The reaction of articular cartilage to injury and osteoarthritis (first of two parts)

Review of pathogenesis and treatment of degenerative joint disease

Treatment of degenerative joint disease (osteoarthritis) is discussed in relationship to pathogenesis of five clinical entities, defined to facilitate discussion:-1) occurring in high motion joints and associated with synovitis; 2) associated with low motion joints; 3) "non-progressive" articular cartilage erosion; 4) secondary to other identified problems (intra-articular fractures, ligamentous damage, wounds, septic arthritis, osteochondrosis); and 5) chondromalacia of the patella. In addition to direct damage to articular cartilage, synovitis and capsulitis and depletion of matrical glycosaminoglycans and proteoglycans play important roles. The natural healing response in damaged articular cartilage is inadequate. The principles of treatment are divided into: 1) prevention or treatment of primary causes. These include the effects of track surface, shoeing, and the appropriate resolution of intra-articular fractures, septic arthritis and osteochondritis dissecans. 2) treatment of active soft tissue disease contributing to articular cartilage degeneration, including rest, physical therapy, synovectomy and administration of anti-inflammatory drugs, sodium hyaluronate and polysulfated glycosaminoglycans. 3) attempts at treatment of articular cartilage loss or degeneration, including articular cartilage curettage, subchondral bone drilling, osteophyte removal, articular cartilage grafting and arthrodesis.

Knee injuries in sports

Many knee injuries that previously caused disability can now be diagnosed accurately and treated successfully. Arthroscopy has been instrumental in this progress. The anterior cruciate ligament, which is an important stabilizer of the knee, is commonly injured. Disruption of the restraint provided by the ligament results in an unstable knee that can give way during pivoting motions. Early reconstruction is usually effective in restoring stability and improving function. Considerable progress has been made in knee bracing. However, prophylactic bracing has not been demonstrated to be effective in preventing knee injuries.

Hemophilic arthropathy of the temporomandibular joint: review of the literature, a case report, and discussion

Hemarthrosis of extremity joints in patients with hemophilia has been well documented. However, hemarthrosis of the temporomandibular joint in patients with coagulopathies appears to be rare. Consequently, management of a temporomandibular joint hemarthrosis is difficult because of the lack of treatment guidelines. The purpose of this article is to review the pathophysiology of hemophilic arthropathy and its management. A case of temporomandibular joint hemophilic arthropathy in a patient with a factor XI deficiency will be presented. A brief review of factor XI deficiency and a hypothetical pathophysiological mechanism for internal derangement induced by myofascial pain dysfunction are included.

Effect of S-adenosylmethionine on experimental osteoarthritis in rabbits

Twenty-four rabbits with surgically induced osteoarthritis of the knee were allocated into three treatment groups (placebo, S-adenosylmethionine (SAMe) 30 mg/kg per day, and SAMe 60 mg/kg per day). Intramuscular administration of drug or placebo was begun immediately after surgery and continued for 12 consecutive weeks. At the end of the treatment period, animals were killed, and the articular surfaces of the knees were studied using histologic and histochemical techniques. Microscopic studies showed that the number of cells and the depth of the cartilage were significantly (p less than 0.001) increased in SAMe-treated rabbits in comparison with placebo-treated animals. No difference was found in comparing data in animals given SAMe at the two dosage levels. In conclusion, these results suggest a chondroprotective effect of SAMe in animals with experimental osteoarthritis.

Arthroscopic and immunohistologic characterization of knee joint synovitis in osteoarthritis

We studied 10 patients who had arthritis of the knee joint, but no other signs of rheumatic disease. The clinical diagnosis of osteoarthritis was corroborated by arthroscopic evidence of characteristic cartilage degeneration. Signs of inflammation were confined to areas of the synovial membrane that lay near the cartilage; thus, the major part of the joint cavity was not affected. The intensity of the synovial inflammation varied within the areas involved, but was always most pronounced in regions rimming the cartilage. Biopsy samples selected from regions of intensely inflamed synovium contained foci of T lymphocytes, which were bordered by immunoglobulin-carrying B lymphocytes and plasma cells, as well as strongly HLA-DR positive dendritic-like cells adjoined to alpha Leu-3a+ T helper lymphocytes. In tissue samples taken from macroscopically noninflamed areas, only a few infiltrating lymphocytes were seen. Thus, the inflammatory synovial changes found in osteoarthritis appear to be anatomically restricted and of varied intensity but, when present, are microscopically indistinguishable from the changes that have been previously described as indicative of rheumatoid arthritis.

