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There is little information on the fetal anatomy of the posterior semimembranosus tendinous complex and its associated bursa. We examined histological sections (transverse or sagittal) of the right or left knee in 13 mid-term human fetuses (12-25 weeks of gestation). The medial head of the gastrocnemius provided an aponeurosis facing or attached to the muscles of the pes anserinus by 12 weeks of gestation. The peritendinous tissue of the semimembranosus provided a bursa continuous with a laterally extending plate-like tissue by 15 weeks, but sometimes the typical bursa was absent. The aponeurosis of the medial head consistently accompanied a bursa-like space (false bursa) surrounded by heterogenous structures including the popliteus and a wall of the semimembranosus bursa. Sagittal sections displayed notches on the medial head surface that received the semimembranosus and semitendinosus overriding the medial head of the gastrocnemius. In contrast to a real bursa originating from the peritendinous tissue of the semimembranosus, a false bursa without a homogeneous wall consistently develops at the origin of the medial head of the gastrocnemius. Due to mechanical stress from the tendons, the false bursa is likely to develop into a structure similar to a real bursa with a synovial lining even if the real bursa is absent in the fetus. We hypothesize that the adult gastrocnemio-semimembranosus bursa, largely or partly, originates from the fetal false bursa. Absolute resection of the false bursa is difficult because it is a mere gap between normal tissues., (Copyright © 2010 Elsevier B.V. All rights reserved.)

The small saphenous vein in its modal pattern flows into the popliteal vein by means of a terminal arch (sapheno-popliteal junction), and frequently gives off an anastomotic branch, ascending on the medial aspect of the thigh, to the great saphenous vein. This branch has often been termed thigh extension of the small saphenous vein. As resulted in this report from autopsy, the venous extension coursed on the midline of the posterior aspect of the thigh, tributary to the deep femoral vein, and the small saphenous vein presented neither a sapheno-popliteal terminal arch, nor evident intersaphenous anastomoses. As a consequence, the small saphenous vein by means of its prolongation continued directly from the calf into the deep femoral vein. In the human embryo the small saphenous vein appears as direct communication with the posterior cardinal vein, and accompanies the developing ischiatic artery and nerve, as the main vein (ischiatic vein) of the lower limb bud. At the end of development, its proximal part persists as inferior gluteal vein. Comparative anatomy indicates that in animals the small saphenous vein is the only superficial vein well developed and that in humans its termination into the popliteal one might be an adaptation to the elongation and relative rigidity of the lower limb. In the horse a posterior vein of the thigh connects the small saphenous with the ischiatic one, and ascends along the ischiatic nerve to anastomose with the deep femoral vein. It would appear also that in the lower animals the small saphenous vein ascends to a higher level on the posterior aspect of the thigh. Thus, a venous extension like that we observed might be an atavism. Therefore, on the basis of these embryological and phylogenetical data, the Authors hypothesized that a small saphenous vein and a thigh extension of such a feature might be regarded as a unique venous channel, wholly axial throughout its course, formed by the small saphenous vein proper in the leg and by a persistent and functional sciatic (ischiatic) vein, which usually disappears, satellite of the ischiatic nerve, in the thigh.

Knee injuries commonly occur in children and adolescents who participate in athletic activities. Open growth plates, apophyses, and chondroepiphyses are unique to the skeletally immature knee and account for the differences in injury patterns observed in children and adults. An understanding of anatomy and classification as related to treatment and outcome of fractures in the skeletally immature knee is important.

Purpose: The purpose of this study is to better understand the function of the popliteomeniscal fasciculi and their relationship to the popliteus tendon and the lateral meniscus by describing these structures during embryonic development., Type of Study: Anatomic dissection and histologic evaluation., Methods: Twelve fresh-frozen lower extremity specimens (6 paired limbs) from second and third trimester human fetuses were obtained from spontaneous abortions. Each specimen was fixed in formalin and decalcified in 9.0% nitric oxide. The specimens were prepared by removal of all skin and most of the soft tissues before dissection of the lateral meniscus, parts of the posterolateral joint capsule, and the popliteus tendon and muscle. The right-side specimens were sectioned in the transverse plane, and the left-side specimens in the coronal plane. Histologic sections were prepared with H&E and Masson's trichrome stains. Light microscopy was used to evaluate the lateral meniscal attachment, with detailed attention to the popliteomeniscal fasciculi., Results: The close interrelationship of lateral meniscus and popliteus tendon, especially during embryologic development, does give a better understanding how the fasciculi stabilize the lateral meniscus and allow the popliteus tendon to function as a retractor of the lateral meniscus. The fasciculi consist of 3 layers including a dense collagen layer, a vascular layer, and a synovial or capsular layer., Conclusions: During embryologic development, the fasciculi appeared to provide a vascular supply to the lateral meniscus adjacent to the popliteal hiatus where the meniscus is devoid of capsular attachments.

