Classification of high-grade spondylolistheses based on pelvic version and spine balance: possible rationale for reduction

Clinical and radiological outcomes of gradual reduction and circumferential fusion of high-grade spondylolisthesis in adolescents: a prospective cohort study of 29 young patients

AIM

The objective of this study was to evaluate the safety and efficacy of a novel technique of formal reduction and circumferential fusion for pediatric high-grade spondylolisthesis (HGS).

PURPOSE

The safety and efficacy of formal reduction for high-grade spondylolisthesis (HGS) has never been thoroughly examined. This study reports the outcomes of 29 children with HGS who underwent a procedure of gradual reduction and circumferential fusion.

METHODS

29 children (13 males, 16 females) were recruited between 2006 and 2010. Radiographic measurements (including % of slip, lumbosacral angle-LSA, pelvic incidence-PI, pelvic tilt-PT, sacral slope-SS, and proximal femoral angle-PFA) and quality of life assessment (SRS-22 questionnaire) were prospectively obtained at baseline and at the last post-operative follow-up (> 2 years post-op). Radiological measurements were used to classify patients according to the Spine Deformity Study Group (SDSG) classification.

RESULTS

Mean baseline slip % was 69.9 ± 16.5%. There were 13 patients with a balanced pelvic (SDSG Type 4) and 16 with an unbalanced pelvis (SDSG Type 5 and 6). On average, a reduction of 45.5 ± 15.3% (range 20-86%) was achieved safely with no major complication. In particular, of the 29 patients, only 3 had a L5 radiculopathy postoperatively that was self-resolved at follow-up. From a radiological standpoint, we observed a mean improvement of LSA from 80.3 ± 17.9° to 91.7 ± 13.6°. We also observed a statistically significant improvement in global HRQOL, and in the function and body image domains.

CONCLUSION

This prospective study suggests that formal reduction of HGS followed by circumferential fusion is safe when using a standardized surgical technique based on gradual reduction. Performing this intervention could also help improve QOL in some patients.

Restoration of Spinopelvic Alignment After Reduction of High-grade Spondylolisthesis: Myth or Reality? A Systematic Review of the literature and Meta-analysis

STUDY DESIGN

Systematic review and meta-analysis of literature.

OBJECTIVE

The aim of the presented study is to assess whether the reduction of high-grade spondylolisthesis (HGS) through the correction of lumbosacral kyphosis leads to a decrease in the sagittal spinopelvic compensatory mechanisms.

SUMMARY OF BACKGROUND DATA

HGS is as an anterior translation of a vertebra, >50%. It is also characterized by a kyphotic deformity of the affected level. This combination of translation and kyphosis leads to compensatory mechanisms on the sagittal plane [pelvic retroversion, increased lumbar lordosis (LL), reduction in thoracic kyphosis (TK)].

METHODS

A systematic search of electronic databases was conducted. Inclusion criteria were diagnosis of HGS (Meyerding >II, Slip% >50%), partial or complete reduction surgery (with a significant decrease in Slip%), and report of spinopelvic parameters (pelvic incidence, pelvic tilt, or sacral slope). Clinical and radiographic outcomes were extracted and summarized. Meta-analyses were performed to estimate the differences between preoperative and postoperative spinopelvic alignment measures. P<0.05 was considered significant.

RESULTS

Eighteen studies were included. PT showed a statistically significant decrease of -2.1217 (95% CI: -3.4803 to -0.7630), while SS showed a significant increase of 4.8349 (95% CI: 2.7462-6.9236). Conversely, both LL and TK showed nonsignificant changes, -4.7043 (95% CI: -10.4535 to 1.0449) and 6.3881 (95% CI: -0.8344 to 13.6106), respectively. VAS significantly decreased by -3.1950 (95% CI: -4.9462 to -1.4439).

CONCLUSIONS

The meta-analysis showed mild, yet statistically significant, decrease of PT and an increase in SS after HGS reduction. Conversely, nonstatically significant decrease in LL and an increase in TK occurred. The clinical significance of these results remains questionable.

LEVEL OF EVIDENCE

Level IV.

Short-segment spinal fusion for chronic low back pain with bone marrow edema adjacent to the vertebral endplate in adult spinal deformity

PURPOSE

Corrective long spinal fusion is a widely accepted surgical method for patients with adult spinal deformities. However, instrumented long fusion is associated with a significant risk of complications. Therefore, we aimed to assess the success of short-segment spinal fusion, particularly for bone marrow edema (BME) adjacent to the vertebral endplate, in patients with low back pain (LBP) and spinal deformity.

METHODS

A prospective study was performed at multiple hospitals wherein we monitored patients with spinal deformities and accompanying LBP. Patients aged ≥ 50 years with a minimum LBP severity score of 40 mm on the visual analog scale (VAS) were included in the study. We also included patients with lumbar BME on magnetic resonance imaging. Short spinal fusion was performed on segments with BME. Clinical evaluations of LBP on VAS and Oswestry Disability Index (ODI), and radiological parameters for sagittal vertical axis (SVA), pelvic incidence (PI), lumbar lordosis (LL) and pelvic tilt (PT) were carried out.

RESULTS

Overall, 35 patients (22 men and 13 women), with a mean age of 66.7 years and a mean follow-up period of 32 months, were included in the study. The mean VAS and ODI scores were 72.4 mm and 49.0% before surgery and 25.5 mm and 29.9% at the final follow-up, respectively; these parameters significantly improved after surgery. The SVA, PI-LL, and PT scores were 70.1 mm, 20.9°, and 22.8° before surgery and 85.4 mm, 13.8°, and 22.7° at the final follow-up, respectively. The spinal alignment parameters did not change significantly after surgery.

CONCLUSIONS

Short-segment spinal fusion is effective for treating LBP and spinal deformity with BME adjacent to the vertebral endplate without spinal correction.

A Surgical Treatment Algorithm for Restoring Pelvic Balance and Health-related Quality of Life in High-grade Lumbosacral Spondylolisthesis: Prospective Multicenter Cohort of 61 Young Patients

STUDY DESIGN

Retrospective multicenter cohort-study.

OBJECTIVE

We propose an evidence-based surgical algorithm for achieving normal pelvic balance while optimizing health-related quality of life (HRQoL) in high-grade spondylolisthesis.

SUMMARY OF BACKGROUND DATA

The principles of surgical treatment for young patients with high-grade L5-S1 spondylolisthesis remain unclear. There is a growing body of evidence supporting the central role of pelvic balance in the postural control and biomechanics of subjects with high-grade spondylolisthesis.

METHODS

This retrospective study assessed a multicenter cohort of 61 patients with high-grade L5-S1 spondylolisthesis. Classification and regression tree analysis was used to identify objective criteria associated with pelvic balance and HRQoL after surgery.

RESULTS

The most important predictor of a postoperative balanced pelvis was a postoperative L5 incidence ≤63.5 degrees. With postoperative L5 incidence ≤63.5 degrees,a residual slip percentage 9% and performing an L5-S1 posterior lumbar interbody fusion (PLIF)/transforaminal lumbar interbody fusion (TLIF) increased the likelihood of achieving a balanced pelvis postoperatively. When L5 incidence was 63.5 degrees,a balanced pelvis was most likely achieved with fusion limited to L5 proximally, residual slip percentage ≤40%, and residual lumbosacral angle 98 degrees. Predictors of postoperative HRQoL were the preoperative HRQoL score, L5 incidence and slip percentage.

CONCLUSIONS

A surgical algorithm is proposed to achieve normal pelvic balance, while optimizing HRQoL. The first step during surgery is to assess L5 incidence and if L5 incidence is <65 degrees, the next step depends on the pelvic balance. With a preoperative balanced pelvis, it is important not to reduce completely the slip percentage by leaving a slip percentage ≥10%. When the preoperative pelvis is unbalanced, a TLIF/PLIF at L5-S1 is recommended to facilitate correcting the angular deformity at L5-S1. If L5 incidence is ≥65 degrees,a TLIF/PLIF at L5-S1 should be performed to correct the angular deformity at L5-S1, and fusion should ideally end at L5 proximally, in addition to performing gradual reduction of the slip percentage. If fusion up to L4 is required, a lumbosacral angle ≥100 degrees is key.

Management of low back pain accompanying sagittal plane pathologies in children: Spondylolysis/spondylolisthesis and Scheuermann's disease

Background

Low back pain in childhood was underappreciated for a long time, but recent studies report higher prevalences, up to 70%. Two of the common causes are spondylolyis/spondylolisthesis and Scheuermann's disease. These disorders are relevant in a way they both cause significant back pain, and may disrupt the sagittal spinal balance.

Purpose

To present the current evidence on the diagnosis, natural history and treatment of these disorders with a special focus on sagittal spinal alignment.

Methods

This study is conducted as a literature review.

Results and Conclusions

Spondylolysis and low-grade spondylolisthesis have a benign course and are typically treated conservatively. When pars repair is indicated, pedicle screw-based techniques achieve more than 90% fusion with acceptable complication rates. High-grade spondylolisthesis, however, is frequently progressive. Surgical treatment involves fusion, which can be done in situ or after reduction. Reduction is useful for "unbalanced" patients to acquire sagittal spinopelvic balance, and it is important to distinguish these patients. Despite lowering the risk for pseudoarthrosis, reduction brings a risk for neurologic complications. With re-operation rates as high as 40%, these patients definitely require careful preoperative planning. Scheuermann's disease generally causes back pain in addition to cosmetic discomfort during adolescence. If the kyphosis is lower than 60°, symptoms typically resolve into adulthood with conservative measures only. However, it must be kept in mind that these patients may experience problems with physical performance and have a lower quality of life even when the problem seems to have "resolved". Severe kyphosis and intractable back pain are the most frequently referred surgical indications, and surgery typically involves fusion. Proper utilization of osteotomies and proper selection of the upper and lower fusion levels are of utmost importance to prevent complications in these patients.

