The thoracolumbar spine lacks the protection of the thorax and has a large degree of mobility due to its unique anatomical structure. The load of the spine easily induces stress concentration. As the bone is destroyed, spinal instability and deformity can easily develop in patients. An intraspinal abscess in the spinal canal will lead to spinal cord compression, which results in severe neurological deficits, numbness of the lower limbs, muscular weakness, dyskinesia, urinary or fecal incontinence, and sexual dysfunction. For these patients, even with active anti-tuberculosis drugs, surgery is often required.
The anterior approach can fully expose the lesion, so lesion removal becomes easy and anterior bone grafting also becomes convenient. However, for thoracolumbar spinal TB patients, the anterior approach requires a combined posterolateral thoracic back and abdominal incision approach. Thus, the operation procedure is very complicated and also causes massive surgical trauma. There are high risks for rupturing of pleura and injuring organs in the thoracic and abdominal cavity. The cardiac and lung functions of the patient are also impaired. Moreover, it is difficult to correct the kyphotic deformity and maintain the correct angle using a single-anterior approach [4, 7]. The single-anterior approach also leads to a risk of nerve injury; thus, making it unsuitable for long segmental fixation and spinal abscesses removal. In patients with complicated anterior fixation, it is necessary to perform posterior fixation, which further increases the surgical trauma. Single posterior surgery (SPS) can achieve lesion removal and bone graft, internal fixation, and deformity correction. Consequently, an SPS method can simplify the operation, reduce surgical trauma, and reduce the risk and cost of surgery [8, 9].
Studies have shown that for thoracolumbar spine TB patients, a single posterior approach has better clinical efficacy than the anterior or anteroposterior approach [10, 11, 12]. Though an extensive laminectomy will lead to easy decompression, lesion removal, and intervertebral bone grafting, spinal instability can occur due to extensive damage to the posterior structure. In contrast, fenestration and decompression to retain most of the posterior anatomical structure have little effect on the spine stability. However, the visual surgery field is limited and makes decompression, lesion removal, and bone grafting difficult. Patients who meet the conditions are few [13, 14].
We developed a simple posterior-only approach to remove the unilateral vertebral plate for decompression and debridement. This method can completely remove the lesion located at the vertebral body and in intervertebral space under direct vision. Anterior intervertebral bone grafting and posterior vertebral plate reconstruction increase stability of the spine [15, 16].
For thoracolumbar spinal TB with spinal canal abscess, the authors have established an operation channel by resecting the spinous process and one side of the lamina. Compared to the anterior approach, this method allows the dural sac and nerve root to be fully exposed, and the lesion to be more directly and safely removed, especially when the abscess encircles the spinal cord because it is a situation in which it would be difficult to achieve complete lesion removal through the anterior approach[17, 18]. When removing the lesion, it is necessary not only to remove the inflammatory necrosis, pus, and the diseased posterior longitudinal ligament to relieve nerve compression but also to completely remove the cheese-like substance, granulation, dead bone, and degenerative and necrotic tissue in the intervertebral space. The intervertebral area is the primary site of spinal TB. During the operation, the inflammatory tissue, dead bone, and damaged intervertebral disc of the prime central lesion were removed entirely, and the surrounding sinus was explored and irrigated. The cyst was repeatedly washed with hydrogen peroxide and saline. For satellite lesions, after the pus, caseous necrotic tissue, and tuberculous granulation tissue removal, the healthy bone surface was scraped with a curette. The primary lesions of adult spinal TB are often located in the intervertebral space, and the intervertebral space lesions must be removed entirely. This is the key to prevent recurrence after surgical treatment.
After thorough removal of the tuberculosis lesions, reliable reconstruction of the anterior vertebral body is considered essential for the success of the operation. The anterior approach is often selected because anterior bone grafting is convenient [19, 20], but a combined chest and abdominal incision is required, which causes massive trauma.
This incision is suitable for intervertebral bone grafting if performing an extensive posterior laminectomy; however, it will inevitably cause excessive destruction of the posterior column, which damages the stability of the spine. Resecting one side of the lamina mostly maintains the stability of the posterior column, while fixing the posterior pedicle screw and the titanium mesh on the anterior side of the column provide strong support to balance the spine. Therefore, surgery will have little effect on spine stability. The stability of the spine was reconstructed with bony fusion achieved due to interbody fusion and interlaminar bone fusion. We used titanium mesh for anterior intervertebral bone grafting. The autologous bone particles in the titanium mesh came from the posterior lamina, spinous processes, and ribs. When the autologous bone was insufficient, the titanium mesh was filled with allogeneic bone particles. However, we ensured that the bone grafting area was in contact with autologous bone, which is a good condition for bone fusion. After placing the titanium mesh, the intervertebral space was appropriately enlarged; hence, the titanium mesh was set and was adequately pressed against the gap to achieve immediate stability. Also, the deformity could also be corrected by avoiding movement and displacement of the titanium mesh. Titanium mesh can be selected and constructed according to the anterior defect area, and a single large titanium mesh is always implanted. However, when a single large titanium mesh is difficult to implant, multiple shaped titanium meshes can be selected to facilitate anterior interbody fusion [21, 22]. For all patients in our study, the kyphosis angle was significantly corrected, from an average of 29.36 ± 13.29° before surgery to an average of 3.58 ± 5.44° after surgery. At the last follow-up, there was no significant loss of correction angle. All patients achieved bony fusion without loosening or collapsing the titanium mesh.
The study has two limitations: a retrospective study, a single-centered study with small sample size. We call upon multicenter studies with a large sample size to be carried out in the future for further verification of our findings.