Minimally invasive transforaminal lumbar interbody fusion for spondylolisthesis and degenerative spondylosis: 5-year results

Learning curve analyses in spine surgery: a systematic simulation-based critique of methodologies

BACKGROUND CONTEXT

Various statistical approaches exist to delineate learning curves in spine surgery. Techniques range from dividing cases into intervals for metric comparison, to employing regression and cumulative summation (CUSUM) analyses. However, their inherent inconsistencies and methodological flaws limit their comparability and reliability.

PURPOSE

To critically evaluate the methodologies used in existing literature for studying learning curves in spine surgery and to provide recommendations for future research.

STUDY DESIGN

Systematic literature review.

METHODS

A comprehensive literature search was conducted using PubMed, Embase, and Scopus databases, covering articles from January 2010 to September 2023. For inclusion, articles had to evaluate the change in a metric of performance during human spine surgery across time/a case series. Results had to be reported in sufficient detail to allow for evaluation of individual performance rather than group/institutional performance. Articles were excluded if they included cadaveric/nonhuman subjects, aggregated performance data or no way to infer change across a number of cases. Risk of bias was assessed using the Risk of Bias in Nonrandomized Studies of Interventions (ROBINS-I) tool. Surgical data were simulated using Python 3 and then examined via multiple commonly used analytic approaches including division into consecutive intervals, regression and CUSUM techniques. Results were qualitatively assessed to determine the effectiveness and limitations of each approach in depicting a learning curve.

RESULTS

About 113 studies met inclusion criteria. The majority of the studies were retrospective and evaluated a single-surgeon's experience. Methods varied considerably, with 66 studies using a single proficiency metric and 47 using more than 1. Operating time was the most commonly used metric. Interval division was the simplest and most commonly used method yet inherent limitations prevent collective synthesis. Regression may accurately describe the learning curve but in practice is hampered by sample size and model choice. CUSUM analyses are of widely varying quality with some being fundamentally flawed and widely misinterpreted however, others provide a reliable view of the learning process.

CONCLUSION

There is considerable variation in the quality of existing studies on learning curves in spine surgery. CUSUM analyses, when correctly applied, offer the most reliable estimates. To improve the validity and comparability of future studies, adherence to methodological guidelines is crucial. Multiple or composite performance metrics are necessary for a holistic understanding of the learning process.

Comparison of facet fusion rates and clinical outcomes between cortical bone trajectory screw and percutaneous pedicle screw fixation for degenerative lumbar spondylolisthesis

BACKGROUND CONTEXT

Cortical bone trajectory (CBT) screws have been introduced as an alternative technique for pedicle screw (PS) insertion because they have greater contact with the cortex and a greater uniaxial pullout load than traditional PS. CBT screwing can also minimize muscle dissection. However, CBT screws and traditional PSs have not yet been compared in terms of fusion rates and clinical outcomes for particular operative procedures.

PURPOSE

This study aimed to assess the fusion rate and clinical outcomes of facet fusion (FF) fixed with CBT screws (CBT-FF) and to compare them with those of FF fixed with percutaneous PS (PPS-FF).

STUDY DESIGN

Retrospective study.

PATIENT SAMPLE

Records of 68 patients who underwent CBT-FF for single-level degenerative lumbar spondylolisthesis (DLS) with at least 1 year of follow-up were retrospectively reviewed. The control group comprised 143 patients who underwent PPS-FF under the same conditions.

OUTCOME MEASURES

Computed tomography was performed to confirm fusion. Therapeutic effectiveness was assessed as a clinical outcome using the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ), Roland-Morris Disability Questionnaire (RMDQ), and visual analog scale (VAS) preoperatively and 1 year postoperatively. The rate of revision surgery was also calculated. Intraoperative blood loss was measured.

METHODS

Fusion rate, clinical outcomes, revision surgery rate, and intraoperative blood loss of CBT-FF and PPS-FF were compared.

RESULTS

The CBT-FF and PPS-FF fusion rates were 91.2% and 90.1%, respectively. The JOABPEQ category scores demonstrated therapeutic effectiveness in 74.5% and 77.1% of the patients for low back pain; the corresponding proportions for walking ability were 84.7% and 89.3%, respectively. No significant differences in therapeutic effectiveness were observed for any category, including the RMDQ and VAS scores for buttock and lower limb pain. Three patients required revision surgery for adjacent segment disease between 6 months and 3.5 years after CBT-FF (revision surgery rate, 4.4%), whereas the revision surgery rate for PPS-FF was 6.3% (9/143 cases). Average intraoperative blood loss was significantly less in the CBT-FF group than in the PPS-FF group.

