Degenerative arthritis of the large joints of the body is an ancient disease, and skeletal changes consistent with the diagnosis have been found in prehistoric remmants of both man and animal species. In 1743 Hunter published an article, "The Structure and Diseases of Articulating Cartilage" in which he said, "From Hippocrates to the present age it is universally allowed that ulcerated cartilage is a troublesome thing and that when once destroyed it is not repaired." However, the histologic characteristics were not well defined until the latter part of the nineteenth century. Numerous studies have been published since that and have carefully documented the histologic change in the articular cartilage and point out the characteristic features.
Until the last 30 years little was known about the biochemistry or metabolism of articular cartilage. In these three decades, the biochemical features of this peculiar tissue have been defined by a small group of scientists, and in the last ten years technical advances have made it possible to explore in depth the abnormalities in cartilage from degenerative arthritic joints.
However, the specific treatment of degenerative arthritis has not yet been improved to the point to warrant full-scale clinical application, although some experimental reports have appeared occasionally.
Mature articular cartilage is an aneural, avascular, and alymphatci specialized from of connective tissue (Hunter, 1743; Paget, 1853; Barnett et al., 1961; Mankin, 1962; 1963; Meachim and Roy, 1967; Fuller and Ghadially, 1972), and it has been
emphasized that destruction of articular cartilage is the starting point in the evolution of degenerative arthritis and that all subsequent changes in the various components of the joint are secondary. The initial destruction may occur spontaneously with normal wear and tear in aging cartilage, or it may occur prematurely in articular cartilage that has been damaged by a local condition, such as infection or injury.
By Gardner (1960), the methods of experimental production of arthritis had been classified as infective, chemical, endocrine, immunological, and physcial. Physical agents damaging to joint have been used experimentally to produce forms of arthritis which most frequently resemble degenerative joint disease in the human.
Experimental methods inducing degenerative joint changes are excision of part of the joint (Key, 1931; Hall, 1969; Talhag, 1972), superficial scarificationof the cartilage (Meachim, 1963), compression of the articular surface (Salter and Field, 1960; Crelin and Southwick, 1964; Ginsberg et al., 1969; Thompson and Bassett, 1970), immobilization of the joint(Evans et al., 1960; Hall, 1963), dislocationof the patella (Bennett and Bauer, 1937), and division of the anterior cruciate ligament (Marshall, 1969).
Potential protective agents against cartilage degeneration are known which can inhibit the enzymes implicated in the pathogenesis of degenerative arthritis; for example, epsilon aminocaproic acid (Ali, 1964), and acidic anti-inflammatory drugs
such as phenylbutazone, mefenamic acid, flufenamic acid, ibufenac, and indomethacin (Anderson, 1969; 1970).
Ali (1964) reported that epsilon aminocaproci acid inhibits plasmin, and also inhibits autodigestion of cartilage matrix by chondrocyte cathepsin.
Simmons and Chrisman (1964; 1965) observed that salicylate has a potential protective effect against cartilage degeneration in vitro and in vivo, and offered the biochemical explanation that salicylate might significantly inhibit the action of the catabolic enzymes, cathepsins.
It has been suggested that the acidic anti-inflammatory drugs may exert their beneficial effect by partially inhibiting some of the lysosomal enzymes (Anderson, 1969; 1970), or in common with anti-inflammatory steroids and chloroquine, by stabilizing cell and lysosomal membranes (Tanaka and Iizuka, 1968). In contrast,
silberberg et al. (1966) have shown that cortisone, by itself, may act as a distruptive agent. They performed electron microscopic studies on articular cartilage after the systemic administration of cortisone and observed an increase in thenumber of lysosomes in the chondrocyte. Mankin and Conger (1966) emphasized that in cartilage, collagen and chondromucoprotein synthesis are both reduced after intra-articular as well as systemic administration of the drug.
The use of alkylating agents in the treatment of rheumatoid arthritis was first described by Diaz et al. (1951), and has sound theoretical basis because of its potential anti-inflamm-another alkylating agent, Thiotepa, in the small joints of
the fingers and noted clinical improvement. However the effect on articular cartilage after the intra-articular administration of Thiotepa has not been defined.
From a clinical aspect, specific treatment to protect against cartilage degeneration has remained a very interesting subject in chronic arthritis including degenerative arthritis.
