Enhancement of bone regeneration with the combination of platelet-rich fibrin and synthetic graft.

INTRODUCTION: Platelet-rich fibrin (PRF) is a relatively new developed platelet concentrate with several benefits over platelet-rich plasma. The aim of this study was to compare healing properties of PRF and its combination with a ceramic synthetic material (graft) composed of hydroxyapatite and b-tricalcium phosphate in an animal model. METHODS: A bone deficit was surgically created in each femoral condyle of 15 New Zealand white rabbits. In each animal, 1 limb had (a) PRF only and the other (b) PRF plus synthetic graft material randomly implanted. Experimental animals were killed 3 months postoperatively. Histological and radiological examinations were made by means of computed tomography and peripheral quantitative computed tomography. RESULTS: Mean density of the healed bone was statistically significantly greater when synthetic material was used (P < 0.0005). Moreover, combination of PRF with the synthetic material resulted in more cortical and subcortical bone formation (P = 0.038 and P = 0.037, respectively). CONCLUSIONS: The addition of the ceramic material significantly increased the formation of new bone, providing a better substrate for bone regeneration.

Correlation of pQCT bone strength index with mechanical testing in distraction osteogenesis.

Distraction osteogenesis is an established method of treatment of non-unions and limb length discrepancies. Despite improvements in surgical techniques and fixation devices there is still a considerable possibility of failure of the regenerate bone after frame removal. The hypothesis of the present experimental study was that a noninvasive bone strength marker, the strength-strain index (SSI) measured by peripheral quantitative computerized tomography (pQCT), could be significantly correlated with a biomechanical bone strength index, the maximum load at bone failure (F(max)), assessed in a three-point bending test. The right tibias of fifteen male New Zealand White rabbits were subjected to gradual lengthening using an external fixator. At the end of the consolidation phase (55th day) the animals were sacrificed and the lengthened tibiae were collected free of soft tissue, after removal of the lengthener, for immediate scanning and mechanical testing. The values of cortical bone mineral density, cortical bone area, and the corresponding SSIy, as measured by pQCT, were assessed for statistically significant correlation relative to the values of the F(max) and stiffness as evaluated by the three-point bending test were assessed. SSIy showed a statistically significant positive correlation with the maximum load (F(max)) with a correlation value R=0.846 (p<0.001), and it was a good predictor of F(max) since it was able to describe the 71.6% of variability of F(max)(R2=0.716). Furthermore, cortical bone area appeared to be highly correlated with F(max) (p<0.005), but it was a less efficient predictor of F(max) (R2=0.471). There was, also, a statistically significant correlation between SSIy and bone stiffness as assessed in the 3-point bending test (p<0.005). In conclusion, the present study reveals that the SSI can be used as a sensitive index of adequate consolidation of the regenerate bone, possibly able to reduce mechanical failure due to premature frame removal. In clinical relevance, the aforementioned hypothesis should be applied in studies of human populations and possible confirmation of its validity would establish pQCT as a valuable diagnostic tool not only in distraction osteogenesis but also in other techniques of bone healing.

Study of bone density by pQCT analysis in healthy adults and patients with B-thalassemia major and intermedia.

BACKGROUND: Bone changes are a prominent symptom of beta-thalassemias, related to expansion of bone marrow and reduction of bone density. Conventional treatment ameliorates bone changes and improves survival, thus increasing the morbidity of bone diseases in adulthood. Peripheral quantitative computer tomography (pQCT) was used recently to assess the changes in volumetric bone mineral density (vBMD) in various bone compartments. OBJECTIVES: Assessment of indices of bone density and structure in patients with thalassemia major (thal-major) and intermedia (thal-interm) on conventional therapy and in healthy adults. MATERIAL AND METHODS: 45 patients with thal-major, 27 with thal-interm and 32 healthy individuals aged 21-42 years were studied by pQCT analysis. The vBMD total (tot), trabecular (trab) and cortical (cort), the bone mineral content (BMC), the cross sectional area (CSA), the cortical thickness (CRTHK) and the stress strain index (SSI) were assessed at the 4% site of the distal radius. RESULTS: Tot, trab, and cort vBMD, BMC, and cortical thickness showed statistically significant differences among the three groups with significant reduction in thalassemics. No significant differences were found in the three groups with CSA and SSI. Impairment of bone density and structure in Greek thalassemics on proper treatment was not as severe as expected. A significant proportion of patients had bone density indices within the normal range and above the 10th percentile of normal. CONCLUSIONS: Peripheral QCT analysis is a convenient method to study the regional changes of bone density in patients with thalassemia. These changes affect mainly the cortical compartment and are more pronounced in thalassemia intermedia.

Patient radiation exposure measurements during interventional procedures: a prospective study.

This is a prospective study with the purpose of assessing patient radiation dose and stochastic risk (risk for fatal cancer) in a patient population undergoing interventional radiological (IR) procedures. Measurements were performed on 36 consecutive patients undergoing percutaneous transluminal angioplasty (PTA, n=18), transjugular intrahepatic portosystemic shunt (TIPS, n=3), diagnostic angiography (DA, n=6), arterial embolization (AE, n=3), and hepatic neoplasm chemoembolization (HCE, n=6). Kerma area product (KAP) was used as a measure of x-ray exposure to the patient. Mean KAP value per procedure was 79+/-50 Gy cm for PTA, 139+/-55 Gy cm for TIPS, 110+/-44 Gy cm for DA, 325+/-145 Gy cm for AE, and 150+/-76 Gy cm for HCE. Forty-six percent of total KAP value was attributed to fluoroscopy. In conclusion, we showed that a linear correlation between effective dose and KAP was found (r=0.84), which could be used for estimating patient effective dose using KAP measurements. Small changes to the number of digital frames acquired result in substantial change of the total KAP in interventional radiological procedures. Stochastic risk from IR procedures is quite low for the patient. Measuring KAP is a simple and accurate method, which provides the interventional radiologist with a good estimation of the patient's relative risk for stochastic effects.