CONCLUSIONS

Both procedures were equally useful in terms of fusion rate and clinical outcomes for DLS management.

Fusion's Location and Quality within the Fixated Segment Following Transforaminal Interbody Fusion (TLIF)

Transforaminal interbody fusion (TLIF) has gained increased popularity over recent decades and is being employed as an established surgical treatment for several lumbar spine pathologies, including degenerative spondylosis, spondylolisthesis, infection, tumor and some cases of recurrent disc herniation. Despite the seemingly acceptable fusion rates after TLIF (up to 94%), the literature is still limited regarding the specific location and quality of fusion inside the fixated segment. In this single-institution, retrospective population-based study, we evaluated all post-operative computed tomography (CT) of patients who underwent TLIF surgery at a medium-sized medical center between 2010 and 2020. All CT studies were performed at a minimum of 1 year following the surgery, with a median of 2 years. Each CT study was evaluated for post-operative fusion, specifically in the posterolateral and intervertebral body areas. The fusion's quality was determined and classified in each area according to Lee's criteria, as follows: (1) definitive fusion: definitive bony trabecular bridging across the graft host interface; (2) probable fusion: no definitive bony trabecular crossing but with no gap at the graft host interface; (3) possible arthrosis: no bony trabecular crossing with identifiable gap at the graft host interface; (4) definite pseudarthrosis: no traversing trabecular bone with definitive gap. A total of 48 patients were included in this study. The median age was 55.6 years (SD ± 15.4). The median time from surgery to post-operative CT was 2 years (range: 1-10). Full definitive fusion in both posterolateral and intervertebral areas was observed in 48% of patients, and 92% showed definitive fusion in at least one area (either posterolateral or intervertebral body area). When comparing the posterolateral and the intervertebral area fusion rates, a significantly higher definitive fusion rate was observed in the posterolateral area as compared to the intervertebral body area in the long term follow-up (92% vs. 52%, p < 0.001). In the multivariable analysis, accounting for several confounding factors, including the number of fixated segments and cage size, the results remained statistically significant (p = 0.048). In conclusion, a significantly higher definitive fusion rate at the posterolateral area compared to the intervertebral body area following TLIF surgery was found. Surgeons are encouraged to employ bone augmentation material in the posterolateral area (as the primary site of fusion) when performing TLIF surgery.

Postoperative cage migration and subsidence following TLIF surgery is not associated with bony fusion

Pseudarthrosis following transforaminal interbody fusion (TLIF) is not infrequent. Although cage migration and subsidence are commonly regarded as evidence of the absence of solid fusion, there is still no evidence of the influence of cage migration and subsidence on fusion. This study aimed to evaluate cage migration and subsidence using computed tomography (CT) DICOM data following lumbar interbody fusion. The effects of cage migration and subsidence on fusion and clinical outcomes were also assessed. A postoperative CT data set of 67 patients treated with monosegmental TLIF was analyzed in terms of cage position. To assess the effects of cage migration and subsidence on fusion, 12-month postoperative CT scans were used to assess fusion status. Clinical evaluation included the visual analog scale for pain and the Oswestry Disability Index. Postoperative cage migration occurred in 85.1% of all patients, and cage subsidence was observed in 58.2%. Radiological signs of pseudarthrosis was observed in 7.5% of the patients Neither cage migration nor subsidence affected the clinical or radiographic outcomes. No correlation was found between clinical and radiographic outcomes. The incidence of cage migration was considerable. However, as cage migration and subsidence were not associated with bony fusion, their clinical significance was considered limited.

OLIF versus MI-TLIF for patients with degenerative lumbar disease: Is one procedure superior to the other? A systematic review and meta-analysis

PURPOSE

To compare the effectiveness and safety of oblique lateral interbody fusion (OLIF) and minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) for degenerative lumbar disease.

METHODS

We searched relevant studies in Embase, PubMed, Cochrane, and Web of Science databases comprehensively from inception to March 2022. The data were extracted from included studies, including operation indications, radiographic parameters, and clinical outcomes. Random or fixed-effects models were used in all meta-analyses according to the between-study heterogeneity.

RESULTS

In total, 30 studies, including 2,125 patients, were included in this meta-analysis. Our study found similar disk height, length of hospital stay, visual analog scale (VAS), and Oswestry disability index(ODI) between the two groups. However, the OLIF showed an advantage in restoring lumbar lordotic angle compared with MI-TLIF, with the pooled mean change of 17.73° and 2.61°, respectively. Additionally, the operative time and blood loss in the OLIF group appeared to be less compared with the MI-TLIF group. Regarding complications, the rates of the two groups were similar (OLIF 14.0% vs. MI-TLIF 10.0%), but the major complications that occurred in these two procedures differed significantly.

