A case of calcification of articular cartilage in association with a parathyroid tumour is described. Previously reported cases of articular calcification are briefly discussed, and it is recommended that patients with articular calcification of undetermined cause should be investigated for hyperparathyroidism

1. Idiopathic calcification of articular cartilages is described in a Jamaican woman of thirty-one years who had intermittent joint pains for ten years and who had evidence of past gonococcal infection. She was otherwise normal. 2. The etiology of the condition is unknown. 3. Previous literature is reviewed

Subtotal synovectomy was performed in the knee joints of New Zealand white rabbits. The changes noted in the articular cartilage as manifest by decreased metachromatic staining of the matrix were considered to indicate matrix degradation caused by the altered joint environment. The documentation of the enzyme changes suggests that the histological alteration in the articular cartilage noted after synovectomy may be mediated through the activation of endogenous chondrocyte lysozomal enzymes, particularly cathepsin and acid hydrolases

Tissue engineering is an increasingly popular method of addressing pathological disorders of cartilage. Recent studies have demonstrated its clinical efficacy, but there is little information on the structural organisation and biochemical composition of the repair tissue and its relation to the adjacent normal tissue. We therefore analysed by polarised light microscopy and immunohistochemistry biopsies of repair tissue which had been taken 12 months after implantation of autologous chondrocytes in two patients with defects of articular cartilage. Our findings showed zonal heterogeneity throughout the repair tissue. The deeper zone resembled hyaline-like articular cartilage whereas the upper zone was more fibrocartilaginous. The results indicate that within 12 months autologous chondrocyte implantation successfully produces replacement cartilage tissue, a major part of which resembles normal hyaline cartilage

1. The surface of mature adult human articular cartilage from the knee has been studied by electron microscopy in eleven patients ranging in age from thirty-seven to eighty-three years. The ultrastructural appearance varies from person to person and often from area to area in the same specimen. These variations range from an intact surface to one showing overt fibrillation visible with the light microscope. 2. In areas where the articular surface appears intact the underlying superficial matrix consists of closely packed collagen fibres with only a small amount of interfibrillary ground substance. The collagen fibres show a predominantly tangential orientation in this region of the cartilage. Osmophilic lipidic bodies are sometimes seen in the matrix very close to the joint surface. 3. The appearances under the electron microscope are altered in what is interpreted as an early ultrastructural change in the development of cartilage fibrillation. In the affected areas the collagen fibres show abnormally wide separation by an excessive amount of interfibrillary matrix. Collagen fibres become directly exposed to the joint cavity, and the surface can also show accumulations of finely granular material and sometimes tuft-like projections containing collagen fibres and fine fibrils. At a slightly later stage shallow clefts and steeply sloping curves are apparent at the surface. It is suggested that these various alterations precede the development of overt fibrillation visible under the light microscope. 4. Electron micrographs occasionally show small "blisters" at the articular surface. Electron microscopy has not given evidence of shedding of cells into the joint cavity from non-fibrillated areas of adult human articular cartilage. Cells can, however, sometimes become exposed at the surface in fibrillated areas

Acetabular dysplasia was produced in 24 immature white rabbits. A rotational acetabular osteotomy was then carried out and radiological and histological studies of the articular cartilage were made. In the hips which did not undergo osteotomy, radiographs at 26 weeks showed that residual subluxation remained and arthritic changes such as narrowing of the joint space or dislocation were still seen. However, in the operated group there was a remarkable increase in cover, but arthritic changes were not observed. After 24 weeks, the Mankin grading score in the operated group was significantly lower than that in the non-operated group. The latter hips showed an irregular surface of the cartilage, exfoliation and proliferation of synovial tissue. In those undergoing osteotomy, primary cloning of chondrocytes or hypercellularity was seen and at 24 weeks after operation and metaplasia of the cartilage in the fibrous tissue was observed in the boundary between the medial area of the acetabulum and the acetabular fossa

Biochemical and histochemical studies have indicated that there is specific cellular activity in the region of the calcification front of articular cartilage implying that a regulation process takes place there. Using scanning and transmission electron microscopy and light microscopy to examine tissue sections of both undecalcified and decalcified articular cartilage in the region of the calcification front, we have looked at its morphology with particular reference to its cellular control. Our observations show that physiological calcification is an active process under cellular control and is related to the presence of extracellular membrane-bound matrix vesicles

1. Sixteen patients with articular cartilage erosions after slight injury have been described, as have the results of their treatment. 2. The clinical features of this rarely diagnosed condition are discussed. Attention is drawn to "articular crepitus" and "synovial crepitus" as useful physical signs in establishing the diagnosis. 3. A radiographic sign of localised subarticular osteoporosis is reported and discussed. 4. The surgical treatment used was either shaving of the affected area of cartilage or a combination of shaving with drilling of the subchondral bone plate

