Radiographic results of single level transforaminal lumbar interbody fusion in degenerative lumbar spine disease: focusing on changes of segmental lordosis in fusion segment

Single-position oblique lumbar interbody fusion with navigation: improved efficiency and screw accuracy compared to dual-position with fluoroscopy

Dual-position oblique lumbar interbody fusion with fluoroscopy (D-OLIF) requires repositioning the patient to a prone position for pedicle screw insertion. Recently, single-position surgery with navigation has been introduced. However, there are concerns regarding pedicle screw accuracy and achieving appropriate sagittal balance in single-position OLIF with navigation (S-OLIF). The purpose of this study is to evaluate the clinical and radiological outcomes of S-OLIF compared to D-OLIF. A retrospective analysis was conducted on 102 patients who underwent single-level OLIF at a single institution. The patients were divided into two groups: 55 in the S-OLIF group and 47 in the D-OLIF group. The numeric rating scale for back and leg, Oswestry disability index, and walking distance improvements showed no significant difference. However, the EuroQol 5-dimension 5-level index showed higher improvement in the S-OLIF (P = 0.029). The segmental lordosis, lumbar lordosis, and C7 sagittal vertical axis showed no significant difference. S-OLIF had significantly fewer cases of pedicle screw malposition (P = 0.045). Additionally, the surgery time was shorter in the S-OLIF (P = 0.002). In conclusion, S-OLIF exhibited clinical and radiological outcomes comparable to D-OLIF, with the added advantages of reduced surgery time and enhanced accuracy in pedicle screw placement.

Effects of Cage Implantation Depth on Sagittal Parameters and Functional Outcomes in Posterior Lumbar Interbody Fusion for the Treatment of L4-L5 Lumbar Degenerative Spondylolisthesis

OBJECTIVE

In the treatment of lumbar degenerative spondylolisthesis (LDS) with Posterior lumbar interbody fusion (PLIF) surgery, interbody fusion implants play a key role in supporting the vertebral body and facilitating fusion. The objective of this study was to assess the impact of implantation depth on sagittal parameters and functional outcomes in patients undergoing PLIF surgery.

METHODS

This study reviewed 128 patients with L4-L5 LDS between January 2016 and August 2019. All patients underwent an open PLIF surgery that included intravertebral decompression, implantation of pedicle screws and cage. We grouped according to the position of the center of the cage relative to the L5 vertebral endplate. Patients with the center of the cage located at the anterior 1/2 of the upper end plate of the L5 vertebral body were divided into Anterior group, and located at the posterior 1/2 of the upper end plate of the L5 vertebral body were divided into Posterior group. The lumbar lordosis (LL), segmental lordosis (SL), sacral slope (SS), pelvic incidence (PI), pelvic tilt (PT) and slope degree (SD) was measured for radiographic outcomes. We used the visual analog scale (VAS) and the oswestry disability index (ODI) score to assess functional outcomes. Paired t-test was used to compare imaging and bedside data before and after surgery between the two groups, and independent sample t-test, χ2 test and Fisher exact test were used to compare the data between the two groups.

RESULT

The mean follow-up of Anterior group was 44.13 ± 9.23 months, and Posterior group was 45.62 ± 10.29 months (P > 0.05). The LL, SL, PT, SS, SD and PI-LL after operation showed great improvements, relative to the corresponding preoperative values in both groups (P < 0.05). Compared to Posterior group, Anterior group exhibited far enhanced SL (15.49 ± 3.28 vs. 13.67 ± 2.53, P < 0.05), LL (53.47 ± 3.21 vs. 52.08 ± 3.15, P < 0.05) outcomes and showed depressed PI-LL (8.87 ± 5.05 vs. 10.73 ± 5.39, P < 0.05) outcomes at the final follow-up. Meanwhile, the SL in Anterior group (16.18 ± 3.99) 1 months after operation were also higher than in Posterior group (14.12 ± 3.57) (P < 0.05). We found that VAS and ODI at the final follow-up in Anterior group (3.62 ± 0.96, 25.19 ± 5.25) were significantly lower than those in Posterior group (4.12 ± 0.98, 27.68 ± 5.13) (P < 0.05).

CONCLUSIONS

For patients with LDS, the anteriorly placed cage may provide better improvement of SL after PLIF surgery. Meanwhile, the anteriorly placed cage may achieve better sagittal parameters of LL and PI-LL and functional outcomes at the final follow-up.

Preoperative Disc Angle is an Important Predictor of Segmental Lordosis After Degenerative Spondylolisthesis Fusion

STUDY DESIGN

Retrospective Cohort Study.

OBJECTIVES

To determine the effect of interbody cages inserted via posterior approach on segmental lordosis in the setting of preoperative lordotic vs kyphotic discs in patients with lumbar degenerative spondylolisthesis (LDS).

METHODS

Retrospective analysis of prospectively collected data on assessment and management of LDS patients from 2 contributing centres. Patients were analyzed preoperatively and at 12-month follow-up with standing lumbar radiographs. Index level segmental lumbar lordosis (SLL), disc angle and global lumbar lordosis was measured. Patients were stratified into 4 groups based on index level disc angle and procedure: preoperative lordotic posterolateral fusion (group L-PLF); preoperative kyphotic PLF (group K-PLF); preoperative lordotic interbody fusion (IF) (group L-IF); preoperative kyphotic IF (group K-IF).

RESULTS

A total of 100/111 (90%) patients completed follow-up with 40 in group L-IF and 48 in group K-IF. There were 18 patients in group L-PLF and 5 in group K-PLF. Among patients with preoperatively lordotic disc angles who had a worsening of SLL, group L-IF had worse SLL than group L-PLF patients, with differences persisting at one-year (mean difference 2.30, 95% CI, .3, 4.3, P = .029). Patients in group K-IF achieved improvement in SLL at one-year more frequently than group L-IF (67% vs 44%, P = .046), with similar mean improvement magnitude between groups L-IF and K-IF (-1.1, 95% CI, -3.7, 1.6, P = .415).

CONCLUSION

Segmental lordosis worsening was greater with preoperative index lordotic disc angles when an interbody cage was used. Patients who have a kyphotic disc preoperatively gain more lordosis with interbody cage use.

Approaches in Anterior Column Support in Adult Spinal Deformity Surgery: A Meta-Analysis of Clinical and Radiologic Outcomes

OBJECTIVE

This meta-analysis was conducted to compare anterior lumbar interbody fusion (ALIF) with transforaminal lumbar interbody fusion (TLIF) in terms of postoperative complications, improvement in radiographic parameters, and patient-reported outcomes.

METHODS

PubMed, Cochrane, and Google Scholar (pages 1-20) databases were searched up to June 2023. The studied outcomes were the rate of rod failures, rod failures requiring revision surgery, all complications, all revision surgeries, the change in pelvic tilt, sacral slope, Cobb angle, lumbar lordosis (LL), sagittal vertical axis, the postoperative pelvic incidence-LL, and LL, and the improvement in back pain and Oswestry Disability Index (ODI).

RESULTS

Six studies were included in this meta-analysis. ALIF showed higher postoperative lordosis (P = 0.003) and better improvement in ODI (P = 0.0001). No difference was seen in the remaining outcomes between ALIF and TLIF.

CONCLUSIONS

Although ALIF had better improvement in ODI, the mean difference was 6.5 points, which is below the minimal clinically important difference, stripping this result of any clinical value. Furthermore, even though ALIF had better postoperative lordosis, the change in LL postoperatively was not different between ALIF and TLIF. With no difference in complications, sagittal and coronal alignment, and patient-reported outcomes, TLIF was shown in this study to be favored instead of ALIF in adult spinal deformity surgery to avoid all the double approach-related comorbidity.

Comparison of Long-term Follow-Up of n-HA PA66 Cage and PEEK Cage of Lumbar Interbody Fusion in Multi-level Degenerative Lumbar Diseases: A Stepwise Propensity Score Matching Analysis

OBJECTIVE

Previous studies have confirmed that the nanohydroxyapatite/polyamide-66 (n-HA/PA66) cage is an ideal alternative material for degenerative lumbar disease (DLD) comparable to the polyether ether ketone (PEEK) cage due to its similar radiographic fusion, subsidence rate, and clinical results. However, these studies were restricted to one-level surgery. The aim of this study was to analyze the long-term clinical and radiologic outcomes between n-HA PA66 cage and PEEK cage for patients with multi-level degenerative lumbar diseases (DLDs).

METHODS

We retrospectively reviewed all patients who underwent multi-level transforaminal lumbar interbody fusion (TLIF) from June 2010 to December 2016 with a minimum 6-year follow-up. Matched-pair analysis was performed using a 1-to-1 closest neighbor approach to match patients who received an n-HA PA66 cage with those who received a PEEK cage. Clinical outcomes and radiographic evaluations were compared between the two groups. The independent student's t-test and χ2 -test were applied to compare the differences between groups.

RESULTS

At the end of the propensity score matching (PSM) analysis, 48 patients from n-HA/PA66 group were matched to 48 patients in the PEEK group. No significant difference was observed in cage subsidence and bony fusion except for adjacent segment degeneration (ASD). The occurrence of ASD was 14.58% (7/48) in the n-HA/PA 66 group, which was significantly less than that in the PEEK group (33.33% [16/48]) (p = 0.031). Although the intervertebral space height (IH), segmental angle (SA) and lumbar lordosis (LL) significantly increased after surgery in both groups, there was no significant difference at any time point after surgery (p > 0.05). The visual analogue scale (VAS) and Oswestry disability index (ODI) scores significantly improved in both groups at 3m postoperative, 1y postoperative and at final follow-up. However, there were no significant differences in the VAS and ODI score at any time point (p > 0.05). The total complications and re-admission rate were not different between the two groups.

CONCLUSION

Overall, our data suggest that the outcomes of n-HA/PA66 cage group are comparable to those of the PEEK cage group, with a similar high fusion rate and low cage subsidence rate as PEEK cages, except its lower rate of ASD occurrence.

