Point-to-point computer-assisted navigation for precise transfer of planned zygoma osteotomies from the stereolithographic model into reality.
OBJECTIVE
To evaluate the feasibility and accuracy of a new method for planning and realizing zygomatic osteotomies in cases of established post-traumatic deformities using stereolithographic (SL) models and computer assisted navigation.


METHODS
In 5 patients, osteotomy and repositioning of the zygomatic complex was planned using SL models. The desired position of the zygoma in the patient was determined by fixing individualized osteosynthesis plates to predefined screw positions. The SL model and the patient were registered to the same 3-dimensional computed tomography data set via an occlusal reference frame on the patient and corresponding reference markers on the model. Prebent osteosynthesis plates from the surgical simulation on the model were fixed to corresponding screw positions on the patient, which were located by computer-assisted navigation. Evaluation of accuracy was performed by image fusion of postoperative computed tomography scans of the model and the patient.


RESULTS
Clinical outcome was satisfactory in all cases. The evaluation by image fusion showed alignment of the patient's and the model's zygoma in 4 of 5 cases. Mean measured distance between screw positions in the models and the patients were 1.1 +/- 0.3 mm for 44 screws. In 1 patient the treatment plan was changed intraoperatively because of unforeseen soft tissue limitations.


CONCLUSIONS
Point-to-point navigation is an accurate method to transfer the planning of a complex osteotomy from the SL model to the actual surgical procedure. Surgery is facilitated considerably because repositioning and osteosynthesis are achieved in 1 step.
University Hospital of Cranio-Maxillofacial and Oral Surgery, Medical University of Vienna, Vienna, Austria. clemens.klug@univie.ac.at
Clemens
C
Klug
Kurt
K
Schicho
Oliver
O
Ploder
Kaan
K
Yerit
Franz
F
Watzinger
Rolf
R
Ewers
Arnulf
A
Baumann
Arne
A
Wagner
D000328:Adult; D005146:Facial Asymmetry / Q000000981:diagnostic imaging / Q000209:etiology / Q000601:surgery*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D008953:Models, Anatomic; D010027:Osteotomy / Q000379:methods*; D010347:Patient Care Planning; D025321:Surgery, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D015050:Zygoma / Q000000981:diagnostic imaging / Q000293:injuries / Q000601:surgery; D015051:Zygomatic Fractures / Q000150:complications / Q000000981:diagnostic imaging / Q000601:surgery*