Risk factor of contralateral radiculopathy following microendoscopy-assisted minimally invasive transforaminal lumbar interbody fusion

Is Minimally Invasive Spinal Surgery Superior to Endoscopic Spine Surgery in Postoperative Radiologic Outcomes of Lumbar Spine Degenerative Disease? A Systematic Review

BACKGROUND

 Minimally invasive spinal surgery (ESS) are both well-established surgical techniques for lumbar spinal stenosis; however, there is limited literature comparing the efficacy of the two techniques with respect to radiologic decompression data.

METHODS

 In this review, PubMed, Google Scholar, and Scopus databases were systematically searched from inception until July 2022 for studies that reported the radiologic outcomes of endoscopic and minimally invasive approaches for decompressive spinal surgery, namely, the spinal canal area, neural foraminal area, and neural foraminal heights.

RESULTS

 Of the 378 articles initially retrieved using MeSH and keyword search, 9 studies reporting preoperative and postoperative spinal areas and foraminal areas and heights were finally included in our review. Of the total 581 patients, 391 (67.30%) underwent MISS and 190 (32.70%) underwent ESS. The weighted mean difference between the spinal canal diameter in pre- and postoperative conditions was 56.64 ± 7.11 and 79.52 ± 21.31 mm2 in the MISS and ESS groups, respectively. ESS was also associated with a higher mean difference in the foraminal area postoperatively (72 ± 1 vs. 35.81 ± 11.3 mm2 in the MISS and ESS groups, respectively), but it was comparable to MISS in terms of the foraminal height (0.32 ± 0.037 vs. 0.29 ± 0.03 cm in the MISS and endoscopic groups, respectively).

CONCLUSIONS

 Compared with MISS, ESS was associated with improved radiologic parameters, including spinal canal area and neural foraminal area in the lumbar spinal segments. Both techniques led to the same endpoint of neural decompression when starting with a more severe compression. However, the present data do not allow the correlation of the radiographic results with the related clinical outcomes.

Comparison of minimally invasive transforaminal lumbar interbody fusion (Mis-TLIF) with bilateral decompression via unilateral approach and open-TLIF with bilateral decompression for degenerative lumbar diseases: a retrospective cohort study

OBJECTIVE

Presently, no study has compared the clinical outcomes of minimally invasive transforaminal lumbar interbody fusion (Mis-TLIF) with bilateral decompression via the unilateral approach (BDUA) and Open-TLIF with bilateral decompression for degenerative lumbar diseases (DLD). We aimed to compare the clinical outcomes of through Mis-TLIF combined with BDUA and Open-TLIF with bilateral decompression for the treatment of DLD, and reported the learning curve of the procedure of MIS-TLIF with BDUA.

METHODS

We retrospectively analyzed the prospectively collected data of consecutive DLD patients in the two groups from January 2016 to January 2020.

RESULTS

The operative time (OT) was significantly longer in the Mis-TLIF group (n = 113) than in the Open-TLIF group (n = 135). The postoperative drainage volume (PDV) and length of stay (LOS) were significantly higher in the Open-TLIF group than in the Mis-TLIF group. Additionally, the complication rate was significantly higher in the Open-TLIF group than in the Mis-TLIF group (14.8% vs. 6.2%, P = 0.030), while there was no significant difference in the reoperation and adjacent segment disease rates between the two groups. There were no significant differences in back pain and leg pain Numerical Rating Scale (NRS) scores and Oswestry Disability Index (ODI) between the two groups preoperatively, at discharge, and 2 years postoperatively. Patients in both groups showed significant improvements in NRS scores and ODI scores after surgery. OT was negatively correlated with the number of surgeries performed (P < 0.001, r =  -0.43). The learning curve of Mis-TLIF with BDUA was steep, with OT tapered to steady state in 43 cases.

CONCLUSION

Compared with Open-TLIF with bilateral decompression, Mis-TLIF with BDUA can achieve equivalent clinical outcomes, lower PDV and LOS, and lower complication rates. Although this procedure took longer, it could be a viable alternative for the treatment of DLD after a steep learning curve.

Effects of "fixation-fusion" sequence of lumbar surgery on surgical outcomes for patients with lumbar spinal stenosis: study protocol for a multicenter randomized controlled trial

BACKGROUND

New-onset neurological symptoms such as numbness and pain in lower extremities might appear immediately after conventional lumbar interbody fusion (LIF) surgery performed in patients with lumbar spinal stenosis.

