficiently with 1.5 Tesla (T) MR, they were seen very clearly with 3 T MR. Structural differences between adult and fetal ligaments revealed in histological and MRI images.

El objetivo del estudio fue examinar y comparar los ligamentos de la articulación de la rodilla y del codo en fetos y adultos y determinar histológicamente como estos ligamentos cambian con el tiempo. Además, las imágenes de los ligamentos de las articulaciones fetales y adultas se examinaron con imágenes de resonancia magnética (IRM). Fueron utilizados 10 fetos masculinos entre 14 y 17,5 semanas, y dos cadáveres adultos masculinos obtenidos del Departamento de Anatomía, Facultad de Medicina de la Universidad Gazi junto con las IRM de las regiones de la rodilla y del codo de 10 hombres adultos obtenidos de Atatürk Educativa y del Hospital de Investigación entre los años 2009 y 2011. Para las secciones de rodilla y codo de los diez fetos y de los cadáveres masculinos se utilizó el mismo método de disección. Después de procesar los tejidos e incluirlos en parafina, se obtuvieron cortes en micrótomo los cuales fueron posteriormente teñidos con Tricrómico de Masson y Orceína-picro-índigo Carmín. Las secciones fueron fotografiadas y examinadas bajo microscopio. Se obtuvieron IRM del codo y de la rodilla de los fetos y adultos. Las diferencias encontradas entre los ligamentos de adultos y fetos estaban en relación a la densidad de fibroblastos y espesor de colágeno. Aunque no fue posible observar los ligamentos fetales con 1,5 Tesla (T) MR, se observaron claramente con 3 T MR. Las diferencias estructurales entre los ligamentos fetales y adultos se observan tanto a nivel histológico y de resonancia magnética.

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