The Quest of Sagittal Balance Parameters and Clinical Outcome after Short Segment Spinal Fusion

Postoperative impact of rod bending in the lumbar spine fusion surgery with polyaxial screws - Validation of a study

Introduction

In 2019, Moufid and Gille published a study in which they proposed certain radiological parameters that may justify the mismatch between the lordosis of the lumbar segment and the lordosis of the rod bar using polyaxial screws. The aim of this study is to reproduce the measurements performed by Moufid and Gille and try to validate their findings.

Material and methods

A retrospective study was performed including patients submitted to L3-L5 posterior fusion with or without interbody devices using polyaxial screws and titanium rods, for degenerative disease. Radiological parameters were analysed:the distance between the posterior wall and the rod for each vertebra(the standard deviation of the three distances was called Alpha); the angle between the screw and the rod for each screw(mean of the three was called Theta); the angle between screws and superior endplate for each instrumented vertebra(mean of the three was called Lambda). The difference between post-operative segmental lordosis and the lordosis of the rod was called DiffL.

Results

A total of 58 cases were included. The most frequent fusion surgery was posterolateral fusion(77.6%). The mean value of lumbar lordosis, fused segmental lordosis, pelvic incidence, Alpha, Theta, Lambda and DiffL were 48.7 ± 12.7°, 28.4 ± 9.2°, 60.7 ± 11.9°, 3.4 ± 1.6 mm, 90.5 ± 1.8°, 3.9 ± 1.8° e 9.9 ± 9.5° respectively. The mean value of rod lordosis was 20.5 ± 8.1°. DiffL varied between 0.1° (practically no mismatch) and 30.5° of mismatch. DiffL didn't correlate with gender, fusion type, age, PI and Alpha, Theta or Lambda. There was a significant positive correlation between lumbar lordosis and DiffL(ρ = 0.28; p = 0.03). No correlation was found between the radiological parameters for the cut-off point proposed by Moufid and Gille(Alpha 4.7 mm, Theta 86°, Lambda 2.8°) and the DiffL value.

Conclusion

No significant factors were identified in this study to aid in achieving an ideal match between rod and segmental spine lordosis, therefore not validating the study by Moufid and Gille.

Effect of interbody fusion compared with posterolateral fusion on lumbar degenerative spondylolisthesis: a systematic review and meta-analysis

BACKGROUND CONTEXT

Lumbar degenerative spondylolisthesis is a relatively common pathology, and surgical treatment is an option in selected cases. The common use of anterior column support by interbody fusion (IBF) has not been adequately studied.

PURPOSE

The primary objective of this systematic review and meta-analysis was to compare the functional and surgical outcomes after posterolateral fusion (PLF) and IBF for the treatment of degenerative spondylolisthesis.

STUDY DESIGN

A systematic review and meta-analysis was conducted to identify studies analyzing the effects of IBF compared to those of instrumented PLF on degenerative spondylolisthesis.

PATIENT SAMPLE

A total of 1,063 patients were included in the analysis. Of them, 470 patients were treated with PLF and 593 with IBF.

OUTCOME MEASURES

The outcomes analyzed were the visual analog scale and numerical rating scale scores for back pain, Oswestry Disability Index (ODI), 36-Item Short Form Health Survey (SF-36) score, 12-Item Short Form Health Survey (physical and mental components) score, blood loss amount, surgical time, hospital stay duration, fusion rate, lumbar lordosis, sacral slope, and postoperative complications.

METHODS

A search was conducted using the MEDLINE, Cochrane, and Google Scholar databases for studies published between January 1985 and February 2021. Both retrospective and prospective studies that compared between IBF and PLF were included.

RESULTS

A total of 2,819 articles were screened, and 38 full-text articles were selected for a detailed investigation, of which 12 articles were found to match all the inclusion criteria and were included in the meta-analysis. There was an improvement in the sacral slope (mean difference [MD] = 3 [95% confidence interval {CI} = 0.83-5.17]) and fusion rate (odds ratio [OR] = 0.47 [95% CI = 0.26-0.86]) in the IBF group. The incidence of neural injury was higher in the IBF group (OR = 0.28 [95% CI = 0.13-0.60]) than in the PLF group. There were no differences in the back pain scores, ODI, SF-36 score, blood loss amount, surgical time, hospital stay duration, lumbar lordosis, infection, and durotomy between the groups.

