Comparison of Clinical Outcomes of Posterior-Only Transforaminal Debridement and Interbody Fusion With Preservation of Posterior Ligamentous Complex Versus Conventional Posterior-Only Debridement and Interbody Fusion for Thoracic Spine Tuberculosis: A Prospective, Randomized, Controlled, Clinical Trial - A Pilot Study
Article information
Abstract
Objective
The main objective of this study was to analyze the efficacy and feasibility of surgical management for patients with thoracic spinal tuberculous spondylitis (STB) by using posterior-only transforaminal debridement and interbody fusion (PTDIF) with preservation of posterior ligamentous complex (PLC) and noninferior of PTDIF compared with conventional posterior-only debridement and interbody fusion (CPDIF).
Methods
From January 2019 to January 2022, a prospective, randomized, controlled trial was conducted in which patients with thoracic STB were enrolled and assigned to undergo either the PTDIF group (group A) or CPDIF group (group B) in a 1:1 ratio. The clinical efficacy was evaluated on average operation time, blood loss, hospitalization durations, visual analogue scale, Oswestry Disability Index scores, erythrocyte sedimentation rate (ESR), C-Reactive protein (CRP), and neurological function recovery using the American Spinal Injury Association’s impairment scale and operative complications. Radiological measurements included kyphosis correction, loss of correction. The outcomes were compared between the groups at preoperation, postoperaion, and final follow-up.
Results
All 65 patients were completely cured during the follow-up. The intraoperative blood loss and operation time in group B were more than that in group A. All patients were pain-free at the final follow-up visit. ESR, CRP returned to normal limits in all patients 3 months after surgery. All patients had improved neurological signs. No significant difference was found in kyphosis angle correction, loss of correction between the 2 groups.
Conclusion
PTDIF, with preservation of PLC, achieved debridement, decompression, and reconstruction of the spine’s stability, similar to CPDIF in the surgical treatment of thoracic STB. PTDIF has less surgical trauma with less intraoperative blood loss and operation time.
INTRODUCTION
Spinal tuberculosis, the most common pattern of extrapulmonary tuberculosis, is a severe spinal disease that frequently causes kyphotic deformity, neurologic deficit and even spinal cord compression, especially in thoracic spinal segment, which may due to narrow thoracic spinal canal and low blood supply to the thoracic spinal cord [1]. Anti-tuberculosis (TB) chemotherapy remains the mainstay of treatment for spinal TB [2]. However, conservative medical management cannot entirely prevent the potential progression of kyphosis, which may lead to chronic back pain and neurologic deficit [3]. Conservative treatment failure, neurological deficiency, the development of an epidural abscess, intolerable pain, or significant vertebral damage leading to either immediate or delayed spinal instability or segmental kyphosis all warrant surgical intervention.
Anterior or posterior approaches, single-stage or 2-stage surgery, with or without instrumentation—these are only some of the options available for surgical therapy of spinal tuberculosis. Historically, an anterior approach has been used because it provides the best opportunity for reaching infected tissues and performing thorough debridement. However, one must not overlook the complex anatomical layers, segmental vessels, sporadic main vessels, and nerves [4]. Single-lung ventilation using an anterior approach can be especially challenging for some patients who also have heart or lung problems [5]. To acquire stability and allow early ambulation, however, some surgeons in the last few decades have turned to posterior instrumentation in cases of spinal tuberculous [5,6]. The placement of posterior instrumentation and anterior debridement necessitate simultaneous anterior and posterior procedures. Furthermore, the risks, duration of anesthesia, and volume of blood loss associated with a combined posterior and anterior operation are all increased.
We have already succeeded with conventional posterior-only debridement and interbody fusion (CPDIF) in the treatment of spinal tuberculosis [3,5,7,8]. However, there is still a higher risk of injury to the nerve root and dural sac during conventional posterior-only approach because they must be pulled through the midline. By preserving the posterior ligamentous complex (PLC), contralateral lamina, and facet joints, transforaminal lumbar interbody fusion technique through the most lateral part of the vertebral foramen keeps the spine stable and lessens the chance of neural injury from retraction [9,10]. In light of this, we modified the CPDIF in this prospective, randomized controlled trial: we preserved the PLC. We aimed to investigate whether posterior-only transforaminal debridement and interbody fusion (PTDIF) is noninferior to CPDIF in treating thoracic spinal tuberculous spondylitis (STB). The clinical, radiological and functional outcomes were reported here.