METHODS AND ANALYSIS

This is a multicenter, randomized, open-label, parallel-group, active-controlled trial investigating the clinical outcomes of modified LIF sequence versus conventional LIF sequence in treating patients with lumbar spinal stenosis. A total of 254 eligible patients will be enrolled and randomized in a 1:1 ratio to either modified LIF sequence or conventional LIF sequence group. The primary outcome measure is the perioperative incidence of new-onset lower extremity neurological symptoms, including new adverse events of pain, numbness, and foot drop of any severity. Important secondary endpoints include visual analogue scale (VAS) pain score and lumbar Japanese Orthopaedic Association (JOA) recovery rate. Other safety endpoints will also be evaluated. The safety set used for safety data analysis by the actual surgical treatment received and the full analysis set for baseline and efficacy data analyses according to the intent-to-treat principle will be established as the two analysis populations in the study.

CONCLUSION

This study is designed to investigate the clinical outcomes of modified LIF sequences in patients with lumbar spinal stenosis. It aims to provide clinical evidence that the modified "fixation-fusion" sequence of LIF surgery is effective in treating lumbar spinal stenosis.

TRIAL REGISTRATION

http://www.chictr.org.cn/index.aspx ID: ChiCTR2100048507.

Analysis of risk factors for contralateral symptomatic foraminal stenosis after unilateral transforaminal lumbar interbody fusion

PURPOSE

To analyze the risk factors of contralateral symptomatic foraminal stenosis (FS) after unilateral transforaminal lumbar interbody fusion (TLIF) and to guide and standardize the operation process of unilateral TLIF to reduce the occurrence of contralateral symptomatic FS.

METHODS

A retrospective study was undertaken on 487 patients with lumbar degeneration who underwent unilateral TLIF in the Department of Spinal Surgery of Ningbo Sixth Hospital between January 2017 and January 2021, comprising 269 males and 218 females, with a mean age of 57.1 years (range, 48-77 years). Cases of intraoperative improper operations, such as screw deviation, postoperative hematoma, and contralateral disc herniation, were excluded, and cases of nerve root symptoms caused by contralateral FS were analyzed. Post-surgery, 23 patients with nerve root symptoms caused by contralateral FS were categorized as group A, and 60 patients without nerve root symptoms were randomly selected as group B during the same period. The general data (gender, age, body mass index (BMI), bone mineral density (BMD), and diagnosis) and imaging parameters before and after operation (including contralateral foramen area (CFA), lumbar lordosis angle (LL), segmental lordosis angle (SL), disc height (DH), foramen height (FH), foramen width (FW), fusion cage position, and the difference between postoperative and preoperative) were compared between the two groups. Univariate analysis was performed, and multivariate analysis was undertaken through logistics analysis to determine the independent risk factors. Additionally, the clinical outcomes of the two groups were compared immediately before surgery and one year after surgery, using the visual analogue scale (VAS) score and the Japanese Orthopaedic Association (JOA) score for evaluation.

RESULTS

The patients in this study were followed up for a period of 19-25 (22.8atien months. Among them, 23 cases (4.72% incidence) were diagnosed with contralaterally symptomatic FS after the surgery. Univariate analysis indicated significant differences between the two groups in CFA, SL, FW, and cage coronal position. Logistic regression analysis identified preoperative contralateral foramen area (OR = 1.176, 95% CI (1.012, 1.367)), small segmental lordosis angle (OR = 2.225, 95% CI (1.124, 4.406)), small intervertebral foramen width (OR = 2.706, 95% CI (1.028, 7.118)), and cage coronal position not crossing the midline (OR = 1.567, 95% CI (1.142, 2.149)) as independent risk factors for contralateral symptomatic FS after unilateral TLIF. However, there was no statistically significant difference in the pain VAS score between the two groups one year after the operation. In contrast, there was a significant difference in the JOA score between the two groups.

CONCLUSION

The identified risk factors for contralateral symptomatic FS after TLIF include preoperative contralateral intervertebral foramen stenosis, a small segmental lordosis angle, a small intervertebral foramen width, and the coronal position of the cage not crossing the midline. For patients with these risk factors, it is recommended to carefully lock the screw rod during the recovery of lumbar lordosis and ensure that the coronal position of the fusion cage is implanted beyond the midline. If necessary, preventive decompression should also be considered. However, this study did not quantify the imaging data for each risk factor, and further research is needed to improve our understanding of the topic.

