Osteocyte Viability Research Articles

The trapezius osteomusculocutaneous flap in dogs.

A pedicled osteomusculocutaneous flap, composed of the cervical part of the trapezius muscle with its overlying skin and the central spine and body of the scapula, was elevated on the prescapular branch of the superficial cervical vascular pedicle in four dogs. The flap was replaced in an orthotopic location. Bone viability was evaluated using histology, fluorescence bone labeling, and angiography. Bone from the scapular spines had a high percentage of viable osteocytes, positive fluorescence, and vessels were outlined in the angiographic study. Bone from the body of the scapula was not viable based on similar criteria.

Osteocyte death and hip fracture.

The viability of osteocytes can be demonstrated in sawn decalcified sections of bone by their lactate dehydrogenase activity. In the cancellous bone of the femoral head, the proportion of lacunae containing viable osteocytes decreased from 88 +/- 7% (mean +/- SD) at 10-29 years to 58 +/- 12% (P < 0.001) by 70-89 years. Viability in the second lumbar vertebra was 88 +/- 3% in subjects aged 25-90 years and did not decrease with age. Mean osteocyte viability in the femoral head of 21 hip fracture patients aged 72-94 years was 58 +/- 21%, similar to controls of a similar age, though there was greater variation and, in five patients, osteocyte viability was less than 25%. In hip fracture patients, microfracture callus incidence correlated positively with osteocyte viability, with little or no fracture callus observed if the bone viability was low. Ultimate compressive strength did not correlate with osteocyte viability. In the femoral head there is gradual, age-related reduction in osteocyte viability that can be more pronounced in hip fracture. Osteocyte death may affect bone quality by impairing repair of fatigue damage.

Bone remodeling in hip fracture.

Hip fracture incidence has shown strong upward secular trends in many societies with wide differences in age adjusted incidence between nations. Falls and reduced physical activity have emerged as the strongest risk factors in epidemiological studies, while clinical investigations have pointed to secondary hyperparathyroidism as an important candidate cause of the loss of femoral cortical bone in old age. Until recently there have been few studies performed directly on the region of interest in the proximal femur. Non-invasive methodology using 85Sr has now been developed by our group for measuring bone formation and (with concurrent serial DXA densitometry) resorption in the femoral neck. Bone turnover averaged about 8% annually in controls. A group of younger cases of femoral fracture showed similar indices of total and regional bone formation to a control group; but their resorption was higher. To further investigate this, a femoral neck bone biopsy technique has been developed which can be applied to fracture cases treated by arthroplasty. Preliminary studies have established that the anatomical asymmetry of the neck in cross-section is considerable and imposes restraints on the interpretation of smaller or incomplete femur biopsies. Prospects are quite good that, in the absence of tetracycline pre-labeling, mineralization can be studied by assessment of alkaline phosphatase-positive surfaces in cryostat sections. Moreover, such sections will permit study of other anatomically localized metabolic activities as well as antigen expression and osteocyte viability. Candidate mechanisms for the regional decline in bone quality as well as bone mass in subjects suffering hip fracture can now be investigated more effectively.

Effect of intermittent mechanical force on bone tissue in vitro: preliminary results.

The structure of metatarsal bones from 18-day-old rats subjected to intermittent mechanical force in organ culture are reported. The application of mechanical force enhances the osteoid thickness and osteoblast number in the periosteum and increases the number of viable osteocytes. These results indicate that (1) the mature bone tissue survives in organ cultures; (2) the mechanical forces better preserve the structure of the osteocytes and stimulate the osteoblasts, and (3) stimulate the osteogenesis.

Reperfusion injury in bone: effects of CV-3611, a free radical scavenger, on ischemic revascularized bone grafts in rats.