MATERIALS AND METHODS
We conducted a prospective, randomized study on single center clinical trial on posterior-only approach surgical treatment in thoracic spine TB. This study approved by the Institutional Review Board (IRB) of Xiangya Hospital of Central South University (IRB No. 202004324). Between January 2019 and January 2022, 65 patients who presented with a preliminary diagnosis of thoracic spine TB based on clinicoradiological and laboratory parameters (later confirmed by histopathological examination, TB culture and/or metagenomics next-generation sequencing [mNGS], gene xpert [TB polymerase chain reaction]) involving the thoracic spine were enrolled for the study (Fig. 1). All patients had detailed laboratory evaluation included hematological inflammatory indices included the T-cell spot test of tuberculosis infection (T-SPOT.TB), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), biochemical and microbiological and imaging evaluation included plain anteroposterior and lateral radiographs, 3-dimensional (3D) computed tomography (CT), and magnetic resonance imaging (MRI) (Figs. 2A–E, 3A–E, and 4A–D). Patients with any of the following conditions were chosen as candidates for surgery, which were finally considered for the study: (1) failure of conservative treatment, (2) intractable back pain, (3) significant vertebral destruction creating spinal instability or/and spinal deformity, (4) neurological decline, and (5) apparent abscess formation. Those who did not have any definitive evidence of TB on microbiological or histopathological evaluation were excluded.
Consort diagram of participants’ flow. PTDIF, posterior-only transforaminal debridement and interbody fusion; CPDIF, conventional posterior-only debridement and interbody fusion.
(A–E) Preoperative radiographs, CT and MRI showed that T1–7 spinal tuberculous spondylitis and lesion around vertebral body of T1–7 developed paravertebral abscess with marked bony destruction in T4. There were obvious intraspinal abscess in T3–7 which lead to severe spinal cord compression in MRI. (F) Posterior transforaminal debridement with preservation of PLC, interbody graft using titanium mesh cage, pedicle screw instrumentation was done. (G–I) Postoperative radiographs and CT showed that posterior transforaminal debridement with preservation of PLC, interbody graft using titanium mesh cage and posterior pedicle screw instrumentation. (J–M) Final follow-up radiographs and CT showed good bone fusion. MRI showed there were no paravertebral and intraspinal abscess with no spinal cord compression. A, anterior; P, posterior; R, right; L, left; CT, computed tomography; MRI, magnetic resonance imaging; PLC, posterior ligamentous complex.
(A–E) Preoperative radiographs, CT and MRI showed that T7–10 spinal tuberculous spondylitis and lesion around vertebral body of T7–10 developed paravertebral abscess with marked bony destruction in T7–9. There were obvious intraspinal abscess in T8–9 which lead to severe spinal cord compression in MRI. (F) Posterior transforaminal debridement with preservation of PLC, interbody graft using titanium mesh cage, pedicle screw instrumentation was done. (G–I) Postoperative radiographs and CT showed that posterior transforaminal debridement with preservation of PLC, interbody graft using titanium mesh cage and posterior pedicle screw instrumentation. (J–M) Final follow-up radiographs and CT showed good bone fusion. MRI showed there were no paravertebral and intraspinal abscess with no spinal cord compression. A, anterior; P, posterior; R, right; L, left; CT, computed tomography; MRI, magnetic resonance imaging; PLC, posterior ligamentous complex.