CONCLUSION

The results of disk height, length of hospital stay, VAS, and ODI between the OLIF and MI-TLIF groups were similar. And the OLIF was superior in restoring lumbar lordotic angle, operative time, and blood loss. However, the OLIF group's complication rate was higher, although not significantly, than that in the MI-TLIF group.

Full-Endoscopic Lumbar Interbody Fusion Versus Minimally Invasive Transforaminal Lumbar Interbody Fusion with a Tubular Retractor System: A Retrospective Controlled Study

OBJECTIVE

The objective of this study was to compare the safety and clinical efficacy of full-endoscopic lumbar interbody fusion (FE-LIF) and minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF).

METHODS

A total of 70 patients with single-level lumbar degenerative diseases underwent FE-LIF or MIS-TLIF with a tubular retractor system from August 2018 to August 2020. Postoperatively, the efficacy and safety were compared using several clinical and radiological indices.

RESULTS

A total of 32 patients underwent FE-LIF and 38 received MIS-TLIF with a tubular retractor system, and all patients had no apparent complications. The FE-LIF group had higher radiation exposure, longer operation time, and less bleeding than the MIS-TLIF group (P < 0.05). Postoperative lumbar magnetic resonance imaging showed that the nerve decompression was sufficient. The pain in the lower back and legs was significantly relieved, and the Oswestry Disability Index (ODI) score was greatly improved after surgery (P < 0.01) in both the groups. The sensory and motor functions of nerve roots were remarkably recovered in both the groups at the 1-year follow-up (P < 0.05), and there was no significant difference in MacNab scores between the 2 groups. As per Mannion's fusion classification, the interbody fusion rate was significantly better in the FE-LIF group than in the MIS-TLIF group.

CONCLUSIONS

FE-LIF, which is safe, effective, and minimally invasive, exhibits the same clinical efficacy as MIS-TLIF but with longer operation time and increased radiation exposure.

Impact of Body Mass Index on Postsurgical Outcomes for Workers' Compensation Patients Undergoing Minimally Invasive Transforaminal Lumbar Interbody Fusion

BACKGROUND

Increased morbidity associated with obesity imposes a greater financial burden on companies that provide insurance to their employees. Few studies have investigated the relationship between body mass index (BMI) and patient-reported outcome measures (PROMs) for minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) in the workers' compensation (WC) population.

METHODS

WC patients who underwent a primary, single-level MIS TLIF were included/grouped according to BMI: nonobese (<30 kg/m2); obese I (≥30, <35 kg/m2); severe + morbid (≥35). PROMs were collected pre- and postoperatively: visual analog scale (VAS), Oswestry Disability Index (ODI), 12-Item Short Form (SF-12) physical composite score (PCS), and Patient-Reported Outcome Measurement Information System physical function (PROMIS-PF). BMI predictive power grouping on PROMs was evaluated using simple linear regression. Established minimum clinically important difference values were used to compute achievement rates across PROMs using logistic regression.

RESULTS

A total of 116 nonobese, 70 obese I, and 61 severe + morbid patients were included. Demographics among BMI grouping significantly differed in gender, hypertensive status, and American Society of Anesthesiologists score (P ≤ 0.037, all). Operative time was significantly different in perioperative values among BMI grouping (P ≤ 0.001). Increased BMI was significantly associated with greater VAS back at 12 weeks and 2 years (P ≤ 0.026, all), greater ODI preoperatively at 12 weeks and 6 months (P ≤ 0.015, all), and decreased PROMIS-PF at 12 weeks (P ≤ 0.011, all). Mean PROMs between obese I and severe + morbid cohorts differed in SF-12 PCS at 12 weeks, only (P = 0.050). ODI overall was the only parameter for which minimum clinically important difference was achieved among BMI cohorts (P ≤ 0.023).

CONCLUSION

WC patients with increased BMI were more likely to develop significant back pain and disability at numerous postoperative timepoints compared with nonobese individuals. Our findings highlight the weight management importance within WC population to minimize back pain and disability following MIS TLIF, but provide a sense of reassurance with comparable clinical improvement regardless of BMI.

CLINICAL RELEVANCE

When considering the effect of weight, surgeons may incorporate these findings in managing patient expectations in the WC population undergoing lumbar spine surgery.

LEVEL OF EVIDENCE: 3

[Comparison of effectiveness between percutaneous coaxial large-channel endoscopic lumbar interbody fusion and minimal invasive transforaminal lumbar interbody fusion in treatment of degenerative lumbar spinal stenosis]

OBJECTIVE

To compare the effectiveness of percutaneous coaxial large-channel endoscopic lumbar interbody fusion (PE-LIF) and minimal invasive transforaminal lumbar interbody fusion (MIS-TLIF) in the treatment of degenerative lumbar spinal stenosis.

