Lumbar alignment and clinical outcome after single level asymmetrical transforaminal lumbar interbody fusion for degenerative spondylolisthesis with local coronal imbalance

The Effectiveness of Tritanium Cages in Preventing Osteolytic Vertebral Endplate Cysts After Lumbar Interbody Fusion

OBJECTIVE

Lumbar interbody fusion (LIF) is a common surgical procedure, but postoperative complications, such as osteolytic vertebral endplate cysts, can adversely affect patient outcomes. This study aims to investigate whether tritanium cages (Stryker, Mahwah, New Jersey, USA) are effective in preventing osteolytic vertebral endplate cysts after LIF.

METHODS

Clinical data from 8 years (2013-2020) of LIF procedures at our hospital were analyzed. Computed tomography was used to assess the formation of osteolytic vertebral endplate cysts 6 months after surgery. Clinical factors potentially associated with cyst formation were compared among 3 different interbody spacer materials: tritanium, titanium, and polyetheretherketone.

RESULTS

LIF was performed for 169 patients at 205 spinal levels, employing tritanium cages in 56 levels (48 patients), titanium in 103 levels (86 patients), and polyetheretherketone in 46 levels (35 patients). At 6 months after LIF, 27.3% of patients showed worsening of osteolytic vertebral endplate cysts. Multivariate logistic regression analysis showed that tritanium cages (odds ratio [OR], 3.86; 95% confidence interval [CI], 1.46-10.21) and titanium (OR, 2.55; 95% CI, 1.13-5.75), and posterior LIF (OR, 5.74; 95% CI, 2.24-14.74) were associated with a reduced risk of postoperative osteolytic vertebral endplate cysts.

CONCLUSIONS

Tritanium cages have shown promise in preventing postoperative osteolytic vertebral endplate cysts, suggesting their potential as a stable and effective choice in LIF procedures. These findings have significant implications for improving patient outcomes and warrant further investigation to optimize surgical techniques and materials.

Comparison of Unilateral versus Bilateral Instrumented Transforaminal Lumbar Interbody Fusion in Lumbar Degenerative Diseases: A Minimum of 5-Year Follow-Up

Background and Objective: There is a paucity of literature comparing unilateral instrumented transforaminal lumbar interbody fusion (UITLIF) with bilateral instrumented TLIF (BITLIF) regarding radiological alignment, including the coronal balance, even though UITLIF might have asymmetric characteristics in the coronal plane. This retrospective study aimed to compare the clinical and long-term radiological outcomes of 1-level UITLIF and BITLIF in lumbar degenerative diseases (LDD) including lumbar spinal stenosis with or without spondylolisthesis (degenerative or spondylolytic). Materials and Methods: Patients who underwent 1-level UITLIF with two rectangular polyetheretherketone (PEEK) cages or BITLIF between November 2009 and June 2016 by four surgeons with ≥5 years of follow-up at a single hospital were included. We compared the clinical and radiological outcomes between the UITLIF and BITLIF. Results: In total, 63 and 111 patients who underwent UITLIF and BITLIF, respectively, were enrolled. The median follow-up was 85.55 months (range: 60-130). The UITLIF group had a significantly shorter operation time (185.0 [170.0-210.0] vs. 225.0 [200.0-265.0], p < 0.001) and lower estimated blood loss (300.0 [250.0-500.0] vs. 550.0 [400.0-800.0], p < 0.001) than the BITLIF group. Regarding the clinical outcomes, there were no significant differences in the intermittent claudication score (p = 0.495) and Kirkaldy-Willis criteria (p = 0.707) at 1 year postoperatively. The interval changes in the local coronal Cobb angle at the index level, L1-S1 lordotic angle, and coronal off-balance from the immediate postoperative radiograph to the last follow-up were not significantly different (p = 0.687, p = 0.701, and p = 0.367, respectively). Conclusions: UITLIF with two rectangular PEEK cages may provide comparable clinical outcomes and radiological longevity including coronal alignment to BITLIF in 1-level LDD. In addition, UITLIF has advantages over BITLIF in terms of operative time and blood loss.

