Vascularization of coralline versus synthetic hydroxyapatite orbital implants assessed by gadolinium enhanced magnetic resonance imaging

Purpose: To evaluate the fibrovascular in-growth of coralline and synthetic hydroxyapatite orbital implants by reporting the enhancement patterns on Gadolinium-Dietilen triamin penta acetic acid (Gad-DTPA) enhanced magnetic resonance imaging (MRI).

Methods: The medical records of 26 patients who had undergone primary or secondary orbital implantation between April 2008 and February 2011 were reviewed. T1 weighted Gad-DTPA MRI was performed between 5 and 12 months (mean 9.2 ± 5.9 months) after implantation and graded as follows to evaluate the fibrovascular in-growth of the implants; grade 1 (rim enhancement), grade 2 (peripheral foci of enhancement, not including the center), grade 3 (central, non-homogenous enhancement), grade 4 (central, homogenous enhancement) and grade 5 (central, intense enhancement).Results were analysed according to vascularization patterns on Gad-DTPA MRI.

Results: Central vascularization patterns (grade 3, 4 or 5) were seen 62.5% of coralline orbital implants and 46.1% of synthetic orbital implants. Central fibrovascular in-growth of the coralline implants were found significantly more than synthetic implants (p < 0.05). Central vascularization of coralline implants with primary implantation was 75% and with secondary implantation was 50%. Synthetic orbital implantation with primary surgery demonstrated 66.6% and synthetic orbital implantation with secondary surgery demonstrated 26.6% central vascularization pattern. In both natural coralline and synthetic implants, primary orbital implantation was demonstrated significantly better fibrovascular in-growth than secondary implantation (p < 0.05). Two patients with synthetic orbital implants had dehiscence that was repaired by using autogenous fascia lata.

Conclusions: In both coralline and synthetic orbital implants, central vascular in-growth was observed much more with primary orbital implantation. This study indicates that coralline HA orbital implants significantly supply more rapid and homogenous vascularization than synthetic implants.