METHODS

The clinical data of 134 patients with single-segment degenerative lumbar spinal stenosis who met the selection criteria between January 2019 and January 2021 were retrospectively analyzed, including 52 cases in PE-LIF group and 82 cases in MIS-TLIF group. There was no significant difference in general data such as gender, age, disease duration, surgical segment, and preoperative visual analogue scale (VAS) scores of low back pain and lower extremity pain, and Oswestry disability index (ODI) between the two groups ( P>0.05). The operation time, intraoperative blood loss, postoperative drainage, hospitalization stay, and complications were recorded and compared between the two groups. The level of serum creatine kinase (CK) was recorded at 1 day before operation and at 1 and 3 days after operation to evaluate intraoperative muscle damage. The Brantigan criteria was used to evaluate the interbody fusion in the two groups. The VAS scores of low back pain and lower extremity pain at 1 day before operation and at 3 days, 3 months, and 1 year after operation, and the ODI scores at 1 day before operation and at 3 months and 1 year after operation were recorded and compared between the two groups.

RESULTS

There was no significant difference in operation time and hospitalization stay between the two groups ( P>0.05). The intraoperative blood loss and postoperative drainage in the PE-LIF group were significantly lower than those in the MIS-TLIF group ( P<0.05). There was no significant difference in serum CK between the two groups before operation ( P>0.05), and the serum CK in the PE-LIF group at 1 and 3 days after operation were significantly lower than those in the MIS-TLIF group ( P<0.05). All patients were followed up regularly for 1 year. The postoperative VAS scores of low back pain and lower extremity pain and ODI score in both groups were significantly lower than those before operation ( P<0.05); there was no significant difference between the two groups ( P>0.05). At 1 year after operation, 48 patients in PE-LIF group had successful interbody fusion, and 77 patients in MIS-TLIF group had successful interbody fusion. There was no significant difference in the interbody fusion distribution between the two groups at 3 months and 1 year after operation ( P>0.05). There were 2 and 3 cases of lower limb numbness, 1 and 3 cases of neuroedema pain, 1 and 1 case of Cage displacement, 1 and 1 case of pedicle screw loosening in the PE-LIF group and MIS-TLIF group, respectively. No infection or dural sac tearing occurred in the two groups. There was no significant difference in the incidence of complications between the two groups (9.6% vs. 9.8%) ( χ ²=0.001, P=0.979).

CONCLUSION

In the treatment of single-segment degenerative lumbar spinal stenosis, PE-LIF can achieve similar effectiveness as MIS-TLIF, and PE-LIF has less intraoperative blood loss and less muscle damage.

Clinical Evaluation of Paraspinal Mini-Tubular Lumbar Decompression and Minimally Invasive Transforaminal Lumbar Interbody Fusion for Lumbar Spondylolisthesis Grade I with Lumbar Spinal Stenosis: A Cohort Study

Objective

To investigate the clinical outcome data and difference in efficacy between paraspinal mini-tubular lumbar decompression (PMTD) and minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) in the treatment of degenerative lumbar spondylolisthesis grade I with lumbar spinal stenosis (DLS-I-LSS).

Methods

Patients with DLS-I-LSS, who underwent PMTD or MIS TLIF from September 2017 to March 2020, were included retrospectively. The follow-up period was 24 months after surgery. Outcome measurements included the Oswestry disability index (ODI) score, visual analog scale (VAS) low back pain score, VAS leg pain score, surgical data, and adverse events.

Results

A total of 104 patients with DLS-I-LSS were included in this study. The average improvement in ODI at 12 months (2.0%, 95% CI, −5.7% to 1.8%; p = 0.30) and 24 months (1.7%, 95% CI, −2.7% to 6.1%; p = 0.45) after surgery between the two groups were not statistically significant. The improvement in VAS low back pain score after 24 months and improvement in VAS leg pain score were not significantly different between the two groups. Compared with the PMTD group, the MIS TLIF group had more estimated blood loss and longer hospital stays. The cumulative reoperation rates were 5.66% and 1.96% in the MIS TLIF and PMTD groups, respectively (p = 0.68). The results of multivariate analysis showed that BMI, diabetes, and baseline ODI score were the main factors influencing the improvement in ODI in patients with DLS-I-LSS after minimally invasive surgery, accounting for 50.5% of the total variance.

Conclusions

The clinical effectiveness of PMTD was non-inferior to that of MIS TLIF for DLS-I-LSS; however, there was a reduced duration of hospital stay, operation time, blood loss, and hospitalization costs in the PMTD group. BMI, presence or absence of diabetes and baseline ODI score were influencing factors for the improvement of ODI (Trial Registration: ChiCTR2000040025).

