A novel minimally invasive, dorsolateral, tubular partial odontoidectomy and autologous bone augmentation to treat dens pseudarthrosis: cadaveric, 3D virtual simulation study and technical report

OBJECTIVE The goal of this study was to demonstrate the clinical and technical nuances of a minimally invasive, dorsolateral, tubular approach for partial odontoidectomy, autologous bone augmentation, and temporary C1–2 fixation to treat dens pseudarthrosis. METHODS A cadaveric feasibility study, a 3D virtual reality reconstruction study, and the subsequent application of this approach in 2 clinical cases are reported. Eight procedures were completed in 4 human cadavers. A minimally invasive, dorsolateral, tubular approach for odontoidectomy was performed with the aid of a tubular retraction system, using a posterolateral incision and an oblique approach angle. Fluoroscopy and postprocedural CT, using 3D volumetric averaging software, were used to evaluate the degree of bone removal of C1–2 lateral masses and the C-2 pars interarticularis. Two clinical cases were treated using the approach: a 23-year-old patient with an odontoid fracture and pseudarthrosis, and a 35-year-old patient with a history of failed conservative treatment for odontoid fracture. RESULTS At 8 cadaveric levels, the mean volumetric bone removal of the C1–2 lateral masses on 1 side was 3% ± 1%, and the mean resection of the pars interarticularis on 1 side was 2% ± 1%. The median angulation of the trajectory was 50°, and the median distance from the midline of the incision entry point on the skin surface was 67 mm. The authors measured the diameter of the working channel in relation to head positioning and assessed a greater working corridor of 12 ± 4 mm in 20° inclination, 15° contralateral rotation, and 5° lateral flexion to the contralateral side. There were no violations of the dura. The reliability of C-2 pedicle screws and C-1 lateral mass screws was 94% (15 of 16 screws) with a single lateral breach. The patients treated experienced excellent clinical outcomes. CONCLUSIONS A minimally invasive, dorsolateral, tubular odontoidectomy and autologous bone augmentation combined with C1–2 instrumentation has the ability to provide excellent 1-stage management of an odontoid pseudarthrosis. The procedure can be completed safely and successfully with minimal blood loss and little associated morbidity. This approach has the potential to provide not only a less invasive approach but also a function-preserving option to treat complex C1–2 anterior disease.