Effects of Ilial and Ischial Osteotomy Angles on the Structural Pelvic Anatomy in Triple and 2.5 Pelvic Osteotomy Using 3D-printed Bone Models

To describe the effects of varying ilial and ischial osteotomy angles on the structural anatomy of the pelvis in triple (TPO) and 2.5 pelvic osteotomy (2.5 PO) models regarding femoral head coverage (FHC), interischiatic tuberosity distance (ITD), and displacement of the caudal ilial fragment. Descriptive, anatomical study on three-dimensionally printed, pelvic models. A total of 10 identical three-dimensionally printed polyethylene models replicating a non-dysplastic, pelvic specimen of a 20 kg dog were used. Three types of ilial osteotomy were compared in TPO models and combined with two types of ischial osteotomy in 2.5 PO models. Computed tomography (CT) scans were performed, and measurements were obtained using multiplanar reconstructed (MPR) images and thick-slab mean rendering. The ilial osteotomy perpendicular to the pelvic floor (TC) provided greater and more equally distributed FHC in TPO and 2.5 PO models. Combination of TC ilial osteotomy with a sagittal ischial osteotomy (LO) resulted in the least amount of displacement of the caudal ilial fragment in 2.5 PO. Medially angled ischial osteotomy (MO) resulted in a high degree of lateralization of the caudal ilial segment. Ilial osteotomy perpendicular to the pelvic floor (TC) may potentially reduce bending and shearing forces on implants and bone in TPO and 2.5 PO surgery. Sagittal orientation of the partial ischial osteotomy in 2.5 PO appears to be imperative to achieve reduction of the ilial osteotomy site. Clinical relevance of these findings would need to be investigated further.