Is sagittal spinopelvic alignment a cause of low back pain in pediatric spine pathologies? A review

Purpose

Altered spinopelvic morphology is observed in many spine pathologies occurring during growth. The aim of the study is to better understand the sagittal compensatory mechanisms and their possible influence on the occurrence of pain in selected pediatric spine pathologies.

Methods

A bibliographic search in the PubMed database included articles published between September 1965 and July 2023. The keywords contained in the search were "spondylolysis," "spondylolisthesis," "scoliosis," "kypho," "sagittal," "pediatric," "child," "adolescent," "grow," "development," and "pain."

Results

The largest diversity in sagittal alignment patterns was reported in idiopathic scoliosis, with global flattening of the spine being the most common. Kyphotic deformations occurring during growth are characterized by structural thoracic or thoracolumbar kyphosis compensated by lumbar hyperlordosis and lower pelvic incidence. Whereas in spondylolisthesis, altered morphology of the spinopelvic junction with high values of pelvic incidence is observed. Pain does not seem to be related to sagittal alignment in idiopathic scoliosis. In Scheuermann disease, it is localized at the apex of the deformity and is associated with the curve pattern, whereas in spondylolisthesis, sagittal alignment correlates with pain scores only in high-grade slips.

Conclusion

Most of the patients with spine disorders that occurred during growth present a clinically balanced posture in the sagittal plane. It suggests that compensatory mechanisms before achieving skeletal maturity are really significant. A comprehension of sagittal alignment in spine deformities and its relationship to pain is essential for the proper assessment and treatment of these disorders.

Management of High-Grade Dysplastic Spondylolisthesis

The Meyerding classification grades the degree of slippage in the sagittal plane on lateral standing neutral imaging: 0% to 25% Grade I, 25% to 50% Grade II, 50% to 75% Grade III, 75% to 100% Grade IV, and greater than 100% Grade V (Spondyloptosis). Grades I and II are considered low-grade and Grades III-V are considered high-grade. There are several etiologies of spondylolisthesis. A classification system of the most common causes: Type I - Dysplastic, Type II - Isthmic (including subtypes: A - Lytic, B - Elongation, and C - Acute fracture), Type III - Degenerative, Type IV - Traumatic, Type V - Pathologic, and Type VI - Iatrogenic. Dysplastic spondylolisthesis is a type of spondylolisthesis that occurs at L5-S1 when dysplastic lumbosacral anatomy is present, and is associated with high-grade slip and spina bifida occulta.

Scoliosis risk factors and outcomes in children with dysplastic spondylolisthesis undergoing surgical reduction and fixation

Purpose

To explore scoliosis risk factors and outcomes in children with dysplastic spondylolisthesis undergoing surgical reduction and internal fixation.

Methods

We retrospectively analyzed 56 children with dysplastic spondylolisthesis who underwent surgical reduction and internal fixation. Patients were grouped according to presence of scoliosis before surgery. Radiographic parameters measured before surgery included pelvic incidence, pelvic tilt, sacral slope, coronal Cobb angle, slip percentage, Dubousset's lumbosacral angle, lumbar lordosis, sagittal vertical axis, and Spinal Deformity Study Group index. Groups were compared using logistic regression. Receiver operating characteristic analysis was performed to determine the optimal Spinal Deformity Study Group index cut-off value. All patients were followed up for at least 2 years.

Results

The scoliosis group comprises 36 patients (mean age: 9.6 ± 2.7 years), while the no scoliosis group comprises 20 (mean age: 9.1 ± 2.4 years). Slip percentage and Spinal Deformity Study Group index were significantly higher in the scoliosis group (p < 0.01). Sacral slope and pelvic incidence were lower in the scoliosis group (p < 0.05). Univariate logistic regression analysis showed that slip percentage, Spinal Deformity Study Group index, pelvic incidence, and sacral slope were significantly associated with scoliosis. In the multivariate logistic regression analysis, only Spinal Deformity Study Group index was an independent risk factor for scoliosis. The optimal cut-off value for Spinal Deformity Study Group index was 0.288. Mean Cobb angle decreased from 20.3° ± 8.8° before surgery to 8.5° ± 8.9° at last follow-up; the mean scoliosis correction rate was 59.3%.

Conclusion

Severe S1 dysplasia and high slip percentage may be risk factors for developing scoliosis in patients with dysplastic spondylolisthesis. Scoliosis resolved spontaneously after spondylolisthesis reduction and fixation in most patients.

Level of evidence

3.

Analysis of the Spinopelvic Parameters in Patients with Fragility Fractures of the Pelvis

BACKGROUND

We investigated the spinopelvic parameters of lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT) and sacral slope (SS) in patients with fragility fractures of the pelvis (FFPs). We hypothesized that these parameters differ from asymptomatic patients.

METHODS

All patients treated for FFPs in a center of maximal care of the German Spine Society (DWG) between 2017 and 2021 were included. The inclusion criteria were age ≥ 60 years and the availability of a standing lateral radiograph of the spine and pelvis in which the spine from T12 to S1 and both femoral heads were visible. The baseline characteristics and study parameters were calculated and compared with databases of asymptomatic patients. The two-sample t-Test was performed with p < 0.05.

RESULTS

The study population (n = 57) consisted of 49 female patients. The mean age was 81.0 years. The mean LL was 47.9°, the mean PT was 29.4°, the mean SS was 34.2° and the mean PI was 64.4°. The mean value of LLI was 0.7. LL, LLI and SS were significantly reduced, and PI and PT were significantly increased compared to asymptomatic patients.

CONCLUSIONS

The spinopelvic parameters in patients with FFPs differ significantly from asymptomatic patients. In patients with FFPs, LL, LLI and SS are significantly reduced, and PI and PT are significantly increased. The sagittal spinopelvic balance is abnormal in patients with FFPs.

Modified unilateral iliac screw fixation with partial reduction in the treatment of high-grade spondylolisthesis at L5/S1 in adult patients: introduction of key technique, report of clinical outcomes and analysis of spinopelvic parameters

BACKGROUND

Management of high-grade spondylolisthesis (HGS) remains challenging. Spinopelvic fixation such as iliac screw (IS) was developed to deal with HGS. However concerns regarding constructs prominence and increased infection-related revision surgery have complicated it's use. We aim to introduce the modified iliac screw (IS) technique in treating high-grade L5/S1 spondylolisthesis and it's clinical and radiological outcomes.

METHODS

Patients with L5/S1 HGS who underwent modified IS fixation were enrolled. Pre- and postsurgical upright full spine radiographs were obtained to analyze sagittal imbalance, spinopelvic parameters, pelvic incidence-lumbar lordosis mismatch (PI-LL), slip percentage, slip angle (SA), and lumbosacral angle (LSA). Visual analogue scale (VAS), Oswestry disability index (ODI) were evaluated pre- and postoperatively for clinical outcomes assessment. Estimated blood loss, operating time, perioperative complications and revision surgery were documented.

RESULTS

From Jan 2018 to March 2020, 32 patients (15 males) with mean age of 58.66 ± 7.77 years were included. The mean follow-up period was 49 months. The mean operation duration was 171.67 ± 36.66 min. At the last follow-up: (1) the VAS and ODI score were significantly improved (p < 0.05), (2) PI increased by an average of 4.3°, the slip percent, SA and LSA were significantly improved (p < 0.05), (3) four patients (16.7%) with global sagittal imbalance recovered a good sagittal alignment, PI-LL within ± 10° was observed in all patients. One patient experienced wound infection. One patient underwent a revision surgery due to pseudoarthrosis at L5/S1.

CONCLUSION

The modified IS technique is safe and effective in treating L5/S1 HGS. Sparing use of offset connector could reduce hardware prominence, leading to lower wound infection rate and less revision surgery. The long-term clinical affection of increased PI value is unknown.

A novel less invasive endoscopic-assisted procedure for complete reduction of low-and high-grade isthmic spondylolisthesis performed by anterior and posterior combined approach

PURPOSE

The optimal surgical management of low- and high-grade isthmic spondylolisthesis (LGS and HGS -IS) is debated as well as whether reduction is needed especially for high-grade spondylolisthesis. Both anterior and posterior techniques can be associated with mechanical disadvantages as hardware failure with loss of reduction and L5 injury. We purpose a novel endoscopic-assisted technique (Sled technique, ST) to achieve a complete reduction in two surgical steps: first anteriorly through a retroperitoneal approach to obtain the greatest part of correction and then posteriorly to complete reduction in the same operation.

METHODS

ST efficacy and complications rate were evaluated through a retrospective functional and radiological analysis.

RESULTS

Thirty-one patients, 12 male (38.7%) and 19 female (61.3%), average age: 45.4 years with single level IS underwent olisthesis reduction by ST. Twenty-three IS involved L5 (74.2%), 7 L4 (22.5%) and 1 L3 (3.3%). No intraoperative complications were recorded. One patient required repositioning of a pedicle screw. A significant improvement of functional and radiological parameters (L4-S1 and L5-S1 lordosis) outcomes was recorded (p < 0.001).