(A–D) Preoperative radiographs, CT and MRI showed that T5–10 spinal tuberculous spondylitis and lesion around vertebral body of T5–10 developed paravertebral abscess with marked bony destruction in T6–7. There were obvious intraspinal abscess in T6–7 which lead to spinal cord compression in MRI. (E) Conventional posterior-only debridement without preservation of PLC, interbody graft using titanium mesh cage, pedicle screw instrumentation was done. (F–H) Postoperative radiographs and CT showed that conventional posterior-only debridement without preservation of PLC, interbody graft using titanium mesh cage and posterior pedicle screw instrumentation. (I–K) Final follow-up radiographs and CT showed good bone fusion. CT, computed tomography; MRI, magnetic resonance imaging; PLC, posterior ligamentous complex.
Patients were randomly assigned, in a 1:1 ratio, to undergo either PTDIF group or CPDIF group (Fig. 1). Randomization was performed with the use of a random number table method and opaque envelopes, which enabled random treatment assignment. Random numbers were selected and concealed in the envelopes. The patients submitted to PTDIF or CPDIF were determined by odd or even numbers in the envelopes. In this trial, patients, data collectors, and statistical analysts were blinded to the treatment, but surgeons were aware of the treatment.
Then these 65 patients were randomly divided into 2 groups, namely groups A and B. While patients in group A were scheduled by PTDIF with preservation of PLC, patients in group B were planned for CPDIF. The clinical data on patients in the 2 groups were similar (Tables 1 and 2).
Clinical characteristics of the 2 groups
Comparison of the surgical and experimental information in the 2 groups
The demographic details (including comorbidities) of patients, detailed clinical history and examination findings (including complete neurological examination), radiological findings (level of disease, extent of vertebral destruction, degree of kyphosis deformity, presence and extent of paraspinal or intraspinal abscess, etc.), intraoperative details (operative time and blood loss) and postoperative details (length of hospital stay, complications, etc.) were recorded.
1. Preoperative Management
Antituberculosis medicines including isoniazid (5 mg/kg), rifampicin (10 mg/kg), ethambutol (15 mg/kg), and pyrazinamide (25 mg/kg) were given to patients with STB 2 to 4 weeks prior to surgery. Objectives for the management of coexisting conditions included lowering blood pressure to less than 140/90 mmHg, reducing blood sugar to less than 11.0 mmol/L, improving appetite, and gaining weight. In addition, elderly patients were given an antiosteoporosis medication before surgery. After restoring normal levels or having significantly decreased of ESR, CRP, and temperature and correcting anemia and hypoproteinemia, surgery was conducted.
2. Surgical Procedure
The same group of surgeons performed all surgical procedures. In group A, the medial ribs, lamina, facet joints, transverse processes, and costotransverse articulations were all exposed during surgery on all patients while lying on a prone position under general anesthesia. Exposing the vertebral laminae of involved segments, followed by posterior pedicle screw installation. The afflicted vertebrae had transpedicular screws fixation. To avoid having the screw exposed following debridement, the site for transpedicular screw insertion should be located away from the foci but close to the endplate. Then, it was advised to perform 1 or 2 levels above or below the affected vertebra. A temporary rod was used to stabilize the focus’ mild side to prevent thecal sac or cauda equina injury brought on by spine instability during decompression and focal debridement. Under the premise of ensuring the integrity of the posterior ligament complex, debridement of the damaged intervertebral discs and vertebrae was conducted after unilateral partial laminectomy or hemilaminectomy and resection of transverse process at the more severe lesion or more abscess side of the affected vertebrae. Also carried out was a complete unilateral facetectomy. Resection of pedicle on the debridement side of afflicted vertebrae was done if the pedicle was involved and cannot have transpedicular screws fixation. One spinal nerve on the targeted side may be sacrificed to get a wider perspective. A corpectomy, a discectomy, and an abscess evacuation were done (Fig. 5A and B). Compression wash and negative pressure suction were carried out by incubating a urethral catheter in the abscess cavity to enhance debridement. Additionally, motor-evoked and sensitive-evoked spinal cord monitoring was applied. Autogenous bone was used to fill 1 or 2 titanium mesh cages made from the healthy lamina, and allograft bone was molded to fit the size and shape of the bone graft bed (Figs. 2F and 3F). The posterior interbody graft was placed posterolaterally once the spinal cord was not compressed. Following the implantation of interbody titanium mesh cages, compression was carried out. In all cases, the contralateral decortication of the lamina and articular process was then performed for posterolateral fusion using autogenous bone or an allograft. Incision sutures and drainage were done postoperatively. Streptomycin 1.0 g and isoniazid 0.3 g were administered topically. Intraoperative samples were sent for histological analysis, mNGS, culture and sensitivity for tuberculous organisms, Gram and acid-fast Bacillus staining, and other tests.
