Kappa: Preliminary Results on a Novel Technique for Pelvic Fixation in Adult Spinal Deformity Correction.

Study Design: Retrospective cohort study. Objectives: Pelvic fixation in degenerative spinal deformation is as crucial as demanding. Several pelvic anchoring technics have been described, but loosening rates remain high for most solutions. Here is described the "Kappa" technic, combining ilio-sacral screws to S2A1 screws at 2 years of follow-up. Methods: Thirteen patients that underwent a spinal deformity correction with "Kappa" fixation to the pelvis and with more than 2 years of follow-up were prospectively included in this study. The surgical technic is described, and clinical and radiographic data have been collected for all patients. Results: The population exhibited an important pre-operative sagittal imbalance (mean SVA of 104,4 mm, mean PI-LL mismatch of 22,8°) that had improved significatively after surgery (mean SVA of 75,5 mm and mean PI-LL mismatch of 4,9°). No loosening of pull-out of the implants was to deplore at 2 years of follow-up. Conclusions: The association of ilio-sacral screw, resistant to pull-out because of the traction axis perpendicular to the construct, to S2A1 screws, known to be effective in sagittal balance restoration seems to be an effective and safe option to pelvic fixation for adult spinal deformity correction. Level of Evidence: IV.

Sagittal balance of the spine.

The static sagittal balance of the normal spine is a physiological alignment of the spine in the most efficient manner by the muscular forces. During gait, this balance is constantly thwarted by single-foot support. This analysis involves the study of parameters which are now well defined. The pelvic incidence is constant, and the sacral slope and the pelvic tilt are positional. The cervical parameters are the upper (O-C2) and lower cervical curvatures (C2-C7), the C7 slope, the spino-cranial angle and the vertical cervical offset. At the thoracic and lumbar level, they are, respectively, kyphosis and lordosis. The OD-HA (odontoid hip axis) angle is the most efficient parameter to analyse the global balance. The average values of these parameters are reported with the new 3D measurements by Le Huec et al. The relationship between these different parameters was analysed, and Roussouly proposed his classification of the different spine shape. Ageing makes it possible to show compensation mechanisms at three levels: spinal, pelvic and lower limbs. Understanding these different data allows for better planning of the surgical management of the patients. Global evaluation of the entire spine and the measurement of the aforementioned parameters allow to determine the extent of the correction to be performed during surgery. Taking these parameters into account also enables us to understand the complications involved in this type of surgery: transitional syndromes or junctional syndromes. Integration of these parameters into the study of gait is an area still under investigation. These slides can be retrieved under Electronic Supplementary Material .