Outcomes of Dorsolumbar and Lumbar Spinal Tuberculosis Treated by Minimally Invasive and Open Techniques: A Prospective Comparative Study

Abstract

Purpose of Study

To compare the outcomes of minimally invasive and open techniques in the surgical management of dorsolumbar and lumbar spinal tuberculosis (STB).

Methods

Skeletally mature patients with active STB involving thoracolumbar and lumbar region confirmed by radiology (X-ray, MRI) and histopathological examination were included. Healed and mechanically stable STB, patients having severe hepatic and renal impairment, coexisting spinal conditions such as ankylosing spondylitis and rheumatoid arthritis, and patients unwilling to participate were excluded from the study. The patients were divided in to two groups, group A consisted of patients treated by MIS techniques and group B consisted of patients treated by open techniques. All the patients had a minimum follow-up of 24 months.

Results

A total of 42 patients were included in the study. MIS techniques were used in 18 patients and open techniques were used in 24 patients. On comparison between the two groups, blood loss (234 ml vs 742 ml), and immediate post-operative VAS score (5.26 vs 7.08) were significantly better in group A, whereas kyphotic correction (16° vs 33.25°) was significantly better in group B. Rest of the parameters such as duration of surgery, VAS score, ODI score and number of instrumented levels did not show significant difference between the two groups.

Conclusion

MIS stabilization when compared to open techniques is associated with significant improvement in immediate post-operative VAS scores. The MIS approaches at 2-year follow-up have functional results similar to open techniques. MIS is inferior to open techniques in kyphosis correction and may be associated with complications.

Introduction

Minimally invasive spine surgery (MIS) has been gaining popularity in the last 2 decades because of decreased intraoperative blood loss, decreased tissue damage, shorter operative time, and reduced post-operative pain [1–5]. MIS techniques are being routinely applied to treat spinal disorders such as trauma, tumors, and deformity with good results [6–8]. MIS techniques for spondylodiscitis has steadily and increasingly been recognized as treatment for spinal tuberculosis (STB) [9, 10]. The goals of MIS are to achieve spinal decompression and stabilization matching that of its open counterpart while reducing iatrogenic muscle injury to the back [8].This concept can be used in spondylodiscitis patients who frequently suffer from severe comorbidities. MIS has the advantage of minimal tissue damage during the procedure and sparing of posterior midline structures leads to decreased pain, and superior functional outcome in post-operative period aiding in early rehabilitation [11, 12]. There is plethora of literature which compares MIS techniques and open techniques for spinal trauma and degenerative conditions, but there are very few such comparative studies in surgical management of STB. We conducted this prospective study to compare the outcomes of the two techniques with a hypothesis that all advantages of MIS techniques can be passed on to the cases of STB while achieving similar outcomes when compared to gold standard open techniques.

Materials and Methods

This was a prospective cohort study conducted in a tertiary health care center. After obtaining ethical clearance (Reg No: ECR/736/IEC/89), 42 patients were recruited into the study from June 2019 to June 2020 according to the inclusion and exclusion criteria mentioned below (Fig. 1). All the patients included in the study provided a written informed consent. Patients fulfilling the inclusion criteria were offered surgical intervention. Choice of surgery was discussed with the patient and final decision on the technique was made by the patient. The patients were grouped accordingly into two groups. Group A was treated by MIS technique and group B treated by open technique (examples Figs. 2 and 3). All the patients had a minimum follow-up of 24 months (24–30 months). Routine radiographs were done and final fusion was assessed using the criteria by Bridwell et al. [13].

Fig. 1.

Flowchart showing selection of the patients.

Fig. 2.

Pre-operative AP and lateral X-ray of Spinal Tuberculosis (L1-L2) treated by open technique (A); Pre-operative MRI and CT Scan sagittal and axial view (B); Immediate post-operative view (C); Follow up X-ray at 6 months (D); Final follow-up (E)

Fig. 3.