The Effect of Indirect Decompression Through Extraforaminal Interbody Fusion for Degenerative Lumbar Disease

Purpose

Extraforaminal lumbar interbody fusion as with other methods that involve the mechanism of indirect decompression, the discussion not only focuses on the benefit of minimizing the risk of thecal sac injury and postoperative scarring, but also on the risk of insufficient decompression in the affected neural structures during the reduction of the affected segment.

Methods

Eighty-two patients presenting with degenerative lumbar disease with segmental instability underwent ELIF combined with transpedicular fixation and circumferential fusion. Clinical and radiographic evaluations were performed.

Results

The mean ODI significantly improved from 63.4 preoperatively to 32.3 1 year postoperatively. The mean VAS back pain significantly improved from 5.95 to 2.63 postoperatively and VAS (leg pain) improved from 6.04 to 2.44. The mean CSA increased from 103  mm2 preoperatively to 169  mm2 postoperatively. The median extension ratio of CSA was 33%. Disc height, segmental disc angle, and lumbar lordosis also improved significantly. Only three (3.7%) patients were revised using direct central decompression due to neurologic deterioration.

Conclusion

Spinal stenosis was resolved successfully by indirect decompression through extraforaminal interbody fusion via a transmuscular limited approach.

Comparative Analysis of Radiologic Outcomes Between Polyetheretherketone and Three-Dimensional-Printed Titanium Cages After Transforaminal Lumbar Interbody Fusion

OBJECTIVE

Transforaminal lumbar interbody fusion (TLIF) is performed worldwide with polyetheretherketone (PEEK) and titanium (Ti) cages for the treatment of degenerative lumbar diseases. The aim of this study was to compare radiologic outcomes between a PEEK and three-dimensional-printed titanium (3DP-Ti) cage after TLIF with >1 year of follow-up.

METHODS

A total of 140 patients with degenerative lumbar diseases who underwent TLIF operation were included in this study. Intervertebral disc height and whole lumbar lordosis were measured and evaluated from the preoperative stage to the final follow-up. Subsidence of the cage was indicated if the cage sunk into the adjacent vertebral body or if there was a reduction in height of the fused segment by ≥3 mm during the postoperative follow-up. Migration of the cage was determined as the displacement of the interbody cage by ≥2 mm during the postoperative period. Fusion status was assessed at the 1 year and final follow-up using standard methods.

RESULTS

Both disc height and lumbar lordosis were well maintained throughout the study period, and no significant differences were observed between PEEK and 3DP-Ti groups. Both PEEK and 3DP-Ti cages demonstrated low rates of cage subsidence, with no significant difference was noted. A significant cage migration rate was observed in the PEEK group and the revision operation was required for 2 patients. The fusion rate of this study was not found to be statistically significant, although the 3DP-Ti cage was known to have an improved fusion rate than PEEK cage after lumbar interbody fusion.

CONCLUSIONS

Radiologic results suggest that the 3DP-Ti cage may be a better interbody cage for TLIF than is the PEEK cage.

A Comparison of Radiographic Alignment between Bilateral and Unilateral Interbody Cages in Patients Undergoing Transforaminal Lumbar Interbody Fusion

STUDY DESIGN

Retrospective cohort study.

PURPOSE

To compare radiographic outcomes between unilateral and bilateral cage placement in transforaminal lumbar interbody fusions (TLIF) and to determine if the rate of fusion at the 1-year postoperative point was different in patients who received bilateral versus unilateral cages.

OVERVIEW OF LITERATURE

There is no clear evidence to dictate whether bilateral or unilateral cages promote superior radiographic or surgical outcomes in TLIF.

METHODS

Patients >18 years old who underwent primary one- or two-level TLIFs at our institution were identified and propensitymatched in a 3:1 fashion (unilateral:bilateral). Patient demographics, surgical characteristics, and radiographic outcomes, including vertebral endplate obliquity, segmental lordosis, subsidence, and fusion status, were compared between groups.

RESULTS

Of the 184 patients included, 46 received bilateral cages. Bilateral cage placement was associated with greater subsidence (1.06±1.25 mm vs. 0.59±1.16 mm, p=0.028) and enhanced restoration of segmental lordosis (5.74°±14.1° vs. -1.57°±10.9°, p=0.002) at the 1-year postoperative point, while unilateral cage placement was associated with an increased correction of endplate obliquity (-2.02°±4.42° vs. 0.24°±2.81°, p<0.001). Bilateral cage placement was significantly associated with radiographic fusion on bivariate analysis (89.1% vs. 70.3%, p=0.018) and significantly predicted radiographic fusion on multivariable regression analysis (estimate, 1.35; odds ratio, 3.87; 95% confidence interval, 1.51-12.05; p=0.010).

CONCLUSIONS

Bilateral interbody cage placement in TLIF procedures was associated with restoration of lumbar lordosis and increased fusion rates. However, endplate obliquity correction was significantly greater for patients who received a unilateral cage.

The Significance of Extra-Cage Bridging Bone via Radiographic Lumbar Interbody Fusion Criterion

STUDY DESIGN

Prospective observational study.

OBJECTIVES

We aimed to analysis the distributional patterns of the intra- and extra-cage bridging bone (InCBB and ExCBB) and the significance of ExCBB using suggested lumbar interbody fusion criterion.

METHODS

This study included the patients with planned single-level transforaminal lumbar interbody fusion. We divided bridging bone into InCBB (in void of right or left cage) and ExCBB (outside of cages; anterior, posterior, intermediate, right, or left) and graded bridging scores from 0 to 2 on postoperative 1-year computed tomography. The fusion was defined as at least having one or more graded 2 and the evaluation were conducted twice by 2 raters.

RESULTS

Sixty-five patients were enrolled. All values of intra- and inter-rater reliability in left InCBB, anterior, and posterior ExCBB showed good agreements (≥0.75). Both InCBBs showed similar mean bridging scores (Rt:1.43 vs Lt:1.48), and in ExCBBs, the anterior was the highest (1.43), followed by the posterior (1.14); the right and left were the lowest (0.49 and 0.52 respectively). In subjects determined as fusion (85.4%), complete bridging was observed more in ExCBB (88.8%) than in InCBB (69.9%).

CONCLUSIONS

Given the higher bridging scores in both InCBBs and Ant. ExCBB, bone grafting is important promoting factor to increase the interbody bridging bone regardless of outside or in void of cages. Based on our suggested criterion, ExCBB has a greater proportion compared to InCBBs for determining the fusion and extra-cage bone grafting should be considered as important procedures for interbody fusion.

Does Interbody Cage Lordosis and Position Affect Radiographic Outcomes After Single-level Transforaminal Lumbar Interbody Fusion?

STUDY DESIGN

This was a retrospective cohort study.

OBJECTIVE

The objective of this study was to determine if the degree of interbody cage lordosis and cage positioning are associated with changes in postoperative sagittal alignment after single-level transforaminal lumbar interbody fusion (TLIF).

SUMMARY OF BACKGROUND DATA

Ideal sagittal alignment and lumbopelvic alignment have been shown to correlate with postoperative clinical outcomes. TLIF is one technique that may improve these parameters, but whether the amount of cage lordosis improves either segmental or lumbar lordosis (LL) is unknown.

METHODS

A retrospective review was performed on patients who underwent single-level TLIF with either a 5-degree or a 12-degree lordotic cage. LL, segmental lordosis (SL), disk height, center point ratio, cage position, and cage subsidence were evaluated. Correlation between center point ratio and change in lordosis was assessed using the Spearman correlation coefficient. Secondary analysis included multiple linear regression to determine independent predictors of change in SL.

RESULTS

A total of 126 patients were included in the final analysis, with 51 patients receiving a 5-degree cage and 75 patients receiving a 12-degree cage. There were no differences in the postoperative minus preoperative LL (∆LL) (12-degree cage: -1.66 degrees vs. 5-degree cage: -2.88 degrees, P =0.528) or ∆SL (12-degree cage: -0.79 degrees vs. 5-degree cage: -1.68 degrees, P =0.513) at 1-month follow-up. Furthermore, no differences were found in ∆LL (12-degree cage: 2.40 degrees vs. 5-degree cage: 1.00 degrees, P =0.497) or ∆SL (12-degree cage: 1.24 degrees vs. 5-degree cage: 0.35 degrees, P =0.541) at final follow-up. Regression analysis failed to show demographic factors, cage positioning, or cage lordosis to be independent predictors of change in SL. No difference in subsidence was found between groups (12-degree cage: 25.5% vs. 5-degree cage: 32%, P =0.431).

CONCLUSION

Lordotic cage angle and cage positioning were not associated with perioperative changes in LL, SL, or cage subsidence after single-level TLIF.

LEVEL OF EVIDENCE

Level III.

Correlation Between Cage Positioning and Lumbar Lordosis in Transforaminal Lumbar Interbody Fusion (TLIF)

Objective  The present study evaluates radiographic outcomes and the lumbar lordosis achieved with a transforaminal lumbar interbody fusion (TLIF) arthrodesis technique according to the positioning of an interbody device (cage) in the disc space. Methods  This is a retrospective radiographic analysis of single-level surgical patients with degenerative lumbar disease submitted to a TLIF procedure and posterior pedicle instrumentation. We divided patients into two groups according to cage positioning. For the TLIF-A group, the cages were anterior to the disc space; for the TLIF-P group, cages were posterior to the disc space. Considering the superior vertebral plateau of the lower vertebra included in the instrumentation, cages occupying a surface equal to the anterior 50% of the midline were placed in the TLIF-A group, and those in a posterior position were placed in the TLIF-P group. We assessed pre- and postoperative orthostatic lateral radiographs to obtain the following measures: lumbar lordosis (LL) (angle L1-S1), segmental lordosis (LS) (L4-S1), and segmental lordosis of the cage (SLC). Results  The present study included 100 patients from 2011 to 2018; 44 were males, and 46 were females. Their mean age was 50.5 years old (range, 27 to 76 years old). In total, 43 cages were "anterior" (TLIF-A) and 57 were "posterior" (TLIF-P). After surgery, the mean findings for the TLIF-A group were the following: LL, 50.7°, SL 34.9°, and SLC 21.6°; in comparison, the findings for the TLIF-P group were the following: LL, 42.3° ( p  < 0.01), SL 30.7° ( p  < 0.05), and SLC 18.8° ( p  > 0.05). Conclusion  Cage positioning anterior to the disc space improved lumbar and segmental lordosis on radiographs compared with a posterior placement.