Oxygen-derived free radicals have been shown to play an important role in reperfusion injury. The protective effect of CV-3611, a new free radical scavenger, on reperfusion injury in an ischemic revascularized hind limb model in rats was examined. Warm ischemia (25 degrees C) was produced by vascular pedicle clamping and sustained for 0, 3, and 6 hr. Histologic and fluorochrome bone-labeling analyses demonstrated improved overall viability of osteocytes, osteoblasts, and marrow cells in the CV-3611-treated group compared to controls. The CV-3611-treated group had statistically significant improvement in the ratio of lacunae, maintained osteogenetic ability, and preserved normal growth plate architecture after 6 hr of ischemia. The control group showed local central areas of disorganization by 3 hr and complete destruction of the growth plate with early growth arrest after 6 hr of ischemia. These results indicate that administration of CV-3611 prior to reperfusion can prevent reperfusion damage in bone tissue and maintain osteogenetic ability. This technique may have clinical application for reducing the complications of prolonged ischemia to bone tissue.

血管柄付同種骨移植の実験的研究 （第３報） 免疫抑制剤長期投与群と短期投与群の比較

A study of vascularized massive bone allograft was performed, using the devised model of inbred rat with cyclosporin A as immunosuppressive drug. This model was designed for making it easy to observe callus formation on both proximal and distal sites of massive interaclary bone allograft and the montitoring of the viability of osteocytes by the bone scan. Cyclosporin A was used postopertively both continuously and short term (14 days after transplant) at 10mg/kg/day (i. m.) as recipient treatment.Bone scintigram indicated remakable difference between continuous cyclosporin group and short term cyclosporin group. High uptake was continuously observed in the continuous cyclosporin groups. In the short term cyclosporin group, howevever, the high uptake was observed during the 3 to 4 weeks. and it changed into the weak or mottled uptake until 6 weeks after transplantation.In the continuous cyclosporin group periosteal new bone formation was observed on both donor and recipient bone, and each of them united until 4 weeks postoperatively at the proximal side and it took one more week to get a union at the distal side. These results were very similar to those of the vascularized bone isograft. On the other hand, in the short term cyclosporin group, the union was remarkably delayed and it took 8 weeks to obtain the union at the proximal side, and failure of the bone union developed in few of models at the distal side.In conculsion, under immunosuppression, viability of he allogratted bone was maintaind and the union of both osteosynthetic side occurred surely as soon as the vasucularized bone isograft. However, in the short term (14 days) cyclosporin group, vascularized allografted bone was rejected after stopping cyclosporin. The union delayed than the continuous cyclosporin group when the cyclosporin was stopped 14 days after transplantation and before union.

Bone death in hip fracture in the elderly

We examined femoral head bone from 50 cadavers and from 21 patients who had suffered pathologic fracture of the femoral neck. We used a histochemical technique for lactate dehydrogenase (LDH) activity to demonstrate osteocyte viability. The femoral heads were removed within 36 hours of death or fracture, as LDH activity persists in the cytoplasm of viable cells for this time at 37 degrees after interruption of the blood supply. In the controls, there was an age-related reduction in mean osteocyte viability, from 88 +/- 7% (mean +/- SD) at age 10-29 years to 58 +/- 12% at age 70-89 years. In the hip fracture patients, mean osteocyte viability was 58 +/- 21% but there was much variability in both osteocyte viability and bone mass. In 5 fracture patients, there was extensive osteocyte death, suggesting that most of the femoral head bone was nonviable; these patients had little microfracture callus. Others had predominantly viable bone which was usually osteoporotic, and their bone frequently showed microfracture callus. Osteomalacia was not seen in any patient. It is suggested that bone death, in addition to osteoporosis, may sometimes contribute to hip fracture in the elderly.

Role of Free Vascularized Bone Grafts in the Experimentally-Induced Ischemic Necrosis of the Femoral Head

In 15 mongrel adult dogs, an ischemic necrosis of the femoral head was produced, following the technique described by Gartsman and colleagues. Five weeks later, a 6- to 8-cm long rib graft was harvested with its vascular bundle and transferred into the previously induced ischemic femoral head. Microsurgical anastomoses were performed for revascularizing the rib graft. Dogs were studied using scintigraphy, blood flow measurements, roentgenograms, angiograms, and histology at four, eight and 12 weeks after grafting. New bone and vascular formation was exhibited throughout the study, as demonstrated by a highly positive scintigraphic activity and the formation of numerous arterial terminal branches arising from the rib graft circulation which entered the femoral head and reached the subchondral plate. The formerly necrotic femoral head bone exhibited osteoblastic activity, viable osteocytes, and well-populated bone marrow. The rib graft was also incorporated into the femoral head. These results suggest that a vascularized bone graft is able to repair a femoral head necrosis, and may be considered a rational approach for clinical purposes.