Magnetic resonance imaging of knee hyaline cartilage and intraarticular pathology

Injuries to the hyaline cartilage of the knee joint are difficult to diagnose without invasive techniques. Even though these defects may be the most important prognostic factors in assessing knee joint injury, they are usually not diagnosed until arthrotomy or arthroscopy. Once injuries to hyaline cartilage are found and/or treated, no technique exists to follow these over time. Plain radiographs, arthrograms, and even computed tomography fail to detail most hyaline cartilage defects. We used magnetic resonance imaging (MRI) to evaluate five fresh frozen cadaver limbs and 10 patients whose pathology was known from arthrotomy or arthroscopic examination. Using a 0.35 Tesla superconducting magnet and spin-echo imaging technique with a head coil, we found that intraarticular fluid or air helped to delineate hyaline cartilage pathology. The multiplane capability of MRI proved to be excellent in detailing small (3 mm or more) defects on the femoral condyles and patellar surface. Cruciate ligaments were best visualized on sagittal oblique projections while meniscal pathology was best seen on true sagittal and coronal projections. MRI shows great promise in providing a noninvasive technique of evaluating hyaline cartilage defects, their response to treatment, and detailed anatomical information about cruciate ligaments and menisci.

Structural characteristics of articular cartilage proteoglycan in IgG induced experimental immune synovitis

The early changes (five weeks) in the structure of newly synthesised and endogenous articular cartilage sulphated proteoglycans were studied in lapine IgG induced experimental immune synovitis. Rabbits with immune synovitis (IS-IgG) were compared with animals with a developed hypersensitivity to IgG (I-IgG) and with non-treated normal weight matched controls. Medial and lateral femoral condyle and tibial plateau cartilage was pooled and radiolabelled for 24 h in vitro with 35SO4. The samples constituted tissue from regions underlying pannus and from pannus free sites. Cartilage from animals with IS-IgG showed a significantly diminished amount of newly synthesised and endogenous proteoglycan aggregate and an increased amount of hydrodynamically small proteoglycans. Newly synthesised (obtained by in vivo radiosulphate labelling) and endogenous proteoglycans showed a similar profile. The proteoglycan monomer fraction from animals with IS-IgG failed to form proteoglycan aggregates in the presence of excess hyaluronic acid. In the group with IS-IgG linear regression analysis showed a statistically significant relationship between the synovial pathology scores (but not cartilage pathology score) and diminished newly synthesised and endogenous proteoglycan aggregate.

Brachygnathia superior and degenerative joint disease: a new lethal syndrome in Angus calves

Brachygnathia superior and generalized diarthrodial degenerative joint disease were seen in 17 related, purebred Angus calves ranging in age from 2 days to 4 months. Craniometrical studies revealed decreased maxillary and palatine bone lengths and increased cranial, skull, and facial indices. Radiological evaluation of major appendicular joints demonstrated lipping of the joint margins with osteophyte formation, sclerosis of subchondral bone, and narrowing of joint spaces. Synovial fluid evaluation indicated joint degeneration but no etiologic agent. Rheumatoid factor analysis of plasma was negative. Grossly, all major appendicular joints were defective including the atlanto-occipital articulation. Lesions ranged from loss of surface luster to erosions and deep ulcers with eburnation of the subchondral bone and secondary proliferative synovitis. Histological changes were degeneration of the articular cartilage matrix, chondrocyte necrosis, flaking and fibrillation, chondrone formation, erosions and ulcers of the articular cartilage with subchondral bone sclerosis, vascular invasion with fibrosis, and chronic, nonsuppurative, proliferative synovitis. Growth plates had defective chondrocyte proliferation and hypertrophy with aberrant ossification of calcified cartilaginous matrix. Histochemical analysis of cartilage and bone failed to incriminate which component was defective, glycosaminoglycan or collagen, but indicated different distribution or absence of one or the other. Genealogic studies revealed a genetic basis for the new defect.

