Research

A new adhesive technique for internal fixation in midfacial surgery

Kira Endres^1* , Rudolf Marx² , Joachim Tinschert¹ , Dieter Christian Wirtz³ , Christian Stoll⁴ , Dieter Riediger⁵ and Ralf Smeets^5*

¹  University Hospital Aachen, Dental Prosthetics Clinic, Medical Materials R&D Laboratory, Pauwelsstraße 30, 52057 Aachen, Germany

²  CC&A Medical Components Ltd., Pauwelsstraße 19, 52057 Aachen, Germany

³  University Clinic Bonn, Clinic for Orthopaedics and Accident Surgery, Sigmund-Freud-Straße 25, 53127 Bonn, Germany

⁴  University Hospital Charité Berlin, Ruppiner Kliniken GmbH, Plastic Surgery Clinic for the Teeth, Mouth, Jaw and Face, Fehrbelliner Straße 38D, 16816 Neuruppin, Germany

⁵  University Hospital Aachen, Departement for oral and maxillofacial surgery, Pauwelsstr. 30, 52057 Aachen, Germany

author email corresponding author email* Contributed equally

BioMedical Engineering OnLine 2008, 7:16doi:10.1186/1475-925X-7-16

Published:	19 May 2008

Abstract

Background

The current surgical therapy of midfacial fractures involves internal fixation in which bone fragments are fixed in their anatomical positions with osteosynthesis plates and corresponding screws until bone healing is complete. This often causes new fractures to fragile bones while drilling pilot holes or trying to insert screws. The adhesive fixation of osteosynthesis plates using PMMA bone cement could offer a viable alternative for fixing the plates without screws. In order to achieve the adhesive bonding of bone cement to cortical bone in the viscerocranium, an amphiphilic bone bonding agent was created, analogous to the dentin bonding agents currently on the market.

Methods

The adhesive bonding strengths were measured using tension tests. For this, metal plates with 2.0 mm diameter screw holes were cemented with PMMA bone cement to cortical bovine bone samples from the femur diaphysis. The bone was conditioned with an amphiphilic bone bonding agent prior to cementing. The samples were stored for 1 to 42 days at 37 degrees C, either moist or completely submerged in an isotonic NaCl-solution, and then subjected to the tension tests.

Results

Without the bone bonding agent, the bonding strength was close to zero (0.2 MPa). Primary stability with bone bonding agent is considered to be at ca. 8 MPa. Moist storage over 42 days resulted in decreased adhesion forces of ca. 6 MPa. Wet storage resulted in relatively constant bonding strengths of ca. 8 MPa.

Conclusion

A new amphiphilic bone bonding agent was developed, which builds an optimizied interlayer between the hydrophilic bone surface and the hydrophobic PMMA bone cement and thus leads to adhesive bonding between them. Our in vitro investigations demonstrated the adhesive bonding of PMMA bone cement to cortical bone, which was also stable against hydrolysis. The newly developed adhesive fixing technique could be applied clinically when the fixation of osteosynthesis plates with screws is impossible. With the detected adhesion forces of ca. 6 to 8 MPa, it is assumed that the adhesive fixation system is able to secure bone fragments from the non-load bearing midfacial regions in their orthotopic positions until fracture consolidation is complete.