Apical Vertebras Distribution Modifier for Coronal Balance Classification in Adult Idiopathic Scoliosis

Background: We aimed to propose the apical vertebras distribution modifier to supplement the coronal balance (CB) classification for adult idiopathic scoliosis (AdIS). An algorithm to predict postoperative coronal compensation and avoid postoperative coronal imbalance (CIB) was proposed. Methods: Patients were categorized into CB and CIB groups according to the preoperative coronal balance distance (CBD). The apical vertebras distribution modifier was defined as negative (-) if the centers of the apical vertebras (CoAVs) were on either side of the central sacral vertical line (CSVL) and positive (+) if the CoAVs were on the same side of the CSVL. Results: A total of 80 AdIS patients, with an average age of 25.97 ± 9.20 years, who underwent posterior spinal fusion (PSF) were prospectively recruited. The mean Cobb angle of the main curve was 107.25 ± 21.11 degrees at preoperation. The mean follow-up time was 3.76 ± 1.38 (2-8) years. At postoperation and follow-up, CIB occurred in 7 (70%) and 4 (40%) CB- patients, 23 (50%) and 13 (28.26%) CB+ patients, 6 (60%) and 6 (60%) CIB- patients, and 9 (64.29%) and 10 (71.43%) CIB+ patients. Health-related quality of life (HRQoL) was significantly better in the CIB- group compared with that of the CIB+ group in the dimension of back pain. To avoid postoperative CIB, the correction rate of the main curve (CRMC) should match the compensatory curve for CB-/+ patients; the CRMC should be greater than the compensatory curve for CIB- patients; and the CRMC should be less than the compensatory curve for CIB+ patients, and the inclination of the LIV needs to be reduced. Conclusions: CB+ patients have the least postoperative CIB rate and the best coronal compensatory ability. CIB+ patients are at a high risk of postoperative CIB and have the poorest coronal compensatory capacity in the event of postoperative CIB. The proposed surgical algorithm facilitates the handling of each type of coronal alignment.

The effect of sagittal alignment, coronal balance, and segmental stability on preoperative patient-reported outcomes in patients with degenerative lumbar spondylolisthesis

OBJECTIVE

The aim of this study was to investigate the association between spinal alignment and preoperative patient-reported outcomes (PROs) in patients with degenerative lumbar spondylolisthesis (DLS) and to identify the independent risk factors for worse preoperative PROs.

METHODS

In total, 101 patients suffering from DLS were retrospectively studied within a single medical center. Age, sex, height, weight, and body mass index were uniformly recorded. PRO-related indicators include the Oswestry Disability Index (ODI), the Japanese Orthopedic Association's (JOA) score, and the visual analog scale (VAS) for back and leg pain. Sagittal alignment, coronal balance, and stability of the L4/5 level were evaluated through whole-spine anteroposterior and lateral radiographs and dynamic lumbar X-ray.

RESULTS

Increasing age (P = 0.005), higher sagittal vertical axis (SVA) (P < 0.001), and global coronal imbalance (GCI) (P = 0.023) were independent risk factors for higher ODI. Patients with GCI had lower JOA scores (P = 0.001) than those with balanced coronal alignment. Unstable spondylolisthesis (P < 0.001) and GCI (P = 0.009) were two vital predictors of VAS-back pain. Increasing age (P = 0.031), local coronal imbalance (LCI) (P < 0.001), and GCI (P < 0.001) were associated with higher VAS-leg pain. Moreover, patients with coronal imbalance also exhibited significant sagittal malalignment based on the subgroup analysis.

CONCLUSION

DLS patients with higher SVA, unstable spondylolistheses, a combination of LCI/GCI, or increasing age were predisposed to have more severe subjective symptoms before surgery.

