High-grade Isthmic Spondylolisthesis Research Articles

Clinical efficacy of minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) in the treatment of II° lumbar isthmic spondylolisthesis: A retrospective cohort study.

Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) is not suitable for high-grade isthmic spondylolisthesis, whether MIS-TLIF can treat II° lumbar isthmic spondylolisthesis (IS) is still controversial. This retrospective cohort study compared the clinical efficacy of MIS-TLIF and open transforaminal lumbar interbody fusion (OPEN-TLIF) in the treatment of II° lumbar IS. From January 2017 to January 2023, 101 patients with II° lumbar IS were diagnosed in our hospital and underwent surgical treatment, of which 53 received MIS-TLIF surgery and 48 received OPEN-TLIF surgery. The operation time, blood loss and surgical complications were compared between the 2 groups. The pain, function, reduction rate and fusion rate of the patients were evaluated during follow-up. The amount of intraoperative blood loss, postoperative drainage, and postoperative hospital stay in the MIS-TLIF group were significantly lower than those in the OPEN-TLIF group were (P < .01). In the MIS-TLIF group, there were 1 case of dural sac injury and 3 cases of lower limb paralysis. The complication rate of MIS-TLIF was lower than the OPEN-TLIF group (P = .032). In the visual analog scale score of low back pain, the MIS-TLIF group was lower than the OPEN-TLIF group after operation and at the last follow-up. There were no significant differences in postoperative leg pain score, slippage rate, and fusion rate between the 2 groups. Compared with OPEN-TLIF, MIS-TLIF has the advantages of better low back pain relief, less trauma, less bleeding and faster recovery, and is worthy of clinical promotion.

P132. Clinical and radiological outcomes between anterior lumbar interbody fusion with percutaneous pedicle screw fixation and transforaminal lumbar interbody fusion in the treatment of high-grade isthmic spondylolisthesis

P132. Clinical and radiological outcomes between anterior lumbar interbody fusion with percutaneous pedicle screw fixation and transforaminal lumbar interbody fusion in the treatment of high-grade isthmic spondylolisthesis

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

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. ST efficacy and complications rate were evaluated through a retrospective functional and radiological analysis. Thirty-one patients, 12 male (38.7%) and 19 female (61.3%), average age: 45.4years 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). 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. gov Identifier: NCT03644407.

Clinical and radiological outcomes between anterior lumbar interbody fusion with percutaneous pedicle screw fixation and transforaminal lumbar interbody fusion in the treatment of high-grade isthmic spondylolisthesis

Clinical and radiological outcomes between anterior lumbar interbody fusion with percutaneous pedicle screw fixation and transforaminal lumbar interbody fusion in the treatment of high-grade isthmic spondylolisthesis

Clinical appearance and reliability in visual assessment after in situ fusion for high-grade isthmic spondylolisthesis.

The current literature on clinical appearance after surgery for high-grade spondylolisthesis is inconclusive. The few long-term comparative studies on surgical reduction versus in situ fusion report contradictory findings concerning appearance-related issues. The purpose of the current study was to evaluate and quantify clinical appearance three decades after in situ fusion for high-grade isthmic spondylolisthesis. The Scoliosis Research Society (SRS)-22r questionnaire, digital photographs and standing lateral radiographs were used to evaluate clinical appearance for 22 patients three decades after in situ fusion for high-grade spondylolisthesis. The appearance was assessed by two spine surgeons, by the patient themselves, and by quantification of cosmesis relevant radiographic variables including pelvic parameters and sagittal balance. The surgeon inter- and intraobserver reliability of the photographic evaluation of the trunk deformity was at most moderate (Cohen's kappa 0.5). Correlation analysis revealed at most medium correlation between radiographic outcome and self-rated (SRS-22r) self-image (Spearman's rank correlation coefficient 0.3). The agreement between patient and surgeon-rated trunk appearance was poor (Cohen's kappa 0.2). Photographic evaluation of the trunk deformity in high-grade spondylolisthesis is unreliable. There were only weak correlations between patient self-assessed trunk appearance and radiographic parameters. The results reflect the pronounced subjectivity of cosmesis, and that the trunk deformity in high-grade spondylolisthesis is not easily observed. IV.