Pre-operative AP and lateral X-ray of Spinal Tuberculosis (L4-L5) treated by MIS technique (A); Pre-operative MRI scan sagittal and axial view (B, C); Immediate post-operative view (D); Follow up X-ray at 6 months (E); Final follow-up (F)

Inclusion Criteria

Inclusion criteria were: skeletally mature population (age group 18–60 years), patients with active spinal tuberculosis involving thoracolumbar (D10–L2) and lumbar (L2–3 disc-S1) tuberculosis confirmed by radiology (X-ray, MRI) and histopathological examination, mechanical instability of spine [14, 15], patient developing new neurological deficits, progressive deficits or deficits persisting during the course of conservative treatment (3–4 weeks), and severe pain and disability not responding to conservative methods.

Exclusion Criteria

Exclusion criteria were: healed and mechanically stable STB, patients having severe hepatic and renal impairment, coexisting spinal conditions such as ankylosing spondylitis and rheumatoid arthritis, and patients unwilling to participate in the study. The patients with multilevel STB requiring intervention in dorsal spine alongside dorsolumbar or lumbar spine were also excluded from the study.

Treatment Protocol

The patients were labeled as tubercular cases only after thorough clinico-radiologic examination and histopathological confirmation. The diagnostic workup included blood investigations (ESR, CRP, and screening for HIV status), radiographs, CT, and MRI scans. Antitubercular therapy was started according to institutional protocol, i.e., HRZE (Isoniazid (H) 5 mg/kg, Rifampicin (R) 10 mg/kg, Pyrazinamide (Z) 25 mg/kg, Ethambutol (E) 15 mg/kg) for 2 months and HRE for 10 months. Liver functions and erythrocyte sedimentation rates were monitored carefully at regular intervals. The patients who failed conservative management for STB were planned for surgery.

Statistical Analysis

Once the data were collected and tabulated, descriptive statistics were used for continuous variables. t-test was used to find the significance in changes of VAS, ODI scores, and kyphosis correction before and after surgery. A p value of < 0.05 was considered significant.

Results

A total of 42 patients were included in the study. The demographic details of both the groups are enumerated in Table 1. The intraoperative variables and radiologic outcomes in both the groups are enumerated in Table 2.

Table 1.

Demographic details of group A and group B

	Group A MIS n = 18	Group B (open) n = 24	p value
Age (mean)	43 years (24–60)	36.7 years (18–60)	0.15
Sex (M/F)	13/5	15/9	0.83
Preop neurological deficit (A/B/C/D/E)	1/0/3/2/12	4/1/2/1/16	0.88
Indication (neurological deficit/instability or deformity/doubtful diagnosis)	6/11/1	8/14/2	0.903
Levels—single	17	21	0.893
Multilevel	1	3	–
Dorsolumbar	10	16	–
Lumbar	8	8	–

Table 2.

Intraoperative variables and radiologic outcomes in group A and group B

Clinical parameters	Pre-operative score (mean ± SD) (Group A)	Post-operative score (mean ± SD) (Group A)	p value	Pre-operative score (Mean ± SD) (Group B)	Post-operative score (mean ± SD) (Group B)	p value
VAS	8.93 ± 0.59	2.93 ± 1.03	< 0.05	8.25 ± 0.59	2.29 ± 0.85	< 0.05
ODI	89.5 ± 5.06	21.2 ± 6.36	< 0.05	87.9 ± 11.02	28.25 ± 8.27	< 0.05
Kyphotic angle DL spine	+ 17.14° ± 7.01	7.42° ± 3.73	< 0.05	+ 17.69 ± 9.26	5.38 ± 6.85	< 0.05
Kyphotic angle lumbar spine	+ 6° ± 20	− 17.5° ± 4.98	< 0.05	+ 19.27 ± 14.87	− 19.1 ± 5.088	< 0.05

Comparison Between Group A and Group B

On comparing the group A and group B, kyphotic correction, post-operative VAS score and blood loss showed significant difference. The other parameters such as duration of surgery, VAS score, ODI score and number of instrumented levels did not show any significant difference between the two groups. The details are enumerated in Table 3.

