Stefano Marchetti

Improvement of the bone-pin interface strength in osteoporotic bone with use of hydroxyapatite-coated tapered external-fixation pins. A prospective, randomized clinical study of wrist fractures

Background: Achieving adequate fixation strength in osteoporotic bone is a challenge. In this study, we examined the use of hydroxyapatite-coated tapered external-fixation pins for the fixation of wrist fractures in patients with osteoporosis. Methods: Twenty female patients with osteoporosis and a fracture of the wrist were divided into two paired groups and randomized to receive either standard tapered pins or hydroxyapatite-coated tapered pins. Two pins were inserted in the distal part of the radius, two pins were inserted in the second metacarpal, and an external fixation device was mounted. All fixation devices were removed six weeks after surgery. Results: The mean pin-insertion torque (and standard deviation) was 461 ± 254 Nmm in the group managed with standard pins and 332 ± 176 Nmm in the group managed with hydroxyapatite-coated pins (p = 0.01). The mean pin-extraction torque was 191 ± 155 Nmm in the group managed with standard pins and 600 ± 214 Nmm in the group managed with hydroxyapatite-coated pins (p < 0.0001, power 95%). The mean extraction torque was lower than the corresponding insertion torque at each pin position in the group managed with standard pins (p < 0.05), whereas the mean extraction torque was higher than the corresponding insertion torque at each pin position in the group managed with hydroxyapatite-coated pins (p = 0.001). Two patients managed with standard pins and no patient managed with hydroxyapatite-coated pins had a pin-track infection. Pain during pin removal did not differ between the two groups. Conclusions: The present study showed that hydroxyapatite-coated tapered external-fixation pins provided improved fixation in the treatment of wrist fractures in patients with osteoporosis.

Non-parametric bootstrap mean squared error estimation for M-quantile estimators of small area averages, quantiles and poverty indicators

Small area estimation is conventionally concerned with the estimation of small area averages and totals. More recently emphasis has been also placed on the estimation of poverty indicators and of key quantiles of the small area distribution function using robust models, for example, the M-quantile small area model. In parallel to point estimation, Mean Squared Error (MSE) estimation is an equally crucial and challenging task. However, while analytic MSE estimation for small area averages is possible, analytic MSE estimation for quantiles and poverty indicators is difficult. Moreover, one of the main criticisms of the analytic MSE estimator for M-quantile estimates of small area averages is that it can be unstable when the area-specific sample sizes are small. A non-parametric bootstrap framework for MSE estimation for small area averages, quantiles and poverty indicators estimated with the M-quantile small area model is proposed. Emphasis is placed on second order properties of MSE estimators with results suggesting that the bootstrap MSE estimator is more stable than corresponding analytic MSE estimators. The proposed bootstrap is evaluated in a series of simulation studies under different parametric assumptions for the model error terms and different scenarios for the area-specific sample and population sizes. Finally, results from the application of the proposed MSE estimator to real income data from the European Survey of Income and Living Conditions (EU-SILC) in Italy are presented and information on the availability of R functions that can be used for implementing the proposed estimation procedures in practice is provided.

Small Area Model-Based Estimators Using Big Data Sources

Abstract The timely, accurate monitoring of social indicators, such as poverty or inequality, on a finegrained spatial and temporal scale is a crucial tool for understanding social phenomena and policymaking, but poses a great challenge to official statistics. This article argues that an interdisciplinary approach, combining the body of statistical research in small area estimation with the body of research in social data mining based on Big Data, can provide novel means to tackle this problem successfully. Big Data derived from the digital crumbs that humans leave behind in their daily activities are in fact providing ever more accurate proxies of social life. Social data mining from these data, coupled with advanced model-based techniques for fine-grained estimates, have the potential to provide a novel microscope through which to view and understand social complexity. This article suggests three ways to use Big Data together with small area estimation techniques, and shows how Big Data has the potential to mirror aspects of well-being and other socioeconomic phenomena.

Effect of Stimulation by Low-Frequency Pulsed Electromagnetic Fields in Subjects with Fracture of the Femoral Neck

Low-frequency pulsed electromagnetic fields (hereafter PEMFs) have now been in use in orthopaedics and traumatology for upwards of twenty years. The technique is employed to promote osteogenesis and hence to favour bone repair proc esses1–4. It has recently been shown that PEMFs may be the treatment of choice in avascular necrosis of the femoral head. The treatment has emerged as especially effective in the earliest forms in the staging according to Ficat5.

Nanoparticles for Tendon Healing and Regeneration: Literature Review

Tendon injuries are commonly met in the emergency department. Unfortunately, tendon tissue has limited regeneration potential and usually the consequent formation of scar tissue causes inferior mechanical properties. Nanoparticles could be used in different way to improve tendon healing and regeneration, ranging from scaffolds manufacturing (increasing the strength and endurance or anti-adhesions, anti-microbial, and anti-inflammatory properties) to gene therapy. This paper aims to summarize the most relevant studies showing the potential application of nanoparticles for tendon tissue regeneration.

