Orthopaedics poly

In order to be successful as part of a medical device a polymer has to resist both biological rejection by the patient s body and degradation. The human body is an enviromnent which is simultaneously hostile and sensitive, so that materials for application in medicine must be carefully selected. The essential requirement is that these materials are biocompafible with the particular part of the body in which they are placed. The extent to which polymers fulfil this requirement of biocompafibility depends partly on the properties of the polymer and partly on the location in which they are expected to perform. For example the requirements for blood biocompafibility are stringent since blood coagulation may be triggered by a variety of materials. By contrast, the requirements for materials to be used in replacement joints in orthopaedic surgery are less severe and materials as diverse as poly (methyl methacrylate) and stainless steel can be used with minimal adverse reaction from the body. 

Engineering plastics, particularly thermosets, are also used in composite materials. Their excellent technological properties make them suitable for applications in cars, ships, aircraft, telecommunications equipment, etc. In recent years, important new areas of application for plastics have emerged in medicine (fabrication of artificial organs, orthopaedic implants, and devices for the controlled release of drugs), electronics (development of conductive poly-... 

Peter, S. J., Nolley, J. A., Widmer, M. S., Merwin, J. E., Yaszemski, M. J., Yasko, A. W., Engel, P. S. Mikos, A. G. (1997) In vitro degradation of a poly(propylene fumarate)/beta-tricalcium phosphate composite orthopaedic scaffold. Tissue Engineering, 3, 207-215. 

Timmer, M. D., Carter, C., Ambrose, C. G. Mikos, A. G. (2003b) Fabrication of poly(propylene fumarate)-based orthopaedic implants by photo-crosslinking through transparent silicone molds. Biomaterials, 24, 4707-4714. 

Poly(ether ether ketone) (PEEK), in various formulations, is found in a wide variety of applications as an alternative biomaterial to ceramic, metal and other polymer implants (such as UHMWPE). These applications include trauma fixation, as well as dental, orthopaedic and spinal implants and, as a result of ongoing research, the uses of PERK as a biomaterial continue to grow (Toth et al. 2006). Research conducted by Morrison et al. (1995) emphasised the biocompatibility of PEEK and its composites. This may mean that the probability of adverse tissue reactions induced by wear debris may be minimised through the use of PEEK as an implant material. 

Orthopaedic surgeons must fill defects created by trauma, removal of cancerous tumors, or abnormal development. Bone replacement and fixation are also issues for plastic surgeons in craniofacial procedures, hand and foot deformities, and extremity injuries. Though poly(methyl methacrylate) (PMMA) bone cement is currently in use to address these problems, it in nonbiodegradable, remaining in... 

Ertel, S.I., Kohn, J., Zimmerman, M.C. and Parsons, J.R. (1995) Evaluation of poly(DTH carbonate), a tyrosine-derived degradable polymer, for orthopaedic applications./, Biomed. Mater. Res., 29(11), 1337-1348. 

Aston R, Canham LT (2001) A porous and/or poly crystalline silicon orthopaedic implant. International Patent WO 01/95952 A1... 

S.J. Peter, J.A. Nolley, M.S. Widmer, J.E. Merwin, M.J. Yaszemski, A.W. Yasko, PS. Engel, and A.G. Mikos, In vitro degradation of a poly (propylene fumarate)/(i-tricalcium phosphate composite orthopaedic scaffold. Tissue Eng., 3 (2), 207-215,1997. 

Other acryl polymers used for orthopaedic applications include poly(n-butyl methacrylate) (PBMA), characterized by lower exothermic effect, higher fracture toughness and superior fatigue life as well as lower toxicity to soft tissue and dental pulp [121], and poly(hydroxyethylmethacrylate) (PHEMA), which shows enhanced biocompatibility [122]. 

Petricca SE, Marra KG, Kumta PN (2006) Chemical synthesis of poly(lactic-co-glycolic acid)/hydroxyapatite composites for orthopaedic applications. Acta Biomater 2 277-286... 

Attawia MA, Uhrich KE, Botchwey E et al (1996) In vitro bone biocompatibihty of poly(anhydride-co-imides) containing pyromeUityhmidoalanine. J Orthopaedic Res 14 445 54... 

Biodegradable synthetic polymers such as poly(glycolic acid), poly(lactic acid) and their copolymers, and copolymers of trimethylene carbonate and glycolide have been used in a number of clinical applications [26-30]. The major applications include resorbable sutures, drug delivery systems and orthopaedic fixation devices such as pins, rods and screws [31, 32]. 

Otto Rohm is credited with the development of perhaps the most widely used polymer in orthopaedic surgery— poly(methylmethacrylate) (PMMA)—in 1901 [1] but the material did not come into widespread use in orthopaedics until Sir John Chamley described its use for bonding prostheses to bone in the early 1960s [2]. A good review of the early work in characterizing PMMA including the evolution of the use in orthopaedics can be found in the article by Dennis Smith where he describes his collaboration with Chamley [3]. 

---