Do Radiographic Results of Transforaminal Lumbar Interbody Fusion Vary with Cage Position in Patients with Degenerative Lumbar Diseases?

Objective

To investigate whether the radiographic results are affected by cage position in single‐level transforaminal lumbar interbody fusion (TLIF).

Method

Between January 2016 and June 2018, 130 patients (62 males and 68 females, average age: 55.28 ± 10.11 years) who underwent single‐level TLIF were analyzed retrospectively. Standing lateral radiographs of the lumbar spine were collected and evaluated preoperatively, postoperatively, and at the time of last follow‐up. Cage position in the fused segment was recorded using a central point ratio (CPR), which indicated the cage position. CPR is calculated by dividing the distance between the cage center point and the posterior extent of the superior endplate of the inferior vertebra by the length of the superior endplate of the inferior vertebra. Based on cage positions, the patients were divided into three groups: Anterior Group (n = 38); Middle Group (n = 68); and Posterior Group (n = 24). Segmental lumbar lordosis (SLL), foraminal height (FH), posterior disc height (PDH), and anterior disc height (ADH) were evaluated. A subanalysis was also performed on cage height within each group.

Results

The average follow‐up time of the patients was 35.20 ± 4.43 months. The mean values of CPR in Anterior Group, Middle Group, and Posterior Group were 0.64, 0.51, and 0.37, respectively. The FH, PDH, and ADH were significantly increased after TLIF in all groups (P < 0.05). There were significant differences in increase of SLL in Anterior Group (4.4°) and Middle Group (3.0°), but not in Posterior Group (0.3°). Furthermore, in the comparison of the three groups, the increase of SLL, FH, and PDH was statistically different (P < 0.05), while not for ADH (P > 0.05). The significant correlations in surgery were: CPR and ΔSLL (r = 0.584, P < 0.001), CPR and ΔFH (r = −0.411, P < 0.001), and CPR and ΔPDH (r = −0.457, P < 0.001). However, ADH had a positive correlation with cage height when the cage was located in anterior and middle of the endplate. Moreover, cage height had a positive correlation with SLL when the cage was located anteriorly and had a negative correlation with SLL when the cage was located posteriorly. FH and PDH both had a positive correlation with cage height in any cage position.

Conclusion

The cage located in different positions has different effects on radiographic results in single‐level TLIF. A thicker cage located anteriorly will gain maximum SLL and avoid the reduction of FH and PDH.

Prospective, randomized, double-blinded clinical trial comparing PEEK and allograft spacers in patients undergoing transforaminal lumbar interbody fusion surgeries

BACKGROUND CONTEXT

Allograft and polyether-ether-ketone (PEEK) radiographic, biomechanical, histological properties have been extensively studied and both spacers have their advantages and shortcomings. There are no comparative randomized or double-blinded spinal fusion clinical trials reported to date.

PURPOSE

The study's primary objective was to prospectively investigate clinical and radiological outcomes in patients undergoing lumbar interbody fusions and randomized to receive either PEEK or structural bone allografts.

STUDY DESIGN/ SETTING

A prospective, randomized, double-blinded clinical trial was initiated at a single center.

PATIENT SAMPLE

A total of 138 patients were enrolled, randomized and 121 patients completed the study.

OUTCOME MEASURES

The primary clinical outcome parameters were scored from standardized patient-reported questionnaires. The severity of lower back and leg pain was evaluated using the 11-point Visual Analog Scale (VAS). The Oswestry Disability Questionnaire was used to evaluate chronic disability and activities of daily living. Health-related quality of life and functional outcomes were assessed using Health-related Quality of Life Questionnaire (SF-36 v2). Two scores within the scoring algorithm were analyzed: Physical Component (PCS) and Mental Component Summary (MCS). The primary radiological outcomes included restoration and maintenance of vertebral body height, lumbar sagittal and segmental alignment, and fusion status.

METHODS

All patients were followed for 2 years ± 2 months; radiographic and clinical outcomes were assessed at 3, 6, 12 and 24 months with an additional follow-up at 3 weeks for radiographic assessment.

RESULTS

A total of 138 patients undergoing transforaminal lumbar interbody fusions (TLIF) were randomized (1:1) to receive either cortical allograft or PEEK interbody lordotic spacers. Although no differences were detected between the allograft and PEEK patient groups at any of the follow-up time points, there was a highly significant (p<.0001) improvement in all clinical outcome measures. Overall, evidence of radiographic fusion was achieved in 118 (97.5%) patients at the 24 months follow-up. Three patients, all in the allograft group, had pseudoarthrosis and underwent revision surgeries. Postoperative improvement of sagittal alignment, anterior (ABH) or posterior body height (PBH) was initially achieved, but it was mainly lost or reduced at the final follow-up and there were no statistically significant differences between the groups. At the end of the study, improvement and maintenance of lumbar lordosis were achieved in 43.3% and 49.2% patients and segmental alignment in 38.3% and 36.1% for the allograft and PEEK patient groups, respectively. Similarly, ABH was improved and maintained in 28.3% and 36.1% patients and PBH in 28.3% and 44.3% for the allograft and PEEK groups, respectively.

CONCLUSIONS

Although allograft-assisted surgeries may have reduced fusion rates, the study findings demonstrated that TLIF surgery with two different types of cages and in conjunction with rhBMP-2 resulted in similar radiological or clinical outcomes and a highly statistically significant improvement in all clinical outcome measures at the end of the study regardless of the randomization group.

The Morphological Changes in Adjacent Segments Amongst Patients Receiving Anterior and Oblique Lumbar Interbody Fusion: A Retrospective Study

Adjacent segment disease (ASD) is troublesome condition that has proved to be highly related to spinal malalignment after spinal surgery. Hence, we aimed to evaluate the morphological changes after anterior lumbar interbody fusion (ALIF) and oblique LIF (OLIF) to establish the differences between the two surgical methods in terms of possible ASD avoidance. Fifty patients, half of whom received ALIF while the other half received OLIF, were analyzed with image studies and functional outcomes during the pre-operative and post-operative periods, and 2 years after surgery. Image measurements obtained included spinal-pelvic parameters, index lordosis (IL), segmental lordosis (SL), anterior disc height (ADH), posterior disc height (PDH) and adjacent segment disc angle (ASDA). The ADH and PDH in the adjacent segment decreased in the two groups while OLIF showed greater decrease without radiological ASD noted at 2-year follow-up. Both groups showed an increase in IL after surgery while ALIF showed greater improvement. No statistical difference was identified in functional outcomes between LIFs. We suggest that both ALIF and OLIF can restore adequate lordosis and prevent ASD after surgery. However, it should be noted that patient selection remains crucial when making any decision involving which of the two methods to use.

Comparing hyperlordotic and standard lordotic cages for achieving segmental lumbar lordosis during transforaminal lumbar interbody fusion in adult spinal deformity surgery

Background

Few studies directly compare the effect of interbody cages with different degrees of lordosis in producing segmental lumbar lordosis (SLL) in the transforaminal lumbar interbody fusion (TLIF) procedure. Thus, we aimed to investigate changes in SLL in hyperlordotic cages compared to standard lordotic cages in open TLIF procedures.

Methods

Thirty-eight consecutive patients who received open TLIF procedures performed by a single surgeon between 2017 and 2018 were reviewed. Twenty patients had "hyperlordotic cages" (20° lordosis), while 18 patients had "standard lordotic cages" (6° lordosis). Twenty-three patients had one-level TLIF procedures and 15 had two-level TLIF. Standard radiographic measurements, including SLL were assessed preoperatively, postoperatively, and at 1-year follow-up. SLL was measured from the superior endplate of the cephalad vertebra to the inferior endplate of the caudal vertebra. Changes in SLL were compared using Student's and paired t-tests.

Results

In one- and two-level open TLIF, both hyperlordotic and standard lordotic cages produced significant improvement in SLL. Among those receiving a one-level TLIF, SLL increased 7.8° (P=0.024) in those with standard lordotic cages; it increased 8.2° (P=0.020) in those with hyperlordotic cages. Among those receiving a two-level TLIF, SLL increased 13.9° (P=0.032) in those with standard lordotic cages; it increased 8.8° (P=0.023) in those with hyperlordotic cages. However, the improvement in SLL was not significantly different between the two cage types in either one or two-level TLIF procedures (P=0.917, P=0.389). At 1-year follow-up, there was no significant change in SLL, among standard lordotic and hyperlordotic cages (P=0.501, P=0.781).

Conclusions

Although it is theorized that hyperlordotic cages would increase SLL during open TLIF procedures more than standard lordotic cages, our data failed to demonstrate that. As our study examined cases performed by a single surgeon immediately before and after adoption of these lordotic cages, it is likely that surgical technique is of equal or greater importance in improving SLL than the amount of lordosis designed into interbody cages.

Preoperative Radiographic Prediction Tool for Early Postoperative Segmental and Lumbar Lordosis Alignment After Transforaminal Lumbar Interbody Fusion

Objective

Transforaminal lumbar interbody fusion (TLIF) is a common approach and results in varying degrees of lordosis correction. The purpose of this study is to determine preoperative radiographic spinopelvic parameters that predict change in postoperative segmental and lumbar lordosis after TLIF.

Materials & Methods

This study is a single surgeon retrospective review of one-level and two-level TLIFs from L3-S1. All patients underwent bilateral facetectomies, 10 mm TLIF cage (non-lordotic) insertions, and bilateral pedicle screw-rod construct placements. Pre- and post-operative X-rays were assessed for preoperative segmental lordosis (SL), lumbar lordosis (LL), and pelvic incidence (PI). Univariate and multi-predictor linear regression analyses were performed to determine the relationships between preoperative radiographic findings and change in early postoperative segmental and lumbar lordosis.