CONCLUSION

ST provides a complete reduction in the slippage in LGS and HGS. The huge anterior release as well as the partial reduction in the slippage by the endoscopic-assisted anterior procedure, because of the cage is acting as a "guide rail", facilitate the final posterior reduction, always complete in our series, minimizing mechanical stresses and neurological risks.

CLINICALTRIALS

gov Identifier: NCT03644407.

The L3 Flexion Angle Predicts Failure of Non-Operative Management in Patients with Tandem Spondylolithesis

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

Determine impact of standard/novel spinopelvic parameters on global sagittal imbalance, health-related quality of life (HRQoL) scores, and clinical outcomes in patients with multi-level, tandem degenerative spondylolisthesis (TDS).

METHODS

Single institution analysis; 49 patients with TDS. Demographics, PROMIS and ODI scores collected. Radiographic measurements-sagittal vertical axis (SVA), pelvic incidence (PI), lumbar lordosis (LL), PI-LL mismatch, sagittal L3 flexion angle (L3FA) and L3 sagittal distance (L3SD). Stepwise linear multivariate regression performed using full length cassettes to identify demographic and radiographic factors predictive of aberrant SVA (≥5 cm). Receiver operative curve (ROC) analysis used to identify cutoffs for lumbar radiographic values independently predictive of SVA ≥5 cm. Univariate comparisons of patient demographics, (HRQoL) scores and surgical indication were performed around this cutoff using two-way Student's t-tests and Fisher's exact test for continuous and categorical variables, respectively.

RESULTS

Patients with increased L3FA had worse ODI (P = .006) and increased rate of failing non-operative management (P = .02). L3FA (OR 1.4, 95% CI) independently predicted of SVA ≥5 cm (sensitivity and specifity of 93% and 92%). Patients with SVA ≥5 cm had lower LL (48.7 ± 19.5 vs 63.3 ± 6.9 mm, P < .021), higher L3SD (49.3 ± 12.9 vs 28.8 ± 9.2, P < .001) and L3FA (11.6 ± 7.9 vs -3.2 ± 6.1, P < .001) compared to patients with SVA ≤5 cm.

CONCLUSIONS

Increased flexion of L3, which is easily measured by the novel lumbar parameter L3FA, predicts global sagittal imbalance in TDS patients. Increased L3FA is associated with worse performance on ODI, and failure of non-operative management in patients with TDS.

A Review of the Main Classifications of Lumbar Spondylolisthesis

OBJECTIVE

This study was conducted to review the main classifications and to present author's recommendations.

METHODS

Review of English language medical literature.

RESULTS

In recent decades, classification systems of lumbar spondylolisthesis have been proposed based on many factors, from essential causes to combinations of imaging features and clinical manifestations; the latter type of system is more clinically practical. We have systematically listed the main types of classification systems in chronological order to make it easier for clinicians to find the type of diagnosis and treatment suitable for their patients and develop an appropriate treatment plan.

CONCLUSIONS

Classification systems for lumbar spondylolisthesis have been proposed that have been based on the study of the essential causes or the combination of imaging features and clinical manifestations; the latter type of system is more clinically practical. We still have much work to do in exploring a more applicable classification of lumbar spondylolisthesis.

Transdiscal Screw Fixation in L5-S1 Adult Spondylolisthesis: Technical Note and Midterm Outcomes of a Case Series

BACKGROUND

Spondylolisthesis changes the pelvic morphology and sagittal spinopelvic alignment with abnormality compared to individuals with similar pelvic morphology. There are many treatment options including a combination of decompression and fusion. In spondylolisthesis patients with high-grade spondylolisthesis, bone to bone contact (closed intradiscal space), and high-grade disc degeneration with disc collapse, fusion is challenging.

METHODS

From 2011 through 2020, an analysis of L5-S1 spondylolisthesis patients who had L5-S1 transdiscal screw fixation with a minimum follow-up of 2 years was performed. Radiological evaluation and clinical measures were compared preoperatively and postoperatively. Postoperative complications were analyzed. Also, L5-S1 degree fusion was analyzed using a computed tomography scan.

RESULTS

Eight patients of L5-S1 spondylolisthesis with a mean follow-up of 69 (25-122) months. All patients were female; the average age was 58 (43-78) years. 4 patients presented with high-grade spondylolisthesis (Meyerding grade III). Among the patients, 3 patients were undergoing revision surgery. Only 5 patients had interbody fusion for their adjacent levels. In the postoperative follow-up, none of the patients had neurological deficits. Radiological evaluations of L5-S1 level showed fusion in all patients. Only 1 patient had rod failure and was advised for revision surgery.

CONCLUSIONS

L5-S1 transdiscal screw fixation may provide a satisfactory rigid fixation and fusion at the L5-S1 level in cases of spondylolisthesis. This technique requires a surgeon's experience. Despite the challenge of this technique, it can provide a safe option for acquiring rigid stabilization.

Biomechanical Performances of an Oblique Lateral Interbody Fusion Cage in Models with Different Bone Densities: A Finite Element Analysis

Study Design

Finite element models of the L3-S1 vertebrae were reconstructed using computed tomography scans.

Objective

We compared the biomechanical performances of an oblique lateral interbody fusion (OLIF) cage in different bone density mode.

Summary of Background Data

Low bone density is an els.key factor limiting the use of stand-alone OLIF cage.

Methods

Four models-intact (M0), normal bone density with OLIF (M1), bone mass loss with OLIF (M2), and osteoporotic with OLIF (M3)-were created based on 3-dimensional scans. Flexion, extension, and lateral bending movements (each lasting 10 N·m) were performed on the superior surface of the L3 vertebra with a compressive preload of 500 N. Range of motion (ROM), peak stresses in the L4-5 cortical endplates, cage stress, and adjacent intervertebral disk stress were evaluated.

Results

ROMs during different physiological movements were similar to those reported by previous researchers. Compared with that in M0, L4-5 ROMs of all movements decreased in M1, M2 and M3, most evidently in M3. Stress distribution in the cortical endplates rose to 7.8% in M1 and M2, even 16.2% in M3. Cage stress increased by less than 8.1% in M1 and M2, but by 25.3% in M3, especially in the movements of extension and right rotation. Compared with that in M0, L3-4 and L5-S1 intervertebral disk stress increased with bone density in all the other models, by up to 69.8% and 98.3%, respectively. As osteoporosis worsened, stress in the adjacent intervertebral disk also increased.

Conclusion

Stand-alone OLIF in M3 is not recommended because of the risk of cage subsidence. OLIF in M1 and M2 achieved similar results in various lumbar spine movements. In M1 and M2 model (T >  - 2.5), the L4-L5 showed reduced mobility in all directions, increased rigidity, limited cage displacement, lessened deformation, and better stability.

Clinical and radiographic outcomes of stand-alone oblique lateral interbody fusion in the treatment of adult degenerative scoliosis: a retrospective observational study

BACKGROUND

Open fusion and posterior instrumentation has traditionally been the treatment for adult degenerative scoliosis (ADS). However, minimally invasive treatment such as oblique lateral interbody fusion (OLIF) technique was developed as a new therapeutic method for the treatment of ADS. In addition, it is associated with decreased blood loss and shorter operative time without posterior instrument. The purpose of this study was to evaluate the efficiency of stand-alone OLIF for the treatment of ADS in terms of clinical and radiological results.

METHODS

A total of 30 patients diagnosed with ADS who underwent stand-alone OLIF in our hospital from July 2017 to September 2018 were enrolled in the study. Scores from the Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI) obtained preoperatively and at the final follow-up were compared. Radiography and computed tomography were performed preoperatively and at the final follow-up. The coronal cobb angle, lumbar lordosis, disc height, sacral slope, pelvic incidence and Pelvic tilt were recorded at each time point.

RESULTS

The study cohort comprised 30 patients with a mean age of 64.5 ± 10.8 years and mean follow-up of 19.3 ± 4.2 months. The mean operative time was 96.8 ± 29.4 minutes and the mean estimated blood loss volume was 48.7 ± 9.4 ml. The mean coronal Cobb angle was corrected from 15.0° ± 3.7° preoperatively to 7.2° ± 3.1° postoperatively and 7.2° ± 3.3° at final follow-up (P < 0.0001). Lumbar lordosis significantly improved from 32.2° ± 11.3° preoperatively to 40.3° ± 11.8° postoperatively and 40.7° ± 11.0° at final follow-up (P < 0.01). The respective mean sacral slope and pelvic tilt improved from 26.1° ± 8.1° and 25.1° ± 6.9° preoperatively to 34.3° ± 7.4° and 19.2° ± 5.7° at final follow-up (P < 0.001). The mean disc height (defined as the mean of the anterior and posterior intervertebral disc heights) increased from 0.7 ± 0.3 cm preoperatively to 1.1 ± 0.2 cm at final follow-up (P < 0.0001). The interbody fusion rate on CT was 93.3%. The mean VAS pain score improved from 5.3 ± 0.6 before surgery to 2.3 ± 0.6 at final follow-up (P < 0.001). The mean ODI improved from 29.9% ± 6.8% preoperatively to 12.8% ± 2.4% at final follow-up (P < 0.001).

CONCLUSIONS

Stand-alone OLIF is an effective and safe option for treating ADS in carefully selected patients.

TRIAL REGISTRATION

The study was registered in the Chinese Clinical Trial Registry (ChiCTR2100052419).

Comparison of 3-level anterior cervical discectomy and fusion and open-door laminoplasty in cervical sagittal balance: A retrospective study

Objective

To compare the clinical efficacy and radiological outcomes of 3-level anterior cervical discectomy and fusion (ACDF) and open-door laminoplasty (LP).