Correlation between direction of pedicle screw and restoration of lumbar degenerative scoliosis in degenerative lumbar spondylolisthesis: a retrospective study

Background

Inferior clinical outcomes have been reported in patients with degenerative lumbar spondylolisthesis (DLS) accompanied by lumbar degenerative scoliosis, but little attention has been paid to its radiologic assessment or preoperative planning. The aim of this study was to analyze the effect of transforaminal lumbar interbody fusion on patients with DLS and lumbar degenerative scoliosis and explore the surgical aspects benefiting the restoration of lumbar degenerative scoliosis.

Methods

All patients with DLS and lumbar degenerative scoliosis undergoing single-level unilateral transforaminal lumbar interbody fusion surgery between July 1, 2015, and April 30, 2021, were screened in this retrospective cohort study. Clinical outcomes including visual analog scale (VAS), Oswestry disability index (ODI), and radiographic parameters of sagittal and coronal alignment, cage spatial locations, and angle of pedicle screw (parallel, cranial, and caudad angle) were assessed. Coronal asymmetry was demonstrated by the intervertebral height difference between the medial and lateral margins of indexed intersegmental space. The correlations between Δintervertebral height difference (postoperative intervertebral height difference-preoperative intervertebral height difference) and radiographic parameters and clinical outcomes were analyzed by univariable, multivariable, mediation, and correlation analyses. Significance was set at a bilateral P<0.05.

Results

A total of 57 included patients were followed up for a minimum of 1 year. Reduction of VAS, ODI, and improvement of radiographic parameters were found after surgery. The cranial angle of the lower pedicle screw positively correlated with Δintervertebral height difference restoration (b=0.54; standard error=0.11; P<0.001).

Conclusions

Transforaminal lumbar interbody fusion surgery appears to be an effective approach to improving the radiographic and clinical outcomes of patients with DLS and lumbar degenerative scoliosis. The cranial direction of the lower pedicle screws in single-level unilateral transforaminal lumbar interbody fusion surgery may be associated with a better postoperative restoration of lumbar degenerative scoliosis.

Radiographic analysis of dynamic lumbar motion during the five-repetition sit-to-stand test in degenerative lumbar spondylolisthesis

Background

To investigate the mechanisms of low back pain triggered by the five-repetition sit-to-stand test (5R-STS test) in degenerative lumbar spondylolisthesis (DLS) from radiographic perspective, as well as to determine the most useful diagnostic modalities in the evaluation of segmental instability.

Methods

We retrospectively performed a study of 78 patients (23 men and 55 women) with symptomatic DLS at L4/5 in our institution between April 2020 and December 2021. Each patient was assessed by using the 5R-STS test and received a series of radiographs including the upright standing, normal sitting, standing flexion–extension radiographs, and supine sagittal MR images. Enrolled patients were divided into two groups based on the 5R-STS test score: severe group and mild group. Translational and angular motion was determined by comparing normal sitting radiograph (N) with upright standing radiograph (U) (Combined, NU), flexion/extension radiographs (FE) as well as normal sitting radiograph (N) with a supine sagittal MR image (sMR) (Combined, N-sMR).

Results

Overall, 78 patients were enrolled, and there were 31(39.7%) patients in group S and 47(60.3%) patients in group M, with an average age of 60.7 ± 8.4 years. The normal sitting radiograph demonstrated the maximum slip percentage (SP) and the highest kyphotic angle both in group S and group M. Compared with group M, group S revealed significantly higher SP in the normal sitting position (24.1 vs 19.6; p = 0.002). The lumbar slip angular in group S with a sitting position was significantly higher than that in group M (-5.2 vs -1.3; p < 0.001). All patients in group S had objective functional impairment (OFI) and 28 patients of them were diagnosed with lumbar instability by using the combination of normal sitting radiograph (N) and supine sagittal MR image (sMR) (Combined, N-sMR).

Conclusion

DLS patients with positive sign of the 5R-STS test is a distinct subgroup associated with lumbar instability. The modality of the combination of normal sitting radiograph (N) and supine sagittal MR image (sMR) had a significant advantage in terms of the ability to identify segmental instability.

