Accessing the pedicle of the spine for fixation in spinal deformity surgery is challenging. Drs. Baron Lonner and Yuan Ren have developed a new technique, the Transverse Process Trajectory Technique, to be tested and compared to the traditional free-hand technique. CT scan evaluation, axial pullout, and torsional testing will be performed in this cadaver study. 

A number of techniques, including free-hand (FH) and the in-out-in techniques, have been utilized for pedicular fixation and correction of scoliosis. Placement of thoracic pedicle screws is confounded by spinal deformity and a learning curve. Dr. Lonner introduced the innovative Transverse Process Trajectory (TPT) technique that takes advantage of the patient’s innate anatomy serving as a conduit into the pedicle. The approach also has the potential to improve torsional loading properties for derotation techniques due to its very lateral starting point away from the axis of rotation. The technique utilizes a starting point at the lateral aspect of the superior facet and its junction with the cephalad 1/3 of the transverse process (TP). The TP is drilled to its ventral cortex along its entire length from the tip. This provides a corridor for a 2mm power drill that follows the TP trajectory (Figure 1).

Three surgeons of varying experience level (1. experienced with 20yrs of practice, 2. surgeon with <10yrs of experience and 3. resident trainee) will perform TPT alternating with the FH technique on 2 cadavers each. Time for screw placement will be assessed. CT scan and visual inspection will be performed to assess accuracy of screw placement for the two techniques specifically observing for critical breaches that might result in neurological injury. Screw pull-out strength and torsional loading will also be compared. Learning curve assessment will be performed between surgeons and techniques by comparing the above between the three surgeons.