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Ultrastructural study of the A-W GC-bone interface after long-term implantation in rat and human bone.

The interface between apatite- and wollastonite-containing glass-ceramic (A-W GC) and bone after long-term implantation was studied by scanning and transmission electron microscopy (SEM and TEM) using rat and human specimens. First, particles of A-W GC (100-220 microns in diameter) were implanted into rat tibiae, and specimens were prepared for observation at 24, 48, 72, and 96 weeks after the operation. These long-term specimens showed an A-W GC-bone interface different from that at an earlier stage, which was investigated in our previous studies. SEM showed that the Ca-P-rich layer was wider, suggesting that leaching of ions from the A-W GC had continued even after bonding with bone. In some regions, the material particles were evidently replaced by the bone. TEM showed that the intervening apatite layer had become indistinct, and that A-W GC had intermingled with bone at the interface. In some regions, the surface of the A-W GC was degraded. These findings suggest that the surface region of A-W GC is slowly replaced by bone. Second, a human bone specimen, which included A-W GC particles (300-700 microns in diameter) implanted as a bone filler for about 75 weeks was harvested and investigated. Excellent A-W GC-bone bonding was observed, and the ultrastructure of the interface was similar to that in rats after long-term implantation. This finding demonstrated that A-W GC possibly worked in human bone in the same way as in rat bone, showing excellent bioactivity.

Adult↗

Reconstruction of skull bone defects using the hydroxyapatite cement with calvarial split transplants.

PURPOSE: We sought to present a new method for primary reconstruction of traumatic or tumor calvarial defects. PATIENTS AND METHODS: Forty-one patients underwent reconstruction of calvarial bone defects between October 1998 and December 2001. Among them were 19 patients who needed reconstruction of the calvaria due to traumatic bone loss. Five of these trauma cases had insufficient primary reconstruction of the calvaria. Tumor resection caused calvarial defects in 22 patients. For primary reconstruction of the skull bone defects, calvarial split grafts were used to cover the defect as accurately as possible. The monocortical layers of the calvaria were fixed with titanium miniplates. Irregular defects surrounding the transplanted regions were filled with hydroxyapatite cement. In one case of posttraumatic bone loss, hydroxyapatite cement alone was sufficient to reconstruct the defect. RESULTS: The follow-up of each patient was at least 6 months; the longest period was 38 months. Evaluated clinical and radiologic results are stable, showing no measurable side effects. CONCLUSION: Hydroxyapatite cement alone or in combination with calvarial split grafts gave clinically and aesthetically stable results in the reconstruction of skull bone defects. The cement can be used for many reconstruction possibilities in craniofacial surgery.

Adult↗

Bone ultrastructure and x-ray microanalysis of aluminum-intoxicated hemodialyzed patients.

In hemodialyzed patients aluminum (Al) intoxication may induce osteomalacic lesions which are mainly observed when plasma immunoreactive parathyroid hormone (iPTH) concentrations are low, and osteitis fibrosa absent. In this study, the bone tissue of eight hemodialyzed patients with elevated plasma and bone Al concentrations was examined by histomorphometry, electron microscopy, and x-ray microanalysis. Five patients (group 1) had osteomalacia and minimal osteitis fibrosa, three patients (group 2) had severe osteitis fibrosa. In group 1, Al was concentrated at the mineralizing front, in hexagonal structures measuring 200 to 1,000 A which also contained phosphorus, but not calcium. Hydroxyapatite needles had a normal aspect. Osteoblasts appeared inactive. In group 2, Al was also present at the mineralizing layer of osteoid, but, in these cases, in small clusters next to abnormal calcium deposits. Osteoblasts appeared very active. Their mitochondria contained calcium and phosphorus granules, or amorphous material, measuring 1,500 to 2,000 A, emitting x-rays characteristic for Al and phosphorus. These results suggest that secondary hyperparathyroidism, by stimulating the cellular activity, may increase the uptake and release of Al by the osteoblasts. The presence of Al within the mitochondria of these cells may be one of the factors inducing the mineralization defect.

Adult↗

Surgical treatment of congenital fronto-orbitomalar asymmetries.

Congenital fronto-orbital asymmetries can be of various origin. Correction of these malformations, whether due to maldevelopment of the foetus or to a congenital tumour, generally require a combined intracranial and extracranial approach. In recent years, a working group of plastic surgeons and neurosurgeons in the French-speaking part of Switzerland have been particularly interested in these problems. Some of their results are presented here.

Bone Transplantation↗

Hydroxyproline.

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Bone Diseases↗

Demineralized bone implants for nonunion fractures, bone cysts, and fibrous lesions.