Methods

A total of 74 patients from January 2017 to January 2020 were enrolled in this retrospective study. There were two groups. Group A (30 cases) received 3-level ACDF, while Group B (44 cases) received open-door LP. Clinical evaluation included perioperative parameters, Neck Disability Index (NDI), and Japanese Orthopaedic Association (JOA) scores. Radiological evaluation included cervical curve depth (CCD), C2–7 angle, C2–7 sagittal vertical axis (cSVA), C7 slope (C7S), and T1 slope (T1S).

Results

Perioperative parameters such as blood loss, drainage volume after surgery, and hospital stay of patients in Group A were significantly less than those in Group B (P < .001). NDI scores decreased and JOA scores increased significantly after surgery in both groups (P < .05). There was a significant difference in both scores postoperatively and at 1 month after surgery between the two groups (P < .05). CCD and C2–7 angle of Group A increased significantly postoperatively at 1 month after surgery and at final follow-up (FFU) (P < .05). There was a significant difference in CCD and the C2–7 angle between the two groups postoperatively at 1 month after surgery and at FFU (P < .05). T1S increased significantly in Group A postoperatively and at 1 month after surgery (P < .05).

Conclusion

3-level ACDF and open-door LP achieved favorable clinical outcomes and ACDF benefited patients in the early stage of rehabilitation. Compared with open-door LP, 3-level ACDF had advantages of reconstructing cervical lordosis with increased CCD and C2–7 angle.

Sacral Pedicle Subtraction Osteotomy for Treatment of High-Grade Spondylolisthesis: A Technical Note and Review of the Literature

BACKGROUND

Lumbosacral deformities are caused by high-grade spondylolisthesis, fractures, iatrogenic flat back, and other etiologies. The S1 pedicle subtraction osteotomy (PSO) can facilitate reduction of spondylolisthesis and lower the pelvic incidence. There are limited reports on the indications and outcomes of this technique.

OBJECTIVE

To present a technical description and literature review of the S1 PSO with video summary.

METHODS

This was a retrospective review of a single case to highlight the use of S1 PSO for the treatment of high-grade spondylolisthesis. A literature review was performed in accordance with STROBE guidelines.

RESULTS

A 47-year-old woman presented with back and right leg pain related to grade 4 spondylolisthesis at L5-S1 with sagittal imbalance and lumbosacral kyphosis. She was taken for an L2-pelvis instrumented fusion with S1 PSO. Three days later, she was taken for an L4-5 and L5-S1 anterior lumbar interbody fusion with the L5-S1 segmental plate. Her postoperative course was notable for right foot drop that resolved in 6 weeks. Postoperative x-rays showed successful reduction of spondylolisthesis with normal alignment and sagittal balance. Based on 6 studies involving 22 true sacral PSOs in the literature, the procedure carries a 27% risk of neurological deficit, typically in the form of L5 palsy.

CONCLUSION

The S1 PSO is a technically challenging operation that has a unique role in the treatment of high-grade spondylolisthesis. It carries a significant risk of L5 palsy and should be reserved for surgeons with experience performing complex 3-column osteotomies.

Vertebral Slip Morphology in Dysplastic Spondylolisthesis as a Criterion for the Choice of the L5/S1 Support (ALIF, PLIF, Fibular Graft) in Surgical Treatment

Dysplastic spondylolisthesis is a severe pathological condition, based on dysplastic changes in the lumbosacral part of the spine, that causes the asymmetry of the lumbosacral junction. The appropriate therapeutic algorithm remains controversial. As the gold standard, the surgical reposition of the slipped vertebra and 360° fusion of the affected spinal segment is preferred. Thirty-two patients were operated on between the years 2005 and 2018. Different techniques of 360° fusion, based on the severity of the displacement of the affected vertebral segment, were used. Herein, the advantages and disadvantages of different techniques of interbody fusion are discussed. The slippage and retention after reduction in the vertebrae are evaluated prior to the operation, postoperatively, one year after the surgery, and during follow-up, which was 7 years on average (minimum 2 years for a follow-up). Complications associated with the surgery are evaluated, in addition to the operation time, blood loss, spinopelvic parameters, and patient satisfaction with the surgery. All surgical techniques improved the slippage compared to preoperative conditions. The retention of the reposition was not changed significantly in postoperative controls. The incidence of neurological complications reached 12.5%. Surgical treatment is the only treatment option that successfully addressed the pathological principle of dysplastic spondylolisthesis. All of the surgical methods used led to restoring the symmetry of the lumbar spine, and to the improvement in both radiological parameters and the alleviation of subjective difficulties. The aim of this article is to summarize surgical methods in patients having dysplastic spondylolisthesis with a slip of more than 25%, who were operated on, and to determine the optimal treatment algorithm according to the severity of the slip.

L5 Radiculopathy After Formal Reduction of High-Grade SDSG Type 5 and 6 L5-S1 Isthmic Spondylolisthesis with 2-Year Follow-Up

BACKGROUND

Surgery is the main treatment for patients with high-grade L5-S1 isthmic spondylolisthesis, which can result in neurologic complications, but little is known about its clinical course. The present study evaluated the presence of L5 radiculopathy in high-grade L5-S1 spondylolisthesis in adults in pre- and postoperative periods and after a 2-year follow-up.

METHODS

A series of 16 patients who underwent reduction and instrumented fusion for high-grade 5 and 6 spondylolisthesis between 2018 and 2019 were retrospectively evaluated in the pre- and postoperative periods as well as after 6 weeks, 3 months, 6 months, and 1 and 2 years of follow-up. Clinical and surgical data on possible neurological complications of L5 radiculopathy were prospectively collected.

RESULTS

The age was 20.1 ± 12.0 years, and preoperative L5-S1 slip was 89.0%. Five patients presented motor deficit in the preoperative period. In the immediate postoperative period, 9 patients (56%) experienced motor deficits or worsening of the preoperative condition. At the 6-week follow-up, only 1 patient showed resolution of the motor deficit. Three patients presented healed motor deficits after 3 months, and 1 patient demonstrated a healed L5 motor radiculopathy after 6 months. At the 1-year follow-up, only 1 patient exhibited an L5 radiculopathy motor deficit, and at the 2-year follow-up, none of the patients exhibited an L5 radiculopathy motor deficit.

CONCLUSION

L5 radiculopathy was frequent in the preoperative period and increased after reduction and instrumented fusion of high-grade L5-S1 spondylolisthesis in the postoperative period and in the 6-week follow-up. Three and 6 months after the surgery, there were consecutive motor improvements. After 2 years of follow-up, no patients showed neurological deficit of L5 radiculopathy.

LEVEL OF EVIDENCE

2.

CLINICAL RELEVANCE

This is the first study reporting a reduction in complications of L5 neurological motor deficit over a 2-year follow-up in high-grade L5-S1 spondylolisthesis in young adults.

Cervical balance and clinical outcomes in cervical spondylotic myelopathy treated by three-level anterior cervical discectomy and fusion and hybrid cervical surgery: A CONSORT-compliant study with minimum follow-up period of 5 years

As the technology of combining with fusion and nonfusion procedure, cervical hybrid surgery (HS) is an efficacious alternative for treatment with cervical spondylotic myelopathy. While studies on cervical alignment between 3-level HS and anterior cervical discectomy and fusion (ACDF) were seldom reported. The effects of cervical imbalance on its related clinical outcomes are yet undetermined as well.Patients with cervical spondylotic myelopathy, who underwent 3-level ACDF or HS, were included to compare cervical alignment parameters after surgery and then explore the relationship between cervical balance and clinical outcomes.Forty-one patients with HS (HS group) and 32 patients who with ACDF (ACDF group) were reviewed from February 2007 to September 2013 with the mean follow-up of 90.3 ± 25.5 (m) and 86.3 ± 28.9 (m), respectively. Cervical alignments parameters including the C2 to C7 cervical lordosis (CL), C2 to C7 sagittal vertical axis, T1 slope. and T1SCL (T1 slope minus CL), and the clinical outcomes like neck disability index (NDI) and Japanese Orthopedic Association (JOA) score were measured and recorded preoperatively (PreOP), intraoperatively, and on the first preoperative day and the last follow-up (FFU). The balance and imbalance groupings were sorted based on the T1SCL: T1SCL≤20°,balance; T1SCL > 20°, imbalance.We found significant improvements (P < .001) in NDI and JOA at intraoperatively and FFU after ACDF and HS, and no difference on cervical alignment and clinical outcomes between the 2 procedures on the basis of intergroup comparisons. By between-subgroups comparisons, however, we found significant differences in CL and T1SCL at PreOP (P < .05). Nonetheless, there was no significant difference on the clinical outcomes between balance and imbalance subgroups at FFU at PreOP (P > .05), indicating that the change of T1SCL was not correlated to NDI and JOA at FFU.Both HS and ACDF groups showed significant clinical improvements after surgery. There was no correlation between cervical balance and clinical symptoms.

Health-related quality of life and sagittal balance at two to 25 years after posterior transfixation for high-grade dysplastic spondylolisthesis

Aims

High-grade dysplastic spondylolisthesis is a disabling disorder for which many different operative techniques have been described. The aim of this study is to evaluate Scoliosis Research Society 22-item (SRS-22r) scores, global balance, and regional spino-pelvic alignment from two to 25 years after surgery for high-grade dysplastic spondylolisthesis using an all-posterior partial reduction, transfixation technique.