Effect of preoperative contralateral foramen stenosis on contralateral root symptoms after unilateral transforaminal lumbar interbody fusion: a ambispective cohort study

PURPOSE

To evaluate the correlation between the degree of preoperative contralateral foraminal stenosis(CFS) and the incidence of contralateral root symptoms after unilateral transforaminal lumbar interbody fusion(TLIF) and to evaluate the appropriate candidate of preventive decompression according to the degree of preoperative contralateral foraminal stenosis.

METHODS

An ambispective cohort study was conducted to investigate the incidence of contralateral root symptoms after unilateral transforaminal lumbar interbody fusion (TLIF) and the effectiveness of preventive decompression. A total of 411 patients were included in the study, all of whom met the inclusion and exclusion criteria and underwent surgery at the Department of Spinal Surgery, Ningbo Sixth Hospital, between January 2017 and February 2021. The study was divided into two groups: retrospective cohort study A and prospective cohort study B. The 187 patients included in study A from January 2017 to January 2019 did not receive preventive decompression. They were divided into four groups based on the degree of preoperative contralateral intervertebral foramen stenosis: no stenosis group A1, mild stenosis group A2, moderate stenosis group A3, and severe stenosis group A4. A Spearman rank correlation analysis was used to evaluate the correlation between the preoperative contralateral foramen stenosis degree and the incidence of contralateral root symptoms after unilateral TLIF. From February 2019 to February 2021, 224 patients were included in the prospective cohort group B. The decision to perform preventive decompression during the operation was based on the degree of preoperative contralateral foramen stenosis. Severe intervertebral foramen stenosis was treated with preventive decompression as group B1, while the rest were not treated with preventive decompression as group B2. The baseline data, surgical-related indicators, the incidence of contralateral root symptoms, clinical efficacy, imaging results, and other complications were compared between group A4 and group B1.

RESULTS

All 411 patients completed the operation and were followed up for an average of 13.5 ± 2.8 months. In the retrospective study, there was no significant difference in baseline data among the four groups (P > 0.05). The incidence of postoperative contralateral root symptoms increased gradually, and a weak positive correlation was found between the degree of preoperative intervertebral foramen stenosis and the incidence of postoperative root symptoms (rs = 0.304, P < 0.001). In the prospective study, there was no significant difference in baseline data between the two groups. The operation time and blood loss in group A4 were less than those in group B1 (P < 0.05). The incidence of contralateral root symptoms in group A4 was higher than that in group B1 (P = 0.003). However, there was no significant difference in leg VAS score and ODI index between the two groups at 3 months after the operation (P > 0.05). There was no significant difference in cage position, intervertebral fusion rate, and lumbar stability between the two groups (P > 0.05). No incisional infection occurred after the operation. No pedicle screw loosening, displacement, fracture, or interbody fusion cage displacement occurred during follow-up.

CONCLUSION

This study found a weak positive correlation between the degree of preoperative contralateral foramen stenosis and the incidence of contralateral root symptoms after unilateral TLIF. Intraoperative preventive decompression of the contralateral side may prolong the operation time and increase intraoperative blood loss to some extent. However, when the contralateral intervertebral foramen stenosis reaches the severe level, it is recommended to perform preventive decompression during the operation. This approach can reduce the incidence of postoperative contralateral root symptoms while ensuring clinical efficacy.

Spinal Canal Remodeling and Indirect Decompression of Contralateral Foraminal Stenosis After Endoscopic Posterolateral Transforaminal Lumbar Interbody Fusion

