Patient-specific three-dimensional composite bone models for teaching and operation planning.
BACKGROUND
Orthopedic trauma care relies on two-dimensional radiograms both before and during the operation. Understanding the three-dimensional nature of complex fractures on plain radiograms is challenging. Modern fluoroscopes can acquire three-dimensional volume datasets even during an operation, but the device limitations constrain the acquired volume to a cube of only 12-cm edge. However, viewing the surrounding intact structures is important to comprehend the fracture in its context. We suggest merging a fluoroscope's volume scan into a generic bone model to form a composite full-length 3D bone model.


METHODS
Materials consisted of one cadaver bone and 20 three-dimensional surface models of human femora. Radiograms and computed tomography scans were taken before and after applying a controlled fracture to the bone. A 3D scan of the fracture was acquired using a mobile fluoroscope (Siemens Siremobil). The fracture was fitted into the generic bone models by rigid registration using a modified least-squares algorithm. Registration precision was determined and a clinical appraisal of the composite models obtained.


RESULTS
Twenty composite bone models were generated. Average registration precision was 2.0 mm (range 1.6 to 2.6). Average processing time on a laptop computer was 35 s (range 20 to 55). Comparing synthesized radiograms with the actual radiograms of the fractured bone yielded clinically satisfactory results.


CONCLUSIONS
A three-dimensional full-length representation of a fractured bone can reliably be synthesized from a short scan of the patient's fracture and a generic bone model. This patient-specific model can subsequently be used for teaching, surgical operation planning, and intraoperative visualization purposes.
Matthews
Felix
F
Brigham and Women's Hospital, Surgical Planning Laboratory, Harvard Medical School, Boston, MA 02115, USA. matthews@bwh.harvard.edu
Messmer
Peter
P
Raikov
Vladislav
V
Wanner
Guido A
GA
Jacob
Augustinus L
AL
Regazzoni
Pietro
P
Egli
Adrian
A
D002102:Cadaver; D005240:Feasibility Studies; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging*; D050723:Fractures, Bone / Q000000981:diagnostic imaging*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008953:Models, Anatomic; D011300:Preoperative Care / Q000379:methods; D015203:Reproducibility of Results; D013663:Teaching / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000379:methods