Mycobacterium tuberculosis, which stains positive for the acid-fast stain, is the pathogenic bacterium that causes tuberculosis (TB). TB remains a global public health threat despite the emergence of new diagnostics, drugs, and therapeutic options (Churchyard et al., 2017). TB consists of two main types of infections: pulmonary tuberculosis and extrapulmonary tuberculosis (EPTB). EPTB affects areas of the body other than the lung, such as bones, spine, or joints, which is called bone or skeletal TB, reducing the patient’s quality of life. Spinal TB is one of the most common forms of skeletal TB, with the thoracolumbar spine most commonly affected (Du et al., 2022; Khanna and Sabharwal, 2019). Spinal TB often leads to complications such as paravertebral abscess, bone destruction, and spinal instability (spinal deformity and vertebral collapse) (Jain and Kumar, 2013; Zhuang et al., 2021). Anti-tuberculous chemotherapy is currently considered the best treatment for milder forms of spinal TB with no neurological deficit. In contrast, surgical treatment is the best option for patients with neurological complications or vertebral instability and spinal deformity (Louw et al., 2020; Dunn and Ben Husien, 2018).

Debridement of infected bone and other tissue is an important part of the surgical treatment of TB. In patients with spinal tuberculosis, debridement has also been shown to play an important role in controlling abscess formation (Dunn and Ben Husien, 2018; Du et al., 2020; Fuentes Ferrer et al., 2012). There are two main surgical strategies for spinal tuberculosis: anterior and posterior. Anterior surgery provides direct access to the intervertebral disc, has the advantage of debridement under direct vision, and may increase the fusion rate of the surgical wound (Li et al., 2019). The large surgical trauma in anterior surgeries also brings the risk of damaging the iliac blood vessels, peritoneal contents, ureters, and autonomic nervous system (Sasso et al., 2005). On the other hand, posterior surgery has good deformity correction and stable reconstruction capabilities, which is the most significant advantage (Wu et al., 2022). Posterior surgery is an indirect debridement method. Compared with anterior surgery, it is not particularly thorough in removing abscesses caused by tuberculosis. This surgical method would not only increase the probability of late recurrence but also increase the risk of M. tuberculosis being introduced from the anterior column to the posterior column (Ukunda and Lukhele, 2018). Furthermore, posterior surgery may cause chronic low back pain or lower limb weakness, which may be caused by unilateral or bilateral dissection of the facet joint and opening of the spinal canal during the operation. In general, both anterior and posterior surgeries have advantages and disadvantages, and the choice between them remains controversial (Ekinci et al., 2015). However, reducing trauma is necessary to improve the effectiveness of treating spinal tuberculosis. Novel surgical methods are urgently needed.

With the advancement of surgical methods and materials technology, minimally invasive surgery provides new options for the treatment of spinal tuberculosis. Minimally invasive surgery techniques have gained wider acceptance among surgeons performing lumbar diseases because they allow direct access and visualization of intervertebral discs in order to achieve a more complete discectomy and theoretically a better fusion, while potentially decreasing morbidity (Eck et al., 2007; Shen et al., 2007; Kaiser et al., 2002). Oblique lateral interbody fusion (OLIF) is a minimally invasive technique of lumbar anterior approach (Mayer, 1997)and officially named “OLIF” by Silvestre et al., in 2012 Silvestre et al. (2012). Specifically, the psoas muscle is pushed back in OLIF to allow surgical passage through the space between the aorta and psoas muscle to reach the target vertebrae or intervertebral space. Using OLIF reduces blood loss, speeds recovery, and reduces the likelihood of nerve damage. Moreover, the surgical approach of OLIF has shown definite clinical results in the treatment of degenerative lumbar diseases (Jin et al., 2018; Woods et al., 2017; Ye et al., 2020; Shimizu et al., 2021). Additionally, from a biomechanical perspective, tuberculosis lesions extensively damage the intervertebral discs and vertebral bodies, leading to disc space collapse. This in turn causes local kyphotic deformities, significantly disrupting the sagittal plane balance of the spine (Tobing et al., 2021). Through sufficient interbody fusion and posterior supplemental fixation, OLIF can better correct sagittal plane imbalance of the spine (Xiao et al., 2020). We speculate that OLIF would have great potential in treating lumbar tuberculosis.

In the current study, we used OLIF combined with posterior percutaneous pedicle screw fixation to treat spinal tuberculosis. Compared with traditional anterior and posterior surgical methods, our combined treatment took advantage of minimally invasive technology and achieved more satisfactory clinical results. This study provides evidence of evidence-based medicine for the clinical application of OLIF technology.