Effect of patellar shaving in the rabbit

Shaving of the articular cartilage on the undersurface of the patella was carried out in mature white New Zealand rabbits to determine whether the removed cartilage reformed or the shaving led to later evidence of degenerative arthritis. The animals were followed for as long as 15 months after surgery, at which time patellae were removed and examined by light and electron microscopy. The depth of shaving varied considerably; however, no evidence of repair and no evidence of degenerative arthritis was noted in either the superficial or deeply shaved patellae. It is concluded that such superficial cartilage defects neither repair or produce subsequent degenerative arthritis.

An experimental study of the healing process of equine chondral and osteochondral defects

Four full thickness cartilage defects, two linear and two elliptical, and four subchondral cavity defects were created at the point of weightbearing of the medial femoral condyle in four experimental ponies. This study showed that subchondral bone cysts can develop following full thickness (cartilage only) linear cartilage defects at a weightbearing location. Subchondral bone cysts did not develop following the removal of an elliptical piece of cartilage, exposing the subchondral bone. Primary subchondral defects created in communication with the joint cavity did not heal by replacement with bone over a six-month period. Fibrous and cartilaginous repair occurred which appeared to be unrelated to the size or depth of the subchondral defect. Irrespective of the size of the defects, the surrounding bone showed marked woven bone formation with remodelling of existing and newly formed bone. The resulting osteosclerosis indicated a positive balance and a natural limitation of cavity expansion. The positive balance affected only the surrounding bone and did not lead to re-establishment of the bone within the cavity during the period studied.

Arthroscopic abrasion arthroplasty historical and pathologic perspective: present status

Arthroscopic abrasion arthroplasty is a modification of open Magnusson "housecleaning" arthroplasty. The arthroscopic approach decreases incision size enhancing postoperative rehabilitation. Arthroscopic techniques enhance the accuracy of diagnosis and provide accuracy of limiting debridement only to diseased tissue in various other dimensions of arthroplasty. The abrasion of a sclerotic lesion superficially removes dead bone, exposes vascularity providing a tissue bed for blood clot attachment. Postoperative joint protection provides an environment for clot organization and fibrous tissue formation. Subsequent fibrocartilage formation has maintained integrity for up to 6 years, the extent of experience. The clinical indication is pain. The patient benefit, therefore, is also subjective. Objective evidence of healing response is demonstrated by second-look arthroscopy, biopsy, and comparison x-ray films. If nothing else, these clinical and pathological observations have challenged "established concepts" and opened new vistas for investigation.

Meniscal remodeling following partial meniscectomy--an experimental study in the dog

The response of the meniscus to partial meniscectomy (in the avascular zone) was evaluated in 15 dogs. Following surgery 10 of the 15 dogs (67%) demonstrated a remodeling of the cut surface of the meniscus. This process appeared to begin with a fibrin clot which adhered to the meniscectomy surface. The organized clot was then populated by fibrocytes and eventually modulated into a fibrocartilage-like tissue by 12 weeks. The origin of the cells is unknown and may represent a migration of cells from the synovium, a proliferation of meniscal fibrochondrocytes, or both. The remodeling process appears to be associated with the presence of a fibrin clot, presumably from residual hemarthrosis. In those menisci that did not remodel [five of 15 (33%)], the meniscectomy surface remained relatively unchanged with no signs of progressive degeneration.