Sacrum osteotomy to change pelvic parameters: Surgical technique and 3D modeling

PurposeSome clinical situations, such as great sagittal imbalance, high-grade isthmic spondylolisthesis or sacral malunion could require a sacral osteotomy to decrease pelvic parameters, horizontalize the sacrum or correct sacral malunion. Here is described a novel technique to perform a sacral osteotomy to decrease pelvic parameters with a lumbo-pelvic construct, with first a sacral slope decrease, then a pelvic tilt decrease. MethodsSimulations have been performed using tridimensional reconstructions of the lumbar spine and pelvis, made from CT-scan images of a healthy individual. A cadaveric study has then been performed. Results3D modeling exhibited linear relationship between osteotomy angle and pelvic incidence correction, through multiple simulations with 1° increment. Cadaveric study demonstrated feasibility. ConclusionThis preliminary work shows that this technique is efficient to decrease pelvic parameters. A linear relationship has been exhibited between osteotomy angle and PI decrease, as per the following formula: osteotomy angle=PI change/0.84.

High grade isthmic spondylolisthesis – A case series illustrating three different operative instrumented fusion techniques

Adult isthmic spondylolisthesis most commonly occurs at the L5-S1 level. In adults a high-grade slip degree is rare comprising less than 1% of cases. Progressive axial lumbar backache characterizes the early stage of the disease which over time commonly complicates with the development of a super-imposed L5 radiculopathy. These are difficult cases to manage and the attending spinal surgeon must have an understanding of several different surgical options. These options include conservative treatment in those who are mildly symptomatic, decompression alone with its inherent tendency to facilitate further slip, decompression and fusion without instrumentation, decompression and fusion with instrumentation, and if so the extent of the construct both cranially and caudally. Another important consideration is whether, or not, reduction is necessary or whether fusion in situ will suffice. Regarding the surgical approach some surgeons regard an anterior approach, to perform an anterior release, as necessary if reduction is to be achieved. Others consider nerve root decompression and posterior spinal fusion in situ as the technique of choice. Others advocate a combined anterior and posterior surgical approach.We report a case series of three adult female patients with high grade isthmic spondylolisthesis complicated by L5 nerve root compression. Each patient was successfully managed with a different instrumented fusion technique. Our case series serves to highlight several of the specific surgical nuances pertaining to the management of high-grade isthmic spondylolisthesis and as such is valuable to the attending spinal surgeon who may infrequently encounter patient with the high-grade form of this disease.

Minimally Invasive Transforaminal Lumbar Interbody Fusion: Comparison of Grade I Versus Grade II Isthmic Spondylolisthesis.

Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) is often used to treat low-grade isthmic spondylolisthesis (IS). No studies have compared surgical outcomes for grade I and II IS following MIS-TLIF. Therefore, the objective of the current study was to compare outcomes between patients with grade I and II IS following MIS-TLIF. A retrospective cohort analysis was performed on a prospectively maintained database of patients who underwent a primary 1-level MIS-TLIF for treatment of IS between 2007 and 2015. Grade I patients underwent a unilateral tubular approach with a single interbody cage and bilateral pedicle screw instrumentation. Grade II patients underwent a bilateral tubular approach with bilateral interbody cage and pedicle screw placement. Baseline patient demographics and characteristics were compared using Student t test and χ2 analysis. Differences in peri- and postoperative outcomes were assessed using Poisson regression with robust error variance or linear regression adjusted for perioperative variables. A total of 58 patients with IS underwent MIS-TLIF; 21 (36.2%) were grade I and 37 (63.8%) were grade II. The grade I cohort was younger (42.2 versus 50.6 years, P = .029); no other differences in preoperative variables were observed. No significant differences in operative time, estimated blood loss, length of hospital stay, postoperative visual analogue scale scores, or complication and revision rates were demonstrated between cohorts. Arthrodesis rate was lower in the grade I cohort, though not statistically significant. Despite the grade I cohort being younger with less-severe diagnoses, the grade II cohort experienced similar outcomes. This finding may be due to the grade II cohort receiving bilateral cages, potentially providing a better fusion environment. These results suggest that MIS-TLIF provides sufficient stabilization and fusion for treatment of grade II IS despite increased vertebral body displacement. In addition, MIS-TLIF with bilateral approach and interbody cage placement should be examined for treatment of high-grade IS cases.