Objective: There is a lack of literature on indirect decompression in uniportal endoscopic posterolateral transforaminal lumbar interbody fusion (EPTLIF). Our aim is to evaluate the dimensions of the spinal canal and contralateral foramen before and after EPTLIF.Methods: This is a retrospective study of patients who underwent EPTLIF in a tertiary spine centre over a 2-year period. The cross-sectional area of the spinal canal and the contralateral foramen at the level of fusion were measured on magnetic resonance imaging scan at 1-day postoperation and at the final follow-up. Patients were grouped according to the decompression performed as per the clinician’s judgement.Results: One hundred fifty-two levels of fusion were performed in 120 patients. There was a statistically significant clinical improvement in visual analogue scale and Oswestry Disability Index scores postoperation. The measurements of the spinal canal area were 106.0 mm², 138.8 mm², and 195.5 mm²; while contralateral foraminal area were 73.2 mm², 104.4 mm², and 120.7 mm² at preoperation, 1-day postoperation, and at the final follow-up, respectively (p < 0.001). For the subgroup analyses, spinal canal area measurements for the bilateral decompression cohort (n = 35) were 57.0 mm², 123.9 mm², and 191.8 mm²; for the ipsilateral decompression cohort (n = 42) were 89.3 mm², 128.9 mm², 183.3 mm²; and for the cohort without any decompression and only cage inserted (n = 75) were 138.3 mm², 151.2 mm², and 204.1 mm² (p < 0.001). Contralateral foraminal area measurements were 73.3 mm², 106.4 mm² and 120.4 mm² in the bilateral decompression cohort; 69.5 mm², 99.0 mm², 116.9 mm² in the ipsilateral decompression cohort; and 75.1 mm², 106.5 mm², 122.9 mm² in the cohort without any decompression (p < 0.001).Conclusion: Indirect decompression of both the spinal canal and the contralateral foramen can be achieved via EPTLIF. Decompression on an asymptomatic contralateral side is not necessary.

Effects of Different Intervertebral Space Heights on Nerve Root Tension during Posterior Lumbar Interbody Fusion

OBJECTIVE

There is no effective standard method to evaluate whether the nerve root tension is restored during lumbar decompression surgery, which is an important indicator for the recovery of nerve function. This study aimed to investigate the feasibility of intraoperative nerve root tension measurement and to confirm the correlation between nerve root tension and intervertebral space height.

METHODS

A total of 54 consecutive patients (mean age, 54.3 years; range, 25-68 years) received posterior lumbar interbody fusion (PLIF) for lumbar disc herniation (LDH) with lumbar spinal stenosis and instability. The 110%, 120%, 130%, 140% height values of each lesion were calculated based on preoperative measurements of the intervertebral space height. The heights were intraoperatively expanded after the intervertebral disc was removed using the interbody fusion cage model. The tension value of nerve root was measured by pulling the nerve root for 5 mm with a self-made measuring device. The nerve root tension value was measured before decompression, after discectomy at 100%, 110%, 120%, 130%, and 140% of the height of each intervertebral space, and after placement of the cage during intraoperative nerve root tension monitoring.

RESULTS

The nerve root tension values at 100%, 110%, 120%, and 130% heights were significantly lower than those before decompression, and there was no statistical significance among the four groups. The nerve root tension value was significantly higher at 140% height and was statistically significant compared with that of 130% height. The nerve root tension value after cage placement was significantly lower than that before decompression (1.32 ± 0.22 N vs. 0.61 ± 0.17 N, p < 0.01), and the postoperative VAS score was also significantly improved (7.0 ± 2.24 vs. 0.8 ± 0.84, p < 0.01). The nerve root tension was positively correlated with the VAS score (F = 85.19, p < 0.01; F = 78.65, p < 0.01).

CONCLUSION

This study demonstrates that nerve root tonometry can perform instant noninvasive intraoperative nerve root tension measurement. There is a correlation between nerve root tension value and VAS score. We found that when the height of the intervertebral space was increased to 140% of the original height, the nerve root tension increased the risk of injury significantly.

Comparison of clinical effectiveness of fenestrated and conventional pedicle screws in patients undergoing spinal surgery: a systematic review and meta-analysis

INTRODUCTION

Pedicle screws are commonly used for spinal procedures for fusion stability, which is particularly important in osteoporotic patients, who are at an increased risk of requiring revision procedures.

AREAS COVERED

A systematic review and meta-analysis were conducted to compare clinical effectiveness of conventional pedicle screws (CPS) vs fenestrated pedicle screws (FPS) in patients undergoing spinal surgery. Primary outcomes included screw loosening, revision surgeries (involving an implant) and reoperations (not involving intervention on an implant) in patients treated with CPS vs FPS, sub-stratified by with and without osteoporosis. Secondary outcomes included changes in pain scores. Forty-eight studies with 8,302 patients were included, with 1,565 (19.18%) treated with FPS and 6,710 (80.82%) treated with CPS. FPS was associated with a lower risk of screw loosening (p = 0.001) vs CPS. In the general population, there was a non-significant trend of lower revision rate, but no difference in reoperation rate, between patients treated with FPS vs CPS. In osteoporotic patients, revision rates were significantly lower for FPS vs CPS (p = 0.009).