Fluid transport and mechanical properties of articular cartilage: a review

This review is aimed at unifying our understanding of cartilage viscoelastic properties in compression, in particular the role of compression-dependent permeability in controlling interstitial fluid flow and its contribution to the observed viscoelastic effects. During the previous decade, it was shown that compression causes the permeability of cartilage to drop in a functional manner described by k = ko exp (epsilon M) where ko and M were defined as intrinsic permeability parameters and epsilon is the dilatation of the solid matrix (epsilon = tr delta u). Since permeability is inversely related to the diffusive drag coefficient of relative fluid motion with respect to the porous solid matrix, the measured load-deformation response of the tissue must therefore also depend on the non-linearly permeable nature of the tissue. We have summarized in this review our understanding of this non-linear phenomenon. This understanding of these flow-dependent viscoelastic effects are put into the historical perspective of a comprehensive literature review of earlier attempts to model the compressive viscoelastic properties of articular cartilage.

Biosynthesis of sulfated proteoglycan in vitro by cells derived from human osteochondrophytic spurs of the femoral head

Cells derived from organ-explant culture of the cartilaginous component of osteochondrophytic spurs of human femoral heads were incubated with [35S]-sulfate in order to study sulfated proteoglycan biosynthesis in vitro. Secondary monolayer cultures incorporated [35S]-sulfate into macromolecules which were recovered in the bottom fraction (dA1) of a CsCl gradient after ultracentrifugation in associative buffer (0.5 M guanidine X HCl). The incorporated [35S]-sulfate in fraction dA1 from the culture medium eluted in two peaks with average partition coefficients (Kav) of 0.14 and 0.45 respectively, on Sepharose CL-2B eluted with dissociative buffer (4 M guanidine X HCl). A significant percentage of incorporated [35S]-sulfate was found in the medium dA4 fraction (44%). The Kav of this fraction on Sepharose CL-2B was 0.66 with a shoulder of incorporated [35S]-sulfate at Kav, 0.22. In contrast to the culture medium, cellular CsCl gradient fractions dA1-dA3 showed Kav's on Sepharose CL-2B ranging from 0.63-0.75. Cellular fraction dA4 was even more polydisperse. A dD1 fraction (proteoglycan monomer) prepared by CsCl ultracentrifugation in dissociative buffer of [35S]-sulfate labelled culture medium eluted with a Kav of 0.25 on Sepharose CL-2B identical to the Kav of bovine nasal cartilage A1D1 and human tissue osteophyte A1D1 chromatographed under identical conditions. Glycosaminoglycan analysis demonstrated significant amounts of chondroitin 6- and 4-sulfate in unfractionated culture medium and in those proteoglycan fractions generated from culture medium (dA1, dA2 and dD1). In contrast, cellular fractions dA1-dA3 and medium fraction dA4 were enriched in dermatan sulfate. The size of the [35S]-sulfated glycosaminoglycan chains analyzed by Sepharose CL-6B chromatography showed considerable polydispersity (Kav range, 0.29-0.52). The results of this study indicated that cells derived from the cartilaginous component of human osteophyte synthesized several distinct populations of sulfated proteoglycans. These results may reflect the heterogeneity of cells which grow out from osteophyte organ explants and become established in monolayer culture.

The reversibility of osteoarthritis: a review

Osteoarthritis, usually considered a wear and tear, or age-associated disease, is generally regarded as inexorably progressive once it has become clinically symptomatic. Enormous advances in the understanding of the normal cell biology of hyaline cartilage, synovium, and bone have led some to suspect that the process can be arrested, or even reversed. Some of the lines of evidence, both experimental and clinical, supporting this proposition, are presented in this paper. I first noted an apparent partial reversal of severe osteoarthritis of the hips in an 85-year-old man, as assessed by reappearance of hip joint spaces, when examined radiologically. The favorable change persisted until his death at age 92. Since then a number of similar cases have been observed, other types of evidence of reversibility examined, and an extensive study of the literature made. Five main areas are described: Modern and ancient concepts of osteoarthritis; myths and misconceptions; theories of etiology and pathogenesis; advances in basic knowledge of tissue involved and lines of evidence of arrest or reversibility derived from these advances; and an outline of practical, clinical management based on the cell biology of hyaline cartilage, synovium, and bone, especially subchondral bone. Aspirin is emphasized as the drug of choice and a method of administration is described.

