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Supplemental PowerPoint Slides. Biomechanical risk factors for proximal junctional kyphosis: a detailed numerical analysis of surgical instrumentation variables Marco Cammarata, BEng 1,2 , Carl-Éric Aubin, PhD, PEng 1,3 , Xiaoyu Wang, PhD 1,3 , Jean-Marc Mac-Thiong, MD, PhD 2,3
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Supplemental PowerPoint Slides Biomechanical risk factors for proximal junctional kyphosis: a detailed numerical analysis of surgical instrumentation variables Marco Cammarata, BEng1,2, Carl-Éric Aubin, PhD, PEng1,3, Xiaoyu Wang, PhD1,3, Jean-Marc Mac-Thiong, MD, PhD2,3 1. Department of Mechanical Engineering, École Polytechnique de Montréal, Canada 2. Research Center, Hôpital du Sacré-Cœur de Montréal, Canada 3. Research Center, Sainte-Justine University Hospital Center, Canada
A total of 576 numerical simulations and a sensitivity analysis were performed for six adult spinal deformity instrumentation cases to assess four biomechanical indices related to the development of PJK: • Immediate postoperative proximal junctional kyphotic angle; • Thoracic kyphosis; • Proximal junctional intervertebral flexion forces; • Proximal junctional intervertebral flexion moment; • The individual effect of four instrumentation variables on each of the above indices was evaluated: • Proximal dissection procedure; • Implant type at the upper instrumented vertebra; • Sagittal thoracic rod curvature; • Proximal diameter of the proximal transition rod;
Each of the followings biomechanically helps reducing the risk of PJK: • Preserving more intervertebral elements at the proximal end of the instrumentation; • Using transverse process hooks instead of pedicle screws at the upper instrumented vertebra; • Using tapered transition rods at the proximal end of the instrumentation. • Monoaxial and multiaxial screws at upper instrumented vertebra had similar effects on the four biomechanical indices. Resulting average, minimum, and maximum values of each biomechanical index (PJ: proximal junctional; TK: thoracic kyphosis; UIV: upper instrumented vertebra)
Typical results for one case (#2): FSU: intact functional spinal unit; BCF: bilateral complete facetectomy; PLD: posterior ligaments dissection; FAS: fixed angle screw; MAS: multiaxial screw; TPH: transverse process hook; PJ: proximal junctional; UIV: upper instrumented vertebra.