Effect of primary hyperparathyroidism on volumetric bone mineral density and bone geometry assessed by peripheral quantitative computed tomography in postmenopausal women.

CONTEXT: Primary hyperparathyroidism (PH) is characterized by inappropriate PTH elevation with or without hypercalcemia. Bone disease involves catabolic action at cortical sites, whereas cancellous sites and geometry might be relatively preserved. OBJECTIVE: Our objective was to examine the effect of PH on quantitative and qualitative bone characteristics using peripheral quantitative computed tomography at the tibia in postmenopausal women with PH and healthy controls. DESIGN AND SETTING: We conducted a cross-sectional study at a tertiary referral center. PATIENTS: Fifty-two postmenopausal women with PH and 56 healthy controls, comparable for age and anthropometric measures, participated. INTERVENTION: There was no intervention. MAIN OUTCOME MEASURE: We assessed volumetric bone mineral density (vBMD), bone mineral content (BMC), cortical thickness, cortical and trabecular area, peri- and endosteal circumference, and polar stress strength index assessed by peripheral quantitative computed tomography of the left tibia at 4% (cancellous), 14% (transition zone), and 38% (cortical) from the distal end. RESULTS: At 4%, there was a significant decrease of trabecular BMC and vBMD (P < 0.001), effect particularly evident in hypercalcemic patients, whereas trabecular area was comparable. At 38%, cortical BMC (P < 0.01), vBMD (P < 0.01), area (P < 0.05), and thickness (P < 0.001) were reduced in the PH group, particularly in hypercalcemic patients. Endosteal circumference increased (P < 0.001), whereas periosteal circumference was comparable, indicating cancellization of cortical bone. At 14%, polar stress strength index was significantly decreased (P < 0.01) in hypercalcemic patients, indicating impairment of bone mechanical properties. CONCLUSIONS: Normocalcemic PH is characterized by catabolic actions at both cortical and cancellous sites (38 and 4%, respectively), an effect accentuated in hypercalcemic patients. Cortical geometric properties are adversely affected even in normocalcemic patients, whereas trabecular properties are generally preserved.

Effect of oral contraceptive treatment on bone mass acquisition in skeletally immature young female rats.

The objective of the present study was to investigate the effect of oral contraceptive (OC) treatment on bone mass accrual in skeletally immature young female rats. Animals in the baseline group were killed at the beginning of the experiment and were subjected to bone density assessment by peripheral quantitative computerized tomography (pQCT). The control group was fed a base diet free of phytoestrogens, while animals in the contraceptive group received the same base diet mixed with 2.67 microg desogestrel/100 g body weight and 0.0533 microg ethinyl estradiol/100 g body weight. The duration of the treatment period was 16 weeks. Densitometric measurements by dual energy x-ray absorptiometry and serum bone markers assessment were carried out at baseline, at 8 weeks and at 16 weeks, while pQCT densitometry took place after sacrifice. All bone mineral density and bone mineral content indices measured by dual energy x-ray absorptiometry increased significantly throughout the study period in both the OC and control group. Concerning pQCT measurements, animals in both the OC and the control group had significantly higher cortical density compared with baseline (midtibia: p=.0003 and .0003, respectively). Total area and periosteal circumference were significantly higher in OC group, both in proximal (p=.003 and .003, respectively) and midtibia (p=.048 and .042, respectively) compared with baseline. Osteoprotegerin serum levels increased in both groups, and at the end of the experiment, circulating osteoprotegerin was significantly higher in the OC group compared with controls (p=.032). At the end of the experiment, carboxyl-terminal telopeptides of collagen type I levels were significantly lower in the OC-treated animals compared with controls (p=.046). Our results suggest that OC administration to skeletally immature female rats allows normal bone accrual and may even improve bone geometry. This effect may be mediated through enhanced inhibition of bone resorption.

Medical personnel and patient dosimetry during coronary angiography and intervention.

Percutaneous coronary interventions are associated with increased radiation exposure compared to most radiological examinations. This prospective study aimed at (1) measuring entrance doses for all in-room personnel, (2) performing an assessment of patient effective dose and intracoronary doses, (3) investigating the contribution of each projection to kerma-area product (KAP) and irradiation time, (4) comparing results with established DRL values in this clinical setting and (5) estimating the risk for fatal cancer to patients and operators. Measurements were performed during 40 consecutive procedures of coronary angiography (CA), half of which were followed by ad hoc coronary angioplasty (PTCA). KAP measurements were used for patients and thermoluminescent dosimetry for the in-room personnel. The mean KAP value per procedure for CA was 29 +/- 9 Gy cm2. Thirty four per cent of KAP was due to fluoroscopy, whereas the remainder (66%) was due to digital cine. Accordingly, the mean KAP value per PTCA procedure was 75 +/- 30 Gy cm2, and contribution of fluoroscopy is 57%. Effective dose per year was estimated to be 0.04-0.05 mSv y(-1) for the primary operator, and 0.03-0.04 mSv y(-1) for those assisting. Corresponding measurements for radiographer and nurse were below detectable level, implying minimal radiation hazards for them. Regarding radiation exposure, coronary intervention is considered a quite safe procedure for both patients and personnel in laboratories with modern equipment and experienced operators as long as standard safety precautions are considered. Exposure optimization though should be constantly sought through continuous review of procedures.