Posterior and axial illustrations, respectively, of the surgical approaches: (A, B) posterior transforaminal thoracic interbody debridement with preservation of PLC and (C, D) conventional posterior thoracic interbody debridement. For PTDIF, the pathologic lesion is exposed via a transforaminal approach with preservation of PLC, rib and costovertebral joint at the infected level; for CPDIF, the PLC, rib and costovertebral joint at the infected level was removed. The gray and slash areas in the 2 axial views (B, D) indicated scope of intraoperative resection which showed resection of transverse process, unilateral partial laminectomy or hemilaminectomy and facetectomy were performed in PTDIF and resection of PLC, partial rib, costovertebral joint, transverse process, unilateral partial laminectomy or hemilaminectomy and facetectomy were performed in CPDIF. Both PTDIF and CPDIF allowed operation on the vertebral body at a 270° angle under an oblique visualization and posterolateral manipulations facilitate effective focal debridement in the affected intervertebral space. PLC, posterior ligamentous complex; PTDIF, posterior-only transforaminal debridement and interbody fusion; CPDIF, conventional posterior-only debridement and interbody fusion.
In group B, after removing transverse process, spinous process, interspinous and supraspinal ligament of the afflicted vertebrae, resection of partial rib (1–1.5 cm) and costovertebral joint, unilateral partial laminectomy or hemilaminectomy and facetectomy were performed at the more severe lesion or more abscess side of the afflicted vertebrae (Fig. 5C and D). Other procedures were the same with group A (Fig. 4E).
3. Postoperative Management
The drainage tube was usually taken out when the amount of drainage was below 50 mL in a 24-hour period. Following the surgery, patients were permitted to mobilize after staying in a supine position for 14 to 20 days postoperatively. Subsequently, patients received anti-TB chemotherapy for a duration of 12 to 18 months after the surgery. An antiosteoporosis drug was also administrated on patients for at least 3 months postoperatively. The braces were continually used for 6 to 8 months postoperatively. Throughout the first year, follow-up exams were conducted at 4 weeks, 3, 6, 9 months, and 1 year. Follow-ups after then happened once a year. They were evaluated clinically for neurological function and pain at each check-up, and radiologically for spinal alignment and fusion development. When there was no longer pain, roentgenograms or CT scans showed bone fusion (Figs. 2G–L and 3G–L), blood tests showed normalized ESR and CRP levels, and patients reported feeling good overall; the disease was regarded to have healed. Hepatic and renal function were routinely monitored. Fusion success was measured by the lack of local pain and tenderness at the fusion site, the absence of aberrant mobility, the absence of hardware failure and corrective loss, the existence of trabecular bone bridging between the grafts and the vertebrae, and the absence of lucencies at the bone-cage interfaces. Bony fusion was evaluated by a 3D CT scan in inconclusive cases. Presence and extent of paraspinal or intraspinal abscess was evaluated by MRI (Figs. 2M and 3M).
ESR and CRP were monitored before, after, and during follow-up. The severity of the pain was measured using a visual analogue scale (VAS) and Oswestry Disability Index (ODI) scores. The American Spinal Injury Association’s (ASIA) categorization system was used to assign severity levels of neurologic disability. The radiological measurements included magnitude of kyphosis deformity (Cobb angle), which was measured by using the superior endplate of the infected vertebral body above and inferior endplate of the infected vertebra below as reference points, correction of kyphosis, loss of correction during the follow-up.
Blood cell count analysis, CRP, ESR, and the T-SPOT.TB were used to confirm a diagnosis of spinal TB in addition to the patient’s history and physical examination. Microbiological, histopathological, gene xpert (TB polymerase chain reaction) and mNGS analysis of surgically removed tissue verified this.
