A Rib Construct for Severe Spinal Deformity: Clinical, Biomechanical, Animal Studies, and Commercialization

Introduction: Current treatments for early-onset spinal deformity (EOSD) have high complication rates and limited effectiveness. The rib construct (RC) is a novel technique for correcting early-onset spinal deformity. A series of hooks are used on the proximal superior ribs for proximal fixation to contour the thorax, with traditional fixation distally. Methods: The performance of the rib construct was evaluated in ex vivo biomechanical testing, an in vivo animal model, and a clinical study. An R-FIX (Rib-FIXation) System was developed based on these studies for optimization of the technique. Results: Ex vivo biomechanical testing showed that porcine spines instrumented with the rib construct were significantly less prone to proximal fixation failure and less stiff compared to pedicle screws. The porcine animal model study showed that sagittal spinal alignment improved substantially in hyperkyphotic pigs that were instrumented with the rib construct. Histological analysis at the sub-gross and cellular level reveal changes consistent with growth modulation of the spine. The clinical study showed that sagittal and coronal Cobb angles and other parameters of trunk, shoulder, neck and head alignment improved significantly in patients treated with the rib construct. Complication rates were improved compared to traditional methods, with a notable lack of proximal junctional kyphosis or neuromonitoring changes. The refined R-FIX System was tested in cadavers and spine models and functioned appropriately. Interpretation: The rib construct is an effective treatment for early-onset spinal deformity