Bone and joint tuberculosis consist of a group of serious infectious diseases associated with the human skeleton (bones and/or joints), the incidence of which has increased, especially in underdeveloped countries, partly due to the increase of immunocompromised population. Tuberculous spinal infections (i.e., spinal tuberculosis) are common forms of bone and joint tuberculosis, accounting for nearly 50% of tuberculous osteoarticular manifestations (Pigrau-Serrallach and Rodriguez-Pardo, 2013). Of note, the lower thoracic and upper lumbar spine are the most frequently involved sites in spinal tuberculosis. Severe infections lead to instability of the vertebral body, deformity, and even neurological defects and paraplegia. Therefore, clinical treatments for spinal tuberculosis aim to eradicate the infection, prevent or decrease neurological deficits, and correct and avoid the development of spinal deformity (Khanna and Sabharwal, 2019). Although chemical drugs (isoniazid, rifampicin, streptomycin, or pyrazinamide) are the cornerstone of anti-tuberculous therapy (Rajasekaran and Khandelwal, 2013; Moon et al., 2002), they cannot completely clear vertebral infections and paravertebral abscesses and establish spinal stability. Surgical treatments are essential to coordinate with anti-tuberculous chemotherapy. Our findings in the current study suggested that OLIF is a feasible single-level spinal tuberculosis treatment option compared with traditional anterior or posterior approaches.

OLIF has been used to treat degenerative lumbar diseases, and in our opinion, it has its own advantages during surgery and in postoperative recovery in the treatment of lumbar TB. For the surgical treatment of lumbar tuberculosis, the traditional anterior or posterior approach exposes the lesion directly to the field of view, which makes the surgery traumatic and destructive. In contrast, the most intuitive advantage of the OLIF procedure used in this experiment is the smaller operating window during the procedure, in which we make a smaller skin incision centered on the vertebral segment for exposure (Silvestre et al., 2012), for muscle detachment, we dissect the external oblique, internal oblique and transversus abdominis muscles, etc., along the direction of their fibers, and bluntly detach them by accessing to the retroperitoneal space, thus realizing the removal of the lesion. The OLIF procedure in this experiment is a minimally invasive approach, which can greatly avoid muscle disarticulation and tissue damage, and reduce the probability of nerve and vascular damage. In the traditional posterior approach, the above-mentioned steps are performed in a blind field, especially when the lesion is located in the paravertebral region, in which case a surgical window must be created by removing the vertebral plate and articular eminence on one side, and even though pedicle screws can be performed directly under the surgical field to perform fixation, such an open surgery undoubtedly increases the surgical time and the amount of bleeding. For the traditional anterior approach, the larger surgical scope and its muscle soft tissues, etc. are important influencing factors that increase the amount of bleeding and operation time, which also directly lengthens the patient’s hospitalization time (P < 0.05). The operative time, bleeding, and hospitalization time is an intuitive way to evaluate the trauma of a surgical procedure. Thus, in our present study, the operative time, bleeding, and hospitalization time of the OLIF procedure used for the treatment of lumbar spinal tuberculosis were lower than those of traditional anterior or posterior procedures (P < 0.05), which is inextricably linked to the smaller incision exposure of the procedure. For the OLIF surgical approach to spinal tuberculosis, the anterior minimally invasive incision and muscle stripping reduced patient bleeding, accessed multiple levels through minimally invasive incisions, removed lesions under direct vision, and reduced the incidence of abdominal wall pain. Internal fixation is then performed through posterior percutaneous screws, which avoids exposure of open posterior wounds and incision of the lamina, among other things (Alander and Cui, 2018). Importantly, posterior percutaneous pedicle screw fixation has been widely used in recent years for the treatment of degenerative spinal disorders and fractures with satisfactory outcomes (Tian et al., 2018; Jin et al., 2020). The posterior approach of percutaneous pedicle fixation reduces complications such as chronic back pain or lower limb weakness caused by traditional posterior surgery, which may be due to the stripping of unilateral or bilateral paravertebral muscles and the opening of the spinal canal during the surgical procedure (Epter et al., 2009; Lee et al., 2017). Moreover, OLIF combined with posterior pedicle screw fixation provides optimal biomechanical stability (Guo et al., 2020). This surgical approach to the treatment of spinal tuberculosis allows early control and timely fusion, thereby correcting spinal deformity, enabling patients to get out of bed earlier, and reducing postoperative risks. Therefore, the number of cases of postoperative infections occurring after OLIF surgery was zero compared to the other two surgical approaches in our study.

VAS and ODI scores are another important indicator of patients’ postoperative recovery. Through the evaluation of patients’ postoperative pain, we found that the patients’ VAS and ODI scores 1-week post-surgery of OLIF surgical method were lower than those of traditional anterior and posterior surgical methods (P < 0.05), which is closely related to the surgical method. We considered that this might be related to less trauma in OLIF surgery, less pain in the short term after surgery and faster recovery of motor function of the body. However, at the final follow-up, there was no difference in the VAS and ODI scores of the three surgical methods (P > 0.05). The reason might be that, over time, all patients reached a state of bone graft fusion and achieve good results in recovery. There was no significant difference in the indicators of ESR and C-reactive protein between the three surgical methods during the follow-up period (P > 0.05). This might be mainly due to the fact that standardized antibiotics were implemented after all three surgical methods. In terms of correction of spinal deformity, we found that compared with pure anterior surgery or posterior surgery, OLIF can improve the Cobb angle (P < 0.05), and the Cobb angle is also statistically significant at follow-up. This also highlights that restoring intervertebral height through OLIF can better improve lumbar lordosis, facilitating the recovery of biomechanical stability (Guo et al., 2020).

However, our study has certain limitations. We only evaluated the combined treatments for spinal tuberculosis. The current study is mainly retrospective, limited by the small number of patients and short follow-up time.