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Primary hyperoxaluria (PH) type 1 and type 2 are autosomal recessive defects of oxalate metabolism resulting from glyoxylate accumulation which occurs by two distinct pathways. PH1 is associated to glycolic aciduria; PH2 to L-glyceric aciduria. Because hyperoxaluria leads to nephrolithiasis or nephrocalcinosis in both, they can be differentiated only through detection of the associated acidurias. However, glycolate and L-glycerate assays are not widely available and, in the setting of ESRF, diagnosis is hampered by a number of misleading events. At any stage of the disease diagnosis is crucial because there are differences between the two forms in clinical behaviour, long-term prognosis, and treatment. In this paper we outline diagnostic criteria for identification of PH2 in two patients, one with maintained renal function and one with ESRF on CPD, based on the use of a novel HPLC assay of L-glycerate in different body fluids. With the routine application of this procedure PH2 has been identified in two of 23 patients fulfilling criteria for diagnosis of PH. This suggests that the type 2 variant of PH may occur more frequently than so far suspected, and should be tested for even in the setting of ESRF. [ABSTRACT FROM PUBLISHER]

Parathyroid carcinoma is a very rare disease occurring in less than 2-3% of all the cases showing clinical features of primary hyperparathyroidism. Several histological markers have been used for distinguishing between benign and malignant tumors of the parathyroid glands. However, most of these markers are not easily applicable and clinical prognosis cannot be predicted by histopathological criteria alone. A recent study has drawn attention to the role of the cell cycle associated antigen Ki-67 detected by MIB-1 monoclonal immunocytochemistry in parathyroid tumors: in fact, Ki-67 seems to be a valuable marker of malignancy in such tumors since it permits an easy detection of proliferating and dividing cells. Here we report in detail a case of severe recurrent hyperparathyroidism in a 51-year-old female patient undergoing regular hemodialysis treatment. In the surgical specimens of the parathyroid glands, the tumor proliferative fraction of 56, expressed as the number of Ki-67-positive nuclei per thousand cells, and the mean mitosis count of 0.5, expressed as the percentage of the total amount of Ki-67 positive nuclei, support the diagnosis of parathyroid carcinoma despite the scanty amount of microscopical signs considered characteristic of malignancy, i.e. extensive thick fibrous bands or prominent nucleoli. To our knowledge this paper is the first clinical report that supports the diagnostic role of the cell cycle associated antigen Ki-67 in parathyroid carcinoma in a case of secondary hyperparathyroidism in a patient undergoing hemodialysis.

The authors present the results of 19 flexion osteotomies performed in cases of avascular necrosis of the femoral head and followed up after an average of 8 1/2 years. Significant clinical improvement was achieved in 85% of the patients. The radiographic picture is not quite as positive, but only 26% of the patients developed severe degenerative arthritis. The authors therefore consider this technique to be a valid alternative to immediate prosthetic replacement in selected patients.

In a review of 11 cases of ectopic calcification (5 of which in dialyzed patients and one in a paraplegic), the authors attempt to characterize this disorder in all its various forms using histological, clinical, and chemical methods. In dialyzed patients, two contributing factors were identified: hyperphosphatemia (plus hypercalcemia) and secondary hyperparathyroidism. In hyperphosphatemic patients the calcifications are multiple, paraarticular, labile, and have a fluid-viscous consistency. In secondary hyperparathyroidism, in addition to the above metastatic calcification there is dystrophic calcification typically localized in the anterior muscles of the hip and thigh. The ectopic calcification of the non-dialyzed patients is true ossification. The precise moment of the onset of the lesion is not always discernable, but its evolution points to primary or secondary local irritation as the trigger. Ossification is the predominant phenomenon in the paraplegic as well, while the triggering mechanism is still unknown.