Methods

SRS-22r and full-spine lateral radiographs were collected for the 28 young patients (age 13.4 years (SD 2.6) who underwent surgery for high-grade dysplastic spondylolisthesis in our centre (Scottish National Spinal Deformity Service) between 1995 and 2018. The mean follow-up was nine years (2 to 25), and one patient was lost to follow-up. The standard surgical technique was an all-posterior, partial reduction, and S1 to L5 transfixation screw technique without direct decompression. Parameters for segmental (slip percentage, Dubousset’s lumbosacral angle) and regional alignment (pelvic tilt, sacral slope, L5 incidence, lumbar lordosis, and thoracic kyphosis) and global balance (T1 spino-pelvic inclination) were measured. SRS-22r scores were compared between patients with a balanced and unbalanced pelvis at final follow-up.

Results

SRS-22r domain and total scores improved significantly from preoperative to final follow-up, except for the mental health domain that remained the same. Slip percentage improved from 75% (SD 15) to 48% (SD 19) and lumbosacral angle from 70° (SD 11) to 101° (SD 11). Preoperatively, 35% had global imbalance, and at follow-up all were balanced. Preoperatively, 63% had an unbalanced pelvis, and at final follow-up this was 32%. SRS-22r scores were not different in patients with a balanced or unbalanced pelvis. However, postoperative pelvic imbalance as measured by L5 incidence was associated with lower SRS-22r self-image and total scores (p = 0.029).

Conclusion

In young patients with HGDS, partial reduction and transfixation improves local lumbosacral alignment, restores pelvic, and global balance and provides satisfactory long-term clinical outcomes. Higher SRS-22r self-image and total scores were observed in the patients that had a balanced pelvis (L5I < 60°) at two to 25 years follow-up.

Cite this article: Bone Jt Open 2021;2(3):163–173.

Sagittal balance of the spine

Spinal balance can be defined as the trade-off between outside forces acting on the spine and the muscle response of the trunk, under sensorineural regulation, to maintain stable upright posture, both static and dynamic. Homo sapiens developed sagittal alignment along with bipedalism. The upright posture was an important step in human evolution, to master the environment, at the price of some instability in postural control in the trunk, and to maintain horizontal gaze. To make upright stance energetically economical and thus sustainable, reciprocal sagittal curvatures developed. Sagittal spinal organization is governed by strict rules under physiological conditions, enabling alignment between the center of mass and the lower limb joint centers. In children and adolescents, morphologic changes related to skeletal growth and postural control centers maturation alter spinal alignment and hence spinal balance, with increases in pelvic incidence, sacral slope and consequently lumbar lordosis and thoracic kyphosis. Global cervical lordosis remains stable, at the cost of an increase of the inferior cervical lordosis angle in correlation with T1 inclination or T1 slope. In pathology, spinal alignment may induce certain spinal pathologies such as growth-related spinal dystrophy or spondylolisthesis. It can also be altered by spinal deformity such as scoliosis, a regional disorder inducing adjacent compensatory mechanisms. The management of spinal pathologies is indissociable from understanding and maintaining or restoring individual sagittal alignment so as to ensure physiological distribution of stresses and limit onset of complications or decompensation in adulthood.

Health-Related Quality of Life Outcomes of Instrumented Circumferential Spinal Fusion for Pediatric Spondylolisthesis: A Comparison With Age and Sex Matched Healthy Controls

STUDY DESIGN

A prospective study on the clinical, radiographic, and the health-related quality of life (HRQOL) outcomes in adolescents with spondylolisthesis undergoing instrumented circumferential spinal fusion compared with age and sex matched controls.

OBJECTIVE

To determine the outcomes of pediatric spondylolisthesis patients minimum 2 years after surgery and to compare their HRQOL with age and sex matched controls.

SUMMARY OF BACKGROUND DATA

There is limited evidence of the HRQOL of adolescent spondylolisthesis patients after surgery and no studies comparing it with healthy controls.

METHODS

Twenty-six consecutive adolescents (mean age 14.7 yr, range 10-18 yr) undergoing instrumented reduction with intercorporeal spinal fusion for spondylolisthesis (11 low-grade, 15 high-grade) by a single orthopedic surgeon were included to this study cohort and matched by age and sex with two controls. The HRQOL was measured with Scoliosis Research Society-24 (SRS-24) questionnaire before surgery, 6 months and 2 years after the surgery.

RESULTS

The mean (SD) vertebral slip in the low-grade patients was 25% (13%) and 67% (15%) in the high-grade patients and 6% (7%) and 21% (25%) postoperatively, respectively (P ≤ 0.041 for both comparisons). Three (12%) patients developed a non-union during follow-up. None of the patients developed a persistent neurologic deficit, but two (8%) patients presented with chronic postsurgical pain persisting 24 months. Seven (27%) of the patients had reoperations for any reason during the follow-up. Pain and activity domains of the SRS-24 improved significantly from preoperative to 2-year follow-up (P ≤ 0.007 for both). SRS pain, self-image, function domains, and total score were significantly worse as compared with the 52 controls (P ≤ 0.020 for all comparisons).

CONCLUSION

Risk of non-union is relatively low after instrumented spinal reduction in adolescents with spondylolisthesis. HRQOL improves significantly after instrumented reduction and circumferential spinal fusion in adolescents with spondylolisthesis, but remains at statistically lower level than in the controls.

LEVEL OF EVIDENCE

2.

Does the Surgical Reduction of High Grade Spondylolisthesis Restore Spino-Pelvic Alignment? An Analysis of 35 Patients

STUDY DESIGN

Retrospective case series.

PURPOSE

This study aimed to analyze how the sagittal spinopelvic alignment is influenced by an attempted surgical reduction of the L5-S1 segment in patients with high-grade spondylolisthesis (HGS).

OVERVIEW OF LITERATURE

Conventional treatment strategies stress the importance of achieving fusion across the lumbosacral junction in patients with HGS. The role of reduction in this subset of patients is controversial.

METHODS

This is a retrospective case series of 35 patients with Meyerding grades III, IV, or V spondylolisthesis who underwent surgical treatment in our institution. Before and after surgery, we took standing lateral radiographs from L1 vertebra to pelvis, including the femoral heads, and measured the slip grade, pelvic incidence, sacral slope, pelvic tilt, lumbosacral angle, and lumbar lordosis. Patients were subdivided into "balanced" and "unbalanced" pelvis groups. To determine the effect and correlation of reduction on these spinopelvic parameters, we statistically compared the pre- and postoperative measurements.

RESULTS

The average follow-up was 9 months (range, 3-169 months). Slip grade improved from an average 74.0%±13.2% to 30.0%±14.0% (p<0.001), and lumbosacral angle reduced from an average 32.0°±11.6° to 6.0°±0.6° (p<0.001). Although the pelvic tilt was reduced, this was not significant. There was a modest negative correlation between the reduction in slip grade and the increase in sacral slope (r=-0.3, p=0.06). At follow-up, five patients improved, from an unbalanced pelvis to a balanced pelvis. Fusion occurred in 33 patients (95%).

CONCLUSIONS

Surgical reduction of HGS restores the lumbosacral alignment. However, a similar trend is not noted with the pelvic parameters.

Lumbar spinal fusion of low-grade degenerative spondylolisthesis (Meyerding grade I and II): Do reduction and correction of the radiological sagittal parameters correlate with better clinical outcome?

INTRODUCTION

Lumbar and lumbosacral spinal fusion is an established procedure for the treatment of degenerative spondylolisthesis. However, the impact of reduction in the affected segment and of improvement in the radiological sagittal parameters on the clinical outcome remains unclear. Purpose of the study is to analyze the correlation between the radiological sagittal parameters and clinical outcome after lumbar spinal fusion in low-grade degenerative spondylolisthesis.

MATERIALS AND METHODS

In a monocentric prospective, clinical study, patients with low-grade degenerative spondylolisthesis of a single lumbar segment have been included. All patients received a lumbar spinal fusion according to the pathology of the treated segment. Patients attended clinical and radiological follow-up examination 1 and 2 years postoperatively. Clinical outcome was assessed using the Core Outcome Measurement Index (COMI), the Oswestry Disability Index (ODI) and the EuroQol 5D. The sagittal spinopelvic radiological parameters, sagittal rotation and anterior displacement of the affected segment and lumbar lordosis were assessed. The correlation between the sagittal radiological parameters and clinical outcome was analyzed using Spearman-Rho bi-serial test.

RESULTS

Sixty-two patients (35 female and 27 male) with an average age of 59.3 years were included in the study. All patients completed the follow-up examinations. Significant improvement in COMI, ODI and EuroQol 5D scores was shown in all follow-up examinations. Significant reduction in the anterior displacement was measured postoperatively, which was preserved during the follow-up. However, no correlation could be demonstrated between reduction in anterior displacement and improvement in clinical outcome. Nonetheless, correlation between correction of sagittal rotation and clinical outcome was shown.

CONCLUSIONS

Reduction in anterior displacement of the affected segment in the surgical treatment of low-grade degenerative spondylolisthesis does not have an impact on the clinical outcome.

Adjacent segment disk degeneration three decades after fusion without attempted reduction for high-grade isthmic spondylolisthesis

STUDY DESIGN

Observational study.

OBJECTIVES

To evaluate adjacent segment disk degeneration (ASD) after fusion without attempted reduction at a young age for high-grade isthmic spondylolisthesis. The clinical relevance of ASD remains unclear. Previous studies have shown that spinal fusion is associated with increased ASD but without influence on clinical outcome. Since high-grade spondylolisthesis is a severe kyphotic deformity, one could hypothesize that fusion without attempted reduction in young patients leads to accelerated adjacent segment disk degeneration in adult life.