The purpose of the research is to show production of degenerative changes of articular cartilage by means of superficial scarification of the cartilage and immobilization of joint, to investigate protection against cartilage degeneration
with acetylsalicylic acid (aspirin), and to clarify effects on degenerative articular catilage after intra-articular administration of hydrocortisone acetate and triethylene thiophosphoramide (Thioteoa).
One hundred and twenty healthy mature albino rabbits each weighing about 2.0kg. were used for the experimental study. The animals were divided into three large groups as follows;
Group Ⅰ: experimental production of arthritis (36 animals)
a) superficial scarification of the articular cartilage
b) immobilization of the joint after the scarification
Group Ⅱ: oral administration of aspirin (48 animals)
a) early administration after the scarification
b) late administration after the scarification
c) early administration after the scarification and immobilization
Group Ⅲ: intra-articular administration after the scarification (36 animals)
a) normal saline
b) hydrocortisone acetate
The animals were operated on in sterile conditions under nembutal anesthesia (30mg. per kg.). An anteromedial parapatellar incision was made over the knee joint and the articular cartilage of the femoral condyle was exposed, with the patella disolcated laterally. Three longitudinal superficial incisions were made on the medial femoral condyle and the wound closed.
Immobilization of the knee joint in flexed position of about 45 degrees was maintained for eight weeks by plaster of Paris.
Aspirin (0.7gm. per day) was given orally in themorning for eight weeks beginning after the first postoperative dayk or after the first, second, third, and fourth week respectively. Intra-articular normal saline (0.3cc. per week), hydrocortisone acetate (5mg. per week), and Thiotepa (5mg. per week) were injected into the patellar groove for eight weeks begining from the tenth postoperative day.
Serum samples selected randomly were assayed for aspirin at intervals using the method of Brodie et al. (1944).
The operated animals were sacrificed at time intervals of 1, 2, 4, 8, 12, and 24 weeks respectively after the operation, for light microscopy, and at intervals ranging from 2 hours to 8 weeks for electron microscopy.
After sacrifice, the distal portions of femora were resected and fixed in 10 percent neutral formalin. the tissues were decalcified and prepared by standard paraffin embedding procedure and stained with hematoxylin and eosin for histologic observation and safranin O-fast gree for histochemical observation. For electron microscopy, the specimens(from Group Ⅰ and Group Ⅱ, excluding the subgroup of immobilization) were fixed in four percent glutaraldehyde for four hours and postfixed for two hours at 4℃ with one percent osmium tetraoxide in 0.1M phosphate
buffer with pH 7.4 (Palade, 1952). All tissues were dehydrated in graded alcohol and embedded in Epon 812 according to standard procedures (Luft, 1961). They were cut into sections of 500 A with a glass knife. The sections were mounted on copper grids, stained with uranyl acetate and lead citrate, and observed with the Hitachi HU 11-E Electron Microscope.
The results of the histologic, histochemical, and electron microscopic findings are as follows;
1. The effects on the articular cartilage by the method of multiple superficial scarification or scarification and immobilization were observed, and degenerative changes as found in the earliest phases of human degenerative arthritis were seen.
Severe and progres sing degenerative changes were found in the cartilage of the scarified and immobilized animals.
Histochemical changes appeared, and consisted of a decrease in the mucopolysaccharide component of the martix.
2. The degeneratie changes of the articular cartilage after the scarification or scarification and immobilization were significantly inhibited by aspirin, especially in early aspirintreated rabbits.
3. In the weekly intra-articular administration of hydrocortisone acetate and Thiotepa after scarification of the medial femoral condyle, no potential protective effects against cartilage degeneration were determined. More rapid progressing and severe degenerative changes of the cartilage were followed by repeated intra-articular injections. These degenerative changes were present significantly in the hydrocortisone-treated animals.
4. The ultrastructure of articular cartilage inthe middle zones from scarified cartilage ans aspirin-treated cartilage after scarification were studied. In the former, degenerative changes in chondrocytes appeared, and these included dilatation of cisternae of rough endoplasmic reticulum, swlling of mitochondria, the accumulation of fine filaments, many lysosomal bodies and lipid droplets. some of these abnormalities, decreased lysosomal bodies and fine filaments, for example, were less common in the latter subgroup.
5. the synovium showed nonspecific chronic inflammatory changes after scarification or scarification and immobilization, and these changes were reduced by aspirin, hydrocortisone acetate and Thiotepa.