Biosynthesis of proteoglycan in vitro by cartilage from human osteochondrophytic spurs

Proteoglycan biosynthesis by human osteochondrophytic spurs (osteophytes) obtained from osteoarthritic femoral heads at the time of surgical joint replacement was studied under defined culture conditions in vitro. Osteophytes were primarily present in two anatomic locations, marginal and epi-articular. Minced tissue slices were incubated in the presence of [(35)S]sulphate or [(14)C]glucosamine. Osteophytes incorporated both labelled precursors into proteoglycan, which was subsequently characterized by CsCl-isopycnic-density-gradient ultracentrifugation and chromatography on Sepharose CL-2B. The material extracted with 0.5m-guanidinium chloride showed 78.1% of [(35)S]sulphate in the A1 fraction after centrifugation. Only 23.0% of the [(35)S]sulphate in this A1 fraction was eluted in the void volume of Sepharose CL-2B under associative conditions. About 60-80% of the [(35)S]sulphate in the tissue 4m-guanidinium chloride extract was associated with monomeric proteoglycan (fraction D1). The average partition coefficient (K(av.)) of the proteoglycan monomer on Sepharose CL-2B was 0.28-0.33. Approx. 12.4% of this monomer formed stable aggregates with high-molecular-weight hyaluronic acid in vitro. Sepharose CL-2B chromatography of fractions with lower buoyant densities (fractions D2-D4) demonstrated elution profiles on Sepharose CL-2B substantially different than that of fraction D1, indicative of the polydisperse nature of the newly synthesized proteoglycan. Analysis of the composition and chain size of the glycosaminoglycans showed the following: (1) preferential elution of both [(35)S]sulphate and [(14)C]glucosamine in the 0.5m-LiCl fraction on DEAE-cellulose; (2) the predominant sulphated glycosaminoglycan was chondroitin 6-sulphate (60-70%), with 9-11% keratan sulphate in the monomer proteoglycan; (3) K(av.) values of 0.38 on Sephadex G-200 and 0.48 on Sepharose CL-6B were obtained with papain-digested and NaBH(4)-treated D1 monomer respectively. A comparison of the synthetic with endogenous glycosaminoglycans indicated similar types. These studies indicated that human osteophytes synthesized in vitro sulphated proteoglycans with some characteristics similar to those of mature human articular cartilage, notably in the size of their proteoglycan monomer and predominance of chondroitin 6-sulphate. They differed from articular cartilage primarily in the lack of substantial quantities of keratan sulphate and aggregation properties associated with monomer interaction with hyaluronic acid.

Review of the repair of defects in articular cartilage: part I *

A review of the literature was undertaken to determine the extent and nature of the repair of articular cartilage. While repair is normally limited, under appropriate conditions the repair process appears to be of clinical significance. J Orthop Sports Phys Ther 1982;3(4):186-192.

Long-term results of deep defects in articular cartilage. A scanning electron microscope study

Core defects produced in the medial femoral condyle of the rabbit were studied by scanning electron microscopy and light microscopy over a period of 2 years. In some cases the defect was filled by hyaline articular cartilage with a fairly smooth surface, but in others the tissue was markedly fibrillated and resembled fibrous tissue and fibrocartilage. Appearances suggesting disintegration of the newly formed cartilage were seen in some cases. It would appear that a continuation of this process can lead to the exposure of subchondral bone. In one instance no repair tissue or new cartilage could be identified but the surrounding old cartilage had formed a shelf over the defect. The cartilage surrounding the defect was either normal or showed superficial fibrillation, and/or flow formation, and/or fissures.