Table 3.

Comparison between group A and group B

	Group A MIS	Group B open	p value
Blood loss	234.6 ± 276.9 ml	742.08 ± 652.49 ml	0.00040
Duration	191.3 ± 50.54 min	204.16 ± 64.06 min	0.51
Immediate VAS score	5.26 ± 1.16	7.08 ± 1.01	0.000016
Final VAS	2.93 ± 1.03	2.29 ± 0.85	0.08
Final ODI Score	21.2 ± 6.36	28.25 ± 8.27	0.09
Kyphosis correction DL spine	10.43° ± 3.64	10.69° ± 4.27	0.88
Kyphosis correction lumbar spine	16° ± 11.83	33.25 ± 13.41	0.002
Instrumented levels	4.06 ± 0.96	4.75 ± 1.22	0.06

Improvement in the Neurological Deficits

All the patients with neurological deficits in both the groups had improvement in neurology by at least one grade. In group A, patients with DL spine involvement, incomplete neurological deficits were seen in 3 patients (Frankel C). One of them improved to Frankel D and the other two improved to Frankel E. One patient with complete neuro-deficit (Frankel A) improved to Frankel D. Two of the patients (2/6) of lumbar STB with weakness of EHL (MRC3/5) recovered fully at final follow-up. Among four of the neurologically intact patients, one had deterioration of neurology in the post-operative period.

In group B, two patients of lumbar STB had weakness of ankle dorsiflexors and EHL which completely recovered in the final follow-up. In the dorsolumbar STB, four patients had Frankel A neurology, among which three improved to Frankel D and one improved to Frankel C. One patient of Frankel B improved to Frankel D and one patient of Frankel D improved to Frankel E.

Complications

In group A, there was one case of post-operative worsening of neurology which had to be taken up for repeat decompression in the immediate post-operative period. The patient’s neurology improved in the follow-up to ambulatory level. There was one case of superficial infection which healed with regular dressings. There was one case with renal artery injury, which had significant bleeding and nephrectomy was done to control the bleeding in the patient. One case had implant back out from the distal screw entry site at 3 months. The back out stabilized at 6 months and 9 months and so removal was not done.

In group B, there was one case of post-operative infection who required regular dressings before it healed. There was one case of proximal junctional failure (PJF) and one case of screw pull out (Fig. 4). Both the cases were re-operated and fusion levels were extended. Good fusion was obtained in the screw pull out case at 1-year follow-up, whereas the patient with proximal junctional failure (PJF) is under routine observation without any complaints. The complications are summarized in Table 4.

Fig. 4.

Pre-operative AP and lateral X-ray of Spinal Tuberculosis (L3-L4) (A); Pre-operative MRI and CT Scan sagittal and axial view (B); Immediate post-operative view (C); Follow up X-ray at 6 months showing failure (D); Immediate revision post-operative view (E); Follow up X-ray after revision at 6 months (F); Final follow-up (G)

Table 4.

Complications

Complications	Group A (MIS)	Group B (Open)	p value
Neurological	1	0	–
Implant related	2 (screw pullout)	2 (1PJF* + 1 screw pullout)	0.57
Wound related	1 (infection)	1	1
Miscellaneous	1 (renal artery injury)	–	–

