Ossification of the posterior longitudinal ligament (OPLL) in the cervical spine refers to the pathological process of ossification within the posterior longitudinal ligament of the cervical spine, accompanied by sustained hyperplasia that exerts pressure on the spinal cord in the neck. This condition leads to impairments in limb sensation and body movement, and its prevalence is increasing globally.1

Surgical decompression is typically necessary for the treatment of cervical spine OPLL. There are primarily 2 surgical approaches: anterior and posterior. The conventional anterior surgical method offers the advantage of directly removing the ossified tissue, effectively alleviating compression on the spinal cord and nerve roots caused by the vertebrae-OPLL complex (VOC) and facilitating the reconstruction of cervical curvature. However, it comes with certain drawbacks, including an elevated risk of damaging the spinal dura and spinal cord, as well as greater disruption to the cervical spine during VOC excision, resulting in a relatively higher incidence of surgical complications.

On the other hand, LP is a well-established posterior surgical technique known for its relative simplicity and reliable clinical outcomes, coupled with a lower incidence of postoperative complications. Nevertheless, LP achieves decompression indirectly, relying on the extent of backward displacement of the spinal cord for its clinical efficacy. This approach faces challenges in restoring the physiological curvature of the cervical spine and is associated with complications such as C5 nerve root paralysis and axial pain, leading to relatively poorer long-term prognoses.2, 3, 4 A review of the literature indicates that ACCF is more effective in treating OPLL patients with a spinal canal occupancy rate exceeding 60% or those presenting cervical kyphosis, while LP is considered more effective and safer for OPLL patients with a spinal canal occupancy rate below 60% or those with cervical lordosis.5 Despite significant advancements and enhancements in traditional anterior and posterior cervical surgical techniques, there remains a lack of definitive consensus regarding the optimal surgical approach for treating multisegment ossification of the cervical posterior longitudinal ligament.6

In recent years, Shi Jiangang's research team7 at Changzheng Hospital, Naval Medical University, has pioneered a novel approach to achieve controlled decompression of the cervical spinal canal by repositioning the vertebra and the complex of ossified posterior longitudinal ligament to the ventral side as a whole. This innovative technique, known as anterior controllable antedisplacement and fusion (ACAF), is particularly suited for cases of cervical OPLL where the ossified complex is located between the lower part of the C2 vertebra and T1. Studies have demonstrated that utilizing the base of the hook-like process as a reference point for bilateral osteotomy provides sufficient width to accommodate most cases of OPLL.8,9

During the surgical procedure, the disc tissue of the affected segment is intraoperatively removed, and the anterior portion of the vertebral body within the operative segment is excised according to the thickness of the ossified segment. On the opposite side of the surgeon, a slot is carefully created at the level of the uncinate joint of the vertebral body, with a width of approximately 3 mm, until reaching the posterior longitudinal ligament. Meanwhile, the posterior wall of the vertebra on the surgeon's side is temporarily retained to maintain the stable position of the vertebra. It is essential during the operation to ensure that the vertebra is slotted “straight up and straight down.” Fusion implants are then inserted into each intervertebral space, followed by placing prebent titanium plates on the anterior edge of the vertebral body and installing vertebral nails in each vertebral body. Concurrently, the posterior wall of the vertebral body in the ipsilateral trough is resected, entirely dissociating the vertebral body. The screws are gradually tightened, pulling the Vertebrae-OPLL complex forward along with the adherent dural sac to achieve in-situ decompression. An illustrative representation of the procedure can be found in Figure 1, Figure 2, Figure 3.

The ACAF technique not only translates the internal decompression of the vertebral body into a visually perceptible forward movement of the vertebral body but also circumvents the challenges associated with handling ossified adhesions. This approach minimizes the risk of injury to the spinal dura and spinal cord, presenting a promising alternative for the treatment of cervical OPLL. Currently, ACAF is employed in multiple medical centers in China and South Korea.

Recent literature has highlighted the substantial advantages of ACAF in addressing cervical spinal stenosis resulting from extensive cervical OPLL.10, 11, 12, 13, 14, 15, 16 However, most of these studies are based on small sample sizes, and the evidence base for medical practice remains relatively limited. In light of this, we have undertaken a retrospective collection of relevant literature for a comprehensive meta-analysis to assess and compare the clinical efficacy of ACAF and LP in treating patients with multisegment ossification of the cervical posterior longitudinal ligament.