The paper reports an experimental investigation into the mechanisms whereby the joints of living animals maintain their precise contours. The normal patter of joint incongruity in the rabbit's hip having first been established, three groups of experimental animals underwent operative procedures designed to reduce the joint pressure to a level unrealistic in normal life. In one group the hip was dislocated by manipulation; in a second group the muscles around the hip joint were divided; and in a third group the hind limb was disarticulated through the knee. When the animals were killed at intervals of a few weeks after the operations the experimental hip joint showed increased congruity in all cases. It is concluded that in immature animals there is a mechanism in joints to control the modelling of their shapes towards an ideal incongruity, and that that mechanisms is pressure sensitive.
Five cases of Kienbock's disease occurring in a group of fifty-three adults with cerebral palsy are described. The increased incidence of the disease is attributed to the flexed posture habitual in the affected wrist and to an effect on the pattern of blood supply to the lunate.
Cadaver knee joints were mounted so that life-like forces of weight-bearing were simulated. The patello-femoral contact areas were defined under load throughout the range of movement by the dye method. During movement from extension to 90 degrees of flexion a band of contact sweeps across the patella from inferior to superior pole, but the odd facet makes no contact. At about 135 degrees of flexion separate medial and lateral contact areas form, the medial one limited to the odd facet. From extension to 90 degrees of flexion the patella holds the quadriceps tendon away from the femur, but in further degrees of flexion an extensive "tendo-femoral" contact area forms. Between 90 degrees and 135 degrees of flexion the patella rotates and the ridge between the medial and odd facets engages the femoral condyle. The odd facet is shown to be a habitual non-contact area and the ridge to be subject to high load, observations which correlate with cartilage lesions described in Part 2 of the paper.
Two distinct lesions affect the articular cartilage of the patella. Surface degeneration occurs particularly on the odd facet; it is age dependent, often present in youth and it becomes more frequent with increasing age. It probably does not occasion patello-femoral pain in youth, but may predispose to degenerative arthritis in that joint in later years and is regarded as a consequence of habitual disuse. The term "basal degeneration" is used to describe a lesion in which there is a fasciculation of collagen in the middle and deep zones of cartilage without, at first, affecting the surface. It was found astride the ridge separating the medial from the odd facet in twenty-three adolescents who had complained of prolonged patello-femoral pain. They were treated by excision of the disc of affected cartilage, with relief of pain in most cases. The pathogenesis of basal degeneration is related to the functional anatomy of the patella.
1. A predictable pattern of degeneration occurs on both the femoral head and the acetabulum and this pattern is age dependent. 2. The degenerative areas on the femoral head are related to habitual non-use. 3. The hip is shown to be anatomically incongruent, and the dome of the acetabulum, a predictable area of degeneration, is shown also to be an area of habitual non-use. 4. The possible relationships between age-dependent degenerative changes and senile degenerative joint disease is discussed and the importance of changing geometry stressed.
The collagen framework of articular cartilage is disposed, as in other connective tissues, to resist tension forces within the material. In this paper the fine structure of articular cartilage, as demonstrated by polarised light microscopy and electron microscopy, is related to the gross anatomy and to the naked eye changes of chondromalacia and fibrillation.
1. Haemorrhage into the fascial compartment which contains the iliacus muscle and the femoral nerve is a common complication of haemophilia. 2. The iliacus haematoma syndrome is described and illustrated from the authors' study of thirty episodes occurring in twenty-four patients. 3. The anatomy of the iliopsoas fascia is described and the mechanism of femoral nerve compression explained. 4. Differential diagnosis, prognosis and treatment are discussed and the necropsy findings in one patient are presented. 5. An instance of iliacus haematoma occurring as a complication of anticoagulant therapy is recorded.
