Structural And Functional Organisation Of The Capsules And Ligaments Of The Hip And Knee Joints In The Vervet Monkey And Olive Baboon

Abstract

The structural organisation of the capsules and ligaments of the hip and knee joints in the vervet monkey and olive baboon forms the central theme of this thesis. In particular, the study addresses itself to the microscopic organisation of the elastic fibres with respect to their possible specialized function during locomotion and the various habitual postures of these animals. Specifically, the joint capsules and ligaments of the hip and knee joints of the vervet monkey and olive baboon have been investigated macroscopically and microscopically. The study has demonstrated that the capsules and ligaments of the hip and knee joints in these Cercopithecinae are preponderantly collagenous. The elastic fibres, however, are concentrated,in the inferior and postero-inferior aspects of the hip joint capsule and the posterior aspect of the knee joint capsule, areas that are subject to constant stretching during extension and flexion. The high concentration of elastic fibres in them therefore lends support to the hypothesis that elastic fibres have a tensioregulative function (MUNGAI, 1963). The study has also shown that the iliofemoral ligament in these animals is orientated almost horizontally, and is less well developed in contrast to its thickness and almost vertical disposition in man. It is suggested that these differences are related principally to the limitation of the range of movement enjoyed by the habitually semi-flexed hip joint of the vervet monkey and olive baboon and the extended hip joint of man with his erect posture. The study has further shown that the capsules are attached to bone mostly through periosteum, while the ligaments are attached to bone through fibrocartilage in the absence of periosteum, constituting a layered pattern of supporting metaplastic tissue. Furthermore, the study has demonstrated a fibrovesicular suprapatella in the quadriceps tendon of these Cercopithecinae. It is postulated that the presence of this structure is related to the biomechanical requirements of the anterior capsular compartment of the knee joint. These possibly entail the build up of net compressive forces in the deep aspect of the quadriceps tendon, particularly during the hyperflexed ~osition of the knee joint in the initial phases of jumping and springing in these quadrupedal monkeys '(WALJI andFASANA, 1983). It is concluded that the results of this study indicate a very close relationship between posture and locomotion on the one hand, and the morphological organisation of the capsules and ligaments of the hip and knee joints in these Cercopithecinae on the other. In addition, the findings of this study support the hypothesis that elastic fibres have a tensioregulative and may possibly have a tensiometric function (MUNGAI, 1963), while the collagen fibres provide rigid constraints that limit deformation of the tissue and thus play a predominantly protective role.