Biomedical Engineering Reference
In-Depth Information
10
Cements as bone repair materials
M. P. Ginebra, Technical University of
Catalonia (UPC), Spain
Abstract
:
Bone cements can be defined as biomaterials obtained by mixing
a powder phase and a liquid phase, which can be moulded and implanted as
a paste and have the ability to set once implanted within the body. They are
widely used in different applications of orthopaedic surgery. The possibility
of injecting them extends their use to minimally invasive surgical techniques.
The chapter describes the two main families of bone cements, namely,
acrylic bone cements and calcium phosphate bone cements. The basic
physicochemical, mechanical and biological properties of these two types
of bone cement are reviewed and the most relevant clinical applications are
described.
Key words
:
bone cements, calcium phosphates, hydroxyapatite, polymethyl
methacrylate.
10.1 Definition and advantages of bone
cements in orthopaedic surgery
Bone cements can be defined as a family of materials that consist of a powder
phase and a liquid phase which, after mixing, form a plastic paste which
has the ability to self-set once implanted in the body. This means that the
material is mouldable, which ensures perfect fit at the implant site and good
bone-material contact, even in geometrically complex defects. On the other
hand, the fact that the cements undergo a setting reaction once implanted,
forming a solid body, guarantees a certain level of mechanical support,
although as will be described in the following sections, the mechanical
properties achieved are different in different types of bone cement.
Recent advances in orthopaedic surgery are related to the application
of minimally invasive surgical techniques. In this field it is crucial to have
injectable materials available and, in this sense, bone cements can play a
determinant role, provided injectable cements are developed. An example is
the implementation of some minimally invasive surgical procedures, namely
vertebroplasty and kyphoplasty, to repair vertebral compression fractures,
where bone cements are injected into the vertebral body.
The desirable properties that a bone cement should have are summarized
in Table 10.1. An 'ideal' cement should fulfil all of them. However, there
is no 'ideal' bone cement and all bone cements used nowadays have some
limitations. At present the most frequently used bone cements can be classified
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