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

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

A ball-slide-type interbody distractor is effective in posterior reduction and internal fixation for patients with mid- to high-grade isthmic spondylolisthesis enrolled in a randomized clinical trial

Study Design:Clinical and radiographic results of a randomized, controlled, double-blind clinical trialObjective:To investigate the clinical applicability of a ball-point slide-type interbody distractor in posterior reduction and internal fixation for mid- to high-grade isthmic spondylolisthesis.Summary of Background Data:Posterior reduction and internal fixation is the effective treatment for spondylolisthesis. However, for the mid and high-grade isthmic spondylolisthesis patients with the conditions of vertebral osteoporosis and extremely narrow intervertebral space, the reduction is difficult; post-surgery intervertebral space height lost becomes serious; the fracture and loosening rate of fixation system is higher. No study regarding the prevention of these adverse outcomes in this technique is reported.Methods:A total of 59 patients of mid and high-grade isthmic spondylolisthesis were randomly divided into random groups (investigational group and control group) applying simple randomized method in this study. In addition, 30 patients received posterior reduction and internal fixation as control. Twenty-nine patients received posterior reduction and internal fixation by ball-point slide-type interbody distractor were assigned to the investigational group. X-ray examination was performed before and after operation. The degree of reduction, height of intervertebral space were compared. The preoperative and postoperative Visual Analog Scale (VAS) and Oswestry Disability Index (ODI) were evaluated. Additionally, rate of the fixation system fracture was also assessed.Results:Before treatment, there were no significant differences in ISH (P = .72), DR (P = .85), VAS of back pain (P = .55), VAS of leg pain (P = .83) and ODI (P = .68) were found between 2 groups. After 12-month treatment, there were no significant differences in ISH (P = .26), VAS of back pain (P = .09) and VAS of leg pain (P = .96) between two groups. Significant differences of DR (P = .02), ODI (P = .03) and adverse events (P = .00) were found between 2 groups.Conclusions:The results of this prospectively study showed that the ball-point slide-type interbody distractor in the posterior reduction and internal fixation produced good outcomes after 12-month treatment. More high quality randomized controlled trials and cases should still be needed to warrant the results of this study.

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

BackgroundRecently, 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.MethodsThis 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.ResultsBased 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.ConclusionIn 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.

Self-Image and Health-Related Quality of Life Three Decades After Fusion In Situ for High-Grade Isthmic Spondylolisthesis

Study DesignObservational study. ObjectivesTo evaluate self-image after in situ fusion for high-grade isthmic spondylolisthesis. Summary of Background DataCertain clinical findings such as short trunk or waistline skin folds are often seen in high-grade spondylolisthesis. Since treatment with spinal fusion in situ does not address appearance, self-image and also health-related quality of life might be negatively affected in the short-term as well as the long-term perspective. This observational study evaluated health-related quality of life outcome including self-image three decades after in situ fusion for high-grade isthmic spondylolisthesis in relation to healthy controls. MethodsThirty-eight of 39 consecutive patients, fused in situ for high-grade isthmic spondylolisthesis at a young age, completed the Scoliosis Research Society (SRS)-22r questionnaire 28–41 years after surgery. The results were compared with the results of an age- and gender-matched control group. ResultsWe found that the SRS-22r self-image domain scores were statistically significantly lower in patients than in controls whereas the pain and mental health scores were similar in patients and controls. Also, the SRS-22r function domain scores were statistically significantly lower in patients but the difference in means was small. We found no correlation between severity of slip and SRS-22r outcome. ConclusionsIn situ fusion for high-grade isthmic spondylolisthesis is a safe treatment option in the long term from a function and pain perspective, but the results of our study suggest that self-image is negatively affected long into adult life. Level of EvidenceLevel IV.

