Biochemical changes in the articular cartilage of the knees of mature dogs, one with natural and four with surgically induced osteoarthritis, have been investigated. The four dogs were killed three, six, nine and forty-eight weeks after division of the right anterior cruciate ligament, the left knees serving as controls. The cartilage of the joints operated on was thicker and more hydrated than the control cartilage; the proteoglycans were more easily extracted and had higher galactosamine/glucosamine molar ratios. The proportion of proteoglycans firmly associated with collagen, and hence not extractable, diminished before fibrillation was demonstrable by indian ink staining of the surface. These biochemical changes were present throughout the entire cartilage of the joints operated on of the dogs killed more than three weeks later, and of the dog with natural osteoarthritis. The results suggest that in response to altered mechanical stresses the chondrocytes synthesise proteoglycans that contain more chondroitin sulphate relative to keratin sulphate than normally, as in immature articular cartilage

We obtained specimens of growth-plate cartilage from four patients with osteogenesis imperfecta. Light microscopy showed structural changes in the tissue and morphological changes in chondrocytes and matrix, particularly in the hypertrophic zone. There were changes in the process of calcification in the primary mineralisation zone of the cartilage. We also found histochemical changes in the matrix glycosaminoglycans (GAGs) in the zones where physiological mineralisation was disturbed and where the trabeculae were interrupted and poorly mineralised. In addition to the known molecular defects in collagen, changes in GAGs and non-collagenous proteins are important factors in the pathogenesis of the disease

We report the finding of sodium- and phosphorus-based crystallisation in abnormal human articular cartilage. We prepared five chondromalacic, five osteoarthritic and four macroscopically normal specimens of patellar cartilage by a cryofracturing technique and examined them in a scanning electron microscope. An energy-dispersive X-ray microanalysis system was used to identify the crystals, which were found in only three of the five chondromalacic specimens. Star-shaped crystals were seen either individually or in clusters in the matrix of the cartilage. They consisted of sodium and phosphorus, and we have found no previous reports of such findings. The calcified zone, the bone, and the articular surface were free from crystals

1. Decalcified lyophilised rat bone matrix prepared by Urist's method acts as an inductor of cartilage and bone when implanted into animals of other species, namely mice, rabbits and gerbils. Induction in rabbits and gerbils was very much weaker than in the mouse. 2. The site of implantation affected the outcome; intramuscular implants induced cartilage and bone more strongly and regularly than subcutaneous or intraperitoneal implants. 3. Rabbit transitional epithelium, growing in cortisone-treated gerbils, caused bone induction, but in general, results with this species suggest that it responds poorly to bone-inducing stimuli. 4. Cortisone, used as an immunosuppressant, did not inhibit bone and cartilage induction

on in vitro incubation of articular and epiphysial cartilage of the ulna of the domestic pig 70 to 80 per cent of [U-. 14. C] glucose was metabolised to . 14. C-lactate, but cartilage of the epiphysial plate produced up to five times as much . 14. C-CO. 2. as articular cartilage, and the specific radioactivity of . 14. C (or . 35. S)-chondroitin 4 (6)-sulphate isolated from epiphysial cartilage (following . 35. S-sulphate incorporation) was about twice as high as that of articular cartilage. Six weeks after an osteotomy on both sides of the proximal epiphysial plate of the left ulna, the glucose uptake, lactate production, and the specific radioactivity of the glycosaminoglycans displayed no significant differences when compared with those of the corresponding epiphysial plate of the control right ulna, whereas a 50 per cent increase in the oxidation of . 14. C-glucose to . 14. c-co. 2. was observed