Sulphated glycosaminoglycan synthesis in normal and osteoarthrotic hip cartilage

The in vitro sulphated glycosaminoglycan metabolism and uronate content of human aged and osteoarthrotic hip articular cartilages have been examined. Cartilages were sampled from nonfibrillated weight-bearing areas and cultured in Dulbecco Modified Eagle's medium with 35SO4. Uptake of 35SO4 was corrected for total sulphate concentration and related to uronate levels after papain digestion and dialysis. The levels of uronate in these tissues varied between 0 - 96% and 2 - 26% dry weight and did not correlate with either osteoarthrotic grading or sulphated glycosaminoglycan metabolism, irrespective of the source. Glycosaminoglycan metabolism of intact hip articular cartilage from clinically defined osteoarthrotics appears, from these results, to be comparable to that derived from nonsymptomatic hip joints from individuals of similar age. Sodium salicylate was found to depress sulphated glycosaminoglycan metabolism in osteoarthrotic cartilage.

Platelet interaction with modified articular cartilage. Its possible relevance to joint repair

During studies concerned with the platelet-collagen interaction, it was observed that platelets did not adhere to bovine or human articular cartilage and that cartilage did not induce platelet aggregation in vivo or in vitro. To study the mechanism responsible for this observation, the role of proteoglycans was examined. Purified cartilage collagen proved to be fully active as a platelet aggregant. Addition of small amounts of proteoglycan subunit (PGS) blocked platelet aggregation, whereas chondroitin sulfate, a major glycosaminoglycan component of cartilage matrix, impaired platelet aggregation only at concentrations which resulted in a marked increase in viscosity. Moreover, PGS abolished aggregation of platelets by polylysine but did not prevent aggregation by ADP, suggesting that PGS may block strategically placed lysine sites on the collagen molecule. Treatment of fresh articular cartilage with proteolytic enzymes rendered the tissue active as a platelet aggregant. In vivo experiments demonstrated that surgical scarification of rabbit articular cartilage does not result in adhesion of autologous platelets. Treatment of rabbit knee joints with intraarticular trypsin 1 wk before the injection of blood resulted in adhesion and aggregation of platelets on the surface of the lesions. Since there is evidence from other studies that some degree of cartilage healing may take place after initiation of an inflammatory response, it is postulated that induction of platelet-cartilage interaction may eventuate in cartilage repair.

Effect of anti-inflammatory drugs on sulphated glycosaminoglycan synthesis in aged human articular cartilage

The anti-inflammatory drugs, sodium salicylate, indomethacin, hydrocortisone, ibuprofen, and flurbiprofen, were examined for their effects on sulphated glycosaminoglycan synthesis in aged human cartilage in vitro. Cartilage was obtained from femoral heads removed during surgery and drug effects were found to vary significantly from one head to another. Statistical analysis of the results showed that sodium salicylate exhibits concentration-dependent inhibition of glycosaminoglycan synthesis over the concentration range used. Indomethacin, hydrocortisone, and ibuprofen, at concentrations comparable to those attained in man, caused a statistically significant depression of sulphated glycosaminoglycan synthesis in cartilage from some femoral heads but not others, reflecting the variable response of human articular cartilage to anti-inflammatory drugs. Sodium salicylate and indomethacin at higher doses produced significant (Pless than 0-005) inhibition of sulphated glycosaminoglycan synthesis in all femoral heads studied. The results for flurbiprofen were less conclusive; this compound appears not to inhibit glycosaminoglycan synthesis over the concentration range used.

Evidence of cartilage flow in deep defects in articular cartilage

Full thickness defects (core defects) violating subchondral bone were created in the weight-bearing area of articular cartilage lining the rabbit medial femoral condyle. The repair reaction that follows has two components: (1) a sliding and flowing of cartilage over the edge of the defect and (2) a filling of the defect by repair tissue arising from the marrow spaces. Past studies have paid little or no attention to cartilage flow but this first scanning electron microscopic study of deep defects shows that it is an important phenomenon which materially affects the changes that occur and also the outcome of such injuries. Briefly, we have found that in most cases the cartilage flows downwards into the core defect. The repair tissue then grows along and over the "toed-in" catilage. In other cases the flowing cartilage rides over the repair tissue from the marrow spaces and as a result of load bearing and joint movement, becomes frayed and drawn out into long ribbons and rope-like structures.