Sagittal Balance and Health-Related Quality of Life Three Decades After in Situ Arthrodesis for High-Grade Isthmic Spondylolisthesis

This case series of consecutive patients evaluated sagittal balance and health-related quality of life (HRQoL) 3 decades after in situ arthrodesis for high-grade isthmic spondylolisthesis. Global sagittal balance, pelvic parameters, and compensatory mechanisms were evaluated on standing lateral radiographs of the spine and pelvis for 28 of 39 consecutive patients, 28 to 41 years after in situ arthrodesis for high-grade L5 to S1 spondylolisthesis. The mean age at surgery was 14 years (range, 9 to 24 years), and the mean age at the time of follow-up was 48 years (range, 39 to 59 years). A subset of the radiographic parameters was compared with the corresponding data from an 8-year follow-up examination of the same patients. HRQoL was evaluated with the Scoliosis Research Society (SRS)-22r questionnaire. We found that 3 of the 28 patients had a global sagittal imbalance (T1 spinopelvic inclination of >0°). Signs of compensatory mechanisms, such as reduced thoracic kyphosis and pelvic retroversion, were frequent. There was a significant decrease in sacral slope compared with 8-year follow-up data (p = 0.01). The median SRS-22r subscore was on the same level as Swedish normative data. We found no association between radiographic parameters and SRS-22r outcome. Three decades after in situ arthrodesis for high-grade spondylolisthesis, radiographic signs of noncompensated sagittal imbalance were observed in only a few individuals. The patients had normal SRS-22r scores. There was no association between any radiographic parameter and SRS-22r outcome. The findings are relevant in the controversial discussion on whether to perform a reduction procedure to treat high-grade spondylolisthesis. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Treatment of High Grade Isthmic Spondylolisthesis by Anterior Lumbar Interbody Fusion with Structural Fibular Allograft

The treatment for high-grade spondylolisthesis remains controversial. Although several techniques are commonly used, several variables for each patient need to be considered in the decision making process. In addition to the patient’s diagnosis, symptoms, age, bone quality, slip level, and slip grade, severe slip angles present an increased challenge to many approaches. We describe a reverse Bohlman technique with one anterior-to-posterior transdiscal structural fibular allograft at L5-S1, standard anterior interbody fusion at L4-L5, and a minimally invasive L4-S1 posterolateral spinal fusion with instrumentation from S1 into the L5 vertebral body that we have used successfully to treat a high grade isthmic spondylolisthesis. To our knowledge, this is the first description of a minimally invasive posterior approach in combination with an anterior reverse Bohlman technique to address high-grade spondylolisthesis.

Reduction of Pelvic Tilt after Surgical Correction of Low-grade Isthmic Spondylolisthesis is Correlated with Rather Improvement of Back Pain than Quality of Life

IntroductionIt is generally believed that the restoration or improvement of sagittal spino-pelvic alignment may impact clinical outcomes of surgical treatment of high-grade isthmic spondylolisthesis. Little is known about the impact on low-grade slips. The purpose of the study was to determine whether clinical outcomes are correlated with the restoration or improvement of pelvic balance after surgical correction of low-grade isthmic spondylolisthesis. Material and MethodsProspective non-randomized study based on a single-institution series of consecutive patients with isthmic spondylolisthesis during a 10-year period from 2002–2012. 63 adult patients with a low-grade isthmic slip and adequate pre- and postoperative radiograms were available for measurement of spino-pelvic parameters and final assessment of their clinical outcomes. The latter were assessed at least 1 year after the surgery with the use of the Oswestry Disability Index (ODI) and a back pain visual analogue scale. Pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbosacral angle (LSA) and lumbar lordosis were measured on standing lateral view radiograms. We assumed postoperative reduction in pelvic tilt (PT) to reflect improvement in pelvic balance. The Spearman's rank correlation test was used to assess the correlation between the improvement in pelvic balance and the improvement in ODI and back pain. The Mann–Whitney U test was used to identify significant differences in clinical outcomes between patients (i) with a balanced and unbalanced pelvis postoperatively, (ii) who regained and did not regain pelvic balance postoperatively, (iii) who maintained and lost pelvic balance postoperatively, and (iv) with an improved (reduced PT) and worsened (increased PT) pelvic balance postoperatively. ResultsThere were no significant differences in clinical outcomes between patients with a balanced and unbalanced pelvis postoperatively regardless of whether they lost, maintained, or regained pelvic balance after the surgery. However, we found a weak (R= -0.3) but statistically significant (p = 0.035) negative correlation between the degree of reduction in pelvic tilt and intensity of postoperative back pain and a weak (R=0.2) but statistically significant (p = 0.034) positive correlation between the degree of reduction in PT and reduction in back pain. No correlation was found between improvement in pelvic balance and quality of life ConclusionsPostoperative reduction of pelvic tilt may impact improvement of rather back pain than quality of life in low-grade isthmic spondylolisthesis. The latter might be a result of rather neural decompression and stabilization of the affected segment than improvement of pelvic balance.