Long-Term Clinical and Radiological Outcomes of Minimally Invasive Transforaminal Lumbar Interbody Fusion: 10-Year Follow-up Results

BACKGROUND

Many studies have reported that minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) provides satisfactory treatment comparable to other fusion methods. However, in the case of MI-TLIF, there are concerns about the long-term outcome compared to conventional bilateral PLIF due to the small amount of disc removal and the lack of autogenous bone graft. Long-term follow-up studies are still lacking as most of the previous reports have follow-up periods of up to 5 years.

METHODS

Thirty patients who underwent MI-TLIF were followed up for > 10 years (mean, 11.1 years). Interbody fusion rates were determined using a modified Bridwell grading system. Adjacent segment disease (ASD) was defined as radiological adjacent segment degeneration (R-ASDeg) as seen on plain X-rays; reoperated adjacent segment disease referred to the subsequent need for revision surgery. Clinical outcomes after surgery were assessed based on back and leg pain as well as the Oswestry disability index (ODI).

RESULTS

The overall radiological fusion rate, at the 1-, 5-, and 10-year follow-up was 77.1%, 91.4%, and 94.3%, respectively. The incidence of R-ASDeg 1, 5, and 10 years after surgery was 6.7%, 16.7%, and 43.3% at the proximal adjacent segment and 4.8%, 14.3%, and 28.6% at the distal adjacent segment, respectively. R-ASDeg at either the proximal or distal segment was determined in 50.0% of the patients 10 years postoperatively. All clinical parameters improved significantly during follow-up, although the ODI and the visual analog scale (VAS) for leg pain at the 10-year follow-up were significantly worse in the R-ASDeg group than in the other patients (P = 0.009, P = 0.040).

CONCLUSION

MI-TLIF improved both clinical and radiological outcomes, and the improvements were maintained for up to 10 years after surgery. However, R-ASDeg developed in up to 50% of the patients within 10 years, and both leg pain on the VAS and the ODI were worse in patients with R-ASDeg.

Development and Internal Validation of Supervised Machine Learning Algorithms for Predicting the Risk of Surgical Site Infection Following Minimally Invasive Transforaminal Lumbar Interbody Fusion

Purpose: Machine Learning (ML) is rapidly growing in capability and is increasingly applied to model outcomes and complications in medicine. Surgical site infections (SSI) are a common post-operative complication in spinal surgery. This study aimed to develop and validate supervised ML algorithms for predicting the risk of SSI following minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF).

Methods: This single-central retrospective study included a total of 705 cases between May 2012 and October 2019. Data of patients who underwent MIS-TLIF was extracted by the electronic medical record system. The patient's clinical characteristics, surgery-related parameters, and routine laboratory tests were collected. Stepwise logistic regression analyses were used to screen and identify potential predictors for SSI. Then, these factors were imported into six ML algorithms, including k-Nearest Neighbor (KNN), Decision Tree (DT), Support Vector Machine (SVM), Random Forest (RF), Multi-Layer Perceptron (MLP), and Naïve Bayes (NB), to develop a prediction model for predicting the risk of SSI following MIS-TLIF under Quadrant channel. During the training process, 10-fold cross-validation was used for validation. Indices like the area under the receiver operating characteristic (AUC), sensitivity, specificity, and accuracy (ACC) were reported to test the performance of ML models.

Results: Among the 705 patients, SSI occurred in 33 patients (4.68%). The stepwise logistic regression analyses showed that pre-operative glycated hemoglobin A1c (HbA1c), estimated blood loss (EBL), pre-operative albumin, body mass index (BMI), and age were potential predictors of SSI. In predicting SSI, six ML models posted an average AUC of 0.60–0.80 and an ACC of 0.80–0.95, with the NB model standing out, registering an average AUC and an ACC of 0.78 and 0.90. Then, the feature importance of the NB model was reported.

Conclusions: ML algorithms are impressive tools in clinical decision-making, which can achieve satisfactory prediction of SSI with the NB model performing the best. The NB model may help access the risk of SSI following MIS-TLIF and facilitate clinical decision-making. However, future external validation is needed.

Sagittal adjusting screws for the correction of grade IV spondylolisthesis in a patient with Ehlers-Danlos syndrome: illustrative case

BACKGROUND

Ehlers-Danlos syndrome (EDS) and its connective tissue laxity often result in high-grade lumbosacral spondylolisthesis. Patients present with debilitating symptoms and neurological deficits. Reports of surgical techniques in non-EDS patients for the treatment of high-grade lumbosacral spondylolisthesis mainly described an open approach, multilevel fusions, and multiple stages with different circumferential approaches. Sagittal adjusting screws (SASs) can be used in a minimally invasive (MI) fashion, allowing intraoperative reduction.

