The Physical Measurement of Bone

Langton, CM. and Njeh CF(ed.)
IoP Publishing, 2003, 640 pages
ISBN 0750308389

"The Physical Measurement of Bone" is the latest volume in the Series in Medical Physics and Biomedical Engineering published by the Institute of Physics. This is the official book series of the International Organisation for Medical Physics (IOMP) and the International Federation for Medical and Biological Engineering (IFMBE). The series is intended to provide a comprehensive library about the applications of physical science, engineering and mathematics in medicine and biology for graduate students and researchers in medical physics, biomedical engineering, radiology, radiotherapy and clinical research. Other recently published volumes are "Therapeutic Applications of Monte Carlo Calculations in Nuclear Medicine" (September 2002) and "Minimally Invasive Medical Technology" (January 2001).

"The Physical Measurement of Bone" is divided into five sections (although the table of contents mentions only the first four): Introduction (pp. 1-122), Invasive techniques (pp. 123-264), Ionizing radiation techniques (pp. 265-376), Non-ionizing techniques (pp. 377-547) and Clinical applications (pp. 548-600) and counts 600 pages. Editors are CM Langton and CF Njeh. Twenty-two authors, all authorities in their field, contributed to one or more chapters. Despite its title and the preface announcing it as "… the first book that has addressed in one volume the various physical measurement techniques for bone", the book is apparently largely written from the point of view of the diagnosis of osteoporosis. Consequently, it is heavily focused on density measurements and their relation with bone structure and strength. Nevertheless, it indeed covers all types of physical measurements that are done and have been done on bone, in vivo as well as in vitro, both for clinical and for research purposes: mechanical tests, microscopy and histomorphometry, and clinical imaging techniques. The book thus fulfils its promise.

The first chapter of the introductory section gives an overview of the anatomy, physiology and disease of bone. Unfortunately, this is one of the weakest chapters of the book. Bone structure is discussed without any illustration, for instance. Surely, it is a bit strange to have to wait until page 126 (in the chapter about mechanical testing) for a drawing of what bone looks like in a book devoted to bone, certainly if it is also intended for graduate students. The same holds for the discussion of collagen, which is also described without a figure of what it looks like. Important issues like Wolff's law and mechanical adaptation of bone are barely mentioned. The whole chapter comprises 23 pages, thirteen of which discuss the structure and composition of bone and ten give an overview of bone diseases, mostly osteoporosis. This seems a bit biased. The three other chapters of this section are devoted to safety (biological and radiological) and instrument evaluation issues. They are interesting and well written, but it would maybe have been better to put them at the end of the book. Particularly the chapter about radiation safety suffers from the fact that measurement techniques are mentioned which have not yet been described. The second chapter (biological safety) is poorly structured (chemical and electrical hazards are listed under mechanical hazards for one reason or another, for instance). The chapter about instrument evaluation mentions several statistical techniques, but it is too concise to be really useful.

The three other sections are of course the most interesting of the book. Section II (Invasive techniques), discusses mechanical testing (chapter 5), histomorphometry (chapter 6) and microscopy and related techniques (chapter 7). Mechanical testing of bone samples is discussed thoroughly and completely (with a good overview about indentation techniques too). The chapter suffers from poor quality and even erroneous figures, though, and also the text and even formulas contain some errors. In the paragraph about ultrasound velocity v is replaced by frequency "ν" in the formulas (5.9) and (5.10) and in formula (5.24), "ρ" is replaced by p.

The chapter about histomorphometry contains numerous interesting tables with descriptions of the most important processing and staining techniques. It also presents a good overview of microfractures and microcalluses and the way to make them visible and discern them from preparation artefacts. A weakness is the fact that the equations for the derivation of trabecular architectural variables (listed in table 6.1) are not explained. This chapter is focused more on biological background and justification of histomorphometrical techniques than on their explanation or on results. In the chapter about microscopy and related techniques, the paragraphs about immunohistochemistry (7.3) are probably too sophisticated for novices. The discussion about this technique presumes too much (bone)biology knowledge. Again, the other parts present well-written, concise discussions of most microscopical techniques (BSE, EDX, SEM, TEM, AFM and CFM), and their possibilities and limitations. The physical principles at the basis of the techniques are not always explained, however.

The section about ionizing radiation techniques covers all present day clinical imaging techniques (apart from MRI): absorptiometric measurements (chapter 8), QCT (chapter 9) pQCT and "µ"CT (chapter 10). It even discusses outdated techniques such as radiogrammetry (chapter 11) and neutron activation analysis and photon scattering (chapter 12). The two last chapters are certainly interesting from a historical point of view, but they are somewhat long considering the techniques' current insignificance. Each chapter usually gives a short introduction about the physical principles at the basis of the technique (albeit rather concise in some chapters), discusses the practical aspects and clinical applications of the measurements and gives an overview of the results in literature. Safety, accuracy and precision of the technique are usually discussed too.

The same structure is held in the fourth section about non-ionizing techniques. In this section, magnetic resonance imaging (chapter 13) and, very extensively, quantitative ultrasound (chapter 14) and vibration analysis (chapter 16) are reviewed. This section also contains a chapter about finite element modelling, although this is of course not a physical measurement technique in the strict sense. Unfortunately, the chapter about MRI lacks a good explanation of the basic working principle and this makes it hard at times to fully comprehend the extensive overview of results obtained with this technique. The chapters about quantitative ultrasound, finite element modelling and vibration analysis are better in this respect. They give a very good and intelligible overview of their respective fields with a lot of references for the interested reader.

Finally, two more chapters present an overview of human studies and animal studies relating specifically to density measurements and diagnosis and treatment of osteoporosis. Both of them, but particularly the first, are in fact superfluous since they only repeat very briefly what has been said in the previous chapters already. It would probably have been a better idea to put them at the beginning of the book as a kind of introduction.

To summarise: this is an interesting book which fulfils its promise and gives a good overview of all types of physical measurements on bone. In this respect it certainly has its place in any library concerned with bone. A serious drawback however is the poor quality of the illustrations in some chapters and the numerous errors (mostly due to sloppiness) in the text.

Luc Labey, PhD
Division of Biomechanics and Engineering Design
K.U.Leuven
Email: luc.labey@mech.kuleuven.ac.be