Background: Although anterior and posterior decompression surgery are both reported to treat patients with myelopathy caused by OPLL（Posterior longitudinal ligament ossification）. The surgical strategy of the disease is still controversial when the OPLL is multilevel and severe. Novel techniques for better and safer results are required. Dr. Shi recently proposed a new technique as Ossification of anterior decompression surgery, which is also called anterior controllable antedisplacement and fusion (ACAF) , for ossification of the posterior longitudinal ligament (OPLL) with myelopathy. Yet, the effectiveness and safety should be further studied.