A Versatile New Mineralized Bone Stain for Simultaneous Assessment of Tetracycline and Osteoid Seams

A versatile mineralized bone stain (MIBS) for demonstrating osteoid seams and tetracycline fluorescence simultaneously in thin or thick undecalcified sections has been developed. Bone specimens are fixed in 70% ethanol, but 10% buffered formalin is permissible. Depending upon one's preference, these specimens can be left unstained or be prestained before plastic embedding. Osteoid seams are stained green to jade green, or light to dark purple. Mineralized bone matrix is unstained or green. Osteoblast and osteoclast nuclei are light to dark purple, cytoplasm varies from slightly gray to pink. The identification of osteoid seams by this method agrees closely with identification by in vivo tetracycline uptake using the same section from the same biopsy. The method demonstrates halo volumes, an abnormal, lacunar, low density bone around viable osteocytes in purple. This phenomenon is commonly seen in vitamin D-resistant rickets, fluorosis, renal osteodystrophy, hyperparathyroidism, and is sometimes seen in fluoride treated osteoporotic patients. In osteomalacic bone, most osteoid seams are irregularly stained as indicated by the presence of unmineralized osteoid between mineralized lamellae. The method has been used effectively in staining new bone formation in hydroxyapatite implants and bone grafts. Old, unstained, plastic embedded undecalcified sections are stained as well as fresh sections after removal of the coverslip. This stain also promises to be valuable in the study of different metabolic bone diseases from the point of view of remodeling, histomorphometry, and pathology.

同種関節移植の実験的研究

The aims of this paper, carried out in dogs, are to develop the surgical techniques involved in transplantation of the knee, and to study the effects of the immunosuppressnat drugs, cyclosporin, on the fate of allografts taken from unrelated animals. The survival and structure of the grafts were evaluated by serial radiological examinations and radioactive bone scans and by repeated biopsy. The growth of donor and recipient bones were assessed by tetracycline labelling and their structure and viability by histological examination. In vascularized autografts as a pilot study, three months after operation, 4 animals showed apparently normal joints and only minor atrophy of their thigh muscles. By contrast all 3 dogs with allografts rejected the graft within the first 5 days had to be sacrified. In the final group, 3 dogs were given vascularized allogtafts and administration of cyclosporin started at the time of operation and continued for 3 months. At 3 months after grafting, all dogs showed bony union and a constant and active uptake of radioactive tracer in the graft. Histologically, the grafts showed viable chondrocytes and osteocytes, and active turn-over of the bone until withdrawl of cyclosporin. After withdrawl of cyclosporin, the grafts were rejected rapidly.

Use of cryopreserved bone in spinal surgery.

One hundred fifty-two consecutive spinal fusions were performed over a 4-year period in 143 patients. Autogenous bone was used in 62 patients and frozen cryopreserved bone in 90. A variety of anterior and posterior procedures with and without instrumentation were performed. The percentage of successful arthrodesis was 87 in those who received autogenous bone, and 86.6 in those who received allograft bone. Thirty-four spinal fusions were surgically explored. Histologic evaluation of the bone taken at the time of surgical exploration showed viable osteocytes laying down osteoid, woven and lamellar bone, and no inflammatory or foreign body reaction. The authors conclude that cryopreserved bone, harvested and processed as described, is advantageous, safe, and results in a rate of bone union comparable to that of autogenous bone.