EXPERT OPINION

This review suggests that FPS are effective for surgical fixation and reduce rates of screw loosening, and in osteoporotic patients, revision surgeries, compared to CPS.

Contralateral radiculopathy after unilateral transforaminal lumbar interbody fusion: causes and prevention

Background

Unilateral transforminal lumbar interbody fusion (TLIF) with a single cage can provide circumferential fusion and biomechanical stability. However, the causes and prevention of contralateral radiculopathy following unilateral TLIF remain unclear.

Methods

In total, 190 patients who underwent unilateral TLIF from January 2017 to January 2019 were retrospectively reviewed. Radiological parameters including lumbar lordosis, segmental angle, anterior disc height, posterior disc height (PDH), foraminal height (FH), foraminal width, and foraminal area (FA) were measured preoperatively and postoperatively. Preoperative and postoperative visual analog scale scores were also recorded.

Results

The incidence of contralateral radiculopathy after unilateral TLIF was 5.3% (10/190). The most common cause was contralateral foraminal stenosis. Unilateral TLIF could increase the lumbar lordosis, segmental angle, and anterior disc height but decrease the PDH, FA, and FH in patients with symptomatic contralateral radiculopathy. The intervertebral cage should be placed to cover the epiphyseal ring and cortical compact bone of the midline, and the disc height can be increased to enlarge the contralateral foramen.

Conclusion

The most common cause of contralateral radiculopathy is contralateral foraminal stenosis. Careful preoperative planning is necessary to achieve satisfactory outcomes. Improper unilateral TLIF will decrease the PDH, FA, and FH, resulting in contralateral radiculopathy.

Is Unilateral Minimally Invasive Transforaminal Lumbar Interbody Fusion Sufficient in Patients with Claudication? A Comparative Matched Cohort Study

OBJECTIVE

To evaluate clinical and radiologic outcomes between bilateral decompression using the over-the-top technique (group 1) and unilateral decompression (group 2) in patients with claudication who underwent minimally invasive surgery transforaminal lumbar interbody fusion (MIS-TLIF).

METHODS

We enrolled patients with claudication who underwent MIS-TLIF from January 2017 to June 2019. Visual analog scale (VAS) scores and Oswestry Disability Index (ODI), walking distance, and perioperative outcomes were compared between groups. Preoperative and 3-month postoperative magnetic resonance imaging assessed changes in canal cross-sectional area, foraminal height, and lateral recess area.

RESULTS

Sixty-five consecutive patients with ≥1 year of follow-up were enrolled. VAS scores and ODI were not significantly different between groups (VAS and ODI, respectively, at 1 month follow-up, P = 0.62 and 0.88; 3 months follow-up, P = 0.96 and 0.53; 6 months follow-up, P = 0.10 and 0.85; and 12 months follow-up, P = 0.10 and 0.66). Operative time and blood loss between groups was not statistically significant (P = 0.43 and P = 0.55). There was also no difference in the length of hospital stay (P = 0.24). Canal dimensions increased in each group without significant differences between groups (cross-sectional area, P = 0.92; foraminal height [approach and contralateral side, respectively], P = 0.62 and 0.66; and lateral recess area [approach and contralateral side, respectively], P = 0.68 and 0.50).

CONCLUSIONS

A unilateral approach with ipsilateral side direct decompression and contralateral indirect decompression in MIS-TLIF is sufficient for early clinical improvement in patients with claudication.

Enhanced recovery after surgery (ERAS) pathway for microendoscopy-assisted minimally invasive transforaminal lumbar interbody fusion

OBJECTIVES

Enhanced recovery after surgery (ERAS) principle and minimally invasive surgery allow patients to recover faster and better postoperatively. Due to a paucity of their integration, this retrospective study aims to assess clinical outcomes of ERAS pathway in microendoscopy-assisted minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF).