Results

Ninety-seven patients contributing 128 intervertebral segments were examined. The mean change in SL after TLIF was 7.3 (range: 0.10-28.9°, SD 6.39°). The mean change in LL after TLIF was 5.5˚ (range: -14.8-39.2°, standard deviation (SD) 7.16°). Greater preoperative LL predicted less postoperative LL correction, while greater preoperative PI predicted more postoperative SL and LL correction. Greater anterior disk height was noted to be associated with a decreased change in SL (∆SL). An annular tear on preoperative magnetic resonance imaging (MRI) predicted a 2.7° decrease in ∆SL. A Schmorl's node on preoperative MRI predicted a 4.0° decrease in change in LL (∆LL).

Conclusions

A greater preoperative lordosis and a lower spinopelvic mismatch lessen the potential for an increase in the postoperative SL and LL after a TLIF, which is likely due to a ‘ceiling’ effect of an otherwise optimized spinal alignment. A greater anterior disk height and the presence of an annular tear are associated with decreased ∆SL.

Pseudarthrosis and Rod Fracture Rates After Transforaminal Lumbar Interbody Fusion at the Caudal Levels of Long Constructs for Adult Spinal Deformity Surgery

BACKGROUND

Interbody fusion at the caudal levels of long constructs for adult spinal deformity (ASD) surgery is used to promote fusion and secure a solid foundation for maintenance of deformity correction. We sought to evaluate long-term pseudarthrosis, rod fracture, and revision rates for TLIF performed at the base of a long construct for ASD.

METHODS

We reviewed 316 patients who underwent TLIF as a component of ASD surgery for medical comorbidities, surgical characteristics, and rate of unplanned reoperation for pseudarthrosis or instrumentation failure at the TLIF level. Fusion grading was assessed after revision surgery for pseudarthrosis at the TLIF level.

RESULTS

Rate of pseudarthrosis at the TLIF level was 9.8% (31/316), and rate of rod fractures was 7.9% (25/316). The rate of revision surgery at the TLIF level was 8.9% (28/316), and surgery was performed at a mean of 20.4 ± 16 months from the index procedure. Current smoking status (odds ratio 3.34, P = 0.037) was predictive of pseudarthrosis at the TLIF site. At a mean follow-up of 43 ± 12 months after revision surgery, all patients had achieved bony union at the TLIF site.

CONCLUSIONS

At 3-year follow-up, the rate of pseudarthrosis after TLIF performed at the base of a long fusion for ASD was 9.8%, and the rate of revision surgery to address pseudarthrosis and/or rod fracture was 8.9%. All patients were successfully treated with revision interbody fusion or posterior augmentation of the fusion mass, without need for further revision procedures at the TLIF level.

The radiological outcome in lumbar interbody fusion among rheumatoid arthritis patients: a 20-year retrospective study

BACKGROUND

Clinical outcomes amongst Rheumatoid Arthritis (RA) patients have shown satisfactory results being reported after lumbar surgery. The increased adoption of the interbody fusion technique has been due to a high fusion rate and less invasive procedures. However, the radiographic outcome for RA patients after receiving interbody fusion has scarcely been addressed in the available literature.

METHODS

Patients receiving interbody fusion including ALIF, OLIF, and TLIF were examined for implant cage motion and fusion status at two-year follow-up. Parameters for the index correction level including ADH, PDH, WI, SL, FW, and FH were measured and compared at pre-OP, post-OP, and two-year follow-up.

RESULTS

We enrolled 64 RA patients at 104 levels (mean 64.0 years old, 85.9% female) received lumbar interbody fusion. There were substantial improvement in ADH, PDH, WI, SL, FW, and FH after surgery, with both ADH and PDH having significantly dropped at two-year follow up. The OLIF group suffered from a higher subsidence rate with no significant difference in fusion rate when compared to TLIF. The fusion rate and subsidence rate for all RA patients was 90.4 and 28.8%, respectively.

CONCLUSIONS

We revealed the radiographic outcomes of lumbar interbody fusions towards symptomatic lumbar disease in RA patients with good fusion outcome despite the relative high subsidence rate amongst the OLIF group. Those responsible for intra-operative endplate management should be more cautious to avoid post-OP cage subsidence.

Does Interbody Support at L5-S1 Matter in Long Fusions to the Pelvis?: A 5-year Analysis

STUDY DESIGN

Retrospective review of prospectively collected data.

OBJECTIVE

To determine if the addition of L5-S1 interbody support in long fusion deformity constructs is associated with superior long-term clinical and radiographic outcomes. To compare the 5-year clinical and radiographic outcomes and complications between long fusion constructs with L5-S1 interbody support versus posterolateral fusion (PLF) alone.

SUMMARY OF BACKGROUND DATA

Cadaveric biomechanical studies have suggested that an interbody fusion at L5-S1 is beneficial in long fusion constructs with sacropelvic fixation. However, there is limited data reflecting the superiority of interbody support augmentation in optimizing arthrodesis and deformity correction relative to PLF alone.

METHODS

Eighty-eight consecutive adults with spinal deformity who underwent at minimum T11-pelvis posterior pedicle screw instrumentation with 5-year follow-up were included. Two cohorts were compared based on technique used at the lumbosacral junction (L5-S1): (A) no interbody (PLF; n = 23), or (B) interbody support at L5-S1 (IB; n = 65). Radiographic measurements and clinical outcome measures were compared at multiple time points. Complications were recorded and compared.

RESULTS

No differences in baseline patient characteristics between cohorts. One nonunion occurred at L5-S1 in the PLF group (P = 0.091). Initial postop sagittal alignment was better in the IB group (PLF: 6.46 cm, IB: 2.48 cm, P = 0.007); however, this was not maintained over long-term follow-up. No significant differences in proximal junctional kyphosis (PLF: 7/23, IB: 9/65, P = 0.076). Proximal junctional failure was more frequent in the PLF group (PLF: 6/23, IB: 6/65, P = 0.043). No significant differences in complications were found. Both cohorts had improvement from baseline pain and functional scores.

CONCLUSION

There is no absolute long-term advantage for lumbar interbody support in adult spinal deformity patients undergoing spinal arthrodesis to the pelvis.Level of Evidence: 3.

Comparison of outcomes between indirect decompression of oblique lumbar interbody fusion and MIS-TLIF in one single-level lumbar spondylosis

Minimal invasive spinal fusion has become popular in the last decade. Oblique lumbar interbody fusion (OLIF) is a relatively new surgical technique and could avoid back muscle stripping and posterior complex destruction as in minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF). Between December 2016 and September 2018, patients with single level degenerative spondylosis were selected to enroll in this retrospective study. A total of 21 patients that underwent OLIF and 41 patients that received MIS-TLIF were enrolled. OLIF showed significantly less blood loss and shorter surgery time compared to MIS-TLIF (p < 0.05). The improvement in segmental lordosis and coronal balance was significantly more in OLIF group than MIS-TLIF group (p < 0.05). When comparing with MIS-TLIF, OLIF was significantly better in Oswestry Disability Index (ODI) and visual analogue scale for back pain improvement at post-operative 6 months (p < 0.05). Both OLIF and MIS-TLIF are becoming mainstream procedures for lumbar degenerative-related disease, especially for spondylolisthesis. However, the indirect decompression of OLIF has shown to have less perioperative blood loss and shorter surgery time than that of MIS-TLIF. In addition, OLIF gives superior outcome in restoring segmental lordosis and coronal imbalance. While both OLIF and MIS-TLIF provide optimal clinical outcomes, upon comparison between the two techniques, the indirect decompression of OLIF seems to be a superior option in modern days.

A retrospective comparison of radiographic and clinical outcomes in single-level degenerative lumbar disease undergoing anterior versus transforaminal lumbar interbody fusion

Background

Single-level lumbar degenerative disc disease (DDD) remains a significant cause of morbidity in adulthood. Anterior lumbar interbody fusion (ALIF) and Transforaminal lumbar interbody fusion (TLIF) are surgical techniques developed to treat this condition. With limited studies on intermediate term outcomes in a single cohort, we compare radiographic and clinical outcomes in patients undergoing ALIF and TLIF.

Methods

A retrospective chart review was performed on 164 patients (111 TLIF; 53 ALIF) over a 60-month period. X-ray radiographs obtained pre-operatively, prior to discharge, and at one year were utilized for radiographic assessment. Segmental lordosis, lumbar lordosis and HRQOL scores were measured preoperatively and at one-year timepoints.

Results

Changes in lumbar lordosis and segmental lordosis were significantly greater after ALIF (4.6° vs. -0.6°, P=0.05; 4.7° vs. -0.7°, P<0.05) at one year (mean time, 366±20 days). At one year or greater, there was a greater reduction in mean VAS-leg score in TLIF patients (3.4 vs. 0.6, P<0.05) and ODI score (16.2 vs. 5.4, P<0.05). Similar outcomes were seen for VAS-back, SF-12 Physical Health, and SRS-30 Function/Activity. SF-12 Mental Health scores were found to be lower in patients undergoing TLIF (-3.5 vs. 2.7, P<0.05).

Conclusions

ALIF demonstrated a superior method of increasing lumbar and segmental lordosis. TLIF was utilized more in patients with higher pre-operative VAS-leg pain scores and therefore, showed a greater magnitude of VAS-leg pain improvement. TLIF also demonstrated a greater improvement in ODI scores despite similar baseline scores, suggesting a possible enhanced functional outcome.

The impact of increasing interbody fusion levels at the fractional curve on lordosis, curve correction, and complications in adult patients with scoliosis

OBJECTIVE

Radiculopathy from the fractional curve, usually from L3 to S1, can create severe disability. However, treatment methods of the curve vary. The authors evaluated the effect of adding more levels of interbody fusion during treatment of the fractional curve.

METHODS

A single-institution retrospective review of adult patients treated for scoliosis between 2006 and 2016 was performed. Inclusion criteria were as follows: fractional curves from L3 to S1 > 10°, ipsilateral radicular symptoms concordant on the fractional curve concavity side, patients who underwent at least 1 interbody fusion at the level of the fractional curve, and a minimum 1-year follow-up. Primary outcomes included changes in fractional curve correction, lumbar lordosis change, pelvic incidence - lumbar lordosis mismatch change, scoliosis major curve correction, and rates of revision surgery and postoperative complications. Secondary analysis compared the same outcomes among patients undergoing posterior, anterior, and lateral approaches for their interbody fusion.

