“Shelter Technique” in the Treatment of Ossification of the Posterior Longitudinal Ligament Involving the C2 Segment

Anterior or posterior decompression has been widely used to treat patients with ossification of the posterior longitudinal ligament (OPLL). However, when OPLL extends to the C2 level, the complex anatomic structures around the C2 vertebral body and postoperative destabilization or kyphosis would make it difficult to perform anterior or posterior surgery. This study proposed a novel technique named "shelter technique" to deal with C2 OPLL.Sixteen patients with cervical OPLL involving the C2 segment were included. The OPLL below C2 was dealt with anterior controllable antedisplacement and fusion, including diskectomy of involved levels, resection of the anterior vertebral bodies, installation of the intervertebral cages and anterior cervical plate, isolation of the vertebrae-OPLL complex (VOC), and the final hoisting of the VOC. When dealing with C2 OPLL, the posterior portion of the C2 vertebral body was resected to create the shelter based on the thickness of the C2 OPLL, which could provide space for further antedisplacement of the ossified mass behind the C2 vertebra. Finally, OPLL behind C2 was moved forward together with the antedisplacement of VOC below C2.Postoperative magnetic resonance imaging and computed tomography scan showed sufficient decompression of the spinal cord, including the C2 segment, and the shelter provided enough space for the antedisplacement of the ossified mass behind the C2 segment. At the final follow-up of 1 year, neurologic function of all patients recovered significantly.The shelter technique can be relatively effective and safe for patients with OPLL involving the C2 segment. However, further studies with more cases and longer follow-up will be required to reveal the surgical value of the technique.