OBSERVATIONS

A 17-year-old female with EDS presented to the authors’ institute with severe lower back and left L5 radicular pain in 2017. She presented with a left foot drop and difficulty ambulating. Magnetic resonance imaging showed grade IV L5–S1 spondylolisthesis. She underwent lumbar fusion for intractable back pain with radiculopathy. Intraoperatively, percutaneous SASs and extension towers were used to distract the L5–S1 disc space and reduce the spondylolisthesis. MI transforaminal lumbar interbody fusion was completed with significant symptomatic relief postoperatively. The patient was discharged to home 3 days postoperatively. Routine follow-up visits up to 3 years later demonstrated solid fusion radiographically and favorable patient-reported outcomes.

LESSONS

The authors used SASs in a MI approach to successfully correct and stabilize grade IV spondylolisthesis in an EDS patient with a favorable long-term patient-reported outcome.

The Minimum Clinically Important Difference for Patient Health Questionnaire-9 in Minimally Invasive Transforaminal Interbody Fusion

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

To investigate and establish minimum clinically important differences (MCID) for Patient Health Questionnaire-9 (PHQ-9) among patients undergoing minimally invasive transforaminal lumbar interbody fusion (MIS TLIF).

SUMMARY OF BACKGROUND

Spine surgery is linked to postoperative improvements in anxiety, depression, and mental health. These improvements have been documented using patient-reported outcome measures such as PHQ-9. Few studies evaluated the clinical significance of PHQ-9 for lumbar spine surgery.

METHODS

Patients who underwent single-level, primary MIS TLIF from 2015 to 2017 were retrospectively reviewed in a prospective database. Patients with incomplete preoperative and 2-year postoperative PHQ-9 surveys were excluded. Demographic and perioperative characteristics were recorded. PHQ-9, 12-Item Short Form (SF-12), and Veterans RAND 12-Item Health Survey (VR-12) Mental Component Summary (MCS) were collected at preoperative, 6-week, 12-week, 6-month, 1-year, and 2-year intervals. MCID was calculated using anchor and distribution-based methods. SF-12 served as an anchor. MCID was assessed using mean change methodology, four receiver operating characteristic curve assessments, and standard error measurement. Cutoff values were selected from receiver operating characteristic curve analysis. MCID achievement rates for all patient-reported outcome measures were calculated.

RESULTS

A total of 139 patients met inclusion criteria, with a mean age of 55 years and 39% females. The most common spinal pathology was radiculopathy (92%). MCID analysis revealed the following ranges of values: 2.0 to 4.8 (PHQ-9), 6.7 to 12.1 (SF-12 MCS), and 7.5 to 15.9 (VR-12 MCS). Final MCID thresholds were 3.0 (PHQ-9), 9.1 (SF-12 MCS), and 8.1 (VR-12 MCS). MCID achievement at 2-years for PHQ-9, SF-12 MCS, and VR-12 MCS was 89.2%, 85.6%, and 84.9% respectively.

CONCLUSION

Our 2-year postoperative MCID analysis is the first mental health calculation from an MIS TLIF cohort. We report a 2-year MCID value for PHQ-9 of 3.0 (2.0-4.8). MCID values for mental health instruments are important for determining overall success of lumbar spine surgery.Level of Evidence: 3.

Good clinical outcomes in nonunion cases after facet fusion with a percutaneous pedicle screw system for degenerative lumbar spondylolisthesis

There are many satisfactory long-term outcomes after posterolateral fusion (PLF) for degenerative lumbar spondylolisthesis (DLS); nonunion cases have also achieved good clinical outcomes. Facet fusion (FF), a minimally invasive evolution of PLF, also resulted in good clinical outcomes. We aimed to assess the course of nonunion cases after FF and determine whether the nonunion cases achieved good clinical outcomes. We retrospectively reviewed the records of 136 patients who underwent FF for DLS. Range of motion (ROM) at the fused level was measured using a flexion-extension lateral radiograph preoperatively and 1 year postoperatively. Patients were classified into the Fusion or Unconfirmed Fusion group by computed tomography (CT) 1 year postoperatively. Furthermore, patients in the Unconfirmed Fusion group were classified into the Delayed Union or Nonunion group depending on the confirmation status of FF upon the following CT. The average preoperative ROM and clinical outcomes were compared between the three groups. The Fusion, Delayed Union, and Nonunion groups had 109, 14, and 13 patients, respectively. In the Nonunion group, the average ROM significantly decreased from 13.0° preoperatively to 4.9° postoperatively. There was a significant difference in the average preoperative ROM between the groups. The larger the preoperative ROM, the fewer facets fused. There was no significant difference in clinical outcomes between the groups. Five patients (3.7%) required revision surgery for adjacent segment disease 1-5.5 years after FF. Even nonunion cases after FF achieved good clinical outcomes, likely because the unstable spondylolisthesis was stabilized. FF did not require revision surgery for nonunion itself.