The role of three genetically distinct collagen types in the formation of endochondral bone and in calcification and resorption of cartilage has been assessed. Using antibodies specific to types I, II and III collagen we have demonstrated in the embryonic chick tibia that endochondral bone formation began with deposition of type III collagen in lacunae of hypertropic chondrocytes by invading bone-marrow-derived cells. This was followed by the deposition of type I collagen, which is the collagenous constituent of endochondral osteoid. At later stages of development endochondral osteoid was found in the epiphysial growth plate in apparently intact lacunae of hypertrophic chondrocytes; this indicated that the latter might contribute to the synthesis of osteoid type I collagen. Immuno-histological staining for collagen types, and von Kossa staining for calcium phosphate on parallel sections, demonstrated that type I and type II collagen matrices were substrates for calcification. Endochondral bone (with type I collagen) was found on scaffolding of both uncalcified and calcified cartilage (with type II collagen), indicating that calcification of endochondral osteoid and of the underlying cartilage occurred independentyl. Spicules of endochondral cancellous bone of a four-week-old chick contained a core of calcified type II collagen

1. It has been shown that in experimental rickets the well known changes in the epiphysial cartilage which so seriously affect growth are accompanied by severe interference with the progress of the metaphysial vessels into the growth cartilage. 2. Further evidence has been found that, by the repeated increase in their number, the cartilage cells occupying the more distal part of the proliferative segment become more and more affected by their remoteness from the epiphysial vessels, which supply the transudates to these cells. At a given distance these cells are affected and change, becoming hypertrophic, with increasingly large vacuolae, and are rich in glycogen and alkaline phosphatase. 3. The hypertrophic cells alter the nature of the intercellular substance they deposit and this becomes calcifiable. Provided that the metaphysial vessels are situated at an appropriate distance–about three cell capsules away–and that the blood has its necessary components, calcification occurs. 4. Calcification produces the advancing, rigid multitubular structure within which the progressing metaphysial vessels are protected. 5. The interruption of calcification by the withdrawal of fat-soluble vitamins breaks down the whole mechanism of growth and stops the vessels growing into their proper position. The administration of the required vitamins re-establishes the normal sequence of events and allows the vessels to play their decisive role in osteogenesis. 6. Any mechanism which causes the interruption of the vascular progression, whether from metaphysial ischaemia (Trueta and Amato 1960), from severe pressure (Trueta and Trias 1961) or from lack of calcification by withdrawing the fat-soluble vitamins, equally interrupts growth

Multipotential processed lipoaspirate (PLA) cells extracted from five human infrapatellar fat pads and embedded into fibrin glue nodules, were induced into the chondrogenic phenotype using chondrogenic media. The remaining cells were placed in osteogenic media and were transfected with an adenovirus carrying the cDNA for bone morphogenetic protein-2 (BMP-2). We evaluated the tissue-engineered cartilage and bone using in vitro techniques and by placing cells into the hind legs of five severe combined immunodeficient mice. After six weeks, radiological and histological analysis indicated that the PLA cells induced into the chondrogenic phenotype had the histological appearance of hyaline cartilage. Cells transfected with the BMP-2 gene media produced abundant bone, which was beginning to establish a marrow cavity. Tissue-engineered cartilage and bone from infrapatellar fat pads may prove to be useful for the treatment of osteochondral defects

In 16 mature New Zealand white rabbits mesenchymal stem cells were aspirated from the bone marrow, cultured in monolayer and implanted on to a full-thickness osteochondral defect artificially made on the patellar groove of the same rabbit. A further 13 rabbits served as a control group. The rabbits were killed after 14 weeks. Healing of the defect was investigated histologically using haematoxylin and eosin and Safranin-O staining and with immunohistochemical staining for type-II collagen. We also used a reverse transcription-polymerase chain reaction (RT-PCR) to detect mRNA of type-I and type-II collagen. The semiquantitative histological scores were significantly higher in the experimental group than in the control group (p < 0.05). In the experimental group immunohistochemical staining on newly formed cartilage was more intense for type-II collagen in the matrix and RT-PCR from regenerated cartilage detected mRNA for type-II collagen in mature chondrocytes. These findings suggest that repair of cartilage defects can be enhanced by the implantation of cultured mesenchymal stem cells