RESULTS

A total of 78 patients were included. There were no significant differences in age, sex, BMI, prior surgery, fractional curve degree, pelvic tilt, pelvic incidence, pelvic incidence - lumbar lordosis mismatch, sagittal vertical axis, coronal balance, scoliotic curve magnitude, proportion of patients undergoing an osteotomy, or average number of levels fused among the groups. The mean follow-up was 35.8 months (range 12-150 months). Patients undergoing more levels of interbody fusion had more fractional curve correction (7.4° vs 12.3° vs 12.1° for 1, 2, and 3 levels; p = 0.009); greater increase in lumbar lordosis (-1.8° vs 6.2° vs 13.7°, p = 0.003); and more scoliosis major curve correction (13.0° vs 13.7° vs 24.4°, p = 0.01). There were no statistically significant differences among the groups with regard to postoperative complications (overall rate 47.4%, p = 0.85) or need for revision surgery (overall rate 30.7%, p = 0.25). In the secondary analysis, patients undergoing anterior lumbar interbody fusion (ALIF) had a greater increase in lumbar lordosis (9.1° vs -0.87° for ALIF vs transforaminal lumbar interbody fusion [TLIF], p = 0.028), but also higher revision surgery rates unrelated to adjacent-segment pathology (25% vs 4.3%, p = 0.046). Higher ALIF revision surgery rates were driven by rod fracture in the majority (55%) of cases.

CONCLUSIONS

More levels of interbody fusion resulted in increased lordosis, scoliosis curve correction, and fractional curve correction. However, additional levels of interbody fusion up to 3 levels did not result in more postoperative complications or morbidity. ALIF resulted in a greater lumbar lordosis increase than TLIF, but ALIF had higher revision surgery rates.

Radiographic Factors Affecting Lordosis Correction After Transforaminal Lumbar Interbody Fusion With Unilateral Facetectomy

BACKGROUND

The study design was a retrospective cohort study. The objective was to identify preoperative (preop) radiographic features that are associated with increased lordosis correction after transforaminal lumbar interbody fusion (TLIF).

METHODS

We retrospectively reviewed a single surgeon series of TLIF performed at L4-5 since 2010. The surgical technique involved unilateral facetectomy and insertion of a banana-type cage. A total of 107 cases were available with plain radiographs, and 62 with a preop computed tomography (CT) scan. We compared segmental lordosis correction between the preop and 6-week postoperative radiographs. Patients were divided into groups of those with or without more than 5° lordosis correction. Radiographic features were then compared, and a multivariate analysis was performed.

RESULTS

The mean lordosis correction of the entire cohort was 2.5° (range = -9° to 16°). The percentage of patients with a vacuum disc on the preop CT (40% vs 10%, P = 0.01) was higher in the group with greater than 5° lordosis correction, whereas the mean preop segmental lordosis (14.3° vs 18.6°) and the preop segmental disc angle (6.4° vs 8.4°) were both lower (P < 0.05 for each). The percentage of patients with a Meyerding grade of 2 or higher (28% vs 16%) trended higher but was not significant (P = 0.1). There was no significant difference in the mean body mass index, patient age, preop lumbar lordosis, or disc space height.

CONCLUSIONS

Patients with a preop vacuum disc sign on CT scan or those with a more kyphotic disc space on preop radiographs were more likely to achieve lordosis correction. This information may be useful in preop planning.

LEVEL OF EVIDENCE

4.

CLINICAL RELEVANCE

Unilateral TLIF is likely to be neutral or kyphogenic in patients with a segmental disc angle that is neutral or lordotic pre-operatively, but is likely to increase segmental lordosis in patients with a disc angle that is kyphotic pre-oepratively.

Distinct fusion intersegmental parameters regarding local sagittal balance provide similar clinical outcomes: a comparative study of minimally invasive versus open transforaminal lumbar interbody fusion

Background

Most contemporary studies suggested that intersegmental parameters including disc height and local lordosis contribute to the sagittal balance of fused lumbar. Although similar clinical outcomes following MIS- and Open-TLIF were reported essentially at the early postoperative time, the comparison of local balance variables after these two different techniques was lack. The radiological differences maybe not relevant to the postoperative efficacy at an earlier post-operation stage. But during the long-term follow-up, the complications with regards to the sagittal imbalance might occur due to the distinct biomechanical properties of fusion level after MIS- and Open-TLIF.

Methods

The patients who underwent a single-level MIS- and Open-TLIF were reviewed retrospectively. The anterior disc height (ADH), posterior disc height (PDH), and segmental lordosis (SL) of the fusion segment were measured using recognition technical fluoroscopy. The mean disc height (MDH) was calculated by (ADH + PDH)/2. The relative DH was normalized by the anterior height of the upper vertebrae. The body mass index (BMI), the pain score of low back and leg visual analogue scale (VAS), Oswestry disability index (ODI), estimated blood loss, and hospital stay length was collected.

Results

A total of 88 patients undergoing a single-level TLIF (MIS and Open) were included. The pre- and post-operative ADH, PDH, MDH, and SL of MIS-TLIF group were 1.57 ± 0.33 cm, 0.79 ± 0.20 cm, 1.18 ± 0.21 cm, 7.36 ± 3.07 and 1.63 ± 0.30 cm, 1.02 ± 0.28 cm, 1.32 ± 0.24 cm, 10.24 ± 4.79 respectively. Whereas, the pre- and post-operative ADH, PDH, MDH, and SL of Open-TLIF group were 1.61 ± 0.40 cm, 0.77 ± 0.21 cm, 1.19 ± 0.24 cm, 9.05 ± 5.48 and 1.81 ± 0.33 cm, 0.98 ± 0.24 cm, 1.39 ± 0.24 cm, 12.34 ± 4,74 respectively. MIS- and Open-TLIF group showed no significant differences in low back VAS, leg VAS, and ODI both in pre-operation and post-operation (P > 0.05). The estimated blood loss and hospital stay length in the MIS-TLIF group were significantly lower than those in the Open-TLIF group (P < 0.05).

Conclusion

MIS- and Open-TLIF provided similar clinical outcomes as the respect of low back VAS, leg VAS, and ODI. MIS-TLIF significantly reduced the blood loss and length of hospital stay though. The intervertebral parameters of DH and SL were both increased significantly, Open-TLIF group presented better sagittal balance in term of ADH and SL variables. The contrast investigation of intersegmental parameters may help the surgeons to figure out the further advantages of MIS-TLIF technique, and then better manage the rehabilitation and prevent the reoperation.

[Comparison of intervertebral height and lordosis of fusion segment between open- and minimally invasive-transforaminal lumbar interbody fusions]

OBJECTIVE

To analyze the restoration of intervertebral height and lordosis of fusion segment after open-transforaminal lumbar interbody fusion (Open-TLIF) and minimally invasive-TLIF (MIS-TLIF).

METHODS

Between January 2013 and February 2016, patients who treated with TLIF due to lumbar degenerative diseases and met the selection criteria were selected as the study objects. Among them, 41 patients were treated with open-TLIF (Open-TLIF group), 34 patients were treated with MIS-TLIF (MIS-TLIF group). There was no significant difference between the two groups ( P>0.05) in gender, age, body mass index, disease type, disease duration, pathological segment, and other general data. The intraoperative bleeding volume, hospital stay, visual analogue scale (VAS) score of waist and leg, and Oswestry disability index (ODI) were recorded before and after operation. The anterior disc height (ADH), posterior disc height (ADH), and segmental lordosis (SL) of fusion segment were measured by X-ray film before and at 6 months after operation. The differences of ADH, PDH, and SL between pre- and post-operation were calculated.

RESULTS

The intraoperative bleeding volume and hospital stay in Open-TLIF group were significantly higher than those in MIS-TLIF group ( t=14.619, P=0.000; t=10.021, P=0.000). All incisions healed by first intention without early complications. All patients were followed up 6-24 months (mean, 12.6 months) in Open-TLIF group and 6-24 months (mean, 11.5 months) in MIS-TLIF group. The preoperative VAS scores of waist and leg and ODI of the two groups significantly improved ( P<0.05). There was no significant difference in VAS scores and ODI between the two groups before operation and at 2 weeks and 6 months after operation ( P>0.05). Imaging examination showed the good intervertebral fusion. There was no significant difference in ADH, PDH, and SL between the two groups before operation and at 6 months after operation ( P>0.05). The differences of ADH, PDH, and SL between the two groups were not significant ( P>0.05). The ADH, PDH, and SL after operation significantly increased in the two groups ( P<0.05).

CONCLUSION

Open-TLIF and MIS-TLIF show similar effectiveness and radiological change in the treatment of single lumbar degenerative diseases and the improved intervertebral height and lordosis, but MIS-TLIF can significantly reduce hospital stay and intraoperative blood loss.

Effect of intraoperative position in single-level transforaminal lumbar interbody fusion at the L4/5 level on segmental and overall lumbar lordosis in patients with lumbar degenerative disease

The purpose of this study was to investigate the effect of intraoperative positions in single-level (L4-5) transforaminal lumbar interbody fusion (TLIF) on segmental and overall lumbar lordosis (LL) in patients with lumbar degenerative disease. Thirty-eight consecutive patients who had undergone single-segment (L4-5) TLIF with 0° polyetheretherketone (PEEK) cage and pedicle screw fixation were evaluated. Twenty patients underwent surgery on the four-poster type frame with hip flexion at 30° (Group I) and 18 patients were operated on a Jackson spinal table to adjust their hip flexion to 0° (Group II). Preoperative standing, intraoperative prone, and postoperative standing lateral radiographs were obtained in each patient. The overall and segmental LL were analyzed according to the position in which the patients were placed for their operation and results compared between Groups I and II. Intraoperative intervertebral segmental LL at L4-5 and L5-S1 was increased in Group II than in Group I, whereas postoperative intervertebral segmental LL at L4-5 (fused level) was increased LL. In Group I intraoperative intervertebral segmental LL at L4-5 did not achieve sufficient lordosis, whereas postoperative intervertebral segmental LL at L3-4 was increased. The overall spinal alignment was unaffected by the decreased segmental LL in the fused level owing to the compensation of the upper adjacent segments. The more the hip was extended intraoperatively, the more the segmental lordosis increased in the lower lumbar spine. Thus, selecting the appropriate surgical table and hip position are very important. Underachievement of segmental lordosis leads to the acceleration of upper adjacent segment load.