TRANSFORAMINAL INTERSOMATIC LUMBAR ARTHRODESIS: COMPARISON BETWEEN AUTOGRAFT AND CAGE IN PEEK

OBJECTIVE

To compare the postoperative outcomes of transforaminal intersomatic lumbar arthrodesis with structured iliac bone autograft and PEEK device.

METHODS

The total of 93 medical records of patients undergoing transforaminal intersomatic fusion between January 2012 and July 2017 with at least 1 year of postoperative follow-up, with complete medical record, containing clinical file and radiological exams, were reviewed.

RESULTS

From the medical records evaluated, 48 patients underwent the procedure with structured iliac autograft (group 1) and 45 with PEEK device (group 2). There was an improvement in functional capacity in both groups (p < 0.001), however there was no difference when comparing them (p = 0.591).

CONCLUSION

The postoperative clinical and radiological results of lumbar arthrodesis with TLIF technique, using a structured iliac bone autograft compared to a PEEK device, were similar. Level of Evidence II, Retrospective study.

What Are the Patient-reported Outcomes, Complications, and Radiographic Results of Lumbar Fusion for Degenerative Spondylolisthesis in Patients Younger Than 50 Years?

BACKGROUND

The number of young patients with degenerative lumbar spondylosis is expected to increase, and with it, the number of younger patients seeking surgical treatment is likely to rise. The goals of young patients with degenerative spondylolisthesis may differ from those of older patients, but little is known about the levels of pain and function, complication rates, or radiographic union that young patients achieve after interbody fusion.

QUESTIONS/PURPOSES

(1) How likely were patients younger than 50 years to achieve a minimal clinically important difference (MCID) in improvement on any of several validated patient-reported outcomes scores after transforaminal lumbar interbody fusion for degenerative spondylolisthesis at a minimum of 2 years after surgery? (2) What proportion developed complications or underwent reoperations? (3) What proportion achieved radiographic fusion or developed adjacent-segment degeneration?

METHODS

Longitudinally maintained institutional registry data of patients undergoing primary, single-level, transforaminal lumbar interbody fusion for degenerative spondylolisthesis at a single institution from 2006 to 2013 were studied in this retrospective case series. Of the 96 patients who met inclusion criteria, 14% (13 of 96) were missing follow-up data, leaving 83 patients younger than 50 years with complete clinical and radiological data at a minimum of 2 years (97%, 93 of 96 had sufficient data to assess complications and radiographic fusion). The mean age of the cohort was 44 ± 7 years. Radiological parameters for each patient with spondylolisthesis were recorded. Clinical outcomes such as the numeric rating scale for back pain and leg pain, Oswestry Disability Index (ODI) and SF-36 were assessed preoperatively and postoperatively at 1, 3, 6 months and 2 years. The proportion of patients who had an improvement greater than the MCID of each outcome instrument was then calculated. The occurrence of any medical, surgical or wound complications, and reoperations for any reason were recorded. Radiographic fusion using Bridwell grading and adjacent-segment degeneration were assessed by an independent observer not involved in clinical care. The mean follow-up was 5 ± 3 years.

RESULTS

The proportions of patients younger than 50 years who achieved the MCID for the various patient-reported outcomes were 82% (68 of 83) for leg pain, 75% (62 of 83) for back pain, 87% (72 of 83) for ODI and 71% (59 of 83) for SF-36 physical component summary at 2 years. Two perioperative complications occurred, and two reoperations were performed for implant-related complications. A total of 85% (79 of 93) of young patients achieved stable fusion, 8% (seven of 93) had radiologic adjacent-segment degeneration, and one patient underwent a revision procedure.

