New resorbable bone fixation. biomaterials in craniomaxillofacial surgery

Eur J Plast Surg (2004) 26:383–390 DOI 10.1007/s00238-003-0568-8

REVIEW

N. Ashammakhi · A. M. Gonzalez · P. Törmälä · I. T. Jackson

New resorbable bone fixation. Biomaterials in craniomaxillofacial surgery: present and future
Received: 21 April 2003 / Accepted: 26 August 2003 / Published online: 21 November 2003  Springer-Verlag 2003

Abstract Metallic implants have been extensivelyused for osteofixation in craniomaxillofacial surgery (CMF). Although they are mainly inert, the disadvantage of not being resorbable remains. Advances in biomaterials technology led to the development of resorbable polymers composed by monomeric units that are naturally present in the body. Among them are polylactide (PLA), polyglycolide (PGA) and their copolymers [PLGA and P(L/ DL)LA]. Afterin-depth studies of the structure of these materials, the self-reinforced (SR) technology has merged to solve their mechanical limitations. SR is based on reinforcing elements within the same material, increasing their strength. Ultra-high strength implants were then manufactured by the SR technique. In CMF surgery, SR devices have been used for over 10 years without reported complications. Asadvantages, SR devices have shown to be biocompatible, reliable, easily handled, and to have favorable degradation properties. At present, copolymeric SR devices [P(L/DL)LA, BioSorb FX, and PLGA, BioSorb PDX] represent an advance in the clinical application of absorbable devices in CMF surgery. The aim of this review is to give an overall understanding of the ultimate advances in biomaterial researchfor CMF reconstruction, with emphasis in self-reinforced resorbable devices. We also intend to give insight into new devices, such as SR, tacks and their applicability. Keywords Craniomaxillofacial surgery · Resorbable materials · Craniomaxillofacial surgery · PLLA · PLGA · PGA

Introduction
The ultimate goal in surgery is to restore structure and function to a natural state [1]. Incraniomaxillofacial surgery stable and reliable osteofixation is an absolute condition for this. Metal implants usually provide good osteofixation. However, several complications and adverse effects have been described regarding their use [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]. The idea of developing fixation implants that gradually lose strength and resorb after bone healing has stimulated the ultimateresearch in biomaterials. These resorbable implants were produced from polymers whose monomeric units are naturally occurring in the body. This allows their degradation and resorption without toxic organ accumulation. Among the various resorbable polymers, the polyesters polylactide (PLA), polyglycolide (PGA) and their copolymers [P(L/DL)LA and PLGA] are the most important and commonly used. They arebiocompatible, and resorbable through biological processes. They have controlled adjustable mechanical properties and degradation rates [13, 14, 15,16, 17, 18]. Especially successful are the new self-reinforced (SR) resorbable devices. This means reinforcing the polymeric matrix with oriented fibers of the same material, which adds metal-like initial mechanical properties to the implants [17].Plates, screws, pins, and recently, tacks and distraction devices made of resorbable materials have been developed. Results obtained from experimental studies using these implants in craniomaxillofacial surgery have been encouraging [18, 19, 20, 21, 22, 23, 24, 25, 26, 27]. The recent advances in resorbable polymeric biomaterials research, their development, experience and applications will bedescribed and discussed. Copolymers and SR devices applied for craniofacial reconstruction will be focused on particularly.

N. Ashammakhi · P. Törmälä Institute of Biomaterials, Tampere University of Technology, Tampere, Finland A. M. Gonzalez · I. T. Jackson ()) Institute for Craniofacial and Reconstructive Surgery, 16100 W Nine Mile Rd., Fisher Center, 3rd Floor, Southfield, MI 48075, USA e-mail:...