PATIENTS AND METHODS

A total of 72 consecutive cases were enrolled. According to their inclusion order, the former 21 cases received microendoscopy-assisted MIS-TLIF without any ERAS approach (control group), while the latter 51 participants underwent the same surgery with ERAS protocol (observation group). Perioperative parameters, including operative duration, intraoperative estimated blood loss (EBL), length of stay, postoperative analgesic usage and ambulatory time, were recorded. Visual analogue scale (VAS, back and leg), Barthel index were obtained before and at three days, one month, six months postoperatively. Modified MacNab criteria and Bridwell grading were used to assess surgical outcome and interbody fusion at one week and two years after surgery, respectively.

RESULTS

Observation group had statistically improved perioperative parameters (operative duration, intraoperative EBL, length of stay, postoperative analgesic usage and ambulatory time) in comparison with control group. Remarkable decreases in VAS (back and leg) were observed continuously at three days, one month and six months post-surgery in both groups when compared with scores prior to the surgery. More significant improvement of VAS (back and leg) was found in observation group at both three days and one month postoperatively. Regarding Barthel index, despite its transient decrease at three days after surgery in control group, it showed statistical increase at postoperative one month when compared with preoperative values in both groups; moreover, its inter-groups comparison revealed much more improvement in patients receiving ERAS recommendations; while at final follow-up, it continued further increase in either group. Marginally higher proportion of patients in observation group showed perfect or good clinical outcome, as well as solid interbody fusion.

CONCLUSIONS

ERAS pathway in microendoscopy-assisted MIS-TLIF has advantages of decreased operative time, reduced intraoperative haemorrhage, increased initial back pain relief, decreased length of stay, lowered analgesic usage and earlier daily activity recovery and thus, benefit postoperative rehabilitation further.

Defining the MIS-TLIF: A Systematic Review of Techniques and Technologies Used by Surgeons Worldwide

STUDY DESIGN

Systematic review.

OBJECTIVE

To date there is no consensus among surgeons as to what defines an MIS-TLIF (transforaminal lumbar interbody fusion using minimally invasive spine surgery) compared to an open or mini-open TLIF. This systematic review aimed to examine the MIS-TLIF techniques reported in the recent body of literature to help provide a definition of what constitutes the MIS-TLIF, based on the consensus of the majority of surgeons.

METHODS

We created a database of articles published about MIS-TLIF between 2010 and 2018. We evaluated the technical components of the MIS-TLIF including instruments and incisions used as well the order in which key steps are performed.

RESULTS

We could identify several patterns for MIS-TLIF performance that seemed agreed upon by the majority of MIS surgeons: use of paramedian incisions; use of a tubular retractor to perform a total facetectomy, decompression, and interbody cage implantation; and percutaneous insertion of the pedicle-screw rod constructs with intraoperative imaging.

CONCLUSION

Based on this review of the literature, the key features used by surgeons performing MIS TLIF include the use of nonexpandable or expandable tubular retractors, a paramedian or lateral incision, and the use of a microscope or endoscope for visualization. Approaches using expandable nontubular retractors, those that require extensive subperiosteal dissection from the midline laterally, or specular-based retractors with wide pedicle to pedicle exposure are far less likely to be promoted as an MIS-based approach. A definition is necessary to improve the communication among spine surgeons in research as well as patient education.

CHANGES IN THE LUMBAR VERTEBRAL SEGMENT RELATED TO THE CAGE POSITION IN TLIF TECHNIQUE

Objective:

To evaluate the morphological changes on the intervertebral foramen and segmental lordosis related to the transforaminal lumbar interbody fusion (TLIF) positioning.

Methods:

PEEK cages were placed in the disc space (L1-S1) of a polyurethane anatomical model. Cages of different heights (8 mm, 10 mm, 12 mm and 14 mm) were positioned in the posterior, medial or anterior part of the vertebral body surface, and the intervertebral foramen and segmental lordosis heights were measured after their insertion.

Results:

The vertebral foramen height decreased in all positions and heights of the cages in relation to the control. The cage posterior positioning induced a smaller reduction in the vertebral foramen height. Vertebral lordosis tended to increase in relation to the control, and the greatest increase occurred with the cage posterior positioning.

Conclusion:

Cage positioning induces changes in the intervertebral foramen height and in the vertebral segment lordosis. Cage posterior positioning induces a smaller reduction of the intervertebral foramen height and increases the vertebral segment lordosis. Level of evidence III, Therapeutic study.