Changes in spino-pelvic alignment after surgical treatment of high-grade isthmic spondylolisthesis by a posterior approach: a report of 41 cases

To analyze changes in spino-pelvic parameters (SPPs) after surgery of high-grade lumbar isthmic spondylolisthesis (HDIS). We analyzed 41 patients affected by HDIS operated upon by attempt of reduction and posterior spinal fusion with pedicle screw systems with or without interbody fusion. Pelvic tilt (PT), lumbar lordosis (LL), pelvic incidence (PI), and sacral slope (SS) were measured, and patients were further divided into balanced and unbalanced pelvis subgroups. SS passed from 46.8°±9.8° preoperatively to 50.1°±10.1° (p=0.02). PT passed from 26.7°±6.7° preoperatively to 22.9°±7.5° (p=0.003). Unbalanced patients showed significantly higher PT and lower SS compared to the balanced patients preoperatively, and these corrected after surgery. Patients with instrumentation failure (n=5) had significant increase in PT values postoperatively (p=0.018). We confirmed the positive effect of surgery on the SPPs in patients affected by HDIS, which showed different patterns of corrections with surgery for balanced and unbalanced pelvis patients.

Normal Health-Related Quality of Life and Ability to Work Twenty-nine Years After in Situ Arthrodesis for High-Grade Isthmic Spondylolisthesis

The purpose of this mixed prospective and retrospective case series was to evaluate the long-term health-related quality of life and physical disability after in situ arthrodesis for high-grade isthmic spondylolisthesis. Thirty-five of forty consecutive patients who had in situ spinal arthrodesis for high-grade isthmic spondylolisthesis at a mean age of fifteen years (range, nine to twenty-five years) completed validated questionnaires (Short Form-36 [SF-36], EuroQol-5 Dimensions [EQ-5D], Zung depression scale, Oswestry disability index [ODI], Million score, and back and leg pain visual analog scale [VAS]) and underwent physical examination twenty-nine years (range, twenty-three to thirty-five years) after surgery. The mean age at the time of follow-up was forty-three years (range, thirty-seven to fifty-one years). In the absence of a formal control group, the scores on the SF-36 and EQ-5D were compared with Swedish normative data. The proportion of patients at work was compared with an age-matched control group derived from official statistics of Sweden. The Million score at the long-term follow-up was compared with the corresponding results at the mid-term follow-up of the same patients at a mean age of twenty-two years. The scores on the SF-36 and EQ-5D were similar to the scores of the general Swedish population. The mean Zung depression scale score was 30 (range, 20 to 52), the mean ODI score was 10 (range, 0 to 34), the mean back pain VAS score was 13 (range, 0 to 72), and the mean leg pain VAS score was 9 (range, 0 to 60). The Million score averaged 28 (range, 0 to 109) and was slightly worsened compared with the score of 19 (range, 0 to 94) at the mid-term follow-up (p = 0.034). The proportion of patients at work was the same as that for the age-matched general Swedish population. Our study shows good outcomes in health-related quality of life, disability, pain, and ability to work at up to twenty-nine years after in situ lumbar spine arthrodesis for high-grade isthmic spondylolisthesis. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

A Novel Minimally Invasive Technique for the Treatment of High-grade Isthmic Spondylolisthesis Using a Posterior Transsacral Rod

