We studied the early cartilage changes in osteoarthritis, examining the most normal appearing articular cartilage from the hips of 17 patients. Normal appearing cartilage from five patients treated for fractures was used as control material. Two different types of clone were found. The first had increased staining for proteoglycan and was thought to have been engaged in the synthesis of matrix. The other type was associated with a severe deficiency of proteoglycan, matrix streaks and evidence of degradation and phagocytosis of matrix components. Immunohistochemistry demonstrated large amounts of chondroitin 4 and 6 sulphate about the synthetic-type clones, and little or no reactivity about the degenerative clones which lay more superficially and were associated with matrix destruction. Clones appeared to be engaged in either matrix synthesis or its destruction. The disease process of osteoarthritis appeared to begin at the surface of the articular cartilage.

1. A case is reported of a girl aged fifteen with growth hormone deficiency who developed a slip of the left femoral capital epiphysis at the age of seventeen during human growth hormone therapy.

2. The epiphysiolysis is regarded as iatrogenic.

1. Osmium tetroxide and nitrogen mustard were injected into normal adult rabbit joints. Within one week widespread chondrocyte necrosis had occurred as evidenced by electron microscopic examination and radioactive proline uptake autoradiography.

2. Initially, the cartilage matrix was intact but three to seven months later the cartilage surface began to disintegrate.

3. These studies indicate that osmium tetroxide and nitrogen mustard are unsuitable agents for chemical synovectomy.

4. They also indicate that there may be a long latent period between cartilage cell death and cartilage destruction, and that the evaluation of any agent for chemical synovectomy must take this into consideration.

1. The utilisation of labelled proline in normal and injured mature rabbit articular cartilage has been studied and compared simultaneously in one phase of the study with radiosulphate utilisation. The morphologic features of lacerative injury paralleled those reported previously.

2. Labelled proline is actively utilised by mature articular cartilage and can be recovered in time from the matrix as labelled hydroxyproline. This is taken as evidence of collagen synthesis.

3. Evidence is presented to suggest that the rate of formation of labelled hydroxyproline may be augmented after lacerative trauma.

4. Parallel utilisation of radiosulphate and labelled proline suggests that the synthesis of chondromucoprotein and collagen are closely related and that the continual synthesis of both moieties is necessary for the maintenance of normal matrix.

5. Despite evidence of increased chondromucoprotein and collagen synthesis no significant contribution is made to the healing of lacerative defects in mature rabbit articular cartilage.