Coronal Alignment in Adult Spinal Deformity Surgery: Definitions, Measurements, Treatment Algorithms, and Impact on Clinical Outcomes

The major focus of realignment in adult spinal deformity (ASD) surgery has been on the sagittal plane, and less emphasis has been given to the coronal plane. In light of this overlooked area within ASD surgery, we aimed to refocus the narrative on coronal alignment in ASD surgery. The objectives of the current narrative review were to (1) define coronal alignment and discuss existing measurements; (2) report the incidence and prevalence of coronal malalignment (CM); (3) discuss the impact of CM on clinical outcomes; and (4) describe our preferred treatment algorithm of surgical correction of CM in ASD.

Evaluation of the Predictors for Unfavorable Clinical Outcomes of Degenerative Lumbar Spondylolisthesis After Lumbar Interbody Fusion Using Machine Learning

Background

An increasing number of geriatric patients are suffering from degenerative lumbar spondylolisthesis (DLS) and need a lumbar interbody fusion (LIF) operation to alleviate the symptoms. Our study was performed aiming to determine the predictors that contributed to unfavorable clinical efficacy among patients with DLS after LIF according to the support vector machine (SVM) algorithm.

Methods

A total of 157 patients with single-segment DLS were recruited and performed LIF in our hospital from January 1, 2015 to October 1, 2020. Postoperative functional evaluation, including ODI and VAS were, performed, and endpoint events were defined as significant relief of symptom in the short term (2 weeks postoperatively) and long term (1 year postoperatively). General patient information and radiological data were selected and analyzed for statistical relationships with the endpoint events. The SVM method was used to establish the predictive model.

Results

Among the 157 consecutive patients, a postoperative unfavorable clinical outcome was reported in 26 patients (16.6%) for a short-term cohort and nine patients (5.7%) for a long-term cohort. Based on univariate and multivariate regression analysis, increased disc height (DH), enlarged facet angle (FA), and raised lateral listhesis (LLS) grade were confirmed as the risk factors that hindered patients' short-term functional recovery. Furthermore, long-term functional recovery was significantly associated with DH alone. In combination with the SVM method, a prediction model with consistent and superior predictive performance was achieved with average and maximum areas under the receiver operating characteristic curve (AUC) of 0.88 and 0.96 in the short-term cohort, and 0.78 and 0.82 in the long-term cohort. The classification results of the discriminant analysis were demonstrated by the confusion matrix.

Conclusions

The proposed SVM model indicated that DH, FA, and LLS were statistically associated with a clinical outcome of DLS. These results may provide optimized clinical strategy for treatment of DLS.

Analysis of lumbar lateral instability on upright left and right bending radiographs in symptomatic patients with degenerative lumbar spondylolisthesis

Background

To evaluate lumbar mobility in various positions using upright left and right bending radiographs in patients with degenerative lumbar spondylolisthesis (DLS), as well as to assess the impact of lateral instability on patient-reported outcomes.

Methods

This study retrospectively reviewed a consecutive series of patients with DLS between January 2019 and October 2020. The enrolled patients were divided into two groups: the lateral instability group (group L) and non-lateral instability group (group NL). Translational and angular motion in both sagittal and coronal planes and patient-reported outcomes were compared between the two groups.

Results

There were 104 (59.8%) patients in group L and 70 (40.2%) patients in group NL, with an average age of 60.6 ± 7.8 years. Patients with a right bending posture in group L had a higher slip percentage (14.2 ± 7.4% vs 9.2 ± 3.2%, p = 0.01) and slip angle (6.3 ± 1.5° vs 2.2 ± 0.8°, p = 0.021). Compared with group NL, group L demonstrated significantly larger angular motion in the coronal plane (2.4 ± 1.3° vs 1.0 ± 0.7°, p = 0.008). Patients with lateral instability had worse preoperative back pain (6.1 ± 1.6 vs 2.7 ± 1.9, p = 0.01) and Oswestry Disability Index (ODI) scores (37.7 ± 5.5 vs 25.6 ± 2.6, p = 0.002). In terms of pain characteristics, group L was characterized by pain when getting out of a car, when rising from a chair, and when climbing stairs (all p values < 0.05).