Case report of 3 patients with high-grade isthmic spondylolisthesis treated using a novel minimally invasive technique using a posterior transsacral rod. To assess the efficacy, safety, and advantages of this approach in the treatment of high-grade L5-S1 spondylolisthesis. Surgical treatment of high-grade isthmic spondylolisthesis at the L5-S1 level is technically demanding. The most commonly used procedure is posterior spinal fusion. In this report, we present a new minimally invasive technique for the treatment high-grade isthmic spondylolisthesis in 3 patients with sagittally balanced spines. Three patients with high-grade L5-S1 spondylolisthesis underwent L4-S1 fusion with percutaneous pedicle screw fixation supplemented with a transsacral rod implanted through a tubular retractor. We report technical details, clinical, and radiologic results at follow-up. All 3 patients suffered from grade 3 or 4 L5-S1 spondylolisthesis. All patients had neutral sagittal balance on preoperative imaging. There were no postoperative complications and all 3 patients were discharged within 48 hours. At final follow-up (range, 13-18 mo), all patients were pain free off all narcotic pain medication and fusion was observed in all 3 patients. We have shown the technical feasibility of anterior and posterior fusion for severe L5-S1 spondylolisthesis using a minimally invasive percutaneous technique through a transsacral approach. The main advantage of a posterior transsacral axial rod fixation is that it creates a structurally sound anterior column support, thus eliminating the problems related to bone grafts and eliminating the complications associated with an anterior approach. Our preliminary results suggest that this technique is feasible and seems to be associated with favorable outcome, although larger studies are warranted to verify these findings.

Analysis of L5 Incidence in Normal Population Use of L5 Incidence as a Guide in Reconstruction of Lumbosacral Alignment

Cross-sectional study. To establish a statistic model defining the relationship between L5 incidence (L5I) and pelvic incidence (PI) in normal population and to illustrate the importance of L5I in maintaining the normal sagittal profile of spine. L5I was proposed for the evaluation of postoperative improvements in high-grade isthmic spondylolisthesis. It has been proven that a postoperative improvement in L5I was correlated with a better surgical outcome, indicating that the restoration of L5I is important in restoring normal sagittal balance and spinal morphology. This retrospective study recruited 138 healthy volunteers, who were stratified into 2 groups according to age: adolescent group (13-18 yr) and adult group (19-35 yr). Parameters including PI, pelvic tilt, sacral slope, lumbar lordosis (LL), upper arc of the LL, lower arc of the LL, L5I, lumbosacral angle, and height of L5-S1 disc were measured on the long-cassette standing upright lateral radiographs of the spine and pelvis. The relations between all parameters were determined via the Pearson correlation coefficient (r). Linear regression was applied to model the relationship between PI and L5I. This study demonstrated significant correlation between L5I and PI with a coefficient of 0.818, and a formula based on linear regression was established to estimate the ideal L5I from PI as follows: L5I = 0.725 PI - 12.757. Pelvic tilt, sacral slope, lumbosacral angle, LL, lower arc of the LL, and height of L5-S1 disc were also found strongly correlated with L5I, whereas no correlation was found between upper arc of the LL and L5I. Strong correlations were found between L5I and spinopelvic parameters in healthy subjects, indicating that L5I was an important parameter in local lumbosacral alignment. Ideal postoperative L5I could be mathematically calculated by PI according to the formula as follows: L5I = 0.725 PI - 12.757, suggesting that calculated ideal L5I could be regarded as a guide in surgical decision making. 3.

Advanced Minimally Invasive Techniques: Management of High-grade Spondylolisthesis and Thoracic Metastatic Spinal Disease

Recentadvances in spine surgery technology and instrumentation have allowed for the development of minimally invasive (MIS) techniques. These muscle-sparing approaches have been demonstrated to provide superior, if not similar, outcomes to traditional open techniques. However, MIS techniques are associated with a steep learning curve and greater radiation exposure. Furthermore, while suitable for most degenerative spinal conditions, MIS approaches may not be appropriate for complex spinal pathology. This articlediscusses the literature onopen and advanced MIS techniques for high-grade isthmic spondylolisthesis and metastatictumors of the thoracic spine. Additionally, the authors’ preferred techniques along with their associated pearls and pitfalls are presented for both complex pathologies.