Minimally invasive bioabsorbable bone plates for rigid internal fixation of mandible fractures.
OBJECTIVE
To optimize design variables of a bioabsorbable bone plate using a finite element model of the mandible and to discover a minimally invasive bioabsorbable bone plate design that can provide the same mechanical stability as a titanium plate.


METHODS
A finite element model of a mandible with a fracture in the body was subjected to bite loads. An analysis was run to determine the principal strain in the fracture callus and von Mises stress in a titanium plate. These values were then set as the limits within which the bioabsorbable bone plate must comply. The model then considered a bone plate made of the polymer poly(L-lactide-co-D,L-lactide) (P[L/DL]LA) 70/30. An optimization routine determined the smallest volume of bioabsorbable bone plate that can perform as well as a titanium bone plate when fixating mandibular fractures.


RESULTS
A P(L/DL)LA plate volume of 315 mm(2) with a thickness of 1.5 mm provided as much mechanical stability as a commonly used titanium strut structure of 172 mm(2). The peak plate stress was well below the yield strength of the material.


CONCLUSIONS
The P(L/DL)LA bioabsorbable bone plate design is as strong as a titanium plate when fixating fractures of the mandible body despite the polymer material having only 6% of the stiffness of the titanium. The P(L/DL)LA plate can be less than half the volume of its strut-style counterpart.
Ear, Nose and Throat Department, Naval Medical Center San Diego, 34520 Bob Wilson Dr, San Diego, CA 92130, USA.
Curtis
C
Gaball
Scott
S
Lovald
Bret
B
Baack
Garth
G
Olson
D020341:Absorbable Implants; D001732:Bite Force; D001860:Bone Plates; D001863:Bone Screws; D020342:Finite Element Analysis; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D006801:Humans; D008337:Mandibular Fractures / Q000601:surgery*; D019060:Minimally Invasive Surgical Procedures; D011091:Polyesters; D011474:Prosthesis Design; D014025:Titanium; D014057:Tomography, X-Ray Computed
D011091:Polyesters; C033616:poly(lactide); D014025:Titanium