CONCLUSIONS

IBF for the treatment of lumbar degenerative spondylolisthesis showed better results in terms of the fusion rate and sacral slope, but which did not translate into better clinical outcomes. Further randomized and prospective studies are necessary to elucidate the optimal therapeutic options.

A comparison of long-term efficacy of K-rod-assisted non-fusion operation and posterior lumbar interbody fusion for single-segmental lumbar disc herniation

K-rod-assisted non-fusion surgery for the treatment of lumbar disc herniation has been proven to have short-term clinical efficacy. Meanwhile, its long-term effects have not been examined. To observed the long-term clinical efficacy of K-rod-assisted non-fusion operation, this study retrospectively analyzed 22 patients with lumbar disc (L4/5) herniation who underwent K-rod-assisted non-fusion operation (n = 13) or PLIF (n = 9). They were followed-up for more than 5 years. The operation times and blood loss were significantly reduced in the K-rod group compared to the PLIF group. At the last follow-up, the clinical outcomes of the K-rod group were improved compared to those of the PLIF group as observed by the VAS score, JOABPEQ, and ODI. Imaging outcomes at the last follow-up indicated that the loss of height in the L3/4 and L5/S1 intervertebral space, the ROM of L3/4 and L5/S1, and the incidence of adjacent segment degeneration in the PLIF group were significantly higher than those in the K-rod group. According to Pfirrmann grading, Modic changes, and UCLA grading, the incidence of adjacent segment degeneration was 55.6% in the PLIF group and 15.4% in the K-rod group. Changes in spino-pelvic parameters between the two groups were as follows: pelvic index remained unchanged, pelvic tilt angle increased, and lumbar lordosis and sacral slope decreased. Therefore, compared to PLIF, single-segment lumbar disc herniation using K-rod-assisted non-fusion surgery resulted in better long-term clinical efficacy. Our results demonstrate that this procedure can delay adjacent segment degeneration after lumbar surgery.

Bending rod is unnecessary in single-level posterior internal fixation and fusion in treatment of lumbar degenerative diseases

Background

Bending rod is a routine in lumbar fusion and fixation surgery, but there is no study investigating whether bending rod in one level is necessary.

Methods

Patients receiving 1 level lumbar fixation and fusion between May 2018 and September 2020 were included with a minimum 6-month follow-up. The routine of bending rod was omitted during fixation. Preoperative and postoperative radiological parameters were compared.

Results

There were 67 patients included in the study. Segment lordosis angle increased obviously from 10° (1–39°) to 14° (2–30°) immediately after operation (p = 0.000). T5-T12 increased from 22.97 ± 12.31° to 25.52 ± 11.83° by the 3rd months after surgery (p = 0.011). SS decreased from 35.45 ± 10.47 to 32.19 ± 11.37 in 6-month follow-up (p = 0.038), and PI dropped from 56.97 ± 14.24 to 53.19 ± 12.84 (p = 0.016). ROM of SLA decreased from 4.13 ± 3.14° to 1.93 ± 1.87° at that time point (p = 0.028). Those changes were not seen at 12-month follow-up. No evidence of adjacent vertebral disc degeneration was observed at any time point.

Conclusions

No sagittal imbalance, dynamic instability or adjacent vertebral degeneration was observed by the 12th month after single-segment posterior lumbar fusion with the use of unbent rods. Bending rod could be omitted in 1-level lumbar fusion to simplify the procedure and reduce operating time.

Global Sagittal Alignment and Clinical Outcomes after 1-3 Short-Segment Lumbar Fusion in Degenerative Spinal Diseases

Study Design

Level III retrospective study.