4. Statistical Analyses
IBM SPSS Statistics ver. 24.0 (IBM Co., Armonk, NY, USA) was used for analysis. Technical information between the 2 groups were compared using Student t-test and Wilcoxon signed-rank test. A rank sum test was used to analyze any discrepancy in normal data distributions. A p-value of <0.05 was considered statistically significant.
RESULTS
Out of the initial 71 consecutive patients enrolled for the study, 5 patients refused surgery and were lost follow-up before the end of treatment, which were excluded in this study. One patient was finally diagnosed with pyogenic infection. Overall, 65 patients who undergone surgical treatment were included in this study (Fig. 1).
All 65 patients were completely cured during the follow-up. In group A, there were 32 cases (19 males and 13 females) with a mean age 52.0 years (range, 20–75 years). In group B, there were 33 cases (21 males and 12 females) with a mean age of 51.3 years (range, 22–74 years). In group A, involved levels were observed at 1 case in T3–4, 2 cases in T4, 2 cases in T4–5, 1 case in T5, 3 cases in T5–6, 3 cases in T6–7, 1 case in T1–7, 5 cases in T7–8, 3 cases in T8–9, 3 cases in T7–9, 2 cases in T9–10, 2 cases in T9–11, 3 cases in T10–11, and 1 case in T9–12. In group B, involved levels were observed at 1 case in T3–4, 1 case in T4, 2 cases in T4–5, 2 cases in T5–6, 1 case in T5–10, 3 cases in T6–7, 4 cases in T7–8, 5 cases in T8–9, 6 cases in T9–10, 2 cases in T9–11, 4 cases in T10–11, and 2 cases in T10–12.
The mean periods of follow-up were 36.7±3.0 months in group A and 36.8±3.0 months in group B. The intraoperative blood loss and operation time in group B were more than that in group A, with a significant difference (p<0.001) (Table 2). The average hospitalization durations were 20.3±1.6 days and 22.5±1.5 days in groups A and B, respectively (p=0.046) (Table 2). All patients had intractable back pain as prominent clinical symptom. Fifty-five patients suffered from varying degrees of neuro-deficit. Other clinical symptoms reported by patients included low fever, weakness, loss of appetite, and weight loss.
All patients experienced significant back pain relief after surgery. Preoperative VAS score in group A was 7.3±0.4 and decreased to 1.3±0.2 at the final follow-up. Preoperative VAS score in group B was 7.4±0.4 and decreased to 1.2±0.2 at the final follow-up. The ODI was 39.8±2.1 in group A and 38.9±2.1 in group B preoperatively, then reduced to 10.7±1.1 and 10.4±1.1, respectively, at the final follow-up (Table 2). All patients achieved bone fusion. The bony fusion time was 5.4±0.3 months in group A and 5.3±0.3 months in group B.
Before surgery, the ESR were 52.8±5.3 mm/hr and 53.2±5.4 mm/hr in the groups A and B, respectively. The CRP levels were 51.3±4.9 mg/L and 50.7±4.7 mg/L preoperatively in the groups A and B, respectively. At the time of anti-TB drug treatment 3 months after surgery ESR and CRP were within normal limits.
No neurological deterioration after surgery occurred in any of the patients. All 65 patients had improved neurological signs. The results were evaluated by ASIA classification: 2 patients improved by 3 grades, fourteen patients improved by 2 grades, and 12 patients improved by 1 grade in group A, 1 patient improved by 3 grades, 13 patients improved by 2 grades, and 13 patients improved by 1 grade in group B (Table 2). There was no statistically significant difference in neurological outcome at final follow-up between the groups.
The mean preoperative kyphosis angle was similar between the 2 groups (Table 2). There was no significant difference between the 2 groups at postoperative and final follow-up kyphosis angle (p>0.05) (Table 2), and the kyphosis angle of the 2 groups was significantly improved compared with that before operation (p<0.05) (Table 2). There was no obvious loss of correction in both groups (Table 2).