Conclusion

Lumbar lateral instability, that is, increased mobility in the coronal plane on lateral bending radiographs, translational and/or angular, correlates to more pronounced patient related symptoms in degenerative L4–5 spondylolisthesis. The existence of lumbar lateral instability leads to worse impacts on patient-reported outcomes when patients change their positions including getting out of a car, rising from a chair, and climbing stairs.

The Effect of the Severity of Preoperative Disability on Patient-Reported Outcomes and Patient Satisfaction Following Minimally Invasive Transforaminal Lumbar Interbody Fusion

OBJECTIVE

To compare patient-reported outcomes (PROMs), satisfaction, and minimum clinically important difference (MCID) achievement following minimally invasive transforaminal lumbar interbody fusion stratified by preoperative disability.

METHODS

Minimally invasive transforaminal lumbar interbody fusions were grouped by preoperative Oswestry Disability Index (ODI) score: ODI <41 or ODI ≥41. PROMs administered pre/postoperatively included Patient-Reported Outcomes Measurement Information System physical function (PROMIS-PF), visual analog scale (VAS) back/leg, ODI, and 12-Item Short-Form Physical Composite Score (SF-12 PCS)/12-Item Short-Form Mental Composite Score (SF-12 MCS). Satisfaction scores were collected for VAS back/leg and ODI. Coarsened exact match controlled for differences between cohorts. T tests compared mean PROMs and postoperative improvement/satisfaction between cohorts. Simple logistic regression compared MCID achievement.

RESULTS

After coarsened exact matching, there were 118 patients in the ODI ≤41 and 377 patients in the ODI >41 cohort. The ODI >41 cohort saw greater postoperative inpatient VAS pain score and narcotic consumption on days 0/1 (P < 0.018, all). PROMs differed between cohorts: PROMIS-PF, SF-12 PCS, ODI, VAS back/leg at all postoperative time points and SF-12 MCS at 6 weeks/12 weeks/6 months/1 year (P < 0.045, all). Patients in the ODI >41 cohort demonstrated greater proportion achieving MCID for ODI at all postoperative time points and for SF-12 MCS 6-week/12-week/6-month/1-year (P < 0.040, all). The ODI ≤41 cohort demonstrated greater MCID achievement for overall PROMIS-PF and SF-12 PCS 6 months (P < 0.047, all). Postoperative satisfaction was greater in the ODI ≤41 cohort for VAS leg 6 weeks/12 weeks, VAS back 6 weeks/12 weeks, and ODI all postoperative time points (P < 0.048, all).

CONCLUSIONS

Preoperative disability associated with worse postoperative PROMs and patient satisfaction for disability, back/leg pain at multiple time points. MCID achievement rates across cohorts were similar for most PROMs at most postoperative time points. Patients with severe disability may have unrealistic expectations for surgical benefits, influencing corresponding postoperative satisfaction.

Influence of Preoperative Difference in Lumbar Lordosis Between the Standing and Supine Positions on Clinical Outcomes After Single-level Transforaminal Lumbar Interbody Fusion: Minimum 2-year Follow-up

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

The aim of this study was to investigate whether a preoperative difference in lumbar lordosis (D-LL) between the standing and supine positions is associated with clinical outcomes after transforaminal lumbar interbody fusion (TLIF).

SUMMARY OF BACKGROUND DATA

Several factors have been reported to be associated with surgical outcomes after TLIF. However, the association between preoperative D-LL and clinical outcomes after TLIF is unknown.

METHODS

We enrolled 45 lumbar degenerative disease patients (mean age: 65.7 ± 11.3 years old; 24 males) treated with single-level TLIF. Surgical outcomes were assessed using Oswestry disability index, visual analog scale (VAS; low back pain [LBP], lower-extremity pain, numbness, LBP in motion, in standing, and in sitting), Japanese Orthopaedic Association Back Pain Evaluation Questionnaire, Japanese Orthopaedic Association score for intermittent claudication (JOA score), and Nakai's scoring system. The preoperative D-LL between the standing radiograph and computed tomography (CT) in the supine position was defined as LL in supine CT-standing radiograph. Patients were divided into two groups according to D-LL value (D-LL >-4°, and D-LL ≤-4°). Clinical outcomes were compared between the groups, and correlations between preoperative D-LL and clinical outcomes were analyzed.