Intraoperatively predicting postoperative sagittal balance using intraoperative X-rays

This study aimed to assess the correlation of sagittal balance parameters measured intraoperatively, against the gold standard post-operative standing full spine X-ray. A secondary aim was to create a predictive algorithm, that could be used intraoperatively to predict the post-operative balance. 49 patients, who underwent thoracolumbar spinal fusion over a 12-month period were included in this study. Standing full-spine X-rays were obtained both pre and post-surgical fixation. Parallel intraoperative X-rays were taken with the c-arm centred on femoral heads, operative level, S1 and L1. The sagittal parameters pelvic incidence (PI), lumbar lordosis (LL), spino-pelvic mismatch (PI-LL), and sagittal vertical axis were then measured and the correlations statistically analysed. For prone positioned patients the mean LL was 59.9° ± 10.6° intraoperatively (post-fixation) and post-operatively 55.4° ± 10.9° with a mean difference of -4.5° ± 6.1° (p-value < 0.001). For laterally positioned patients the mean LL was 50.9° ± 8.6° intraoperatively and 53.1° ± 10.1° postoperatively for a mean difference of -2.3° ± 6.5° (p-value = 0.117). The linear regression analysis resulted in a predictive algorithm that can be utilised intraoperatively to predict the post-operative standing pelvic mismatch for prone positioned patients. In conclusion, measuring spino-pelvic parameters of sagittal balance intraoperatively can be used to estimate postoperative standing full spine x-ray result. Specifically, in the prone position, the surgeon should aim for intraoperative lordosis that is 4.5° more than the desired post-operative lordosis. The predictive formula provides a direct method to quickly calculate the post-operative pelvic mismatch intraoperatively.

DW. The Deformity TLIF: Bilateral Facetectomy and Osteotomy Closure with a Hinged Table

BACKGROUND

Increasing emphasis has been placed on segmental lordosis correction, even in short segment constructs. However, the majority of reports on TLIF indicate that lordosis correction is modest at best. TLIF with bilateral facetecomy has been described with better lordosis correction, but is usually performed with the spine in extension throughout the case. This report presents a new technique for lordosis correction during TLIF with the use of bilateral facetectomy and osteotomy closure using a mechanically hinged operative table.

METHODS

A 78-year-old male presented with claudicatory back and leg pain due to foraminal stenosis and spondylolisthesis at L4-5 and L5-S1, and was operated on with bilateral facetectomies and TLIF while positioned on a motorized-hinged table, which started in flexion for the decompression and was brought into extension at the end of the case for osteotomy closure.

RESULTS

Segmental lordosis from L4-S1 increased from 15° pre-operatively to 42° postoperatively.

CONCLUSIONS

A comparison of pre- and post-operative lateral radiographs showed 27° segmental lordosis correction, and intra-operative fluoroscopy showed correlation between extension of the table and segmental lordosis correction. Bilateral facetectomy and TLIF allows for segmental lordosis correction. Use of the hinged table allowed for ideal positioning during the decompression and controlled osteotomy closure with close correlation between table position and segmental alignment.Level of Evidence: V.

Clinical, Functional, and Radiologic Outcome of Single- and Double-Level Transforaminal Lumbar Interbody Fusion in Patients with Low-Grade Spondylolisthesis

Objective:

The main objective is to determine the functional, clinical, and radiological outcome of patients with low-grade spondylolisthesis undergoing single- or double-level transforaminal lumbar interbody fusion (TLIF).

Materials and Methods:

This quasi-interventional study was conducted during a 2-year period from 2016 to 2018 in Shiraz, Southern Iran. We included all the adult (≥18 years) patients with low-grade spondylolisthesis (Meyerding Grade I and II) who underwent single- or double-level TLIF in our center. The spinopelvic parameters including pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), and segmental LL (SLL) were measured. The pain intensity and disability were measured utilizing the visual analog scale (VAS) for back and leg pain and Oswestry Disability Index (ODI), respectively, after 1 year.

Results:

Overall, we included a total number of 50 patients with mean age of 54.1 ± 10.48 years. After the surgery, the PI (P = 0.432), PT (P = 0.782), and SS (P = 0.466) were not found to be statistically changed from the baseline. However, we found that single- or double-level TLIF was associated with increased LL (P < 0.001) and SLL (P < 0.001). Regarding the clinical outcome measures, both back (P = 0.001) and leg (P < 0.001) VAS improved after the surgery significantly. In addition, we found that improved leg VAS was positively correlated with improved ODI (r = 0. 634; P < 0.001).

Conclusion:

Single- or double-level TLIF is associated with increased global and SLL along with improved leg and back pain and disability in patients with low-grade spondylolisthesis. Interestingly, improved leg pain is correlated to improved disability in these patients.

[The disputes in the radiographic measurements of sagittal balance and how to deal with them]

Objective

To review the process of radiographic measurements of sagittal balance and offer reference for the clinical practice.

Methods

The related literature of spino-pelvic sagittal parameters and their clinical application was reviewed and analyzed from the aspects such as the clinical application, the advantages and disadvantages, and how to use them effectively.

Results

All parameters have their advantages and disadvantages, and they are influenced by age and race. Sagittal vertical axis can only reflect the global balance, and T 1 pelvic angle which accounts for both spinal inclination and pelvic tilt can't be controlled in the surgery. The correction goal for western people may be not suitable for Chinese.

Conclusion

The parameters should be used wisely when evaluating the sagittal balance, the global balance and local balance should be considered together and the different groups of people need different correction goals.

Adequate Restoration of Disc Height and Segmental Lordosis by Lumbar Interbody Fusion Decreases Adjacent Segment Degeneration

OBJECTIVE

This study aimed to investigate the effects of lumbar interbody fusion-induced biomechanical changes on the adjacent segments, especially disc height and segmental lordosis restoration, and to provide more information for proper surgical strategy selection.

METHODS

The medical records of 528 patients who underwent posterior lumbar interbody fusion were retrospectively reviewed, and a total of 89 patients were included. Surgical indications included degenerative spondylolisthesis (nonspondylolytic), marked disc herniation, or lumbar spinal stenosis requiring extensive decompression at L4/5. Postoperative adjacent segment degeneration (ASD) was assessed based on X-rays and functional status. Disc height, foraminal height, segmental lordosis, lumbar lordosis, and cage geometry were compared between the ASD and non-ASD patients. To identify the possible risk factors for radiographic ASD, univariate analysis was performed first, followed by multivariate logistic regression using variables with P < 0.20.

RESULTS

Univariate analysis revealed that the postoperative disc height in the non-ASD group were significantly greater than in the ASD group. The postoperative segmental lordosis in the non-ASD group was significantly greater than that in the ASD group, and the lumbar lordosis in the non-ASD group was also significantly greater than that in the ASD group at the final follow-up visit. Four variables were identified as independent risk factors for ASD by subsequent multivariate logistic regression: postoperative relative disc height of L4/5 (P = 0.011), postoperative segmental lordosis (P = 0.046), lumbar lordosis at the final follow-up visit (P = 0.007), and cage height (P = 0.038).

CONCLUSIONS

Improved lumbar lordosis is correlated with a lower incidence of ASD, and adequate disc height and segmental lordosis restoration are essential for ASD prevention.

Can Minimally Invasive Transforaminal Lumbar Interbody Fusion Create Lordosis from a Posterior Approach?

The transforaminal lumbar interbody fusion (TLIF) is a well-established 3-column fusion technique that can be used to manage lumbar stenosis, instability, and deformity. Having been in use for more than 20 years, it has evolved into many different renditions. This includes protocols using minimally invasive surgery (MIS) approaches. To avoid the development of flatback syndrome, it is important that a TLIF procedural technique is capable of reproducibly restoring lordosis. This article describes one of many MIS TLIF protocols and presents some of its previously published outcomes.

Do intraoperative radiographs predict final lumbar sagittal alignment following single-level transforaminal lumbar interbody fusion?

OBJECTIVE

The study aimed to determine if the intraoperative segmental lordosis (as calculated on a cross-table lateral radiograph following a single-level transforaminal lumbar interbody fusion [TLIF] for degenerative spondylolisthesis/low-grade isthmic spondylolisthesis) is maintained at discharge and at 6 months postsurgery.

METHODS

The authors reviewed images and medical records of patients ≥ 16 years of age with a diagnosis of an isolated single-level, low-grade spondylolisthesis (degenerative or isthmic) with symptomatic spinal stenosis treated between January 2008 and April 2014. Age, sex, surgical level, surgical approach, and facetectomy (unilateral vs bilateral) were recorded. Upright standardized preoperative, early, and 6-month postoperative radiographs, as well as intraoperative lateral radiographs, were analyzed for the pelvic incidence, segmental lumbar lordosis (SLL) at the TILF level, and total LL (TLL). In addition, the anteroposterior position of the cage in the disc space was documented. Data are presented as the mean ± SD; a p value < 0.05 was considered significant.

RESULTS

Eighty-four patients were included in the study. The mean age of patients was 56.8 ± 13.7 years, and 46 patients (55%) were men. The mean pelvic incidence was 59.7° ± 11.9°, and a posterior midline approach was used in 47 cases (56%). All TLIF procedures were single level using a bullet-shaped cage. A bilateral facetectomy was performed in 17 patients (20.2%), and 89.3% of procedures were done at the L4–5 and L5–S1 segments. SLL significantly improved intraoperatively from 15.8° ± 7.5° to 20.9° ± 7.7°, but the correction was lost after ambulation. Compared with preoperative values, at 6 months the change in SLL was modest at 1.8° ± 6.7° (p = 0.025), whereas TLL increased by 4.3° ± 9.6° (p < 0.001). The anteroposterior position of the cage, approach, level of surgery, and use of a bilateral facetectomy did not significantly affect postoperative LL.