Purpose

We investigated the impact of short-segment lumbar fusion on the restoration of global sagittal alignment and the correlations between spino-pelvic parameters and clinical outcomes.

Overview of Literature

Sagittal imbalance leads to energy consumption and pain in maintaining a standing position. For adult spinal deformity, it is critical to create optimal lumbar lordosis (LL) in order to achieve restoration of sagittal imbalance. However, surgeons do not pay attention to correcting LL in short-segment lumbar fusion.

Methods

A total of 69 patients with transforaminal lumbar interbody fusion (TLIF) for degenerative spinal disease were evaluated with a minimum 2-year follow-up. All patients underwent TLIF with hyper-lordotic angle cages to achieve higher LL. Radiological spino-pelvic parameters including sagittal vertical axis (SVA) and clinical outcomes using the Oswestry Disability Index (ODI) and Numeric Rating Scale (NRS) were evaluated.

Results

The average LL was 35.8°±9.9° before surgery, 42.3°±9.3° 1 year after surgery, and 40.3°±10.2° 2 years after surgery (p <0.01). The average SVA was 43.1±6.2 mm before surgery, 21.2±4.9 mm 1 year after surgery, and 34.0±4.7 mm 2 years after surgery (p <0.01). The average LL and SVA improved in two- or three-segment fusion, but not in one-segment fusion. The correlation between ΔLL and ΔSVA was significant in all segment fusions. The correlation between ΔLL and ΔSVA was more significant at the L4-5 and L5-S1 segments than at L3-4. ODI was significantly correlated with SVA (p <0.05). NRS showed no correlation with the radiological parameters.

Conclusions

Two- or three-segment lumbar fusion using hyper-lordotic angle cages improved LL and SVA. A significant correlation between the correction of LL and SVA was found. Higher correction of LL using hyper-lordotic angle cages is thus recommended in short-segment lumbar fusion, since postoperative improvements of SVA significantly affect clinical outcomes.

How Do Pelvic Parameters Correlate With Postoperative Outcomes When the Parameters Are Not Measured Preoperatively in Patients Undergoing Instrumented Lumbar Fusion?

Objective: A normal age-adjusted sagittal alignment is an important factor in achieving long-term functional results after lumbar spinal fusion. We aim to determine if the changes in spino-pelvic alignment (SPA) correlate with post-operative functional outcomes in patients who underwent instrumented lumbar spine surgery when the parameters were not measured before.

Method: A retrospective review of medical records from 2012 to 2016, and radiographs of the patients who underwent instrumented fusion of the lumbar spine. The X-rays of the available preoperative lumbar spine were reviewed for SPA and compared with the last follow-up postoperative images. The patients were contacted by telephone to complete the EuroQoL 5 Dimensions 5-level questionnaire and visual analog scale for evaluation of their functional outcomes during 2017. Correlation studies were performed using Pearson’s coefficient.

Results: Forty-six patients were included with a mean age of 53 years and a follow-up of 47 months. There was a significant improvement in the functional outcomes and pain in the whole group. All the patients showed improvement in their SPA, and those who underwent more than two levels of fusion showed a significant improvement (P<0.05). Lumbar lordosis and sacral slope had a significant correlation with postoperative clinical improvement (R=0.8).

Conclusion: The study showed that single or double fusion has significant improvement in pain and functional outcome with a significant change in SPA.

Improvements in Back and Leg Pain Following a Minimally Invasive Transforaminal Lumbar Interbody Fusion

BACKGROUND

Improvement in patient-reported outcomes after minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) is poorly defined. As such, the purpose of this study was to quantify improvements in Visual Analogue Scale back and leg pain, Oswestry Disability Index (ODI), and Short Form-12 (SF-12) Mental and Physical Composite scores following MIS-TLIF.

METHODS

A surgical registry of patients who underwent primary 1-level MIS-TLIF during 2014-2015 was reviewed. Comparisons of Visual Analogue Scale back and leg pain, ODI, and Short Form-12 Mental and Physical Composite scores were performed using paired t tests from preoperative to each postoperative time point. Analysis of variance was used to estimate the degree of improvement in back and leg pain over the first postoperative year. Subgroup analysis was performed for patients presenting with predominant back (pBP) or leg (pLP) pain. Multivariate linear regression was performed to compare patient-reported outcome scores by subgroup.