Cartilage formation was provoked in the skull vault of the young rat by making multiple incisions, and scraping the periosteum to reduce the blood supply to the injured area. The hypothesis that ischaemia induces osteogenic cells to produce cartilage in the course of fracture repair thus receives experimental support

Premature fusion of the triradiate cartilage was obtained surgically in 10 three-week-old rabbits, and compared with isolated fusion of the ilio-ischial and of the ilio-pubic limbs of the triradiate cartilage in two further groups of 10 rabbits. Complete fusion caused acetabular dysplasia five weeks after operation in all animals and hip dislocation at nine weeks in half of them; ilio-ischial fusion had a comparable effect. Ilio-pubic fusion had only a minimal effect on acetabular development. The posterior position of the ilio-ischial limb in the acetabulum and its predominance in the formation of the triradiate cartilage in quadrupeds may have contributed to its decisive effect on acetabular development

1. The occurrence of congenital discoid medial cartilages in two patients is reported: in one the abnormality was bilateral. The three specimens are described and illustrated. 2. The literature on the subject is reviewed and the specimens discussed and classified

We investigated the clinical, arthroscopic and biomechanical outcome of transplanting autologous chondrocytes, cultured in atelocollagen gel, for the treatment of full-thickness defects of cartilage in 28 knees (26 patients) over a minimum period of 25 months. Transplantation eliminated locking of the knee and reduced pain and swelling in all patients. The mean Lysholm score improved significantly. Arthroscopic assessment indicated that 26 knees (93%) had a good or excellent outcome. There were few adverse features, except for marked hypertrophy of the graft in three knees, partial detachment of the periosteum in three and partial ossification of the graft in one. Biomechanical tests revealed that the transplants had acquired a hardness similar to that of the surrounding cartilage. We conclude that transplanting chondrocytes in a newly-formed matrix of atelocollagen gel can promote restoration of the articular cartilage of the knee

Twenty-five patients with 30 chondral lesions of the knee were treated with an autogenous strip of costal perichondrium. The graft was fixed to the subchondral bone with Tissucol (Immuno, Vienna), a human fibrin glue. The leg was then immobilised for two weeks followed by two weeks of continuous passive motion. Weight-bearing was permitted after three months. The mean knee score (Ranawat, Insall and Shine 1976) changed from 73 before operation to 90 one year after; in 14 patients evaluated after two years there was no decrease. In 28 cases the defect was completely filled with tissue resembling articular cartilage. We conclude that in most cases perichondral arthroplasty of cartilage defects of the knee gives excellent results

1. The source of nutrition of articular cartilage still remains a subject of controversy. 2. Experiments are described in which an attempt to demonstrate the direct transfer of fluid from the subchondral bone has been made using 355 and an autoradiographic technique. These experiments were based on ones originally performed by Ekholm (1951), except that two distinct groups of animals were used : immature rabbits and adult rabbits whose skeletons were mature. 3. The transfer of fluid to the cartilage could be demonstrated only in the immature rabbits. 4. It is suggested that some of the conflicting opinions which have been advanced on this subject stem from a failure to distinguish between mature and immature joint cartilage. Subchondral nutrition is a feature only of the immature animal

The management of failed autologous chondrocyte implantation (ACI) and matrix-assisted autologous chondrocyte implantation (MACI) for the treatment of symptomatic osteochondral defects in the knee represents a major challenge. Patients are young, active and usually unsuitable for prosthetic replacement. This study reports the results in patients who underwent revision cartilage transplantation of their original ACI/MACI graft for clinical or graft-related failure. We assessed 22 patients (12 men and 10 women) with a mean age of 37.4 years (18 to 48) at a mean of 5.4 years (1.3 to 10.9). The mean period between primary and revision grafting was 46.1 months (7 to 89). The mean defect size was 446.6 mm. 2. (150 to 875) and they were located on 11 medial and two lateral femoral condyles, eight patellae and one trochlea. . The mean modified Cincinnati knee score improved from 40.5 (16 to 77) pre-operatively to 64.9 (8 to 94) at their most recent review (p < 0.001). The visual analogue pain score improved from 6.1 (3 to 9) to 4.7 (0 to 10) (p = 0.042). A total of 14 patients (63%) reported an ‘excellent’ (n = 6) or ‘good’ (n = 8) clinical outcome, 5 ‘fair’ and one ‘poor’ outcome. Two patients underwent patellofemoral joint replacement. This study demonstrates that revision cartilage transplantation after primary ACI and MACI can yield acceptable functional results and continue to preserve the joint. Cite this article: Bone Joint J 2014;96-B:54–8