CONCLUSIONS

Following a single-level TLIF procedure using a bullet-shaped cage, the intraoperative improvement in SLL is largely lost after ambulation. The improvement in TLL over time is probably due to the decompression part of the procedure. The approach, level of surgery, bilateral facetectomy, and position of the cage do not seem to have a significant effect on LL achieved postoperatively.

Effect of Single-Level Transforaminal Lumbar Interbody Fusion on Segmental and Overall Lumbar Lordosis in Patients with Lumbar Degenerative Disease

OBJECTIVE

To investigate the ability of transforaminal lumbar interbody fusion (TLIF) to improve lumbar lordosis (LL).

METHODS

In this retrospective study, 92 patients undergoing single-level TLIF to treat lumbar degenerative disease were divided into a low back pain, radiculopathy, and neurogenic claudication group according to their symptoms. Preoperative and postoperative measures, including segmental LL, whole LL, pelvic incidence (PI), pelvic tilt, thoracic kyphosis, sagittal vertical axis, visual analog scale for back and leg pain, and Oswestry Disability Index, were used to evaluate radiographic and clinical outcomes.

RESULTS

All clinical parameters were significantly improved after TLIF. There was no significant difference in any radiographic parameters in the low back pain group. In the radiculopathy and neurogenic claudication groups, all radiographic parameters were significantly changed after TLIF except for segmental LL and PI in both groups and pelvic tilt in the radiculopathy group. No statistically significant differences were found in improvement of segmental LL, PI, thoracic kyphosis, and visual analog scale (leg) between the radiculopathy and neurogenic claudication groups, whereas the differences in improvement of whole LL, pelvic tilt, PI-LL, sagittal vertical axis, visual analog scale (back), and Oswestry Disability Index were significant between the 2 groups.

CONCLUSIONS

For patients with neurogenic leg symptoms owing to single-level lumbar degenerative disease, whole LL was improved after TLIF as a result of spontaneous restoration of lordosis at the unfused lumbar levels.

Comparison of Clinical and Radiographic Outcomes in Patients Receiving Single-Level Transforaminal Lumbar Interbody Fusion With Removal of Unilateral or Bilateral Facet Joints

STUDY DESIGN

A retrospective cohort study.

OBJECTIVE

The objective of this study is to compare the radiographic and clinical outcomes of transforaminal lumbar interbody fusion (TLIF) with bilateral facetectomy (BF) versus unilateral facetectomy (UF).

SUMMARY OF BACKGROUND DATA

BF is a surgical technique utilized with the intent of creating a greater degree of segmental lordosis than UF alone. However, the clinical benefits of this technique have not been defined. We seek to determine whether a difference exists between bilateral versus UF during TLIF by utilizing both clinical and radiographic outcome measures.

METHODS

The electronic medical records of 57 patients who underwent single-level TLIF with either a UF (n = 28) or BF (n = 29) were reviewed. Clinical outcomes were measured through Patient Health Questionnaire-9 (PHQ-9), Pain Disability Questionnaire (PDQ), EuroQol 5 Dimensions (EQ-5D) Health State, and Quality Adjusted Life Year (QALY). Radiographic parameters including disc height and sagittal balance were measured on plain radiographs at 1 year following operation.

RESULTS

All radiographic parameters showed no significant differences between the UF and BF cohorts. Segmental lordosis increased significantly in both cohorts. However, there was no significant difference in the increase of segmental lordosis between cohorts. Overall lumbar lordosis did not increase significantly in either cohort. Perioperative complications were also similar between cohorts. PDQ and EQ-5D scores improved significantly in both cohorts at 1 year postoperatively. The BF cohort showed a significantly greater improvement in both EQ-5D (0.1 ± 0.2 vs. 0.3 ± 0.2, P = 0.01) and PHQ-9 scores (-0.8 ± 4.6 vs. 4.6 ± 5.2, P = 0.03) than the UF cohort. The PDQ score improved over the minimally clinical important difference (MCID) of 26 in only the BF cohort.

CONCLUSION

The findings in the present study demonstrate that BF during single-level TLIF improves clinical outcomes to a greater degree than UF without any notable differences in perioperative complications or radiographic measurements.

LEVEL OF EVIDENCE

3.

Acute Contralateral Radiculopathy after Unilateral Transforaminal Lumbar Interbody Fusion

Objective

Cases of contralateral radiculopathy after a transforaminal lumbar interbody fusion with a single cage (unilateral TLIF) had been reported, but the phenomenon has not been explained satisfactorily. The purpose of this study was to determine its incidence, causes, and risk factors.

Methods

We did retrospective study with 546 patients who underwent a unilateral TLIF, and used CT and MRI to study the causes of contralateral radicular symptoms that appeared within a week postoperatively. Clinical and radiological results were compared by dividing the patients into the symptomatic group and asymptomatic group.

Results

Contralateral symptoms occurred in 32 (5.9%) of the patients underwent unilateral TLIF. The most common cause of contralateral symptoms was a contralateral foraminal stenosis in 22 (68.8%), screw malposition in 4 (12.5%), newly developed herniated nucleus pulposus in 3 (9.3%), hematoma in 1 (3.1%), and unknown origin in 2 patients (6.3%). 16 (50.0%) of the 32 patients received revision surgery. There was no difference in visual analogue scale and Oswestry disability index between the two groups at discharge. Both preoperative and postoperative contralateral foraminal areas were significantly smaller, and postoperative segmental angle was significantly greater in the symptomatic group comparing to those of the asymptomatic group (p<0.05).

Conclusion

The incidence rate is not likely to be small (5.9%). If unilateral TLIF is performed for cases when preoperative contralateral foraminal stenosis already exists or when a large restoration of segmental lordosis is required, the probability of developing contralateral radiculopathy is increased and caution from the surgeon is needed.

The Fate of L5-S1 With Low-Dose BMP-2 and Pelvic Fixation, With or Without Interbody Fusion, in Adult Deformity Surgery

STUDY DESIGN

Retrospective comparative case series.

OBJECTIVE

Evaluate L5-S1 fusion rates when lower dose of bone morphogenic protein-2 (BMP-2) (average 3.2 mg) and pelvic fixation were used, with or without interbody fusion.

SUMMARY OF BACKGROUND DATA

Pseudarthrosis at L5-S1 is one of the most common complications of long fusions to the sacrum in adult deformity surgery. Strategies for decreasing pseudarthrosis include interbody fusion, use of BMP-2 at the lumbosacral junction, and the use of sacropelvic fixation, individually or in combination. High-dose BMP-2 (20-40 mg) placed posterolaterally has shown comparable fusion rates with interbody fusion.

METHODS

Retrospective review of 61 consecutive patients with minimum 2-year follow-up at a single institution. All patients had an isolated posterior approach, 5 or more levels fused including L5-S1, use of pelvic fixation, and no prior L5-S1 procedures. The patients were divided in 2 groups for comparison on the basis of the use of an interbody cage/fusion at the L5-S1 level. Revision rates and implant-related complications were also reported.

RESULTS

The fusion rate at L5-S1 was 97% (59/61), with no difference between the interbody and no interbody fusion groups (97% vs. 96%, P = 1.0). There were no significant differences in the radiographical parameters or deformity correction between the groups. The mean amount of BMP-2 used in the interbody group was 4.1 mg (2-10), 2.5 mg (0-8) in the disc space, and 1.6 mg (0-4) in the interbody cage, whereas there was no difference in the amount of recombinant human bone morphogenic protein-2 placed posterolaterally between the 2 groups (interbody fusion = 1.6 vs. non-interbody fusion = 2.0 mg, P = 0.08) along with autograft and allograft. The overall revision rate for L5-S1 nonunion was 1.6%.

CONCLUSION

The use of low dose of BMP-2 at the L5-S1 level in combination with sacropelvic fixation achieved satisfactory fusion rates in adult deformity surgery. No additional benefit was encountered by adding an interbody cage.

LEVEL OF EVIDENCE

4.

Clinical outcomes and sagittal alignment of single-level unilateral instrumented transforaminal lumbar interbody fusion with a 4 to 5-year follow-up

PURPOSE

A retrospective study was designed to evaluate clinical outcomes and sagittal alignment following single-level unilateral instrumented transforaminal lumbar interbody fusion (TLIF).

METHODS

From November 2008 to December 2010, a total of 139 patients, who suffered from single-level lumbar degenerative disease, were included in this study. Forty-seven males and seventy-two females with a mean age of 57.3 years were enrolled. The average follow-up period was 51.7 months with a range of 41-66 months. The follow-up rate was 85.6 %. Thirty-one patients had diagnosis of discogenic low back pain, ten had recurrent disk herniation, thirty-four had spinal stenosis, and fourty-four had spondylolisthesis. Clinical outcomes were evaluated using the Oswestry disability index (ODI), visual analog scale (VAS) and Japanese Orthopedic Association. Operating time, blood loss, length of stay, and complications were also evaluated. The sagittal alignment and fusion status were assessed by X-ray and three-dimensional computed tomography.

RESULTS

The average operating time was 92.1 ± 27.5 min, the average blood loss was 135.1 ± 113.5 ml, and the average length of stay was 12.0 ± 2.9 days. The overall complication rate was 13.4 %, and the fusion rate was 82.4 %. The postoperative clinical outcomes and sagittal alignment were significantly different from the preoperative values. The final lumbar lordosis angle and segment lordosis angle were associated with back pain VAS and ODI scores, respectively.

CONCLUSION

Unilateral instrumented TLIF is a safe and effective treatment option for single-level lumbar degenerative disease, and is less invasive, yields good outcomes and has a low complication rate. In addition, the procedure has the potential to partly restore sagittal alignment.