The surgical incisions were healed without chronic infection, fistula formation, and recurrence. Five patients in group B had pleural effusion, which was relieved after drainage and albumin infusion. Three patients had pneumonia and were cured after treatment with suitable antibiotics according to the drug susceptibility test (group A=1, group B=2). Two patients in group B had pneumothorax, which was relieved after drainage and oxygen inhalation. No nonunion, pseudoarthrosis, loosening, or fracture of instruments occurred at the final follow-up visit. No graft fracture, sliding, or resorption was observed.
DISCUSSION
Thoracic spinal tuberculosis accounts for approximately 50% of spinal tuberculosis and typically involves 1–2 vertebrae, even extends across more than 2 vertebrae due to delays in diagnosis and treatment, tuberculosis drug resistance, and other factors in developing countries [11]. Stable thoracic joint support limits motion, besides, the buffer space of the thoracic spinal canal is relatively narrow and the blood supply to the thoracic spinal cord is low [1]. As spinal tuberculosis advances, the condition can lead to the invasion of the spinal canal by caseous necrotic tissue, pus, and dead bone, resulting in the compression of the thoracic spinal cord [1]. The destruction of vertebral bodies, along with subsequent collapse, induces kyphosis deformity, thereby raising the risk of paraparesis or even paraplegia [1]. Therefore, decompression of the spinal cord and reconstruct the stability of the spine are the prerequisites for curing thoracic spinal TB and the key to prevent neurological deterioration.
When it comes to treating thoracic STB, effective anti-TB chemotherapy is still the mainstay of the management. However, long-term immobilization under medical therapy does not prevent major substance defects and subsequent kyphotic deformities, which then require extensive reconstructive procedures despite the fact that chemotherapy effectively inactivates spondylitis [12,13]. When nonoperative methods of treating destructive tuberculous spondylitis have failed, or when patients exhibit signs of neurologic impairments, intraspinal masses, abscesses, and significant destruction with instability or severe spinal deformity, surgical intervention may be necessary [14].
There is considerable debate and room for discretion in the surgical management of STB. Because the inflammation is typically found in the anterior aspect, only an anterior approach can reliably perform debridement of the lesion and, if necessary, spinal cord decompression. Direct pathogen detection at the site of inflammation is another potential benefit of surgical treatment. However, the anatomical position in thoracic spine is deep, the surrounding tissues are complex, and there are many bony occlusions, such as sternal manubrium, clavicle, ribs and scapula. Moreover, the vertebral body is adjacent to the large blood vessel, aorta, thoracic duct and nerve tissues. Therefore, using the anterior route to expose the lesions is difficult and has a high surgical risk. Furthermore, individuals with thoracic spine tuberculosis frequently experience the breakdown of bone structure, which results in kyphotic deformity and makes anterior surgery much more difficult. The surgical operation is not effective in preventing the progression of kyphosis or in correcting the preexisting kyphosis [15], and it may also result in greater mortality, especially for patients with concomitant cardiovascular and pulmonary problems [16]. Some surgeons, aware of the method’s drawbacks, have resorted to using additional posterior instrumentation to prevent graft failure [17]. A more stiff and stable spinal design can also be achieved with anterior and posterior surgery. However, particularly for elderly patients, the operation time, healing time, and surgical trauma associated with this combined procedure are all higher [1].
As more effective regimens of appropriate anti-TB drugs have become available, posterior-only procedure whose surgical approach is very simple have emerged as an alternative treatment for STB [3,7,8]. We opted for the posterior-only technique because some patients were in such precarious health. This method is also less invasive than others because it does not involve the chest. When posterior-only surgery is performed, the high anesthetic risk of an anterior treatment is avoided, along with the serious difficulties it can cause postoperatively.