METHODS

Anterior and posterior disk heights were evaluated on supine radiographs of the spine 8 years and 29 years after fusion without attempted reduction for high-grade spondylolisthesis and also on standing radiographs 8 years and 33 years after surgery. Pelvic parameters were evaluated on standing radiographs obtained 33 years after surgery. Health-related quality of life was evaluated with the Scoliosis Research Society (SRS)-22r questionnaire.

RESULTS

One segment above fusion the anterior disk height significantly decreased on standing radiographs. Two segments above the fusion, the anterior disk height significantly decreased on supine as well as on standing radiographs. The largest reduction was found two segments above the fusion where the disk height was reduced from 33 to 28% of anterior vertebral height between the measurements at mean 8 years and mean 33 years after surgery. There were no statistically significant decreases in posterior disk heights in any measurement. The disk height showed a moderate negative correlation to PT. There was no correlation between disk height reduction and SRS-22r outcome.

CONCLUSIONS

In our long-term follow-up of fusion without attempted reduction for high-grade spondylolisthesis in young patients, we found only a minor but statistically significant reduction in adjacent segment disk height which had no apparent impact on clinical outcome.

LEVEL OF EVIDENCE

Level IV.

High-Grade Spondylolisthesis in Adults: Current Concepts in Evaluation and Management

Background

Information regarding the treatment of high-grade spondylolisthesis (HGS) in adults has been previously described; however, previous descriptions of the evaluation and surgical management of HGS do not represent more recent and now established approaches. The purpose of the current review is to discuss current concepts in the evaluation and management of patients with HGS.

Methods

Literature review.

Results

HGS is diagnosed in up to 11.3% of adults with spondylolisthesis and typically presents as nonspecific lower back pain. Regarding evaluation, a thorough history and physical examination should be performed, which may help predict the presence of HGS. Diagnostic imaging, and specifically the use of spino-pelvic parameters, are now commonly implicated in guiding treatment course and prognosis. When surgical intervention is indicated, surgical approaches include in situ fusion variations, reduction and partial reduction with fusion, and vertebrectomy. Although the majority of studies suggest improvements with these approaches, the literature is limited by a low level of evidence with regards to the superiority of one technique when compared with others.

Conclusions

HGS is a unique cause of low back pain in adults that carries considerable morbidity, but rarely presents with neurologic symptoms. Although the definitions, classifications, and methods of diagnosis of this spinal deformity have been established and accepted, the ideal surgical management of this deformity remains highly debated. Fusion in situ techniques are often technically easier to perform and provide lower risk of neurologic complications, whereas reduction and fusion techniques offer greater restoration of global spino-pelvic balance. Preoperative spino-pelvic parameters may have utility in assisting in procedural selection; however, future, higher-quality and longer-term studies are warranted to determine the optimal surgical intervention among the widely available techniques currently used, and to better define the indications for these interventions.

Cervical sagittal alignment in adolescent high dysplastic developmental spondylolisthesis: how does the cervical spine respond to the reduction of spondylolisthesis?

Background

Although pelvic and related parameters have been well stated in lumbar developmental spondylolisthesis, cervical sagittal alignment in these patients is poorly studied, especially in high dysplastic developmental spondylolisthesis (HDDS). The purpose of this study is to investigate the sagittal alignment of the cervical spine in HDDS and how the cervical spine responds to reduction of spondylolisthesis.

Methods

Thirty-three adolescent patients with lumbar developmental spondylolisthesis who received preoperative and postoperative whole-spine x-rays were reviewed. They were divided into the HDDS group (n = 24, 13.0 ± 2.2 years old) and the low dysplastic developmental spondylolisthesis (LDDS) group (n = 9, 15.6 ± 1.9 years old). Spinal and pelvic sagittal parameters, including cervical lordosis (CL), were measured and compared between groups. In the HDDS group, the postoperative parameters were measured and compared with those before surgery.

Results

HDDS group had a higher proportion of cervical kyphosis (70.8% vs. 22.2%, P = 0.019), and there was a significant difference in CL between the two groups (− 8.5° ± 16.1° vs. 10.5° ± 11.8°, P = 0.003). CL was correlated with the Dubousset’s lumbosacral angle (Dub-LSA), pelvic tilt (PT), and thoracic kyphosis (TK). In the HDDS group, CL in patients with a kyphotic cervical spine was significantly improved after reduction of spondylolisthesis (− 16.4° ± 5.9° vs. − 3.6° ± 9.9°, P < 0.001). In the HDDS group, 46% (6/13) of the patients with postoperative Dub-LSA < 90° still had sagittal imbalance (sagittal vertical axis, [SVA] > 5 cm), while no sagittal imbalance was observed in patients with postoperative Dub-LSA > 90° (46% [6/13] vs. 0% [0/11], P = 0.016).

Conclusions

HDDS can lead to cervical kyphosis through a series of compensatory mechanisms. Reduction of spondylolisthesis and correction of lumbosacral kyphosis may correct the cervical kyphosis and normalize the overall spinal sagittal profile. Correction of Dub-LSA to above 90° might be used as an objective to better improve the sagittal alignment of the spine.

How does sagittal spinopelvic alignment of lumbar multisegmental spondylolysis differ from monosegmental spondylolysis?

OBJECTIVE

The aim of this study was to investigate sagittal alignment and compensatory mechanisms in patients with monosegmental spondylolysis (mono_lysis) and multisegmental spondylolysis (multi_lysis).

METHODS

A total of 453 adult patients treated for symptomatic low-grade spondylolytic spondylolisthesis were retrospectively studied at a single center. Patients were divided into 2 subgroups, the mono_lysis group and the multi_lysis group, based on the number of spondylolysis segments. A total of 158 asymptomatic healthy volunteers were enrolled in this study as the control group. Radiographic parameters measured on standing sagittal radiographs and the ratios of L4-S1 segmental lordosis (SL) to lumbar lordosis (L4-S1 SL/LL) and pelvic tilt to pelvic incidence (PT/PI) were compared between all experimental groups.

RESULTS

There were 51 patients (11.3%) with a diagnosis of multi_lysis in the spondylolysis group. When compared with the control group, the spondylolysis group exhibited larger PI (p < 0.001), PT (p < 0.001), LL (p < 0.001), and L4-S1 SL (p = 0.025) and a smaller L4-S1 SL/LL ratio (p < 0.001). When analyzing the specific spondylolysis subgroups, there were no significant differences in PI, but the multi_lysis group had a higher L5 incidence (p = 0.004), PT (p = 0.018), and PT/PI ratio (p = 0.039). The multi_lysis group also had a smaller L4-S1 SL/LL ratio (p = 0.012) and greater sagittal vertical axis (p < 0.001).

CONCLUSIONS

A high-PI spinopelvic pattern was involved in the development of spondylolytic spondylolisthesis, and a larger L5 incidence might be associated with the occurrence of consecutive multi_lysis. Unlike patients with mono_lysis, individuals with multi_lysis were characterized by an anterior trunk, insufficiency of L4-S1 SL, and pelvic retroversion.

Comparative Sacral Morphology in Spondylolisthesis Patients

STUDY DESIGN

Retrospective comparative case series.

OBJECTIVES

Evaluation of sacral morphology in spondylolisthesis patients compared with asymptomatic controls.

SUMMARY OF BACKGROUND DATA

Patients with spondylolisthesis are known to differ from asymptomatic controls in sagittal plane anatomy, but few studies examine the coronal and axial plane differences in these cohorts.

METHODS

This is a retrospective evaluation of magnetic resonance imaging of the lumbosacral spine in 29 spondylolisthesis patients and an asymptomatic cohort (n = 154). Measurements of the linear distance and angular position of L5 and sacrum were performed in the sagittal, coronal, and axial planes. Receiver operating characteristic (ROC) curve analysis quantified these associations. High- and low-grade spondylolisthesis patients were compared with two-sample t-tests. All p-values are two-sided and considered significant when p < .05.

RESULTS

Axial measurements showed the distance of the right to left anterior ala and the L5 body width did not differ between the cohorts. Sacroiliac (SI) joint angles in the spondylolisthesis cohort were closer to the true sagittal plane than in the controls 109° versus 121° (p < .001). In the sagittal plane, the linear measurement of the ratio of the midpoint anteroposterior width L5 to the sacral end plate was larger in the high-grade patients than the low-grade patients and controls. In addition, the kyphosis between S1-S2 and S2-S3 was larger in the spondylolisthesis cohort.

CONCLUSIONS

The SI joints in patients with spondylolisthesis were orientated closer to the sagittal plane than in the controls. An awareness of this positioning may be important in surgical implant insertion as well as rehabilitation of hip extensor weakness. The main anatomical differences found in this study were in the sagittal plane. Sacral end plate abnormalities were well visualized and consistent with radiographic findings in the literature.

LEVEL OF EVIDENCE

Level III, diagnostic.

High grade isthmic spondylolisthesis; can reduction always re-align the unbalanced pelvis?

Background

Recently, various studies have reported the importance of distinguishing between balanced and unbalanced SL, sustaining the importance of SL reduction in unbalanced cases. In this study we present our experience in the treatment of isthmic spondylolisthesis in young patients, observing the correlation between SL reduction and sagittal correlation between spine and pelvis.