We have compared the concentrations of stromal-cell-derived factor-1 (SDF-1), matrix metalloproteinase-1 (MMP-1), MMP-9 and MMP-13 in serum before and after synovectomy or total knee replacement (TKR). We confirmed the presence of SDF-1 and its receptor CXCR4 in the synovium and articular cartilage by immunohistochemistry. We established chondrocytes by using mutant CXCR4 to block the release of MMPs. The level of SDF-1 was decreased 5.1- and 6.7-fold in the serum of patients with OA and RA respectively, after synovectomy compared with that before surgery. MMP-9 and MMP-13 were decreased in patients with OA and RA after synovectomy. We detected SDF-1 in the synovium and the bone marrow but not in cartilage. CXCR4 was detected in articular cartilage. SDF-1 increased the release of MMP-9 and MMP-13 from chondrocytes in a dose-dependent manner. The mutant CXCR4 blocked the release of MMP-9 and MMP-13 from chondrocytes by retrovirus vector. Synovectomy is effective in patients with OA or RA because SDF-1, which can regulate the release of MMP-9 and MMP-13 from articular chondrocytes for breakdown of cartilage, is removed by the operation

We report the experimental use of three different biological implants to restore articular surface defects: glutaraldehyde-fixed bovine meniscal xenograft, glutaraldehyde-fixed bovine costal cartilage xenograft, and viable osteochondral allografts. The grafts were implanted in the knees of 19 goats who were allowed free-field activity and were studied for up to one year. The natural articular surfaces of meniscal fibrocartilage provided excellent articular surfaces at all times. Equally good articular surfaces were restored by host tissue growth covering costal cartilage grafts at six months, but by 12 months this surface had degenerated. The majority of the allografts survived and integrated with the host at six months, but many showed signs of failure at 12 months. Only three out of seven ungrafted defects healed completely at six months and the healed surfaces were degenerating at 12 months

Allografts of intact cartilage, isolated chondrocytes and cultured chondrocytes taken from the epiphysial growth-plate and from the articular surface of immature rabbits were inserted into full thickness defects in the tibial articular surface of 160 mature rabbits. In the contralateral knees, which were used as controls, similar defects were made but no grafts were inserted. Grafts were followed up for periods of up to one year after transplantation. Both intact articular and intact growth-plate grafts produced significantly better repair than that seen in control ungrafted defects in normal joints (P less than 0.01 and P less than 0.05 respectively) and in arthritic joints (P less than 0.01). Cultured chondrocytes cut to a precise fit also produced significantly better repair than ungrafted defects in arthritic joints (P less than 0.05)

1. Human articular cartilage from normal femoral heads and from cases of osteoarthrosis in subjects of various ages has been examined histologically and by electron microscopy. 2. In specimens from middle-aged and old subjects, peculiar "matrix-streaks" have been observed in the deep zone of the pressure areas as oblique bands extending from the pericellubar halos into the adjacent matrix. 3. Ultrastructurally the streaks are correlated with an undulating pattern of the radially oriented collagen fibres. 4. The streaks are considered to result from a focal lack of acid mucopolysaccharide and from natural forces on the articular cartilage. Their appearance is assumed to be an early sign of cartilage disintegration associated with ageing