Although we have had success treating contiguous STB with posterior-only debridement and fusion using pedicle screw instrumentation [3,5,7,8], the posterior-only procedure for thoracic STB has its own disadvantages due to its special anatomical structure characteristics and position. For most cases of thoracic STB, the anterior and middle columns are not easy to operate from the back. And the relatively narrow thoracic spinal canal allows little room for intraoperative manipulation. Therefore, CPDIF often require PLC, proximal part of rib and costotransverse articulation resection in order to offer a wider perspective to the lateral aspects of the affected vertebral bodies [3,5,7,8]. Nevertheless, excessive exposure of spinal cord after resection of posterior spinal structure, especially including PLC, remain potential complications like injuries to the dura and neural structures [18]. Additionally, the lack of mobility of the dural sac and the limited traction space due to tissue inflammatory adhesion between dural sac and nerve roots and lesion easily lead to nerve injury [19].
Posterior transforaminal thoracic interbody fusion (TTIF) has been regarded as an improvement on posterior thoracic interbody fusion and has several advantages due to easy access of the spinal canal and interbody space via a path that runs through the far-lateral portion of the vertebral foramen [20]. It was successful in resolving the issue of excessive nerve retraction and its associated complications [20]. In light of this, we used PTDIF, whose approach is similar to the posterior TTIF in the treatment thoracic spinal tuberculosis. The modified posterior-only procedure can achieve relatively complete debridement and decompression in an “effective” operative channel by removing the unilateral lamina, facet joint, transverse process. Resection of pedicle on the debridement side of afflicted vertebrae was done to get a wider perspective if the pedicle was involved and cannot have transpedicular screws fixation. Debridement can facilitate healing, aid in creating an environment less favorable for the survival of Mycobacterium tuberculosis, and improve the penetration of anti-TB drugs into the infected area. Since there is no advantage to radical surgery over debridement in the presence of an extensive spinal lesion [21], we only excised localized tissues and those at the periphery, particularly sclerotic walls, cavities, and any other tissue that could lead to localized recurrence and reached the subnormal substance of bones. Because surgery cannot achieve sterility, effective anti-TB drug treatment and improvement of the patient’s general condition are important aspects of the therapy of spinal TB. The rest of the small number of lesions and abscesses could be absorbed by long-term standardized anti-TB chemotherapy postoperatively. Our study showed that all patients were completely cured during the follow-up. Neurological function in patients with paraplegia significantly improved postoperatively.
The supraspinous and interspinous ligaments, as well as the anterior and posterior longitudinal ligaments, and their function as a tension band of the spinal ligaments, remain intact along the journey to the intervertebral space in PTDIF. By retaining the contralateral lamina and facet joint, PLC, and resecting only one of them unilaterally through the posterior approach, less damage is done to the spinal bone and more stability is preserved. Because the rib and costovertebral joint at the infected level are not resected in PTDIF, the exposure of the retropleural space can be avoided, which reduces the risk of iatrogenic pneumothorax and pleural cavity damage. There were no patients suffering from iatrogenic pneumothorax, hemopneumothorax, pleural effusion, and pleural cavity damage in group A, while 2 patients suffering from pneumothorax, 5 patients suffering from pleural effusion in group B. Also, bone removal and soft-tissue disruption are minimal in the procedure of PTDIF, whose PLC, costovertebral joint and rib are preserved. This may simplify surgical procedures and decrease surgical trauma compared with CPDIF. In our study, the intraoperative blood loss and operation time in group A were less than that in group B.
Our clinical experience showed that the PTDIF provides adequate exposure and an “effective” operative channel for focal debridement in thoracic spinal tuberculosis for the following reasons: (1) The approach described here creates enough operating space through resection of one side of the lamina, facet joint, the transverse process and unilateral partial laminectomy or hemilaminectomy allowing operation on the vertebral body at a 270° angle under an oblique visualization and posterolateral manipulations facilitate effective focal debridement in the affected intervertebral space. (2) One spinal nerve and pedicle which was involved on the targeted side may be sacrificed to enlarge the exposure to focal lesions and get a wider perspective for posterolateral manipulation. (3) During focal debridement, the sclerotic bone, dead bone, pus, granulation tissue, and disc that could lead to localized recurrence were completely removed, reaching the subnormal substance of bones. (4) For multilevel thoracic spinal TB, the affected foci were chosen to perform debridement separately, as there is no advantage to radical surgery over debridement in the presence of an extensive spinal lesion [21]. (5) Effective anti-TB chemotherapy, rest, and nutritional support treatment are still the basic methods for tuberculosis treatment.