Discussion

The objective of using MIS in STB is to reach the affected area through as minimal a surgical corridor as possible and to reduce iatrogenic trauma to the surrounding tissues. The anticipated advantages of MIS techniques are decreased post-operative pain, less chances of acute and chronic muscular dysfunction, and hence improved functional recovery. These factors may potentially lead to a significant reduction of in-hospital stay and rehabilitation time [16]. The operative duration between the two groups in our study was not significantly different and was similar to the various studies in the literature. The mean duration of surgery in our study in group A was 191.33 min and 204.16 min in group B. The operative duration in a study done by Kandwal et al. was 255 min which was similar to our study group. In a study done by Fan et al., where minimally invasive techniques were used to treat lumbar tuberculosis, the mean operative duration was 185 min [17]. Prolonged operative duration has been shown to increase the risks of anesthetic-related and surgical site infections [18]. Whenever feasible, it is always better to choose a technique which has similar advantages to open techniques but can be done in a shorter duration. This reduces the infection rates, bleeding and also anesthetic complications. One theoretical concern of MIS techniques in the initial phases is that it has a significant learning curve which may increase the surgical time in the beginning but as the experience increases, the time duration is comparable to open techniques and in the long term the advantages outweigh the steep learning curve. One of the many advantages of MIS techniques is minimal blood loss during the procedure. The studies done in the past show a similar trend where the blood loss was higher in open techniques and lower in MIS techniques. Chen et al. [19] did a study comparing open techniques and minimally invasive techniques where the results confirmed that the groups treated by percutaneous instrumentation showed a marked reduction in intraoperative blood loss. The minimally invasive group in our study had less blood loss (234.6 vs 742.08 ml) when compared to the open group. However, the number of multilevel cases was more in the open group (3 cases) as compared to the MIS group (1 case). The blood loss reported by Fan et al. in his study was 165 ml which was lesser than our study group. This minor difference can be due to the various retractor systems and the stage of the disease being treated [17].

The surgical treatment of spinal tuberculosis should also focus on the correction of local kyphosis and restoring the normal curvatures of spine [20, 21]. The kyphosis correction in both the groups of our study was significant. The kyphosis was studied separately for dorsolumbar (DL) spine and for lumbar spine. The improvement in kyphosis in open lumbar group was significantly higher than the MIS group. Numerous studies have confirmed that posterior instrumentation not only helps in correction of the kyphotic angle, but also allows early mobilization, improve surgical outcomes, and accelerates healing [22, 23]. In two studies by Lee et al. [24] and Pu et al. [25] using conventional methods of posterior transpedicular decompression and fixation, mean pre-operative kyphosis ranged from 18° to 24° which was corrected by 4°–8°, over a mean follow-up of 22.5 months [25].Once the disease heals, the kyphotic deformity does not progress and this was shown by Upadhyay et al. [26] and Jain et al. [27] in their studies on surgically treated cases of STB.

The functional outcomes of MIS techniques and open techniques were evaluated by the VAS scores and ODI scores. Our study showed significant improvement in VAS scores post-operatively across both the groups. However, the immediate post-operative VAS scores were significantly better in MIS group. In a study done by Jain A et al. [28] where the study group compared the outcomes in cases of Potts spine, the improvement of VAS score was from 8.7 to 1.1 post-operatively at 1-year follow-up. In similar studies done by Yadav G et al. [12], the VAS score improved from 7.48 ± 1.16 pre-operatively to 0.47 ± 1.94 post-operatively. Wu et al. [29] also did a study in which the pain score improved from 7.9 ± 1.2 to 2.9 ± 1.1. El-sharkawi et al. [30] in his study showed the improvement of VAS scores from 8.5 ± 1.3 pre-operatively to 1.8 ± 1.1 post-operatively. Debridement of the lesion and stabilization along with antitubercular drugs provides pain relief in majority of cases due to reduced spasm of the muscles and decreased instability. Any pain on movement in the bed should raise the suspicion of instability and should be considered for stabilization irrespective of neurological status of the patient. The improvement in ODI may be due to either improvement in neurology or due to improvement in the alignment and stability of affected spine. The mean pre-operative ODI score improved from 89.5 ± 5.06 to 21.2 ± 6.36 in group A and from 87.9 ± 11.02 to 28.25 ± 8.27 in group B. In a study done by Yadav et al., the ODI score pre-operatively was 76.4 ± 17.9 which improved post-operatively to 6.74 ± 17.2. The improvement in ODI score has been found to be consistent with improvement in VAS score throughout the literature [31]. Most of the studies in the literature which report outcomes of STB treated surgically, observed for post-operative improvement in functional scores and reported a positive functional outcome following surgery [30, 32, 33]. There are very few studies in the literature which compare the functional outcomes of open and minimally invasive techniques. Tschugg et al. [4] did one such study where 67 patients of lumbar spondylodiscitis were treated by minimally invasive techniques. The authors reported over all pain relief at discharge was significantly better in MIS group compared to the open group and the duration of hospital stay was longer in the open group. When the VAS scores were compared in our study, we observed similar results where the immediate pain relief was much better in the MIS group when compared to the open group. However, at the final follow-up both the open and MIS group had similar pain relief. Further Tschugg et al. did not report the improvement/deterioration in the kyphosis of the diseased levels, but measured the disc heights of the affected levels in both the groups but did not find any significant difference in both the groups.