A modified procedure of single-level transforaminal lumbar interbody fusion reduces immediate post-operative symptoms: a prospective case-controlled study based on two hundred and four cases

STUDY DESIGN

This is a prospective case-controlled study.

PURPOSE

The purpose of this study is to investigate the effect of a modified transforaminal lumbar interbody fusion (TLIF) on the immediate post-operative symptoms in patients with lumbar disc herniation (LDH) accompanied with stenosis.

METHODS

A total of 204 LDH patients with single-level TLIF were enrolled. According to the sequence of the placement of rods and cage, patients were divided into group R (rod-prior-to-cage) and group C (cage-prior-to-rod). Neurological function was evaluated by the Japanese Orthopedic Association (JOA) score. Radiological assessment includes height of intervertebral space (HIS), foraminal height (FH), foraminal area (FA), and segmental lordosis (SL). Change of original symptoms (pain/numb) and new-onset symptoms (pain/numb) after surgery were also recorded.

RESULTS

Patients in group R had less change of HIS at L3/4, L4/5, and L5/S1 levels compared with pre-operation (all p > 0.05), whereas group C had larger change (all p < 0.05). No statistical difference was found in FH between the two groups before and after surgery at L3/4, L4/5, and L5/S1, respectively (all p > 0.05). In terms of FA, patients in group R had better improvement after surgery than those in group C at L3/4 and L4/5 (both p < 0.05). Patients in both groups acquired good improvement of neurological function. However, there were fewer patients in group R who experienced post-operative leg pain or numb compared with those in group C (p < 0.05).

CONCLUSION

The modified open TLIF can significantly reduce the incidence of immediate post-operative symptoms for patients with single-level lumbar disc herniation via installation of rods prior to insertion of cage and the "neural standard" should serve as the goal of decompression for spine surgeons to restore disc/foraminal height and to minimize nerve distraction.

Risk Factors for Symptomatic Contralateral Foraminal Stenosis After Unilateral Transforaminal Lumbar Interbody Fusion

OBJECTIVE

The most common cause of contralateral symptoms after unilateral transforaminal lumbar interbody fusion (TLIF) is contralateral foraminal stenosis (FS). This retrospective cohort study aimed to investigate the cause of and risk factors for contralateral FS after unilateral TLIF with a single cage.

METHODS

Patients with degenerative lumbar spinal disorders who underwent unilateral TLIF at L4-5 were divided into 2 groups: those without contralateral radicular symptoms after surgery (group A; n = 340) and those with contralateral radicular symptoms after surgery (group B; n = 16). We investigated the influence of various radiological and cage-related factors on postoperative contralateral FS with radicular symptoms. The cage location indicates whether the cage's anterior tip crosses the disc midline-exceeding 50%-and in such a case, how far.

RESULTS

Group B showed significantly increased postoperative coronal angle and sagittal angle and decreased contralateral foraminal height and foraminal area. Statistically significant (P < 0.01) factors according to the multivariate logistic regression analysis were the preoperative sagittal range of motion (odds ratio [OR]: 1.562, P = 0.004) and cage location (OR: 2.047, P = 0.015). The cutoff values for the sagittal range of motion and the cage location were 9.0° and 50.5%, respectively. The preoperative and postoperative 6-month visual analog scale scores and Oswestry disability index values were not significantly different between the groups.

CONCLUSIONS

The 2 most meaningful risk factors were the preoperative sagittal range of motion and cage location. Inserting the cage beyond the disc midline, especially in patients with a high preoperative sagittal range of motion (≥9.0°), would help reduce postoperative complications.

[Comparative study of microendoscope-assisted and conventional minimally invasive transforaminal lumbar interbody fusion for degenerative lumbar diseases]

OBJECTIVE

To analyze the medium and long-term effectiveness of microendoscope-assisted minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) for lumbar degenerative diseases in comparison with conventional tubular retractor-assisted MIS-TLIF.

