A novel 3D technique to assess symmetry of hemi pelvises

Abstract

Anatomical reconstruction of pelvic fractures has been shown to affect functional outcome. Using the contra lateral side of the extremities to create a template for an ipsilateral reconstruction is common practice in orthopedic surgery. We aimed to assess whether hemi pelvises are symmetrical in terms of translation and rotation using 3D reconstruction, point to point mirroring and merging of the 3D created volumes, a method with previous proven high precision and accuracy. CT images of ten randomly selected patients were used. The DICOM images were converted to STL files. Three dimensional images of left hemi pelvis were reversed and merged with the right side. The posterior aspect of the pelvises was considered static and the anterior aspect as moving. Differences in translation and rotation were measured. There were no statistically significant differences between right and left hemi pelvis. The 95% confidence interval (CI) for all mean angular differences between right hemi pelvis and mirrored left hemi pelvis were − 2° to 1.5°. The 95% CI for all mean translational differences between these two objects were − 2.3 to 2.9 mm. Differences between the right hemi pelvis and the mirrored images of the left hemi pelvis for any patient greater than 3 mm or 2 degrees could be excluded with a 95% confidence. The left and right hemi pelvis of healthy adults are symmetrical enough. The pre-operative planning based on a healthy contra lateral side seems reasonable.

A Novel Technique to Assess Rotational Deformities in Lower Extremities

“…The strength of our study is it´s novelty and it´s automated calculation technique. We have been able to show that this technique is doable precise, accurate and repeatable in previous studies [6][7][8].…”

“…The main nding of our study was that it is possible to use our proposed technique in clinical practice as the software is commercially available and low dose CT scan of the lower extremities is possible [6][7][8].The second nding of our study was that, the left and right lower limbs of healthy adults were highly symmetrical in terms of length and rotation. They were further symmetrical in terms of recurvatum and antecurvatum.…”

“…This study was modelled on a previous similar works on femur and pelvis analysis [6][7][8]. Study protocol was approved by the Imperial College Healthcare and NHS Medical Research Council prior to conduction.…”

“…Further pre-operative planning is widely employed in elective and emergency orthopaedic surgery for its numerous bene ts, including optimization of implant placement and simpli cation of intraoperative decision making. Trauma complicates the planning process by altering anatomy, obscuring the blueprint from which direct inferences can be made [6][7][8].…”

“…There are previous rigorous researches using 3D images of the bone or implants and merging of the surface anatomies to report either excessive motion over time or mismatch in anatomy [6][7][8][14][15][16][17].…”