Desiccation of articular cartilage during surgery is often unavoidable and may result in the death of chondrocytes, with subsequent joint degeneration. This study was undertaken to determine the extent of chondrocyte death caused by exposure to air and to ascertain whether regular rewetting of cartilage could decrease cell death. Macroscopically normal human cartilage was exposed to air for 0, 30, 60 or 120 minutes. Selected samples were wetted in lactated Ringer’s solution for ten seconds every ten or 20 minutes. The viability of chondrocytes was measured after three days by Live/Dead staining. Chondrocyte death correlated with the length of exposure to air and the depth of the cartilage. Drying for 120 minutes caused extensive cell death mainly in the superficial 500 μm of cartilage. Rewetting every ten or 20 minutes significantly decreased cell death. The superficial zone is most susceptible to desiccation. Loss of superficial chondrocytes likely decreases the production of essential lubricating glycoproteins and contributes to subsequent degeneration. Frequent wetting of cartilage during arthrotomy is therefore essential

Seventy-six knees with fracture-separations of articular cartilage are described. The lesion involved the full thickness of the articular surface with exposed subchondral bone in 28 knees and only part of the thickness in 48. The clinical features and distribution of the lesions within the knee are described

Objectives. The purpose of this study was to clarify the appearance of the reparative tissue on the articular surface and to analyse the properties of the reparative tissue after hemicallotasis osteotomy (HCO) using MRI T1ρ and T2 mapping. Methods. Coronal T1ρ and T2 mapping and three-dimensional gradient-echo images were obtained from 20 subjects with medial knee osteoarthritis. We set the regions of interest (ROIs) on the full-thickness cartilage of the medial femoral condyle (MFC) and medial tibial plateau (MTP) of the knee and measured the cartilage thickness (mm) and T1ρ and T2 relaxation times (ms). Statistical analysis of time-dependent changes in the cartilage thickness and the T1ρ and T2 relaxation times was performed using one-way analysis of variance, and Scheffe’s test was employed for post hoc multiple comparison. Results. The cartilage-like repair tissue appeared on the cartilage surface of the medial compartment post-operatively, and the cartilage thickness showed a significant increase between the pre-operative and one-year post-operative time points (MFC; p = 0.003, MTP; p < 0.001). The T1ρ values of the cartilage-like repair tissue showed no difference over time, however, the T2 values showed a significant decrease between the pre-operative and one-year post-operative time points (MFC; p = 0.004, MTP; p = 0.040). Conclusion. This study clarified that the fibrocartilage-like repair tissue appeared on the articular surface of the medial compartment after HCO as evidenced by MRI T1ρ and T2 mapping. Cite this article: H. Nishioka, E. Nakamura, J. Hirose, N. Okamoto, S. Yamabe, H. Mizuta. MRI T1ρ and T2 mapping for the assessment of articular cartilage changes in patients with medial knee osteoarthritis after hemicallotasis osteotomy. Bone Joint Res 2016;5:294–300. DOI: 10.1302/2046-3758.57.BJR-2016-0057.R1

We attempted to repair full-thickness defects in the articular cartilage of the trochlear groove of the femur in 30 rabbit knee joints using allogenic cultured chondrocytes embedded in a collagen gel. The repaired tissues were examined at 2, 4, 8, 12 and 24 weeks after operation using histological and histochemical methods. The articular defect filling index measurement was derived from safranin-O stained sections. Apoptotic cellular fractions were derived from analysis of apoptosis in situ using TUNEL staining, and was confirmed using caspase-3 staining along with quantification of the total cellularity. The mean articular defect filling index decreased with time. After 24 weeks it was 0.7 (. sd. 0.10), which was significantly lower than the measurements obtained earlier (p < 0.01). The highest mean percentage of apoptotic cells were observed at 12 weeks, although the total cellularity decreased with time. Because apoptotic cell death may play a role in delamination after chondrocyte transplantation, anti-apoptotic gene therapy may protect transplanted chondrocytes from apoptosis

Hemiarthroplasty of the hip and some other joints has been used for many years with satisfactory results, but the fate of articular cartilage when weight-bearing against metal has not been reported. Replacement of the head of the femur was carried out in one hip of each of 26 dogs, and the changes in acetabular cartilage studied at intervals of up to 24 weeks. There was early loss of proteoglycan, followed by surface damage to the cartilage, progressive degenerative changes, and growth of pannus from the articular margins. At 24 weeks after operation there was little remaining articular cartilage, while intense subchondral activity suggested that the bony skeleton was being remodelled to conform to the shape of the prosthesis. This study is not intended to suggest that hemiarthroplasty does not help patients

