Purpose
To compare orbital volume replacement between two different acrylic implant sizes (16 and 20 mm diameter) using volumetric calculation, linear and angular parameters by the computed tomography following enucleation
Methods
Prospective randomized comparative study. Thirty two patients underwent enucleation and implantation with a standard techinique by one single surgeon. The selection of the two implant sizes (16 or 20mm) was randomized. Ten months after surgery patients underwent a computed tomography scan of the orbits. Volumetric measureaments of the entire orbital contens and soft tissues were made by the volumetric software tool. Seven new intraorbital (linear and angular) parameters were created. The measurements were made in standardized axial and sagital planes in both orbits. The parameters were made using the interzigomatic line, optical canal and anatomical landmarks of the orbit. The seven parameters was created in order to study the relationship between the soft tissues and implant. Afterwards, they were compared to the normal orbit. Each measurement was subtracted (normal orbit - anophthalmic orbit) and the value used for statiscal analysis. Each parameter was submitted to a apropprated statiscal test (tstudent and Mann Whitney) and the sample size calculated (16 for each group).
Results
Twenty diameter implants had larger volumetric values (4,79±1,20 vs. 2,61±1,26,p<0,0001) and there was no difference in soft tissue volume. The difference between the seven intraorbital parameters was smaller in the twenty diameter implants group: I (0,84±0,15 vs. 0,61±0,17, P = 0,002); II (0,51±0,14 vs. 0,12±0,10, p<0,0001)); III (0,79±0,15 vs. 0,52±0,12, p<0,0001); IV (0,37±0,18 vs. 0,18±0,16, p=0,007); V (0,33±0,15 vs.0,12±0,14, p=0,002), VI (11,18±2,51 vs. 3,35±3,89, p<0,0001) and VII (7,22±2,35 vs. 1,06±2,31, p<0,0001)
Conclusions
A great significance difference was observed between the two different implant sizes. The volumetric measurements and intraorbital parameters demonstrated that volume replacement was better achieved when the twenty diameter implant was used.