RESULTS

A total of 106 patients were identified. Visual Analogue Scale back and leg scores, and ODI improved from preoperative scores at all postoperative time points (P < .05 for each). Patients with pBP (n = 68) and patients with pLP (n = 38) reported reductions in both back and leg pain over the first postoperative year (P < .05 for each). In the pBP cohort, patients experienced significant reductions in ODI after the first 6 postoperative weeks (P < .05 for each). In the pLP cohort, patients experienced significant reductions in ODI throughout the first postoperative year (P < .05 for each). Patients with pLP and pBP experienced similar reductions in back pain, whereas patients with pLP experienced significantly greater reductions in leg pain at all postoperative time points (P < .05 for each).

CONCLUSIONS

The current study suggests patients experience significant improvements in back and leg pain following MIS-TLIF regardless of predominant symptom.

CLINICAL RELEVANCE

These results can assist surgeons when counseling their patients on the magnitude of symptom improvement they may experience following MIS-TLIF.

Patients with predominantly back pain at the time of lumbar fusion for low-grade spondylolisthesis experience similar clinical improvement to patients with predominantly leg pain: mid-term results

BACKGROUND CONTEXT

Patients with back pain predominance (BPP) have traditionally been thought to derive less predictable symptomatic relief from lumbar fusion surgery.

PURPOSE

To compare postoperative clinical outcomes as well as degree of improvement in clinical outcome measures between patients with BPP and patients with leg pain predominance (LPP) undergoing open posterior lumbar fusion.

STUDY DESIGN

Retrospective cohort study.

PATIENT SAMPLE

Analysis of patients who underwent an open posterior lumbar fusion for low-grade (Meyerding Grade I or II) degenerative or isthmic spondylolisthesis from 2011 to 2018 was conducted. Surgery was indicated after failure of conservative treatment to address radiculopathy and/or neurogenic claudication. Patients were excluded if they were under 18 years of age at the time of surgery, had less than 6 months of follow-up, presented with a lumbar vertebral body fracture, tumor, or infection, or underwent a fusion surgery that extended to the thoracic spine, high-grade spondylolisthesis, or concomitant deformity.

OUTCOME MEASURES

Radiographs obtained at preoperative, immediate postoperative, and final visits were evaluated for presence or absence of fusion. Patient-reported outcomes were recorded at preoperative and final clinic visits that included: visual analog scale (VAS) back/leg pain, and Oswestry disability index (ODI). Achievement of minimal clinically important difference (MCID) was analyzed, along with rates of postoperative complication and reoperation.

METHODS

Preoperative and final patient-reported outcomes were obtained. Achievement of MCID was evaluated using following thresholds: ODI 14.9, VAS-back pain 2.1, VAS-leg pain 2.8. For analysis, patients were divided into two groups based on predominant location of pain: predominantly VAS-back pain (BPP) and predominantly VAS-leg pain (LPP).

RESULTS

One hundred forty-one patients met inclusion criteria. Of these, 71 had LPP, and 70 had BPP. Patients with preoperative LPP experienced greater improvements in VAS-leg (p<.001) compared to those with BPP, whereas patients with preoperative BPP experienced greater improvements in VAS-back (p=.011) postoperatively compared to those with LPP. There were no differences in the final clinical outcomes. Additionally, LPP achieved MCID for VAS-leg (p=.027) at significantly higher proportion than BPP and BPP achieved MCID for VAS-back (p=.050) at significantly higher proportion than LPP.

CONCLUSIONS

Patients with low-grade spondylolisthesis who underwent an open posterior lumbar fusion had improvement in symptoms regardless of presentation with BPP or LPP. In properly indicated patients, posterior spinal fusion is effective for those with BPP in the setting of experiencing both leg and back pain, and clinicians can use this information for perioperative discussions and surgical decision-making.