Demineralized bone implants were used to treat eight patients with fracture nonunion, five patients with bone cysts, and eight patients with fibrous lesions. Five of the eight patients with nonunions had had previous unsuccessful attempts at reconstruction. After fixation and implantation with either human or bovine demineralized bone, all eight fractures healed. For those patients with nonunion fractures, mean followup time was 8 years, 5 months, and longest followup was 15 years, 3 months. The cystic lesions in five patients included three typical aneurysmal bone cysts and two recurrent unicameral bone cysts. The aneurysmal bone cysts had excellent healing and bone remodeling. The two unicameral bone cysts were repacked more densely after 1 year and healed. For these patients with bone cysts, the mean followup time was 12 years, 5 months, and longest followup was 15 years, 1 month. The various fibrous lesions in seven of the eight patients were healed within 6 months, with only one requiring repacking. For these patients with fibrous bone lesions, the mean followup time was 9 years, 8 months, and longest followup was 14 years. A biopsy of the lesions in five patients was performed and in two cases showed osteoblasts and new bone around small particles of the implants. These results with long term followup show that allogeneic or xenogeneic demineralized bone implants offer a reasonable alternative for the treatment of typical nonunion fractures, bone cysts, and fibrous lesions of bone.

Adolescent↗

Musculoskeletal lesions with fluid-fluid level: a pictorial essay.

A fluid-fluid level was identified in 11.2% of focal lesions of bone. Fluid-fluid levels are observed on cross-sectional imaging with either computed tomography (CT) or magnetic resonance (MR) imaging. They become apparent when a fluid collection containing substances of different density is allowed to settle, and when the plane of imaging is perpendicular to the fluid level. For instance, within a collection of blood, the cellular components will settle dependently, with the lower density plasma forming a layer superiorly. The difference in the density of these layers can be observed on CT imaging. With MR imaging, these layers will have different signal characteristics, allowing for visualization of the fluid-fluid level. The presence of fluid-fluid levels within a musculoskeletal lesion is an important finding, which can significantly aid in the differential diagnosis. This finding can be observed in a wide variety of lesions: osseous and soft tissue masses, neoplastic or nonneoplastic lesions, malignant or benign neoplasms, and primary or metastatic malignancies. When a fluid-fluid level is detected, in conjunction with clinical history, the differential diagnosis for a lesion can often be limited to a few choices. For this reason, it is important to be aware of the multiple lesions that can produce fluid-fluid levels, as well as their differentiating characteristics and typical presentations. We will review both osseous and soft tissue lesions, focusing on their imaging characteristics and other important findings.

Body Fluids↗

Cylindrically modeled bone grafts.

A technique of autogenous grafting for repair of large defects in long bones is presented. Quadrangular grafts, taken from the external table of the posterior ilium, are modeled by bending them into cylindrical form, which has higher mechanical resistance as compared to flat struts. Cancellous chips are added. The original shape of the bone is immediately restored, and heavy internal fixation is avoided. combination of cortical and cancellous bone grafts provides both strength and rapid bone healing. There is no risk of fracture at the donor site. Of eight consecutive cases operated on, seven were successful. One failed because of relapsing infection. The procedure is suitable in children, adolescents, and young adults, for difficult cases of large defects in long bones left after resection of tumors and tumor-like conditions, as well as after diaphyseal distraction for leg lengthening.

Adult↗

Prevention of osteitis fibrosa, aluminium bone disease and soft-tissue calcification in dialysis patients: a long-term comparison of moderate doses of oral calcium +/- Mg(OH)2 vs Al(OH)3 +/- 1 alpha OH vitamin D3.

Since 1980, moderately large doses of oral calcium (80 +/- 35 mmol/day as CaCO3 +/- calcium polystyrene sulphonate), in association if necessary with Mg(OH)2 (2.5 +/- 1 g/day), with a reduction in the dialysate Mg concentrations from 0.75 to 0.375 mmol/24 h, have replaced A1(OH)3 as phosphate binders in our centre. A1(OH)3 was previously given to our haemodialysis patients in association with small doses of Ca CO3 (less than or equal to 3 g/day) and if necessary with 1 alpha OH vitamin D3. To compare the long-term efficacy of this new approach with the former one in the prevention of renal osteodystrophy and soft-tissue calcification, 32 current patients were selected on the basis of at least 24 months of treatment in our centre and availability of a yearly bone survey (profile of lumbar spine and anteroposterior view of the pelvis, shoulders and hands). A group of 30 patients treated before 1980 were then selected on the same criteria and matched for age, sex, and duration on dialysis. Linear calcifications of the anterior and posterior walls of the aorta in front of L2, L3, L4 and on the lateral walls of the iliac and femoral arteries were measured and the para-articular calcifications and subperiosteal resorptions of the hands evaluated. The initial extent and the subsequent increase of the ocular and para-articular calcification were comparable in the two groups. Plasma alkaline phosphatase was stable in the normal range in both groups, as was plasma concentration of calcium. Plasma phosphate was slightly elevated (1.7 mmol/l) but stable and comparable in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum↗

Desmoplastic fibroma. A case report.

A desmoplastic fibroma occurring in the distal forearm of a 14-year-old black boy is described and the historical background of the tumour together with an outline of the disease emphasizes the differential diagnosis between this condition and other fibrous lesions of soft tissue and bone. The clinical and radiological features as well as the treatment of desmoplastic fibroma are discussed. It is believed that this is the first such patient reported in Africa.

Adolescent↗