Spinal TB, which is the most common presentation of skeletal TB, continues to increase in prevalence globally [13–15]. Multi-segment thoracic TB is a relatively rare but very serious disease. Although medical therapy with anti-TB drugs is the mainstay in the management of tuberculous spondylitis, active and early surgical intervention and stabilization might be advocated to limit the risk of neurologic deficit or progressive instability and deformity [16, 17]. The reduction of bacterial load, and therefore, a better response to medical therapy as well as the ability to avoid prolonged immobilization when on medical therapy alone appear to favor of early surgical intervention .
The primary aim of surgery would be to offer stability when decompressing the spinal cord through debridement at the same time. An anterior surgical approach has been popular due to the predominantly anterior body involvement by tuberculous infection, which allows debridement through direct access to the focus point [19–21]. However, for multi-segment thoracic TB, the anterior approach alone is limited in exposure and ability to offer stabilization across a long disease segment. Instability is associated with the failure of a graft to heal or implant breakages that lead to spinal cord injury. Due to this limitation, a combined anterior and posterior approach has been adopted by surgeons to offer disease control, which allows for stabilization and posterior instrumentation [22, 23]. However, a staged procedure requires the patient to undergo surgical procedure twice and this adds to stress during recovery in an already nutritionally and metabolically challenged state in which TB thrives [24, 25].
With these considerations, the single posterior only approach has gained popularity for the treatment of multilevel spinal TB in the thoracic spine [26–28]. The posterior approach avoids the disturbance of the physiological functions of organs in the thoracic cavity, which causes reduced surgical trauma. Besides, the three-column fixation of pedicle screws could provide strong biological fixation for a short time after surgery, the spine; therefore, could be reconstructed immediately, and a favorable kyphosis correction could be obtained. Finally, the intervertebral defect is adequately implanted with size-matched bone block to reconstruct the anterior column after lesion removal. The long-term stability of the spine could be achieved after bone graft fusion. In addition, favorable outcomes after posterior debridement and internal fixation in elderly patients with multi-segment tuberculous spondylitis have been reported [7, 29]. The comparative assessments in this study supported this finding based on a quantitative analysis of the correction of kyphotic deformities, The VAS score reflecting pain intensity dropped over 80% over the mid-to-long-term follow-up after surgical treatment. Significant increases in the SF-36 scores suggested favorable overall health status during follow-up. These assessments demonstrated that the patients’ quality of life was improved, as expected.
From this series and experience with this posterior only approach, it was noted that the posterior instrumentation provided improved biomechanical support due to its three-column fixation. this type of fixation can correct kyphosis, reduce the angle loss of deformity correction and relieve pains due to spinal instability. Although Mycobacterium tuberculosis does not adhere to the internal fixation, other bacteria can adhere and even form a biofilm. The diagnosis of spinal tuberculosis was often postoperative and difficult to distinguish from other bacterial infections. Because tuberculous lesions are commonly involved in the anterior column, a posterior approach allows internal fixation away from bacteria. In addition, as a chronic disease, many patients with spinal TB are in a poor nutritional state. The posterior approach reduces blood loss and anesthesia time, thereby reducing the risk of intraoperative and postoperative complications. Finally, where there is a need to mobilize the complex anatomical structures through the anterior approach, the posterior has a direct approach; therefore, the complications to the great vessels or viscera are minimized.
This surgical treatment of multi-segment thoracic TB can achieve posterior decompression, unilateral anterior decompression (total 270–360° decompression), and reconstruction of anterior load support by interbody fusion is also achieved by the thoracic reconstruction technique . A thorough removal of TB lesions is the key to surgical treatment of spinal tuberculosis. Since the surgery cannot achieve full sterility of the lesion, effective anti-TB drug treatment and improvement of the patient's general condition are important aspects of the treatment of spinal TB. The debridement of the surgical focus is to promote the quiescence and healing of the tuberculosis focus, destroy the environment favored by the survival of tuberculosis bacilli, and promote the anti-TB drugs to penetrate the focus area. Remove pus, caseous necrotic tissue, dead bone, granulation tissue and necrotic intervertebral discs in the lesion area, and do not emphasize the expansion of lesion removal . For the tubercular lesion wall that has not sclerosed in multi-segment spinal TB, the curettage of the lesion wall should be cautious due to the osteoporosis around the lesion, and imaging data should be referred during the operation to prevent the loss of healthy bone. Complete removal of the central lesion was also feasible for spinal canal decompression, fixation and bone grafting to reconstruct the stability. For satellite lesions, paravertebral pus, caseous necrotic tissue and tuberculous granulation tissue were removed and the lesions were scratched to the normal bone surface with a curette. Paravertebral abscesses can be eliminated by catheter lavage, negative pressure suction and postoperative postural drainage.
The authors agree that the posterior only approach might be radical and requires careful patient selection. They advocated that these considerations should be taken into account when managing multilevel thoracic spine TB: (1) whenever possible and in the presence of adequate bone stock, the affected vertebrae should be incorporated into the instrumentation system; (2) enough graft should be impacted into the defect, and the graft between vertebrae should be fixed to promote fusion; (3) temporary rod stabilization for the spinal cord during transforaminal thoracic debridement should be provided; (4) careful patient selection is required for method, which is mainly used in spinal TB with limited bone destructions in the middle column; (5) careful monitoring to ensure that the spinal cord is not affected (stretched or distracted) when debriding the lesions and spinal monitoring could be added for safety during these procedures. During the whole follow-up process, all patients achieved bone fusion, and no bone nonunion or recurrence caused by insufficient lesion removal was observed.
This study is limited by its small size; however, multilevel spinal TB remains rare, and therefore, these numbers might not be disregarded. Despite the favorable outcomes of this study, the authors would recommend a larger multicenter study with the ability to compare results between the various surgical approaches before advocating only a single-stage posterior approach for all patients.