Neurological deficits in STB occur mainly due to compression of the thecal sac, kyphotic deformity, and instability. The aim of surgical treatment of STB is to address the compression and instability. The STB may heal with medical treatment alone when there is no significant compression and instability [34]. All the patients had improvement in neurology by at least one grade. In a study done by Garg et al., all the patients in the study who were treated by MIS decompression and stabilization reached full power at the final follow-up [35]. Case reports described by Ito et al. [36] and Rigotti et al. [11] also showed neurological improvement in patients treated by minimally invasive methods. Kandwal et al. [8] studied the patients of STB treated with percutaneous instrumentation and debridement with retractor system. All the patients in the study had neurological improvement. The results shown by these studies are similar to the results for neurological improvement in our study and these studies prove that good neurologic recovery can be achieved even by MIS techniques [6, 8, 37]. This also proves that debridement and stabilization when done by minimally invasive techniques definitely gives rise to improvement in neurological status.

None of the patients underwent implant removal in our study. Implant removal remains controversial in those who undergo fixation without fusion, as it requires second surgery and general anesthesia. Studies done by De Iure [38] and Court and Vincent [39] on patients with spinal fractures treated by percutaneous transpedicular fixation methods show that the need for implant removal may be low, as few patients have clinical or radiographic evidence of failure. Infective pathologies may behave differently, as fusions between involved bodies occur in them. Lee et al. [24] did not remove screws in any of their ten patients with infective spondylodiscitis at a mean follow-up of 29 months (maximum, 61 months), although they noticed screw loosening in three patients. We in our study did not remove implants after the disease healed. Removal of implant also means subjecting the patient to another surgery and increased cost in the overall treatment. However, no proven advantages are present in the literature with regard to implant removal after the treatment.

The main goal of MIS techniques in spine surgery is to achieve the same results comparable to open procedures via an approach which is less traumatic. Although minimizing approach-related morbidity is the primary aim of MIS, this must be accomplished without compromising the efficacy of the intended procedure. Due to minimal tissue trauma and minimal damage to tissues, MIS techniques may reduce the amount of iatrogenic injury while still safely accomplishing the goals of the conventional open techniques.

Limitations of the Study

Though this is a prospectively conducted study comparing the outcomes of patients of STB by MIS and Open techniques, there are certain limitations in this study. Small sample size is possibly a drawback of the study. Lack of randomization could have bearing on the outcome. Though our study showed less blood loss in the MIS group, the multilevel cases were more in the open group. This could potentially create a bias in the assessment and comparison of blood loss between the two groups. The distribution of cases with neurologic deficits is asymmetric between the two groups due to lack of randomization. Longer follow-up is desirable to verify the difference in the outcomes of the two procedures.

Conclusion

The advantages of MIS techniques when compared to open techniques are low immediate post-operative VAS scores which translates to better and early rehabilitation. However, MIS approaches at 2-year follow-up is associated with functional results similar to open techniques. Kyphosis correction potential of MIS techniques on the other hand is inferior to open group and MIS may be associated with complications especially during learning curve.

Funding

No funds, grants, or other support was received.

Declarations

Conflict of Interest

None.

Ethical Standard Statement

This article does not contain any studies with human or animal subjects performed by the any of the authors.

Informed Consent

For this type of study, informed consent is not required.