Assessment of tibial fracture healing using dual energy X-ray absorptiometry

The assessment of fracture healing is largely a matter of clinical judgement, often based on observing x-rays showing the formation of bridging callus or obscuration of the fracture line and an impression of fracture stiffness obtained by manual loading. In circumstances where these assessment methods are compromised, for example in fractures stabilised using either external fixation or intramedullary nailing, the determination of healing can be problematic. Dual Energy X-ray Absorptiometry (DXA) provides a quick, non-invasive and quantitative method of measuring bone density, which could enable the change in mineral content at a healing site to be monitored. This study evaluated the viability of using DXA to assess the healing of tibial fractures stabilised using intramedullary nails and external fixators. Trials have been undertaken on a Lunar DPX-L scanner situated at South Cleveland Hospital, Middlesbrough. Aluminium and hydroxyapatite phantoms have been used to determine the accuracy, sensitivity and reproducibility of the DXA measurements. Small fracture gaps of less than 0.05 mm were detectable on both simulated transverse and oblique fractures. BMD values which one might expect at a fracture site could be accurately measured down to 0.16 g cm(^-2)14 Patients with tibial fractures (6 with intramedullary nails and 8 with external fixators) have been measured at 4 week intervals following trauma. The bone mineral density (BMD) at regions of interest along the fractured tibial shaft were compared to the non-fractured contra-lateral. Anatomical landmarks were used to relocate the regions of interest between scans and good reproducibility of results (coefficient of variation = 3.36 %) was obtained. After an initial fall in the first month, the BMD at the fracture site gradually increased to the original unfractured value by approximately the fifth month post-fracture. Proximal and distal to the trauma site there was a gradual decrease in BMD in all of the patients, which persisted for about 5 months post-fracture

Microcomputed Tomography Applications in Bone and Mineral Research

Microcomputed tomography (μCT) has evolved as a development of simple X-ray imaging into an indispensable technique used in both laboratory research and clinical diagnostics. Commercially available systems are capable of creating images at sub-micrometer resolutions to map out the complex web of trabecular bone in small animals, and offer an accurate measurement of bone mineral density for patients at risk of osteoporotic fractures. This review describes the development of μCT, its ability to analyze bone, and how it can be used alongside other clinical and laboratory techniques. μCT offers a non-destructive alternative for imaging mineralized tissues with no required preparation and can also be utilized with living specimen to track skeletal development

Experimental and numerical investigations of bone drilling for the indication of bone quality during orthopaedic surgery

Bone drilling is an essential part of many orthopaedic surgical procedures, including those for internal fixation and for attaching prosthetics. Drilling into bone is a fundamental skill that can be both very simple, such as drilling through long bones, or very difficult, such as drilling through the vertebral pedicles where incorrectly drilled holes can result in nerve damage, vascular damage or fractured pedicles. Also large forces experienced during bone drilling may promote crack formation and can result in drill overrun, causing considerable damage to surrounding tissues. Therefore, it is important to understand the effect of bone material quality on the bone drilling forces to select favourable drilling conditions, and improve orthopaedic procedures. [Continues.

Elastic Photon Scattering for Tissue Analysis

This thesis presents a new technique in which x-ray diffraction has been adapted to the clinical environment in order to quantify the osteoporotic state of bone tissue. The constraints of a clinical system demand diffraction apparatus with short wavelengths, a low photon flux and a short measurement time. Of the two forms of measurement for recording diffraction patterns the fixed detector, energy dispersive technique was found to be better suited to clinical work than the scanning detector, angular distributive approach. Various procedures to remove unwanted effects in the data are presented, along with a Monte Carlo simulation designed to investigate the effect of variation in patient thickness and bone volume on the relative proportion of elastic scatter. Diffraction peaks due to bone and marrow tissue were identified in the scatter pattern of trabecular bone. The relative intensities of the two peaks within the pattern are shown to quantify the relative proportions of the two components, and so the bone-to-marrow peak ratio was proposed as a parameter to assess the osteoporotic state of trabecular tissue. Results from anthropomorphic phantoms demonstrate a significant correlation between this method and the established bone density measurement techniques of quantitative computerised tomography and Compton scatter densitometry. The inherent uniqueness of the diffraction pattern was also applied to tissue characterisation, in particular to the identification of gallstones. Gallstones can be classified into three main categories according to their crystalline constituents, each type requiring different patient treatment. A clear distinction between the three stone types is demonstrated with this method. The principal advantages of this technique are its ability to focus on a small volume within the object, such as the trabecular region within bone, the capability of in-vivo measurement and the ability to isolate the responses from the bone and marrow

Quantitative imaging techniques for the assessment of osteoporosis and sarcopenia

Bone and muscle are two deeply interconnected organs and a strong relationship between them exists in their development and maintenance. The peak of both bone and muscle mass is achieved in early adulthood, followed by a progressive decline after the age of 40. The increase in life expectancy in developed countries resulted in an increase of degenerative diseases affecting the musculoskeletal system. Osteoporosis and sarcopenia represent a major cause of morbidity and mortality in the elderly population and are associated with a significant increase in healthcare costs. Several imaging techniques are currently available for the non-invasive investigation of bone and muscle mass and quality. Conventional radiology, dual energy X-ray absorptiometry (DXA), computed tomography (CT), magnetic resonance imaging (MRI) and ultrasound often play a complementary role in the study of osteoporosis and sarcopenia, depicting different aspects of the same pathology. This paper presents the different imaging modalities currently used for the investigation of bone and muscle mass and quality in osteoporosis and sarcopenia with special emphasis on the clinical applications and limitations of each technique and with the intent to provide interesting insights into recent advances in the field of conventional imaging, novel high-resolution techniques and fracture risk

A review on quantitative ultrasound of fast and slow waves

Offering inexpensive, widely available and safe method to evaluate the bone condition as a prevention step to predict bone fracture which caused by Osteoporosis disease makes ultrasound becomes an alternative method beside X-ray based bone densitometry. Conventional quantitative ultrasound (QUS) applies the analysis of attenuation and velocity to estimate bone health with several measurement techniques which analyzes different types of ultrasound waves and bones. However, most of the QUS results still does not match the accuracy of the Dual X-ray absorptiometry due to the interaction of ultrasound and bone microstructure are not fully exploited. The Biot’s theory has predicted that, porous medium like a cancellous bone supporting two types of longitudinal wave known as fast and slow wave which depends on the type of medium travelled. Both experiment and simulation were conducted to investigate the correlation of fast and slow waves individually with a variety of cancellous bone condition. Some of the analysis methods are based on conventional QUS methods. The fast and slow wave relates more to the microstructure of the cancellous bone compared to overall waves. In addition, overall waves had been proven to consist of fast and slow wave and can be separated using Bayesian methods. Overall waves also found to suffer artifact such as phase cancellation and negative dispersion that could cause confusion in analyzing the parameters of ultrasound wave with bone structure. In vivo application based on fast and slow wave analysis is able to produce results based on mass density which can be compared directly and have high correlation with X-ray based bone densitometry. The recent backscattered simulation result indicates that, fast and slow waves can be reflected inside the cancellous bone might offer a new method to evaluate bone especially in crucial skeletal parts