The use of posterior 3-column instrumentation in the surgical treatment of STB may provide robust biological stability, which may immediately improve the surgical outcomes, accelerate healing, prevent kyphosis aggravation, correct kyphosis and resolve relief of back pain due to spinal instability [3,7,8]. Then, we utilized the PTDIF procedure combined with posterior 3-column instrumentation to manage thoracic TB. This method provides immediate stability, correcting the kyphotic deformity and accelerating infection control, decreasing intractable back pain and painkiller duration. All patients in our study experienced significant back pain relief after surgery. There was no significant difference between the 2 groups at postoperative and final follow-up kyphosis angle, and the kyphosis angle of the 2 groups was significantly improved compared with that before operation.
Reconstructing a defective anterior column with a titanium mesh cage has been shown to be an effective treatment for spinal intervertebral reconstruction after debridement [7,8]. This is because the cage provides immediate stabilization of the spine, enhances sagittal balance, and accelerates bone integration. There are a number of benefits that titanium mesh cages offer over alternative bone struts. The titanium cage can withstand compression and some torque due to its rigidity and the huge weight-bearing surfaces it provides. Due to the high interface strength between the cage and the endplates, graft displacement or collapse can be prevented, and recovery time can be shortened without increasing inherent dangers. Due to its malleability, the titanium mesh cage is especially well-suited for insertion between neighboring vertebral endplates. Mechanically, it is robust enough to forestall the height loss of a fused motion segment that could result from vertebral osteoporosis [22]. The coronal alignment was further enhanced by compressing the titanium mesh interbody cages. In our study, patients in both groups obtained good intervertebral fusion. The 2 groups had no significant difference in the fusion time.
The major advantages of PTDIF include: (1) Posterolateral manipulation during focal debridement produces a “cavitation” of the intervertebral space, allowing complete removal of granulation tissue without retracting the dura sac, minimizing risks of dura tears, cerebrospinal fluid leakages, or worsening neurological deficiencies. (2) Minimal bone removal and soft-tissue disruption, as the PTDIF, obviates the need for dissecting the PLC, rib, and costotransverse articulation, eliminating the risk of pneumothorax complications and diminishing long-term localized pain. (3) The PTDIF, with a single posterior midline incision and minimal bone removal and tissue dissection, results in decreased intraoperative anesthesia, shorter operative time, less blood loss, and shorter hospitalization durations. (4) The PTDIF with preservation of the PLC, combined with posterior 3-column instrumentation and intervertebral fusion, may provide robust biological stability, accelerating healing, correcting kyphosis, and resolving back pain relief due to spinal instability.
Our study has limitations, including its limited patient sample size. The benefits and downsides of our method can only be grasped with a much larger randomized controlled experiment. However, the data presented here could be seen as an early finding that aids surgeons and patients in decision-making and creates future, well-designed prospective trials with larger patient sample sizes.
CONCLUSION
In this study, we conducted a prospective randomized controlled trial and found that PTDIF with preservation of PLC achieved similar debridement, decompression and reconstruction of the spine’s stability as CPDIF in the surgical treatment of thoracic STB. PTDIF has less surgical trauma with less intraoperative blood loss and operation time.
Notes
Conflict of Interest
The authors declare that they have no competing interests.
Funding/Support
The work was supported by the Hunan Province Natural Science Foundation of China (No. 2020JJ4913), Research project on postgraduate education and teaching reform of Central South University (No. 2024JGB035, No. 2021 JGB082), Graduate course ideological and political construction project of Central South University (No. 2022YJSKS032), and Hunan Provincial Degree and Postgraduate Education Reform Research Project (No. 2024JGYB038).
Author Contribution
Conceptualization: YW, HZ; Formal analysis: SX, ZY; Investigation: YW; Methodology: YW, SX, GZ, HZ; Project administration: YW; Writing – original draft: YW; Writing – review & editing: YW, GZ, HZ, EA.