Methods

This is a retrospective study of a series of patients treated surgically for isthmic spondylolisthesis. Inclusion criteria were L5-S1 isthmic spondylolisthesis of III° or IV°, pediatric age, clinical and radiographic follow up of at least 1 year. Radiographic evaluation included the following elements: grade and percentage of listhesis (%L), lumbar lordosis (LL), lumbar-sacral angle (LSA), pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT) distinguishing between “balanced” and “unbalanced” patients. Radiographic values were confronted by using Student’s t- test, obtaining a statistically significant difference for values inferior to 0,05.

Results

Based on inclusion criteria, 28 patients were selected for our retrospective analysis, 19 female and 9 male. Mean age at surgery was 15,6 years. Mean follow up was 3 years and 3 months (min. 1 year – max 6 years and 7 months). Spondylolisthesis reduction was statistically significant both in balanced and in unbalanced patients, but pelvic incidence values did not improve significantly. We observed fewer mechanical complications in patients treated with interbody support.

Conclusion

In our study, differences between pre-op and post-op spinopelvic alignment values were not statistically significant, even though spondylolisthesis reduction was statistically significant in all cases. Our study could be considered an initial attempt to correlate spinopelvic changes to spondylolisthesis reduction in a progressive manner, and possibly in the future, generate threshold values of reduction for ideal spinopelvic alignment in every different patient.

Sagittal Alignment With Downward Slope of the Lower Lumbar Motion Segment Influences Its Modes of Failure in Direct Compression: A Mechanical and Microstructural Investigation

STUDY DESIGN

Microstructural investigation of compression-induced herniation of ovine lumbar discs with and without added component of anterior-inferior slope.

OBJECTIVE

Does increased shear arising from a simulated component of motion segment slope imitating sacral slope weaken the lateral annulus and increase risk of overt herniation at this same region.

SUMMARY OF BACKGROUND DATA

An increase in sacral slope secondary to lordosis and pelvic incidence increases shear stresses at the lumbosacral junction and has been associated with an increase in spondylolisthetic disorders and back injury. The small component of forward shear induced when a segment is compressed in flexion is suggested to cause differential recruitment of the lateral annular fibers leading to its early disruption followed by intra-annular nuclear tracking to the posterolateral/posterior regions. However, the influence of even greater forward shear arising from the added component of slope seen where pelvic incidence and lumbar lordosis are increased in the lower lumbar spine is less understood.

METHODS

Ovine motion segments were compressed at 40 mm/min up to failure; 9 with a horizontal disc alignment and 26 with a segment slope of 15° and then analyzed structurally.

RESULTS

All the horizontal discs failed (11.8 ± 2.4 kN) via vertebral fracture without any evidence of soft tissue failure even in the lateral aspects of the discs. The increased forward shear resulting from the slope decreased the failure load (6.4 ± 1.6 kN). The sloping discs mostly suffered mid-span, noncontinuous disruption of the lateral annulus with some extruding nuclear material directly from these same lateral regions.

CONCLUSION

The increased level of forward shear generated in moderately sloping lumbar segments when compressed was abnormally damaging to the lateral regions of the disc annulus. This is consistent with the view that shear differentially loads the oblique-counter oblique fiber sets in the lateral annulus, increasing its vulnerability to early disruption and overt herniation.

LEVEL OF EVIDENCE

N/A.

High-Grade Lumbar Spondylolisthesis

Most high-grade spondylolistheses are resultant from isthmic spondylolisthesis, as complete discontinuity of the pars is typically necessary to allow for this degree of anterior vertebral translation, although can occur less commonly in other scenarios. Higher-grade slips can affect the global sagittal balance of the patient and often result in altered gait patterns and compensatory posturing. Management usually entails surgical decompression and fusion with instrumentation. The addition of anterior column support carries many advantages, including greater surface area for fusion, dynamic compression load sharing at the lumbosacral junction, and a powerful adjunct for deformity correction.

The Clinical Significance of L5 Incidence in Patients with High Pelvic Incidence: A Case Report

Objective: To present a case of sagittal malalignment with high pelvic incidence and its surgical management. Summary of Background Data: Though rare, patients with high pelvic incidence (PI) around 90° without spondylolisthesis or spondylolysis often show sagittal malalignment with low back pain. However, little has been reported about the treatment of such cases. Methods: We report a case of a 15-year-old female complaining of severe difficulty in maintaining an upright position and gait disturbance due to back pain. Radiographs showed high PI of 88° and L5 incidence (L5I) of 67° combined with hyperlordosis of lumbar segments. A lower Lordosis Distribution Index (LDI; percentage of lordosis on segments L4–S1 in entire lumbar lordosis of L1-S1) was detected despite the high overall lumbar lordosis. The patient was surgically treated by two-stage combined posterior and anterior short fusion from the sacrum. Results: The surgical strategy was planned with attention to L5I instead of PI. L5I decreased to 49° and sagittal alignment of the whole spine—including cervical, thoracic, and lumbar spine—improved without any complications. Activity of daily living (ADL）improved preoperatively with relief of low back pain. Conclusions: Improvement of L5I by performing short fusion from L4 to S1 may be a strategy for patients with high PI complaining of low back pain due to sagittal malalignment.

Restoration of normal pelvic balance from surgical reduction in high-grade spondylolisthesis

PURPOSE

To investigate the effectiveness of surgical reduction in high-grade spondylolisthesis in maintaining or restoring a normal pelvic balance, as related to the QoL.

METHODS

It is a retrospective analysis of prospectively collected data of 60 patients (17 males, 43 females) aged 15 ± 3.1 years who underwent surgery for high-grade spondylolisthesis and were followed for a minimum of 2 years after surgery. Patients with a residual high-grade slip following surgery were referred to the postoperative high-grade (PHG) group, while patients with a residual low-grade slip were referred to the postoperative low-grade (PLG) group. Pelvic balance was assessed from pelvic tilt and sacral slope, in order to identify patients with a balanced pelvis or unbalanced pelvis. The SRS-22 questionnaire was completed before surgery and at last follow-up.

RESULTS

Postoperatively, there were 36 patients with a balanced pelvis and 24 patients with an unbalanced pelvis. The improvement in QoL was better in patients with a postoperative balanced pelvis. There were 14 patients in the PHG group and 46 patients in the PLG group. Four of seven patients (57%) in the PHG group and 21 of 26 patients (81%) in the PLG group with a preoperative balanced pelvis maintained a balanced pelvis postoperatively (P = 0.1). None of the patients in the PHG group and 11 of 20 patients (55%) in the PLG group improved from an unbalanced to a balanced pelvis postoperatively (P < 0.05).

CONCLUSIONS

Surgical reduction in high- to low-grade slip is more effective in maintaining and restoring a normal pelvic balance postoperatively. These slides can be retrieved under Electronic Supplementary Material.

The impact of surgical reduction of high-grade lumbosacral spondylolisthesis on proximal femoral angle and quality of life

BACKGOUND CONTEXT

Abnormal proximal femoral angle (PFA) was recently found to be associated with deteriorating sagittal balance and quality of life (QoL) in high-grade spondylolisthesis (HGS). However, the influence of PFA on the QoL of patients undergoing surgery remains unknown.

PURPOSE

This study compares the pre- and postoperative measurements of sagittal balance including PFA in patients with lumbosacral HGS after surgery. It also determines if PFA is a radiographic parameter that is associated with QoL in patients undergoing surgery.

STUDY DESIGN

Retrospective cohort study.

PATIENT SAMPLE

Thirty-three patients (mean age 15.6 ± 3.0 years) operated for L5-S1 HGS between July 2002 and April 2015. Thirteen had in situ fusion and 20 had reduction to a low-grade slip.

OUTCOME MEASURES

The outcome measures included PFA and QoL scores measured from the Scoliosis Research Society SRS-30 QoL questionnaire.

METHODS

The minimum follow-up was 2 years. PFA and QoL were compared pre- and postoperatively. Statistical analysis used nonparametric Mann-Whitney and Wilcoxon Signed Rank tests, Chi-square tests to compare proportions, and bivariate correlations with Spearman's coefficients.

RESULTS

A decreasing PFA correlated with less pain (r = -0.56, p = .010), improved function (r = -0.51, p = .022) and better self-image (r = -0.46, p = .044) postreduction. Reduction decreased PFA by 5.1° (p = .002), whereas in situ fusion did not alter PFA significantly. Patients with normal preoperative PFA had similar postoperative QoL regardless of the type of surgery, except for self-image, which improved further with reduction (3.73 ± 0.49 to 4.26 ± 0.58, p = .015). Patients with abnormal preoperative PFA tended to have a higher QoL in all domains after reduction.

CONCLUSION

Decreasing PFA correlates with less pain, better function and self-image. Reduction of HGS decreases PFA. Reduction also relates to a better postoperative QoL when the preoperative PFA is abnormal. When the preoperative PFA is normal, in situ fusion is equivalent to reduction except for self-image, which is better improved after reduction.

Interbody Bone Graft via Transdiskal Screw Holes as Treatment for High-Grade Spondylolisthesis

BACKGROUND

Controversy exists regarding surgical treatment of high-grade spondylolisthesis (HGS) in terms of decompression with surgical reduction or in situ fusion. In situ fusion has the advantage of being less technically demanding. However, the residual bone graft area is extremely limited, and posterolateral bone grafting is complex as the transverse process of the slipped vertebrae is located anterior to the sacral ala, which correlates with high rates of pseudoarthrosis.

METHODS

Four cases of L5/S1 HGS complaining of low back pain were treated using our new bone graft technique with an exposed osseous end plate. Transdiskal screw holes were made from the S1 pedicle, and bone chips were packed into the L5/S disk space through the screw holes. The slipped L5 vertebra was fixed with a combination of L5/S1 transdiskal and L5 pedicle screws.