The Pathogenesis of Osteoarthritis of the Hip

Osteocyte viability was investigated in femoral head bone removed from 38 patients with chronic hip disease, with the use of a histochemical stain to demonstrate lactate dehydrogenase (LDH) activity in osteocytes. Where the osteocyte cytoplasm did not show LDH activity, the cell was considered dead; when several adjacent osteocytes were dead, the bone in that area was regarded as nonviable. The preoperative diagnoses were idiopathic osteoarthritis in 25, chondrocalcinosis in six, rheumatoid arthritis in two, Paget's disease in two, avascular necrosis in two, and congenital dislocation of the hip in one patient. In 16 of the patients with idiopathic osteoarthritis and the two with avascular necrosis, nonviable osteocytes were present in the central regions of many trabeculae, these areas usually being separated by cement lines from viable bone. The pattern suggested previous necrosis of part of the femoral head, with later new bone formation. The pattern was not observed in either control subjects, or patients with known articular disease, such as chondrocalcinosis. Bone collapse of variable severity was apparent radiographically in nine patients with histologic bone death, but not in other patients. Bone death is commonly present in idiopathic osteoarthritis and could be a cause rather than a result of the arthritis.

The effect of age on bone composition and viability in the femoral head.

We studied the effect of age on bone composition and osteocyte viability in femoral heads from fifty-one subjects. The assessment included determination of: bone volume, ash weight, calcium, and phosphorus content; osteocyte viability in fresh sections stained for lactate dehydrogenase activity; microfractures in fresh sections after removal of marrow elements; bone area, the presence of metabolic bone disease, and the histology of microfractures in embedded calcified sections; and the extent of trabecular microfractures. Bone area and numbers of microfractures were also assessed in eight elderly hip-fracture patients. Bone volume decreased with age, but there was considerable variation in each age group, and no significant difference between men and women. Ash weight and the bone content of calcium and phosphorus also decreased with age, but were constant if corrected for bone volume. Almost all osteocytes were viable in subjects who were younger than twenty-five years, and thereafter viability progressively decreased to a mean of 74 per cent in the eighth decade of life. There was a significant negative correlation between osteocyte viability and age. There was no evidence of metabolic bone disease in any patient. The numbers of microfractures increased with age and correlated negatively with bone viability (r = -0.31, p less than 0.05); in simple linear correlation a relationship between bone area and microfractures could not be demonstrated but in multiple linear correlation, after the inclusion of bone viability, there was an additional negative correlation between numbers of microfractures and bone area (p less than 0.005). Bone area and numbers of microfractures in hip-fracture patients were similar to those in age-matched controls.

Revascularized segmental diaphyseal bone transfers in the canine. An analysis of viability.

The biologic behavior of free revascularized bone segments was investigated using a unique canine model. Conventional methods to assess bone kinetics included the histologic osteocyte count, tetracycline uptake, appositional bone formation rate, and quantitative microradiography. The percentage of viable osteocytes in the revascularized segment was 52.4%, compared with 66.8% in the normal controls and 28.5% in the nonrevascularized segment. These differences were statistically significant. Both qualitative and quantitative differences were noted regarding deposition of tetracycline. On the basis of this study, we conclude that an apparently successful vascularized bone transfer retains a degree of viability greater than a conventional bone graft but less than that of normal undisturbed bone.

Metal migrations outside the package during accelerated life tests : Philippe Dumoulin, Jean-Paul Seurin and Pierre Marce. IEEE Trans. Components Hybrids mfg Technol.CHMT-5 (4), 479 (1982)

Heat from bone resecting tools used in knee surgery can induce thermal osteonecrosis, potentially causing aseptic implant loosening. This study compared oscillating saws to burrs in terms of temperature generation and histologic damage. Use of irrigation to reduce bone temperature was also investigated.Temperatures were recorded during sawing and burring with or without irrigation (uncooled or cooled). Histologic analyses were then carried out. Differences between groups were tested statistically (α = 0.05).On average, burring produced higher temperatures than sawing (P < .001). When uncooled irrigation was used, bone temperatures were significantly lower in sawed bone than in burred bone (P < .001). Irrigation lowered temperatures and thermal damage depths and increased osteocyte viability (P < .001).These results suggest that irrigating bone during resection could prevent osteonecrosis onset.

Vascularized rib-periosteal and osteocutaneous reconstruction of the maxilla and mandible: an assessment.