Histologic findings of the bone-cement junction are presented for 10 implants in rabbits and 12 human specimens. Nondecalcified sections were made, employing embedding techniques that conserve the cement. Different time periods from operation were considered. The histological approach considers mainly the distribution of the osseous elements, with a description of the sites of new and old bone, of resorptive lacunae and of fibrous tissue. Fluorescent sequential labelling of bone tissue allowed a dynamic evaluation of the viability of bone after insertion of the cement. Histologic features may be summarized as follows: In the initial phase after PMMA implantation a zone of necrosis is present around the cement. In a second phase there is very active bone formation and remodelling in the tissue adjacent to the cement, with fibrous tissue formation. Long-term adaptive bone remodelling leads to extensive resorption of cortical bone and new bone formation producing a shell around the cement with new trabeculae radiating towards the cortex.

Twelve patients affected with various bone pathologies (osteoporosis, renal osteodystrophy, osteogenesis imperfecta, hyperparathyroidism) were submitted to mineralometry of the lumbar spine with double photonic ray and transiliac biopsy for histomorphometry. A comparison of the values obtained for the mineralometric and histomorphometric parameters--despite the small number of cases--revealed a correlation between bone mineral content of the lumbar spine and trabecular and cortical bone volume of the iliac crest. The correlation is even more significant for the sum of these last two parameters. It may be concluded that: 1) both the methods have predictive values for an evaluation of osteopenia; 2) the measurement of cortical and subcortical bone volume increases the significance of the histomorphometric finding (which is usually limited to the trabecular bone volume); 3) there is a correlation between histomorphometry (iliac crest bone volume) and mineralometry (lumbar spine with double photonic ray) in the same individual.

The authors expose their results about the biological compatibility of Bioglass (BG), using a new experimental model; this model implicates the use of Fibronectin (FN), a glycoprotein involved in cellular adhesion. The term Bioglass indicates a family of glasses (of possible use as implants) with the formation of a stable calcium-phosphate film on their surface when in contact with an aqueous environment. Two types of BG, B5 and B6, have been incubated with FN; the first binds three times B6 the FN. The results are discussed considering other preliminary results.

Revision surgery for loosening of the components in total hip prostheses is still a problem and not only from the purely technical aspects. According to our experience, the use of cement is contraindicated, at least in Schneider grades 2 and 3 of aseptic loosening, because of the biological damage it can cause to the bone grafts used in such cases. The stability of non-cemented reimplants is dependant on good biological anchorage through endosteal osteogenesis. The cardinal points of technique are: complete removal of all cement, necrotic bone, and interposed fibrous membrane; the use of autoplastic bone grafts in the form of chips to replace the lost "bone stock"; the use of prostheses designed for optimum load distribution (long stem, large acetabulum). In the case of ruptured stems, diaphyseal osteotomy is necessary for complete removal of the cement and prosthesis; this can be stabilised by using a Lord prosthesis with a long stem.

The preliminary results obtained in a study of the use of scintigraphy with Tc 99 PYP for the evaluation of meniscal lesions of the knee are presented. Three different captation curves are described. Those with an elevated peak and a restricted base are characteristic of meniscal lesions. The use of this method in a series of 50 patients in whom meniscal lesions were suspected demonstrated a high diagnostic sensitivity and specificity with regard to the presence of the lesion, but not to its type.

The authors describe the experimental method used to make histomorphometric determinations in a case of osteomalacia caused by anticonvulsant drugs treated with 25(OH)D3. This comprised double fluorescent markings repeated at set time intervals after taking biopsy samples from the patient. This combined method of study enabled the effect of the treatment to be monitored throughout its course.

A review of the literature in osteochondritis dissecans of the femoral condyles reveals that the aetiopathology is still unclear and that relatively few histopathological studies have been carried out. The authors describe a method of study based on microradiography and on preoperative fluorescent labelling of the osteogenetic area followed by examination of the bone remodelling under ultraviolet light microscopy. The results in 12 adult cases are reported in relation to a topographical scheme which divides the lesions into four separate zones.

