Orbital Floor Reconstruction: 3-Dimensional Analysis Shows Comparable Morphology of Scapular and Iliac Crest Bone Grafts

Abstract

Purpose: Current nonvascular osseous reconstructive options for reconstruction of the orbital floor after maxillectomy include options such as scapular tip and iliac crest bone grafts. The aim of this study was to determine whether these donor sites were morphologically comparable with the orbital floor.

Materials and methods: A retrospective cross-sectional study design was selected. By use of a pre-existing melanoma database (January 1, 2005, through September 20, 2015), computed tomography scans of the head, neck, thorax, and pelvis were obtained from patients without evidence of bony metastases. With the use of 3-dimensional software (Mimics; Materialise, Leuven, Belgium), grafts from the scapulae and iliac crests, the predictor variables, were digitally harvested, co-registered with the orbital floors bilaterally, and analyzed. The primary outcome was conformance. Data were analyzed using descriptive statistics and tests of statistical significance. The significance level was set at P<.05.

Results: The study sample included 10 patients (6 men and 4 women; mean age, 55 ± 18 years). Close conformance was observed when we analyzed the morphology of the orbital floor to the scapular (2.23 ± 0.31 mm) and iliac crest (2.13 ± 0.30 mm) bone grafts, with no significant difference between sites. Conformance mapping showed maximum conformance centrally (scapula, 0.001 ± 0.001 mm; iliac crest, 0.001 ± 0.001 mm), with decreased morphologic similarity peripherally (scapula, 6.09 ± 0.94 mm; iliac crest, 5.74 ± 0.88 mm). There was no significant difference in conformance between sides of graft harvest.

Conclusions: When considering nonvascularized bone grafts for reconstruction of the orbital floor, both the scapula and iliac crest offer nearly complete conformance to the orbital floor structure and represent reasonable reconstructive options.