RESULTS

There were no significant differences in preoperative clinical parameters between the two groups. Postoperative VASs for lower extremity pain, numbness, LBP in standing, and JOA score in D-LL >-4° group were significantly worse than in the D-LL ≤-4° group (P < 0.05). Preoperative D-LL showed a weak correlation with postoperative lower extremity pain and numbness (P < 0.05).

CONCLUSION

This study revealed that lumbar degenerative disease patients, who have greater preoperative kyphotic lumbar alignment in the standing versus supine position, tend to have postoperative residual symptoms after TLIF. A preoperative comparison of lateral radiographs between the standing and supine positions is useful to predict patients' postoperative residual symptoms.Level of Evidence: 3.

Lumbar alignment and patient-reported outcomes after single-level transforaminal lumbar interbody fusion for degenerative lumbar spondylolisthesis with and without local coronal imbalance

OBJECTIVE

The purpose of this study was to compare the preoperative radiographic features of degenerative lumbar spondylolisthesis (DLS) with and without local coronal imbalance (LCI) and to investigate the surgical outcomes of transforaminal lumbar interbody fusion (TLIF) in the treatment of DLS with LCI at the spondylolisthesis level. DLS with scoliotic disc wedging and/or lateral listhesis at the same involved segment, as well as LCI, constitutes a distinct subgroup. However, previous studies concerning surgical outcomes focused mainly on sagittal profiles. There is a paucity of valid data regarding lumbar coronal alignment and patient-reported outcomes (PROs) after surgery in DLS with LCI.

METHODS

The authors reviewed consecutive patients who received TLIF for L4/5 DLS between 2009 and 2018. Patients were assigned to the LCI and non-LCI groups based on preoperative radiographs. Demographics, radiographic parameters related to both sagittal and coronal alignment, and PROs were compared between the 2 groups.

RESULTS

There were 21 patients in the LCI and 80 in the non-LCI group. Compared with the non-LCI group, the LCI group was characterized by lower preoperative lumbar lordosis on sagittal alignment (38.3° vs 43.7°, p < 0.05), higher lumbar Cobb angle on coronal alignment (12.4° vs 5.1°, p < 0.05), and worse lumbar coronal balance (18.5 mm vs 6.8 mm, p < 0.05). After surgery, lumbar alignment in the sagittal and coronal planes was significantly improved in the LCI group, whereas no significant changes occurred in the non-LCI group. Scores on the preoperative Oswestry Disability Index and the visual analog scale for back pain and leg pain scores were significantly higher in the LCI group, whereas no differences were found between the 2 groups in the postoperative evaluation (p > 0.05).

CONCLUSIONS

DLS with LCI constitutes a distinct subgroup characterized by coronal malalignment and loss of whole lumbar lordosis, which may result in worse PROs. The TLIF procedure allows the reconstruction of the coronal and sagittal lumbar profile and achievement of satisfactory PROs.

Useful and innovative methods for the treatment of postoperative coronal malalignment in adult scoliosis: the "kickstand rod" and "tie rod" procedures

STUDY DESIGN

Surgical technique description and case series.

OBJECTIVE

To describe the use of two techniques for the correction of postoperative coronal imbalance after surgical treatment for adult spine deformity (ASD). Sagittal and coronal spinal malalignments are often present in patients with ASD or in patients who have undergone spine surgery. Surgical correction of coronal imbalance is insufficiently investigated, and the literature provides a limited spectrum of surgical options when compared to sagittal imbalance. Nevertheless, this deformity can compromise the surgical outcome and can increase the risk of hardware failure.