RESULTS

All cases exhibited good bony fusion, and the low back pain disappeared in all patients up to the 12-month follow-up. This technique involved packing the bone into the closed space, relieving any concerns regarding bone graft migration.

CONCLUSIONS

Transpedicular bone graft via transdiskal screw holes is an easy and practical technique for raising the fusion rate in surgical treatment of HGS.

Surgical Treatment of Developmental Spondylolisthesis: Contemporary Series With a Two-Surgeon Team

STUDY DESIGN

Retrospective case series.

OBJECTIVES

To report operative outcomes of contemporary surgical treatment of spondylolisthesis in the pediatric population.

SUMMARY OF BACKGROUND DATA

Surgical treatment of developmental spondylolisthesis is controversial, with limited data on complication and reoperation rates.

METHODS

A retrospective study followed pediatric patients with either L5-S1 high-grade spondylolisthesis (HGS) or L5-S1 symptomatic low-grade spondylolisthesis (LGS) for a minimum of two years. All patients underwent a contemporary, single-stage decompression, partial reduction, and posterior instrumented fusion (DRPF) or in situ stabilization by a combined orthopedic and neurosurgeon team at a single institution during 2005-2015. Clinical examination and radiographic data were collected preoperatively and at discharge, 1 year, 2 years, and terminal visit (defined as the last follow-up at >2 years).

RESULTS

Thirty-four patients (79% HGS), mean (±standard deviation) age at surgery 13.5 (±3.3) years, were followed for 4.8 (±2.3) years. The patients who underwent DRPF (n = 26) had mean lumbosacral angle increase from 79.8° (±20.8) to 92.5° (±16.1) (p < .001) and mean listhesis reduce from 63.2% (±21.9) to 26.0% (±20.1) (p < .001). Preoperatively, 18 (53%) had neurologic symptoms. At one- and two-year follow-up, new or residual neurologic symptoms were present in four patients (12%) (p < .001). Postoperative symptoms were not significantly related to amount of reduction. Sixteen (47%) underwent reoperation at an average of 24.8 months, 10 for planned prominent instrumentation removal, and 6 for true complications.

CONCLUSIONS

Surgical reduction and decompression of spondylolisthesis in the pediatric population restores spinopelvic alignment. We found no evidence that a greater amount of reduction was associated with a higher incidence of postoperative complications. However, patients should be advised that prominent instrumentation may require future removal. Although previous reports suggest complication rates and permanent neurologic sequelae in up to 20% after operative treatment of spondylolisthesis, our results suggest that a contemporary approach with a two-surgeon team may provide improved results.

LEVEL OF EVIDENCE

Level IV.

EFFECTS OF SAGITTAL BALANCE DIFFERENCES ON SPONDYLOLISTHESIS

OBJECTIVES

This study aimed to compare the lumbar lordosis (LL) and spinopelvic parameters of patients with stage 1-2 spondylolisthesis to those of the normal population and demonstrate the importance of these parameters in sagittal balance.

METHODS

The lumbosacral parameters on the lateral radiographs of a total of 125 patients were retrospectively compared. Lumbosacral parameters including pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis angle (LLA), L5 incidence (L5I), L5 slope (L5S), and sacral table angle (STA) were compared between groups.

RESULTS

Comparison of the parameters between groups revealed no sex-based differences (p > 0.05).

CONCLUSIONS

Abnormal sagittal spinopelvic parameters are commonly examined for their effects on the development of spondylolisthesis and should be used in routine practice. We found that the low SS values in our study, unlike those of other similar studies, may be a compensatory mechanism developed to reduce pain and maintain sagittal balance. Level of Evidence II; retrospective study.

Impact of decompression surgery without fusion for lumbar spinal stenosis on sagittal spinopelvic alignment: minimum 2-year follow-up

OBJECTIVE

The importance of global sagittal alignment is well known. Patients with lumbar spinal stenosis (LSS) generally tend to bend forward to relieve their neurological symptoms, i.e., they have a positive sagittal vertical axis (SVA). We hypothesized that the positive SVA associated with LSS is symptom related and should improve after surgery. However, little is known about the changes in sagittal alignment in LSS patients after decompression surgery. In this study the authors aimed to evaluate midterm radiographical changes in sagittal spinopelvic alignment after decompression surgery for LSS and to determine the factors influencing the improvement in sagittal spinopelvic alignment.

METHODS

The authors retrospectively reviewed 89 patients who underwent lumbar decompression without fusion between January 2014 and September 2015 with a minimum follow-up of 2 years. Standing whole-spine radiographs at the preoperative stage and at the final follow-up were examined. We analyzed SVA, lumbar lordosis (LL), pelvic tilt (PT), pelvic incidence (PI), thoracolumbar kyphosis (TLK), and thoracic kyphosis (TK).

RESULTS

LL and TK were significantly increased postoperatively. SVA and PI minus LL (PI-LL) were significantly decreased. There were no significant differences between the preoperative and postoperative PT, PI, SS, or TLK. Twenty-nine patients had preoperative sagittal malalignment with SVA > 50 mm. Thirteen of the 29 patients improved to SVA < 50 mm after decompression surgery. Lower ASA grade, preoperative higher LL, and lower PI-LL were related to patient improvement. A receiver operating characteristic curve for the preoperative PI-LL had an area under the curve value of 0.821, indicating moderate accuracy (p = 0.003). A cutoff value for preoperative PI-LL of 19.2° showed a sensitivity of 93.5% and a specificity of 71.4%.

CONCLUSIONS

Lumbar decompression can lead to a reactive improvement in the lumbar and global sagittal alignment. However, some of the sagittal malalignment in LSS was irreversible. Preoperative PI-LL was a useful predictor to distinguish reversible from irreversible sagittal malalignment.

Expectations for Postoperative Improvement in Health-Related Quality of Life in Young Patients With Lumbosacral Spondylolisthesis: A Prospective Cohort Study

STUDY DESIGN

Prospective multicenter study of the changes in Scoliosis Research Society Outcome Questionaire 22 (SRS-22) scores for 78 patients younger than 25 years old surgically treated for lumbosacral spondylolisthesis OBJECTIVE.: Report the change of health-related quality of life (HRQOL) in patients younger than 25 years after surgical treatment of lumbosacral spondylolisthesis.

SUMMARY OF BACKGROUND DATA

There is a paucity of data with regard to the influence of surgical treatment on the HRQOL of patients with lumbosacral spondylolisthesis. Large prospective studies are needed to clearly define the benefits of surgery in the young patient population.

METHODS

A prospective multicenter cohort of 78 patients younger than 25 years (14.8 ± 2.9, range: 7.9-23.6 yr) undergoing posterior fusion for lumbosacral spondylolisthesis were enrolled. There were 17 patients with low-grade (<50%) and 61 with high-grade (≥50%) slips. SRS-22 scores calculated before surgery and after 2 years of follow-up were compared for all patients using two-tailed paired t tests. Subanalyses for low- and high-grade patients were done using two-tailed Wilcoxon signed ranked and paired t tests, respectively. The level of significance was set at 0.05.

RESULTS

HRQOL was significantly improved 2 years after surgery for all domains and for the total score of the SRS-22 questionnaire. The individual total score was improved in 66 patients (85%), and 52 patients (67%) improved by at least 0.5 point. All domains and the total score of the SRS-22 questionnaire were significantly improved for high-grade patients, whereas only pain, function, and total score were improved for low-grade patients.

CONCLUSION

This is the largest study comparing the HRQOL before and after surgery in young patients with low- and high-grade lumbosacral spondylolisthesis. HRQOL significantly improves after surgery for the majority of patients, especially for high-grade patients. This study helps clinicians to better counsel patients with regard to the benefits of surgery for lumbosacral spondylolisthesis.

LEVEL OF EVIDENCE

2.

Radiographic Analysis of Minimally Invasive Transforaminal Lumbar Interbody Fusion versus Conventional Open Surgery on Sagittal Lumbar-Pelvic Alignment for Degenerative Spondylolisthesis

OBJECTIVE

To compare the impact of minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) with open posterior lumbar interbody fusion (PLIF) on sagittal lumbar-pelvic radiographic parameters for degenerative spondylolisthesis (DS).

METHODS

Of 48 patients with L4 single segmental DS, 25 underwent MIS-TLIF with Quadrant system and 23 underwent conventional open PLIF. Comparisons of data from the preoperative and final follow-up standing lateral lumbar x-rays, with the bilateral femoral heads, of the 2 groups were conducted using the following parameters: slip percentage (SP), lumbar lordosis (LL), pelvic incidence, pelvic tilt (PT), sacral slope, lumbosacral angle, slip angle (SA), and the L1 axis and S1 distance (LASD).

RESULTS

The slip reduction rate (ΔSP) in the OPEN group was significantly higher than in the MIS group (67 ± 34% vs. 37 ± 51%, P = 0.018). The change of SA (ΔSA) in the OPEN group was significantly higher than in the MIS group (3 ± 7° vs. -3 ± 5°, P = 0.003). The change of LASD (ΔLASD) in the OPEN group was significantly lower than in the MIS group (-4 ± 15 mm vs. 4 ± 9 mm, P = 0.033). There were positive correlations between the preoperative SP and LASD, and ΔSA and the change of LL (ΔLL), and a negative correlation between ΔLL and the change of PT (ΔPT).

CONCLUSIONS

For low-grade DS, open PLIF has a higher rate of slip reduction compared to MIS-TLIF, and significantly reduces LASD, therefore, it is more conducive to improving lumbar sagittal balance.