René Lagier

An ultrastructural study of articular chondrocalcinosis in cases of knee osteoarthritis.

A study was made by transmission electron microscopy of tissue specimens (cartilage, meniscus and synovial membrane) taken from 5 knees presenting radiological and anatomical signs of articular chondrocalcinosis and osteoarthritis. It was part of a broader study which included analysis of the same specimens by macroscopy and light microscopy as well as by X-ray diffraction of the mineral deposits. In cartilage and meniscus juxta-cellular calcium pyrophosphate dihydrate (CPPD) crystals of variable sizes were observed in the extracellular organic matrix, independent of the collagen fibrils. They occured mainly in the superficial and middle zones but could also be seen intermingled with the apatite crystals in the cartilage calcified zone. In synovial membrane most of the CPPD crystals were extracellular but some of them could be seen in cytoplasmic phagocytic vacuoles. These observations are in agreement with those in the literature regarding the ultrastructural picture of chondrocalcinosis and support the thesis that the crystals originate in the cartilage and are phagocytized in the synovial membrane. Although the results of the present study do not provide direct evidence of a relationship between chondrocalcinosis and osteoarthritis, the data of the ultrastructural investigation appear nevertheless of great interest as a complement to the data furnished by light microscopy.

Value of the bone biopsy in the diagnosis of industrial fluorosis.

Iliac crest biopsies taken from 43 men with industrial fluorosis were compared with control bone samples. The bone fluoride content was determined, histological examinations were made on stained sections and microradiographs, and morphometric analysis performed on the microradiographs alone. In the subjects with fluorosis, the bone fluoride content (5617±2143 ppm) was found to be significantly higher (P<0.00005) than in control subjects (1036±627 ppm). It decreased slowly, however, after exposure had ceased (to about 50% in 20 years). The histological changes consisted of a nonspecific remodeling activity (resulting in increased trabecular bone volume and cortical porosity, as well as hypervascularization and linear formation defects) and modifications of the perilacunar walls (i.e., presence of mottled lacunae and enlarged lacunae). These histological changes were found more likely to occur when the bone fluoride content was high but no correlation between the two parameters was observed. Although certain clinical and radiological data associated with a high urine fluoride content can sometimes establish a diagnosis of skeletal fluorosis, many cases require the use of bone biopsy, which also provides a direct evaluation of the bone fluoride content and can establish the absence of any other bone disease.

Hip arthropathy in ochronosis: Anatomical and radiological study

Anatomical and radiological studies of four cases of ochronotic arthropathy of the hip were based on the examination of a total of six surgically removed femoral heads. One of these had undergone a surgical biopsy 10 years previously.The impregnation of the articular cartilage by the ochronotic pigment causes it to break into small fragments in the weight-bearing zone. This results in a similar osteoarthrotic remodelling to that commonly attributed to the histologically different “degenerative chondropathy”.The labelling of the cartilage in ochronotic arthropathies offers an opportunity for better understanding of the main nonspecific components of osteoarthrotic remodelling. An anatomico-pathological approach explains why their radiological images in the hip may simulate those of rheumatoid arthritis.

Pathology of “knuckle pads”

Histological study of four cases of knuckle pads. — The main lesion is a fibroblastic proliferation which developes into dense fibrosis. It is analogous to that found in Dupuytrens contracture or Ledderhoses disease, with which knuckle pads are often associated. This histological feature and the clinical characteristics suggest a nosological entity of nodules situated at the back of the fingers, as a distinct form of fibromatoses and help to delineate knuckle pads from an abarticular manifestation of inflammatory or degenerative rheumatism.

The concept of osteoarthrotic remodelling as illustrated by ochronotic arthropathy of the hip

This report is an anatomico-radiological study of six femoral heads excised from four patients with diffused ochronotic arthropathy. In one case a biopsy specimen taken eleven years earlier was also studied. The deterioration of the ochronotic cartilage involves a fragmentation process reflected by histological characteristics that are different from those observed in common “cartilaginous degeneration”. The fragments resulting from this process become embedded in the remodelled bone-marrow tissue of the weight-bearing zone and in the synovial membrane. Except for the presence of pigmented cartilage, the intrinsic osteogenic remodelling and the extrinsic osteophytic remodelling (the latter often appearing in the form of minor equivalents) are similar to that of the common form of osteoarthrotic remodelling. The pigment labelling of the ochronotic cartilage provides a particularly favorable opportunity to study the general problem of osteoarthrotic remodelling; it facilitates the differentiation between newly formed and preexisting tissue and consequently our understanding of the entire process. An anatomico-radiological approach provides an explanation for the similarity frequently observed on X-rays between ochronotic and rheumatoid hip arthropathies.

Phagocytosis of chromium during patellar osteoarthritic remodelling associated with a knee prosthesis.

The report is of an anatomico-pathological and electron probe microanalyzer study of a patella with osteoarthritic remodelling, that had been in contact with a cast cobalt-chromium-molybdenum prosthesis for two years and seven months. Abrasion of the metal resulted in preferential phagocytosis of chromium, principally in the wall of an osteoarthritis cyst. This observation indicates that a substance administered by intra-articular pathway for the treatment of osteoarthritis can become phagocytosed, and quite deeply, in the remodelled bone.

Osteoarthrosis and apatite synovitis. Pathological study of a metacarpophalangeal joint.

A case of metacarpophalangeal osteoarthrosis associated with synovial apatite deposits is reported. The size of the crystals indicates that they have been thickened by a recrystallisation process; the latter could have been provoked by Ca and Po4 ions released by dissolution of some apatite crystals brought by calcified debris of bone or cartilage coming from the abraded osteoarthrotic surfaces. The role of such thickened crystals in synovial inflammation is discussed as well as their possible diagnostic value in determining origin and pathogenesis of a given synovial apatite deposit.

Rare femoral erosions and osteoarthrosis of the knee associated with chondrocalcinosis. A histological study of this cortical remodelling.

An anatomo-pathological study of four cases of cortical erosions of the femur, radiologically similar to certain cases described in the literature.—These should be considered as a marginal erosive feature of femoropatellar osteoarthrotic remodelling.—The relation of these lesions to a possible nosological entity of “polyarthrosis+chondrocalcinosis” is discussed.

Case report 591

It has been demonstrated in this 58-year old woman that osteoarthrosis OA coexisted in a hip with microscopic gouty tophi. It is demonstrated that the bone erosions around the hip in this case were due to OA and not gouty arthritis. It is believed that OA is not a consequence of gout and that such an association between gout and OA is exceptional. It is maintained that a true association exists between OA and ochronosis while a relationship may exist between OA and chondrocalcinosis, but the nature of this relationship is not clear.

Histological study of a case of recurrent olecranon bursitis with mixed calcium pyrophosphate dihydrate and apatite crystal deposits

This is the report of a light and transmission electron microscopic study of an olecranon bursitis and of the adjacent distal tricipital tendon in an 83 year-old man. The data are compared with those of a similar study in the same patient performed 2 years ago. Calcium pyrophosphate dihydrate crystals were observed in the bursal fluid, in the inner part of the bursal wall (extracellular localization and intracellular phagocytosis) as well as in the peripheral part of the tendon. In addition, small apatite deposits were observed in the bursa and tendon by electron microscopy. The origin of these bursal deposits is discussed; it is suggested that they may be related to an exchange from the tendon to the remodelled bursal wall.