Three approaches to provide rib-periosteal or osteocutaneous composite tissue in maxillary or mandibular reconstruction are presented. All methods appear to be useful in replacing viable osteocytes and improving vascularity of maxillary or mandibular defects. Disadvantages include the bulk of the transplanted tissue, volume deficiency of bone, and the unreliability in viability of the associated cutaneous tissue, especially with the posterior and posterolateral approach. Significant patient morbidity and pulmonary complications in our series should indicate caution when considering these methods of reconstruction. At present, rib-periosteal transplantation is most often indicated to replace segmental defects of mandibular continuity when the recipient bed is avascular but the quantity of cutaneous cover is adequate. In those patients with deficient soft tissue and a small segmental mandibular loss, reconstruction with musculocutaneous flaps and nonvascularized bone grafts is indicated. With extensive deficiencies of both soft tissue cover and mandibular or maxillary continuity, an iliac osteocutaneous flap based on the deep circumflex iliac vessels may be the most effective. Lower patient morbidity statistics should be anticipated.

Histological Evaluation of Effects Produced in Alveolar Bone Following Gingival Incision with an Electrosurgical Scalpel

Gingival incisions were performed distal to each of the two lower incisors on 25 adult male guinea pigs. For every animal, electrosection with an electrosurgical scalpel was used on one side, and a conventional scalpel was used on the other. The surgical instruments in all cases were brought into direct contact with periosteum. Five animals were sacrificed at each postoperative period (12, 24, 48, 72, and 96 hours), and sections of the areas of surgery were prepared by standard laboratory procedures. At 12 hours postoperatively there were far more soft tissue necrosis, a more extensive inflammatory reaction, and greater destruction of periosteum after electrosurgery. No significant changes in osteocyte viability were seen after either technique. However, by 24 hours, many empty lacunae were observed in the bone associated with electrosurgery, such necrosis being even more extensive by 48 hours. In contrast, only very minor, localised areas devoid of some osteocytes were seen after use of the conventional scalpel. By 96 hours the electrosurgical connective tissue wounds were still lined by coagulum, but repair of the scalpel wounds had begun. The periosteum and bone had the same features that were seen at 48 hours. Throughout the study, no increase in osteoclasts was seen in any section, nor were significant changes in adjacent bone marrow observed.

An SiO 2-Ta 2O 5 thin film capacitor : S. Sato, A. Sato and E. Okamoto. IEEE Trans. Parts, Hybrids & PackagingPHP-9, No. 3 (Sept. 1973). p. 161

Heat from bone resecting tools used in knee surgery can induce thermal osteonecrosis, potentially causing aseptic implant loosening. This study compared oscillating saws to burrs in terms of temperature generation and histologic damage. Use of irrigation to reduce bone temperature was also investigated.Temperatures were recorded during sawing and burring with or without irrigation (uncooled or cooled). Histologic analyses were then carried out. Differences between groups were tested statistically (α = 0.05).On average, burring produced higher temperatures than sawing (P < .001). When uncooled irrigation was used, bone temperatures were significantly lower in sawed bone than in burred bone (P < .001). Irrigation lowered temperatures and thermal damage depths and increased osteocyte viability (P < .001).These results suggest that irrigating bone during resection could prevent osteonecrosis onset.

Sawing alumina substrates with a CO 2 laser : J. Longfellow. Solid St. Technol. (August 1973). p. 45

Heat from bone resecting tools used in knee surgery can induce thermal osteonecrosis, potentially causing aseptic implant loosening. This study compared oscillating saws to burrs in terms of temperature generation and histologic damage. Use of irrigation to reduce bone temperature was also investigated.Temperatures were recorded during sawing and burring with or without irrigation (uncooled or cooled). Histologic analyses were then carried out. Differences between groups were tested statistically (α = 0.05).On average, burring produced higher temperatures than sawing (P < .001). When uncooled irrigation was used, bone temperatures were significantly lower in sawed bone than in burred bone (P < .001). Irrigation lowered temperatures and thermal damage depths and increased osteocyte viability (P < .001).These results suggest that irrigating bone during resection could prevent osteonecrosis onset.