METHODS

The kickstand (KR) and tie rod (TR) techniques utilize an accessory rod, linking the previous instrumentation to an independent iliac screw. After a proper release of the lumbar spine with anterior release or posterior osteotomies, the KR technique pushes with distraction on the concave side, whereas the TR technique pulls with compression on the convex side. Four patients (mean age, 64 years; SD 5.7) affected by severe postoperative coronal imbalance were treated. C7-PL ranges from 39 to 76 mm. The mean preoperative ODI was 70/100 (range from 55 to 82). All patients had previous spinopelvic fixation as a consequence of corrective surgery for adult spine deformity. The patients were surgically treated with the addition of supplementary rods connected to the ilium. The rods were used in the concavity or convexity of the deformity functioning as "kickstand" or "tie" or a combination of both.

RESULTS

The mean surgical correction of C7-PL was 35 mm (range from 20 to 52 mm). In particular, the mean correction for kickstand rod technique was 26 mm and for tie rod technique was 43 mm. All of the patients improved their preoperative disability, and mean ODI was 30/100 (range from 10 to 60) at median 19-month follow-up. All postoperative imaging showed implants were in proper position without hardware failure. All of the patients treated demonstrated an immediate postoperative improvement in terms of coronal displacement of the spine. No complications were observed. At 1-year follow-up, all of the patients remained satisfactory in terms of clinical outcomes.

CONCLUSION

The kickstand and tie rod techniques are effective in the treatment of postoperative coronal malalignment. Further studies are needed to confirm these findings.

LEVEL OF EVIDENCE

V: Case report. These slides can be retrieved under Electronic Supplementary Material.

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.

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 interbody fusion cage on clinical and radiological outcome of surgery in L4-L5 lumbar degenerative spondylolisthesis

Background

Lumbar degenerative spondylolisthesis (LDS) is a degenerative slippage of a lumbar vertebra relative to the adjacent vertebra below that can be clinically symptomatic. We aim to compare radiological and clinical outcome of surgery in L4-L5 LDS with or without applying the interbody fusion cage.

Methods

We studied 60 patients (mean age, 51.3±13.2 years; follow-up, 53.3±14.6 months) with L4-L5 LDS who had been treated by decompression, pedicle screw and rod instrumentation associated with posterolateral fusion (PLF) without and with transforaminal lumbar interbody fusion (TLIF) in equally divided groups A and B, respectively. Intraoperative parameters were recorded and outcome assessment carried out by visual analog scale (VAS), Oswestry Disability Index questionnaire (ODI), subjective satisfaction, radiologic union, and loss of reduction. We judged the differences by t-test and cross-tab.

Results

Using an interbody fusion cage was associated with a significant increase in intraoperative blood loss, operative time, and instrument cost. Improvement in VAS and ODI were significant but comparable. Satisfaction rate was higher in group A (P=0.52). Fusion rate and loss of correction were more favorable in group B but these differences were not significant.

Conclusions

In the surgical treatment of the patients with L4-L5 LDS, interbody fusion cage probably does not significantly improve the radiologic and clinical outcomes and may also be associated with more complication and morbidity.

Current Status of Lumbar Interbody Fusion for Degenerative Spondylolisthesis

Instrumented lumbar fusion can provide immediate stability and assist in satisfactory arthrodesis in patients who have pain or instability of the lumbar spine. Lumbar adjunctive fusion with decompression is often a good procedure for surgical management of degenerative spondylolisthesis (DS). Among various lumbar fusion techniques, lumbar interbody fusion (LIF) has an advantage in that it maintains favorable lumbar alignment and provides successful fusion with the added effect of indirect decompression. This technique has been widely used and represents an advancement in spinal instrumentation, although the rationale and optimal type of LIF for DS remains controversial. We evaluated the current status and role of LIF in DS treatment, mainly as a means to augment instrumentation. We addressed the basic concept of LIF, its indications, and various types including minimally invasive techniques. It also has acceptable biomechanical features, and offers reconstruction with ideal lumbar alignment. Postsurgical adverse events related to each LIF technique are also addressed.