The histology of bone-cement interfaces was studied by using new fixation techniques that preserve the cement, as well as sectioning the samples without decalcification. This permits histological study of the unaltered morphology, and the precise topographical distribution of fibrous tissue, bone necrosis and cellular anomalies in relation to the cement. Twelve cases of implant loosening over an average 7 year follow-up period were examined. By dynamic studies with sequential fluorescent bone labelling it was possible to evaluate precisely the extent of bone damage after the application of cement. The characteristic findings were: fibrous tissue at the bone-cement interface; bone necrosis or reduced remodelling in proximity to the cement; away from the cement, normal bone remodelling is clearly demonstrated by fluorescent labelling.

The pattern of collagen orientation in two human tibiae and fibulae was studied. Serial 100 microns plane parallel cross-sections at 1 cm intervals at the same level in tibia and fibula were cut using an annular blade saw. Distribution of transversely oriented collagen was mapped using circularly polarized light and an image analyzing computer. In both the tibia and fibula the pattern of collagen orientation is characteristic, which may be related to the distribution of the bending forces normally operative in these bones.

A state of hypersensitivity to the metallic constituents of prosthetic implants can be determined by culturing the patients lymphocytes in vitro in a medium containing the appropriate concentration of salts of the metal. If in these circumstances the lymphocytes proliferate, the patient is hypersensitive. Chromium, cobalt and nickel salts can produce such mitosis only in the lymphocytes of hypersensitive patients; the same test produces no such reaction in control subjects. This hypersensitivity can cause delayed loosening of the prosthesis. The lymphocyte transformation test (L.T.T.) is therefore a very useful preoperative measure in detecting patients who are allergic to these metals and so enables the surgeon to choose the right implant.

A Mittelmeier hip prosthesis was removed at autopsy 2 years after implantation in a patient who was fatally injured. Macroscopic, histological, radiographic, and metrological studies revealed interesting new aspects on the remodelling of bone and the behaviour of the components of the prosthesis.

On the basis of previous investigations indicating that the distribution of osteonic and interstitial lamellae in a normal femur depends on its mechanical properties, a procedure has been devised to provide information on the distribution of lamellae in human femora diaphyses deformed by bending. To achieve this, exactly plane parallel cross sections, 100 micron thick, were prepared from the portion of maximum bending, using an annular blade microtome. An index of the distribution of longitudinal lamellae (whose fiber bundles and crystallites have a longitudinal course and withstand loading by tension) and transverse lamellae (whose fiber bundles and crystallites have a transverse course and withstand loading by compression) was determined using circularly polarized light as illuminating source and a Quantimet 720 image analyzing computer. The results show that, even in a pathologically deformed bone, both the microscopic structure of sections at the level of osteonic and interstitial lamellae, and their macroscopic shape may be governed by the distribution of the forces active in bone.

Post-operative infection is still a serious problem in orthopaedic surgery. Technological advances aimed at achieving aseptic conditions in the operating theatre, and the prophylactic use of antibiotics during operation have considerably reduced this complication during the last decade. Two indispensable factors in monitoring the effectiveness of these preventive measures are the determination of the incidence of post-operative infection and monitoring of the microbacterial population of the hospital.

The authors investigated the tissue around a failed knee prosthesis which had a metal-on-metal bearing made of chromium-cobalt-molybdenum alloy. Histological examination and the quantitative analysis of metallic particles found in the bone marrow (by fluorescent spectrometry and laser microsound) provided a detailed picture of the quantity, nature and distribution of the wear debris. The type and nature of the tissue response to the presence of the metal particles was determined by fluorescent microscopy and microradiography.

The writers present the results of the histological and microradiographic study of a femur and acetabulum two years after the implantation of Mittelmeier's prosthesis, the patient having died from an accident. The periprosthetic diaphyseal cortical bone had been fully resorbed, spongy bone had developed in the central portion and subperiosteal elongated lacunae had formed in the antero-medial part. The sclerosis at the calcar and at the apex of the shaft was made up of osteone systems, part of which consisted of newly laid down bone. The periprosthetic osteofibrous layer was separated from the cortical bone by wide inter-trabecular spaces except in the lateral sector where the shaft was supported by cortical bone that had been relatively conserved.