In vivo morphological features of human lumbar discs

Recent biomechanics studies have revealed distinct kinematic behavior of different lumbar segments. The mechanisms behind these segment-specific biomechanical features are unknown. This study investigated the in vivo geometric characteristics of human lumbar intervertebral discs. Magnetic resonance images of the lumbar spine of 41 young Chinese individuals were acquired. Disc geometry in the sagittal plane was measured for each subject, including the dimensions of the discs, nucleus pulposus (NP), and annulus fibrosus (AF). Segmental lordosis was also measured using the Cobb method.In general, the disc length increased from upper to lower lumbar levels, except that the L4/5 and L5/S1 discs had similar lengths. The L4/5 NP had a height of 8.6±1.3 mm, which was significantly higher than all other levels (P<0.05). The L5/S1 NP had a length of 21.6±3.1 mm, which was significantly longer than all other levels (P<0.05). At L4/5, the NP occupied 64.0% of the disc length, which was significantly less than the NP of the L5/S1 segment (72.4%) (P<0.05). The anterior AF occupied 20.5% of the L4/5 disc length, which was significantly greater than that of the posterior AF (15.6%) (P<0.05). At the L5/S1 segment, the anterior and posterior AFs were similar in length (14.1% and 13.6% of the disc, respectively). The height to length (H/L) ratio of the L4/5 NP was 0.45±0.06, which was significantly greater than all other segments (P<0.05). There was no correlation between the NP H/L ratio and lordosis. Although the lengths of the lower lumbar discs were similar, the geometry of the AF and NP showed segment-dependent properties. These data may provide insight into the understanding of segment-specific biomechanics in the lower lumbar spine. The data could also provide baseline knowledge for the development of segment-specific surgical treatments of lumbar diseases.

Can cantilever transforaminal lumbar interbody fusion (C-TLIF) maintain segmental lordosis for degenerative spondylolisthesis on a long-term basis?

PURPOSE

To determine if cantilever transforaminal lumbar interbody fusion (C-TLIF) using the crescent-shaped titanium interbody spacer (IBS) favors acquisition of segmental and lumbar lordosis even for degenerative spondylolisthesis (DS) on a long-term basis.

METHODS

We analyzed 23 consecutive patients who underwent C-TLIF with pedicle screw instrumentations fixed with compression for a single-level DS. Measurements on the lateral radiographs taken preoperatively, 2 weeks postoperatively and at final follow-up included disc angle (DA), segmental angle (SA), lumbar lordosis (LL), disc height (%DH) and slip rate (%slip).

RESULTS

There was a good functional recovery with 100 % fusion rate at the mean follow-up of 62 months. Segmental lordosis (DA and SA) and %DH initially increased, but subsequently decreased with the subsidence of the interbody spacer, resulting in a significant increase (p = 0.046) only in SA from 13.2° ± 5.5° preoperatively to 14.7° ± 6.4° at the final follow-up. Changes of LL and %slip were more consistent without correction loss finally showing an increase of LL by 3.6° (p = 0.005) and a slip reduction by 6.7 % (p < 0.001).

CONCLUSIONS

Despite the inherent limitation of placing the IBS against the anterior endplate of the upper vertebra in the presence of DS, the C-TLIF helped significantly restore segmental as well as lumbar lordosis on a long-term basis, which would be of benefit in preventing hypolordosis-induced back pain and the adjacent level disc disease.

Comparison of TLIF with rhBMP-2 versus no TLIF and higher posterolateral rhBMP-2 dose at L5-S1 for long fusions to the sacrum with sacropelvic fixation in patients with primary adult deformity

STUDY DESIGN

Comparvative case series. Data was prospectively entered and retrospectively analyzed.

OBJECTIVE

To evaluate the need for distal lumbar interbody fusion when sufficient recombinant human bone morphogenetic protein-2 (rhBMP-2) is used posterolaterally at L5-S1 in long spinal constructs for adult deformity via costs and radiographical and patient-reported outcome comparisons.

SUMMARY OF BACKGROUND DATA

Many authors and investigators have suggested that an interbody fusion is mandatory at L5-S1 with long fusion to the sacrum with sacropelvic fixation. Past studies have shown competitive fusion rates using rhBMP-2 versus iliac crest bone graft for long fusions. There are various advocates for anterior lumbar interbody fusion versus posterior lumbar interbody fusion versus transforaminal lumbar interbody fusion (TLIF). The optimal strategy remains elusive.

METHODS

Fifty-seven patients were studied at one institution. Thirty-one patients had no interbody fusion (NI group) with 20 mg of rhBMP-2 posterolaterally on 10 mL of carrier and 26 patients had TLIF at L5-S1 (TLIF group) with 6 mg of rhBMP-2 in the interbody space along with local bone graft and 6 mg of rhBMP-2 on carrier posterolaterally at L5-S1. Patients were followed for 24 to 87 months (mean follow-up, 3.92 yr). Demographics of the 2 groups were similar.

RESULTS

There were no detected nonunions at L5-S1 in either group. By our limited cost analysis, the expense of performing a TLIF at L5-S1 is higher than that of using extra rhBMP-2 posterolaterally at that segment. Improvement in outcomes scores, namely Scoliosis Research Society-22 and Oswestry Disability Index, were the same statistically in both groups. Blood loss was greater in the TLIF group than the NI group. There were no identified rhBMP-2 adverse events in either group.

CONCLUSION

Utilization of 20 mg of rhBMP-2 at L5-S1 has the potential to be less expensive than an interbody fusion in most patients having a primary long fusion for adult spinal deformity. The apparent fusion rates at L5-S1 were identical in both groups. Both strategies were successful in regard to improving patient outcomes and achieving apparent solid arthrodesis at the lumbosacral junction, which was the focus of this study.

LEVEL OF EVIDENCE

2.

Radiographic and clinical evaluation of cage subsidence after stand-alone lateral interbody fusion

Object

Indirect decompression of the neural structures through interbody distraction and fusion in the lumbar spine is feasible, but cage subsidence may limit maintenance of the initial decompression. The influence of interbody cage size on subsidence and symptoms in minimally invasive lateral interbody fusion is heretofore unreported. The authors report the rate of cage subsidence after lateral interbody fusion, examine the clinical effects, and present a subsidence classification scale.

Methods

The study was performed as an institutional review board–approved prospective, nonrandomized, comparative, single-center radiographic and clinical evaluation. Stand-alone short-segment (1- or 2-level) lateral lumbar interbody fusion was investigated with 12 months of postoperative follow-up. Two groups were compared. Forty-six patients underwent treatment at 61 lumbar levels with standard interbody cages (18 mm anterior/posterior dimension), and 28 patients underwent treatment at 37 lumbar levels with wide cages (22 mm). Standing lateral radiographs were used to measure segmental lumbar lordosis, disc height, and rate of subsidence. Subsidence was classified using the following scale: Grade 0, 0%–24% loss of postoperative disc height; Grade I, 25%–49%; Grade II, 50%–74%; and Grade III, 75%–100%. Fusion status was assessed on CT scanning, and pain and disability were assessed using the visual analog scale and Oswestry Disability Index. Complications and reoperations were recorded.

Results

Pain and disability improved similarly in both groups. While significant gains in segmental lumbar lordosis and disc height were observed overall, the standard group experienced less improvement due to the higher rate of interbody graft subsidence. A difference in the rate of subsidence between the groups was evident at 6 weeks (p = 0.027), 3 months (p = 0.042), and 12 months (p = 0.047). At 12 months, 70% in the standard group and 89% in the wide group had Grade 0 or I subsidence, and 30% in the standard group and 11% in wide group had Grade II or III subsidence. Subsidence was detected early (6 weeks), at which point it was correlated with transient clinical worsening, although progression of subsidence was not observed after the 6-week time point. Moreover, subsidence occurred predominantly (68%) in the inferior endplate. Fusion rate was not affected by cage dimension (p > 0.999) or by incidence of subsidence (p = 0.383).

Conclusions

Wider cages avoid subsidence and better restore segmental lordosis in stand-alone lateral interbody fusion. Cage subsidence is identified early in follow-up and can be accessed using the proposed classification scale.

Transforaminal versus anterior lumbar interbody fusion in long deformity constructs: a matched cohort analysis

STUDY DESIGN

Prospectively enrolled, retrospectively analyzed matched cohort analysis.

OBJECTIVE

Evaluate the relative merits of transforaminal lumbar interbody fusion (TLIF) and anterior lumbar interbody fusion (ALIF) when performed in long deformity constructs.

SUMMARY OF BACKGROUND DATA

Interbody fusion is frequently used at the caudal levels of long-segment spinal deformity instrumentation constructs to protect the sacral implants and enhance fusion rates. However, there is a paucity of literature regarding which technique is more efficacious.

METHODS

Forty-two patients who underwent TLIF and 42 patients who underwent ALIF were matched with respect to age, sex, comorbidities, curve magnitude, fusion length, and ALIF/TLIF level. Radiographs and clinical outcomes were compared at minimum 2-year follow-up.

RESULTS

Age averaged 54.0 years and instrumented vertebrae averaged 13.6. TLIFs had less operative time (481 vs. 595 min, P = 0.0007), but greater blood loss (2011 vs. 1281 mL, P = 0.0002). Overall complications (TLIF, 12/42 vs. ALIF, 15/42) and neurological complications (TLIF, 4/42 vs. ALIF, 3/42) did not differ. One pseudarthrosis occurred at an ALIF level, with none at TLIF levels. Patients who underwent ALIF began with lower SRS scores but showed more improvement (44.4 to 70.7 vs. 58.6 to 70.6, P = 0.0043). ODI scores in both groups improved similarly. Regionally, ALIFs engendered more lordosis than TLIFs at L3-S1 (gain of 6.9° vs. -2.6°, P < 0.0001) but not T12-S1 (gain of 11.5° vs. 7.9°, P = 0.29). Locally, ALIFs created more lordosis at L4-L5 (gain of 5.6° vs. -1.7°, P < 0.0001) and L5-S1 (gain of 2.5° vs. -1.4°, P = 0.022), but not at L3-L4 (gain of 5.3° vs. 4.0°, P = 0.65). Patients who underwent TLIF obtained greater correction of anteroposterior Cobb angles in lumbar (reduction of 22.4° vs. 9.9°, P < 0.0001) and lumbosacral curves (reduction of 10.3° vs. 3.4°, P < 0.0001).

CONCLUSION

Spinal deformity surgery used TLIFs rather than ALIFs resulted in shorter operative time with no difference in complication rates. ALIFs provided more segmental lordosis, whereas TLIFs afforded better correction of scoliotic curves.