Most cases of spinal TB involve 1-2 vertebral bodies; however, many spinal TB cases cannot be diagnosed early in China and other economically underdeveloped regions. Therefore, approximately 9.6% of patients had TB involving more than 1 segment . For patients with multisegment thoracic and lumbar TB, surgery is often required to completely remove the TB lesions, correct the spinal deformity and stabilize the spine at the same time. The difficulty and risk of surgery are higher for multisegment cases than for single-segment cases. Therefore, selecting the correct surgical method is particularly important.
The main surgical methods of thoracic and lumbar TB include the anterior-only approach, combined anterior and posterior approach and posterior-only approach [9, 12]. The advantages of the anterior approach include the facts that the lesions can be exposed and removed directly, the deformity can be corrected, and the spine can be stabilized. The results at the long-term follow-up showed that this operation can lead to satisfactory clinical outcomes . However, the anterior approach involves substantial trauma, complex anatomical structures and a risk of vascular injury . Patients with poor pulmonary function may not be able to tolerate this operation because of the impact on lung function, and the operation for upper thoracic vertebra lesions is difficult because of the obstruction of the sternum and scapula [9, 15]. These deficiencies are more pronounced for multisegment cases that require greater exposure.
Due to multisegment vertebral destruction and collapse, patients with multisegment TB are more likely than those with single-segment TB to develop spinal deformity and instability, and their cases of deformity and instability are often more serious. Some studies have shown that spinal TB cases with more than 2 segments destroyed are associated with a higher risk of kyphosis and failure of bone graft fusion [16, 17]. Moreover, anterior internal fixation is not convenient for cases involving many segments. Therefore, combined anterior and posterior surgery is recommended for severe vertebral destruction or severe kyphosis cases . Mohanty et al.  reported that combined anterior and posterior surgery is used to treat T1-L1 TB, as it can effectively correct kyphosis and stabilize the spine while resolving TB. However, combined anterior and posterior surgery has been shown to lead to good clinical results and increased surgical trauma. Memtsoudis et al.  reported that the complication rate of combined anterior and posterior surgery was 23.8%, which was significantly higher than that of anterior- or posterior-only surgery, and the mortality rate was nearly twice that of posterior-only surgery. In this study, the complication rate of group B was higher than that of group A, but there was no significant difference.
In recent years, posterior-only surgery has been used for the treatment of thoracic and lumbar TB. Many surgeons believe that posterior-only surgery is suitable for cases of single-segment TB lesions [7, 8] because partial lesion removal cannot be performed under direct vision, which can increase the risk of incomplete lesion clearance. With advancements in the posterior technique, some surgeons have begun to use posterior-only surgery to treat multisegment thoracic TB. Zhong et al.  and Wu et al. treated TB patients with multisegment lesions and kyphosis by posterior-only surgery, and all patients were cured and had no recurrence of TB. For multisegment thoracic and lumbar TB, posterior surgery can be performed with multisegment transforaminal and paravertebral approaches according to the type of lesion; in some indirect operations, the lesion surrounding the spine can be effectively cleared, and the case of TB can be cured . Moreover, posterior-only surgery can prevent some complications associated with anterior surgery because the posterior spinal anatomical structure is simple. In this study, all cases were cured without recurrence of TB, so we believe that posterior-only approach surgery, as well as anterior-only approach surgery, is safe and effective in treating consecutive multisegment thoracic and lumbar TB.
The advantages of the posterior approach for the correction of deformities have been recognized by most surgeons . A posterior pedicle screw system can stabilize the three columns of the spine, and pedicle screw placement with the diseased vertebral body can further increase the stability [24, 25]. The posterior approach surgery can provide intervertebral support combined with posterior compression and is more convenient for combined osteotomy, so it has a better ability to correct deformities. Some surgeons consider that anterior-only surgery has been shown to have a limited ability to correct kyphosis, while combined anterior and posterior surgery or posterior-only surgery can lead to good orthopedic results, and posterior-only surgery is superior under proven technical conditions . In this study, we found that the kyphosis correction angle and rate in group A were significantly better than those in group B, and the kyphosis correction loss rate in group B was significantly higher than that in group B. For some patients with severe kyphosis in group A, satisfactory correction was achieved only by additionally performing 1-2 grade osteotomy. In addition, internal fixation for multisegment TB cases often requires extension of the involved region to adjacent segments, and it is easier to extend the internal fixation region with the posterior approach.
Of course, a variety of surgical methods are available, and surgeons should select surgical strategies according to their skill levels and patients' pathological characteristics. This study also has some limitations, such as the small number of cases studied and the short follow-up time. The results of this study need to be further confirmed by studies with more cases and long-term follow-ups.