METHODS

Between November 2008 and March 2013, 53 patients with single segment lumbar degenerative diseases were enrolled. According to the different working channel performed, 28 patients were treated by microendoscope-assisted MIS-TLIF (observation group), while the remaining cases received conventional tubular retractor-assisted MIS-TLIF via Wiltse approach (control group). Preoperative baseline data, including age, gender, body mass index, disease etiology, operated level, the ration for requiring bilateral canal decompression, and preoperative visual analogue scale (VAS) socre of low back pain and leg pain, Japanese Orthopedic Association (JOA) score, Oswestry disability index (ODI) score, showed no significant difference between the two groups ( P>0.05). The operation time, intraoperative blood loss, intraoperative fluoroscopy time, postoperative analgesic drug dose, postoperation in-bed time, and perioperative complication incidence were recorded respectively and compared between the two groups. Radiographic evaluation of interbody fusion was performed based on Bridwell grading system at 2 years after operation. VAS scores of low back pain and leg pain, JOA score, and ODI score were assessed before operation, at 2 years after operation, and at last follow-up respectively. Surgical outcome satisfaction was assessed by modified MacNab criteria at last follow-up.

RESULTS

When compared with those in control group, both intraoperative blood loss and postoperative analgesic drug dose were significantly decreased in observation group ( P<0.05); similarly, the operation time and intraoperative fluoroscopy time were also significantly increased in observation group ( P<0.05). There was no significant difference of postoperative in-bed time between the two groups ( t=-0.812, P=0.420). Both groups were followed up 6-10.3 years, with an average of 7.9 years. Regarding perioperative complication, its incidence was 14.3% and 20.0% in observation group and control group, respectively, showing no significant difference between both groups ( χ 2=0.306, P=0.580). Specifically, there were intraspinal hematoma formation in 1 case, incision infection in 1 case, urinary infection in 1 case, transient delirium in 1 case in observation group. By contrast, there were dural tear and cerebrospinal fluid leakage in 1 case, urinary infection in 1 case, pneumonia in 1 case, transient delirium in 2 cases in control group. Bridwell criterion was used to judge the intervertebral fusion at 2 years after operation, the fusion rates of observation group and control group were 92.9% and 92.0%, respectively, showing no significant difference ( χ 2=0.162, P=0.687). At both 2-year postoperatively and last follow-up, the VAS scores of low back pain and leg pain, JOA score, and ODI score were significantly improved when compared with those before operation ( P<0.01), whereas no significant difference between the two groups at either time point was found ( P>0.05). At last follow-up, the results of patients' satisfaction with surgery evaluated by modified MacNab criteria, and the excellent and good rates of the observation group and the control group were 96.4% and 92.0%, respectively, showing no significant difference ( χ 2=0.485, P=0.486).

CONCLUSION

The medium and long-term effectiveness of microendoscope-assisted MIS-TLIF are similar to those of conventional tubular retractor-assisted MIS-TLIF for lumbar degenerative diseases. The former operation has the additional advantages in terms of more clear surgical site visually, less intraoperative blood loss, and reduced postoperative analgesic dose, all of which seem more feasible to clinical teaching.

Morphological changes of contralateral intervertebral foramen induced by cage insertion orientation after unilateral transforaminal lumbar interbody fusion

Background

This study was performed to investigate the morphological changes of contralateral intervertebral foramen (IVF) based on computed tomography images of patients with lumbar spinal stenosis after unilateral transforaminal lumbar interbody fusion (TLIF) and to compare the influence of different orientation of cage insertion on these changes.

Methods

This is a retrospective cohort study. Sixty-nine patients with lumbar spinal stenosis who had undergone single-level unilateral TLIF were retrospectively analyzed. The patients were divided into two groups according to the cage insertion orientation: the oblique group (o-group, 39 cases) and the transverse group (t-group, 30 cases). The morphological parameters of contralateral IVF were measured before and 6 months after the operation. Changes in these parameters were compared and analyzed between the two groups. The 6-month clinical outcomes of the two groups were also collected and analyzed.

Results

There was a significant difference in the rate of increase in the segmental angle (p < 0.01) between the two groups, the mean value of segmental angle increased by an average of 29.08% ± 14.93% in the o-group and 48.63% ± 12.01% in the t-group. Overall, the posterior disc height had a significant positive correlation with the foraminal height and area. In the o-group, however, an increase in the segmental angle resulted in a decrease in the foraminal area. No significant difference in clinical outcomes was found between the two groups.

Conclusions

Compared with oblique cage insertion, transverse cage insertion could achieve greater restoration of segmental lumbar lordosis without decreasing contralateral foraminal dimensions.