During development and at maturity different forms of cartilage vary in morphology and macromolecular content. This reflects heterogeneity of chondrocyte activity, in part involving differential interactions with the adjacent extracellular matrix via specialized cell surface receptors such as integrins. We undertook an immunohistological study on a series of human fetal knee joints to assess variation in the expression of integrins by chondrocytes and potential matrix ligands in articular, epiphyseal, growth plate, and meniscal cartilage. The results show that articular chondrocytes (beta 1+, beta 5 alpha V+, alpha 1+, alpha 2+/-, alpha 5+, weakly alpha 6+, alpha V+) differed from epiphyseal (beta 1+, beta 5 alpha V+, alpha 1+/-, alpha 2+/-, alpha 5+, alpha 6+, alpha V+) growth plate (beta 1+, beta 5 alpha V+, alpha 1-, alpha 2-, alpha 5+, alpha 6+, alpha V+), and meniscal cells (beta 1+, beta 5 alpha V+, alpha 1+, strongly alpha 2+, alpha 5+, alpha 6+, alpha V+ in expression of integrin subunits. There was no expression of beta 3, beta 4, beta 6, or alpha 3 by chondrocytes. These results differ from previous reports on the expression of integrins by adult articular cartilage, where alpha 2 and alpha 6 are not seen. Variation in distribution of matrix ligands was also seen. Fibronectin, laminin and Type VI collagen were expressed in all cartilages but there was restricted expression of tenascin, ED-A and ED-B fibronectin isoforms (articular cartilage and meniscus), and vitronectin (absent from growth plate cartilage). Regulated expression of integrins by chondrocytes, associated with changes in the pericellular matrix composition, is of potential importance in control of cartilage differentiation and function in health and disease.

The menisci are not secondary developments of the joint capsule. Rather they develop quite separately from the parenchyma, independently of the joint capsule, that lies in the interrupted zone of the central bar of the primary anlage of the extremities. In this functional unit of the knee joint, only selective intervention must be carried out in predisposition to disturbances, symptoms of disease or injury, and not unplanned interference. Only then will the joint become capable of carrying a load once more and be spared from further secondary damage. Consequently the die is already cast at the first examination for a systematic and successful treatment.

A new ultrasonic method based on X-ray concepts for depicting prenatally developed centers in the tarsal bones, calcaneus and talus, as well as and especially in the epiphysis centers of the fetal knee joint is described. Investigations of average collectives show that the center in the calcaneus becomes visible during the 24th week of pregnancy, on the average, whereas the center in the talus becomes visible during the 26th week after begin of amenorrhea. The growth charts of both these tarsal centers demonstrate almost linear growth until parturition, the very slight increase per week, however, limits the possibilities for their use in determining the period of gestation. The epiphysis center in the distal femur becomes visible by ultrasonic methods during the 32nd week of pregnancy, on the average, the center in the proximal tibia appears later, during the 37th week after amenorrhea begins. Both epiphysis centers show an almost linear increase in size from the time they first appear; the center in the femur, however, has a growth chart that shows levelling off after the 38th week of pregnancy. The differences between X-ray and ultrasonic representation, which become evident upon comparing growth charts as well as in a separate and direct comparison are shown to be due, through the results of a parallel histological study, to an increase in density of the cartilage matrix prior to ossification. Of the fetal factors which were investigated only the weight and length of the child show a slight, and for practical purposes negligable influence on the size of the epiphysis centers, whereby only the results showing that the femur centers tend to be larger when the child is heavier and longer appear significant. Neither sex nor maternal factors influence the size of the visible epiphysis centers in any way. A slight modification in the case of diabetics and pregnancy induced hypertension patients seems to most likely be due to the macrosomal and retarded children occurring in these groups. None of the factors investigated effect a significant difference in the ultrasonic development or time of appearance of the epiphysis centers. In view of the fact that growth charts show levelling off and of the wider biological scattering range of all parameters currently used to determine the duration of gestation during the last trimenon, making use of this new ultrasonic method with its double advantage - the first appearance of the centers during the last quarter of pregnancy as well as the following near-linear increase in size - seems to suggest itself.(ABSTRACT TRUNCATED AT 400 WORDS)

The radiological appearance of bone maturity can be used as a criterion for fetal maturity. This examination with limited irradiation to the fetus is an alternative to amniocentesis. The practice of the latter is not without risk. The authors carried out 194 examinations of the contents of the uterus to look at the epiphyses of the knee between the 34th and 40th week of amenorrhoea. The found three groups: 1) those with normal development; 2) those with delayed development and 3) those with more advanced development. They did not find significant correlation between small-for-dates growth and bony maturity. On the other hand, where there was increased growth of the fetus in cases where maternal diabetes was excluded there was demonstrated that bony maturity accelerated with the presence of Béclard's point from the 34th week onwards. With such great variation in the dates of the appearance of points of ossification the presence of epiphyseal points in the knee cannot be taken as a criterion to establish fetal maturity nor the minimum duration of the pregnancy.

The accuracy of term--prediction by echographic demonstration of the upper tibial and the lower femoral centre in patients with unknown confinement dates has been compared. The best prediction was given in case of the presence of tibial epiphysis.

A method is described, which permits the determination of fetal maturity by ultrasonic measurement of the ossification centres. This method provides the same data as the x-ray examination without any irradiation and even at an earlier stage of pregnancy. The technique to determine the lower femoral and the upper tibial centre is explained and the advantages of this ultrasonic method for determination of fetal maturity are discussed.