Vibration Testing Procedures for Bone Stiffness Assessment in Fractures Treated with External Fixation

A bone healing assessment is crucial for the successful treatment of fractures, particularly in terms of the timing of support devices. However, in clinical practice, this assessment is only made qualitatively through bone manipulation and X-rays, and hence cannot be repeated as often as might be required. The present study reconsiders the quantitative method of frequency response analysis for healing assessments, and specifically for fractures treated with an external fixator. The novelty consists in the fact that bone excitation and response are achieved through fixator pins, thus overcoming the problem of transmission through soft-tissues and their damping effect. The main objective was to develop and validate a test procedure in order to characterize the treated bone. More than 80 tests were performed on a tibia phantom alone, a phantom with pins, and a phantom with a complete fixator. Different excitation techniques and input–output combinations were compared. The results demonstrated the effectiveness of a procedure based on impact tests using a micro-hammer. Pins and fixator were demonstrated to influence the frequency response of the phantom by increasing the number of resonant frequencies. This procedure will be applied in future studies to monitor healing both in in vitro and in vivo conditions.

Osteoid osteoma: CT-guided radio-frequency ablation

Abstract Purpose. This work aimed to evaluate the feasibility, safety and efficacy of computed Tomography (CT)-guided radio-frequency (RF) treatment for the in situ treatment of osteoid osteoma. Materials and methods. Since March 1997, 17 patients (14 males, 3 females) with 18 osteoid osteomas underwent CT-guided radio-frequency thermal ablation. Lesions were located in the femur ( n =13), tibia ( n =3), radius ( n =1) and ulna ( n =1). All patients had presumptive diagnosis of osteoid osteoma on the basis of clinical and radiographic findings. The duration of pain before treatment ranged between 6 and 18 months (mean: 9 months). Of the 18 procedures, 15 were performed percutaneously while 3 others were performed after surgical exposure of the bone. No surgical treatments were performed before RF ablation. A 17-gauge electrode needle with 2-cm exposed tip was introduced into the nidus through an 11-gauge biopsy set. Results. All the procedures were technically successful. Of 17 patients, 14 were completely free of pain within 2 days post-treatment. In two patients, complete relief from pain was achieved after a second RF ablation. In another case, no clinical response was observed; the patient refused to repeat treatment and underwent surgery. Two cases had superficially dermal burns with skin and soft tissue necrosis.

Fracture Healing Assessment Based on Impact Testing: In Vitro Simulation and Monitoring of the Healing Process of a Tibial Fracture with External Fixator

In clinical practice, bone healing is monitored with X-rays and manipulation. Its assessment is thus subjective, depending on the skills of the operator. Alternative and quantitative approaches hav...

Small Area Estimation of Poverty Indicators

The estimation of poverty, inequality and life condition indicators all over the European Union has become one topic of primary interest. A very common target is the core set of indicators on poverty and social exclusion agreed by the Laeken European Council in December \(2001\) and called Laeken indicators. They include measures of the incidence of poverty, such as the Head Count Ratio (also known as at-risk-of-poverty-rate) and of the intensity of poverty, as the Poverty Gap. Unfortunately, these indicators cannot be directly estimated from EU-SILC survey data when the objective is to investigate poverty at sub-regional level. As local sample sizes are small, the estimation must be done using the small area estimation approach. Limits and potentialities of the estimators of Laeken indicators obtained under EBLUP and M-quantile small area estimation approaches are discussed here, as well as their application to EU-SILC Italian data. The case study is limited to the estimation of poverty indicators for the Tuscany region. However, additional results are available and downloadable from the web site of the SAMPLE project, funded under the 7FP (http://www.sample-project.eu).

In vivo impact testing on a lengthened femur with external fixation: a future option for the non-invasive monitoring of fracture healing?

Non-invasive methods for assessing fracture healing are crucial for biomedical engineers. An approach based on mechanical vibrations was tried out in the 1990s, but was soon abandoned due to insufficiently advanced technologies. The same approach is re-proposed in the present study in order to monitor the healing process of a lengthened femur with an external fixator. The pins screwed into the bone were exploited for the impact testing (IT) to excite the bone and capture its response. Transmission through the soft tissues was thus prevented, and the quality of the signals was improved. Impact tests were performed every three to four weeks for five months. Unfortunately, after seven weeks, some pins were removed due to infection, and thus, the system was modified. Two different configurations were considered: before and after pin removal. An additional configuration was examined in the last two sessions, when the fixator body was removed, while four pins were left in the femur. The evolution of the frequency response function and of the resonant frequencies of the system were analysed for the duration of the monitoring period. The IT results were compared to the indications provided by X-ray images. During the evolution of the callus from the soft phase to the woven bone, the resonant frequencies of the system were found to increase by approximately 2–3% per week. The largest increase (approx. 22%) was observed for the first resonant frequency. After formation of the woven bone, the vibratory response remained almost the same, suggesting that the healing assessment could be related to the relative variation in the resonant frequencies. The results presented support the application of the IT approach for fracture healing assessment.