I was curious as to why my surgeon chose to use hooks at the top of my fusion (T-6 & T-7) and leahdragonfly mentioned to me that Dr Hart told her it was to reduce the risk of proximal junction failure. I couldn't sleep last night, (weaning down the narcotics is messing with me), so I looked for the article in PubMed.

Biomechanical Risk Factors for Proximal Junctional Kyphosis: A Detailed Numerical Analysis of Surgical Instrumentation Variables
Spine Vol 39(8), 15 Apr 2014

Since I can't post the whole article, I'll paste part of the discussion here, I hope that is acceptable. The study design used biomechanical analysis of proximal junctional kyphosis (PJK) through computer simulations and sensitivity analysis.

"The comprehensive sensitivity analyses allowed the establishment of the correlations between the biomechanics of the PJSS and the instrumentation variables and thus the identification of potential biomechanical risk factors of PJK. The tested instrumentation variables had significant effects on the flexion loading on the PJSS and the PJ angle. Putting the results from this study in parallel with those reported in related studies helps to provide a more comprehensive assessment of PJK risk factors. This study showed that the dissection of posterior intervertebral elements was positively correlated to the mechanical stresses within the PJSS and the PJ angle, increasing the risk of PJK, which had previously been postulated in retrospective clinical studies and those based on cadaveric experiments.8,29 The simulated use of transverse process hooks instead of pedicle screws at UIV (upper instrumented vertebra) resulted in significantly lower PJ angle and flexion actions of the proximal moment and forces, which can be explained by the fact that the hook–vertebra connection is less rigid than the screw–vertebra connection. This finding was found to be consistent with clinical studies reporting that the change in junctional kyphosis was significantly greater with all pedicle screw constructs than that with hooks and hybrid constructs, suggesting that using hooks involved less supraadjacent facet capsule disruption than pedicle screws and provided a gradual stiffness transition to the proximal noninstrumented spinal segment until obtaining complete fusion. 5,6,10,30,31 The combination of posterior element disruption and increased construct rigidity is thus biomechanically confirmed to be an important factor involved in PJK. Simulations showed similar results to the finite-element analyses on the use of tapered rods at the proximal end with lower mechanical stresses within the PJSS and PJ angle.32 Although lower construct stiffness at the proximal end of the instrumentation may help reduce the risk of PJK, appropriate attention should be paid to the increased likelihood of pseudarthrosis because of the increased junctional micro motion magnitude under the same functional loading due to the reduced proximal construct stiffness. Our results also provided biomechanical support to the clinical belief that increasing the rod curvature with respect to the preoperative TK helps restore the TK, but could in the meantime lead to higher PJ angle, proximal flexion moment and forces, and cervical lordosis as a result of the postoperative adaptations of the patients such as the adaptation to have a forward field of vision.33–39 Therefore, the results of this study biomechanically support that the risk of PJK could be associated with the loss or changes of thoracic and thoracolumbar sagittal alignment. The deformity characteristics of the particular cases used in this study were found to have less significant effect than the independent variables as the general trends of all biomechanical indices were similar in all cases."

As one of the variables in the model was flexion loading, I am going to make a better effort to not spend so much time looking down at my I Pad and use my desktop instead which keeps me in a better position with my head in a neutral position. Also, my computer chair IS the most comfortable chair in the house for me. It's made of a mesh fabric which is both very forgiving and also has a nice lumbar curve built in.