The effects on articular cartilage of continuous and intermittent excessive pressures have been studied in the knees of rabbits. Severe degenerative changes in the cartilage were observed; these resembled the typical lesions seen in osteoarthritis in man. They included fibrillation of cartilage, death of chondrocytes, eburnation of joint surfaces, sclerosis of bone and the production of "bone cysts." Regeneration of cartilage was common and it was brought about either by the deeply situated chondrocytes which had escaped death or by metaplasia of young connective tissue cells of the bone marrow

Full thickness samples of articular cartilage were removed from areas of chondromalacia on the medial and "odd" facets of the patellae of 21 adults and examined by histology, autoradiography and electron microscopy. Surface fibrillation, loss of superficial matrix staining and reduced 35SO4 labelling was seen, with little change in the deep zone. Ten cases showed "fibrous metaplasia" of the superficial cartilage with definite evidence of cell division and apparent smoothing of the surface. Scattered chondrocyte replication appeared to occur in the surrounding intact cartilage. The findings suggest that early lesions in chondromalacia patellae may heal either by cartilage or fibrous metaplasia and that this may account for the resolution of clinical symptoms

Little is known of the effects of synovectomy on articular cartilage. In order to investigate this matter, anterior synovectomy of the knee was performed in thirty-five normal adult rabbits and in thirty-five which were given 25 milligrams of hydrocortisone intramuscularly each week afterwards. The animals were killed at intervals from four to 110 days after synovectomy. Histological examination of the regenerating synovium in both groups showed complete structural and functional regeneration by eighty days in the first group and a delay in regeneration in the steroid group. . 35. Sulphur autoradiographs of the articular cartilage of femoral and tibial condyles revealed surface fibrillation and chondrocyte death in 23 per cent of normal knees after eighty days but only 1·8 per cent of knees of animals receiving hydrocortisone. Thus synovectomy in a healthy joint may have an unfavourable effect on the physiology of cartilage by alteration of synovial composition and hyaluronate content in normal joints. Systemically-administered hydrocortisone may reduce this harmful effect in normal cartilage

1. The lines of fracture confirm the suggestions of earlier authors on the lines of strength in cartilage, with the additional feature of a transverse plane of weakness at the apex of the calcified zone. 2. The normal nutrition of cartilage is synovial, and access of a free blood supply is followed by destruction of hyaline articular cartilage. 3. Minor traumatic events in the articular lamella are common, particularly in osteoarthritic joints; the results of these on the cartilage are like the changes of osteoarthritis. 4. The removal of uncalcified cartilage can be described in two stages of a physico-chemical kind; the removal of calcified cartilage is a single cellular process. 5. There is evidence that the carbohydrate moiety of cartilage is present in two separable phases, one fixed to collagen, the other free. 6. The repair mechanisms after fracture are those available to restore the damage of osteoarthritis, and reasons can be shown why in fact they are ineffective

Autologous chondrocyte implantation (ACI) and mosaicplasty are methods of treating symptomatic articular cartilage defects in the knee. This study represents the first long-term randomised comparison of the two techniques in 100 patients at a minimum follow-up of ten years. The mean age of the patients at the time of surgery was 31.3 years (16 to 49); the mean duration of symptoms pre-operatively was 7.2 years (9 months to 20 years). The lesions were large with the mean size for the ACI group being 440.9 mm. 2 . (100 to 1050) and the mosaicplasty group being 399.6 mm. 2. (100 to 2000). Patients had a mean of 1.5 previous operations (0 to 4) to the articular cartilage defect. Patients were assessed using the modified Cincinnati knee score and the Stanmore-Bentley Functional Rating system. The number of patients whose repair had failed at ten years was ten of 58 (17%) in the ACI group and 23 of 42 (55%) in the mosaicplasty group (p < 0.001). The functional outcome of those patients with a surviving graft was significantly better in patients who underwent ACI compared with mosaicplasty (p = 0.02)

The thickness of the calcified zone of the articular cartilage and the number of tidemarks at the junction between articular cartilage and bone has been determined in specimens from 41 femoral heads and 42 humeral heads from cadavers aged between 25 and 93. The thickness of the calcified zone decreased with age but the number of tidemarks increased, particularly over the age of 60. These observations suggest that remodelling of the bone ends occurs and that this process is accelerated with increasing age

1. The age changes in the articular cartilage of the elbow joint are presented from a study of twenty-eight necropsy subjects aged eighteen to eighty-eight years. During early adult life those areas of cartilage which do not usually articulate with opposed cartilage always show some degree of chondromalacia. 2. Evidence is presented that the almost inevitable degeneration of the radio-humeral joint in old age is related to the combination of rotation and hinge movements that occur at that joint. This is in marked contrast with the relative immunity of the humero-ulnar articulation which has hinge movement only