How much space of the spinal canal should be restored by hoisting the vertebrae–OPLL complex for sufficient decompression in anterior controllable antedisplacement and fusion? A multicenter clinical radiological study

Anterior controllable antedisplacement and fusion (ACAF) is a novel surgical technique for the treatment of ossification of the posterior longitudinal ligament (OPLL). Its prognostic factors for decompression have not been well studied. Additionally, no detailed radiological standard has been set for hoisting the vertebrae–OPLL complex (VOC) in ACAF. To identify the possible prognostic factors for decompression outcomes after ACAF for cervical OPLL, to determine the critical value of radiological parameters for predicting good outcomes, and to establish a radiological standard for hoisting the VOC in ACAF. This was a retrospective multicenter study. A total of 121 consecutive patients with OPLL who underwent ACAF at a point between January 2017 and June 2018 at any one of seven facilities and were monitored for at least 1 year afterward were enrolled in a multicenter study. Japanese Orthopedic Association (JOA) scores, recovery rate (RR) of neurologic function, and surgical complications were used to determine the effectiveness of ACAF. Patients were divided into two groups according to their RR for neurologic function. Patients with an RR of ≥50% and an RR of