CONCLUSIONS

Young patients with lumbar degenerative spondylolisthesis commonly, but do not always, experience clinically meaningful gains in pain relief, function, and quality of life after transforaminal lumbar interbody fusion. A low risk of complications, reoperations, nonunion and adjacent-segment degeneration were also noted in this population.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Shorter Time to Surgery Is Associated With Better Outcomes for Spondylolisthesis in the Workers' Compensation Population

This study sought to determine the impact of time to surgery on clinical outcomes in patients with spondylolisthesis in the workers' compensation (WC) population. There is conflicting evidence regarding the effect of time to surgery on patients with spondylolisthesis. Patients receiving WC are known to have worse outcomes following spine surgery compared with the general population. A total of 791 patients from the Ohio Bureau of Workers' Compensation were identified who underwent lumbar fusion for spondylolisthesis between 1993 and 2013. The patients were divided into those who had surgery within 2 years of injury date and after 2 years. Confounding factors were corrected for in a multivariate logistic regression to determine predictors of return to work (RTW) status. Multivariate logistic regression determined that longer time to surgery (P=.003; odds ratio, 0.89 per year), age at index fusion (P=.003; odds ratio, 0.98 per year), and use of physical therapy before fusion (P=.008; odds ratio, 0.54) were negative predictors of RTW status. Patients who had surgery within 2 years were more likely to RTW and have fewer days absent from work, lower medical costs, and fewer sessions of psychotherapy, physical therapy, and chiropractor care. The authors demonstrated that for WC patients with spondylolisthesis, longer time to surgery was a negative predictor of RTW status. Patients who had surgery within 2 years of injury date were significantly more likely to RTW compared with after 2 years. [Orthopedics. 2020;43(3):154-160.].

Assessment of radiographic and clinical outcomes of an articulating expandable interbody cage in minimally invasive transforaminal lumbar interbody fusion for spondylolisthesis

OBJECTIVE The inability to significantly improve sagittal parameters has been a limitation of minimally invasive surgery for transforaminal lumbar interbody fusion (MIS TLIF). Traditional cages have a limited capacity to restore lordosis. This study evaluates the use of a crescent-shaped articulating expandable cage (Altera) for MIS TLIF. METHODS This is a retrospective review of 1- and 2-level MIS TLIF. Radiographic outcomes included differences in segmental and lumbar lordosis, disc height, evidence of fusion, and any endplate violations. Clinical outcomes included the numeric rating scale for leg and back pain and the Oswestry Disability Index (ODI) for low-back pain. RESULTS Thirty-nine patients underwent single-level MIS TLIF, and 5 underwent 2-level MIS TLIF. The mean age was 63.1 years, with 64% women. On average, spondylolisthesis was corrected by 4.3 mm (preoperative = 6.69 mm, postoperative = 2.39 mm, p < 0.001), the segmental angle was improved by 4.94° (preoperative = 5.63°, postoperative = 10.58°, p < 0.001), and segmental height increased by 3.1 mm (preoperative = 5.09 mm, postoperative = 8.19 mm, p < 0.001). At 90 days after surgery the authors observed the following: a smaller postoperative sagittal vertical axis was associated with larger changes in back pain at 90 days (r = -0.558, p = 0.013); a larger decrease in spondylolisthesis was associated with greater improvements in ODI and back pain scores (r = -0.425, p = 0.043, and r = -0.43, p = 0.031, respectively); and a larger decrease in pelvic tilt (PT) was associated with greater improvements in back pain (r = -0.548, p = 0.043). For the 1-year PROs, the relationship between the change in PT and changes in ODI and numeric rating scale back pain were significant (r = 0.612, p = 0.009, and r = -0.803, p = 0.001, respectively) with larger decreases in PT associated with larger improvements in ODI and back pain. Overall for this study there was a 96% fusion rate. Fourteen patients were noted to have endplate violation on intraoperative fluoroscopy during placement of the cage. Only 3 of these had progression of their subsidence, with an overall subsidence rate of 6% (3 of 49) visible on postoperative CT. CONCLUSIONS The use of this expandable, articulating, lordotic, or hyperlordotic interbody cage for MIS TLIF provides a significant restoration of segmental height and segmental lordosis, with associated improvements in sagittal balance parameters. Patients treated with this technique had acceptable levels of fusion and significant reductions in pain and disability.

Comparison of Posterior Lumbar Interbody Fusion and Microendoscopic Muscle-preserving Interlaminar Decompression for Degenerative Lumbar Spondylolisthesis With >5-Year Follow-up

STUDY DESIGN

Retrospective analysis of prospectively collected observational multicenter data.

OBJECTIVE

To compare the clinical results and rates of revision surgery after posterior lumbar interbody fusion (PLIF) and microendoscopic muscle-preserving interlaminar decompression (ME-MILD) in patients with single-level, mild degenerative lumbar spondylolisthesis (DLS) and follow-up of at least 5 years.

SUMMARY OF BACKGROUND DATA

Surgery for symptomatic DLS remains controversial. Evaluating long-term results may reveal problems such as adjacent segmental diseases of the PLIF and decreased quality of life because of slippage and restenosis of the ME-MILD.

METHODS

We enrolled 116 patients who underwent PLIF (79 patients) or ME-MILD (37 patients). Operative times, blood losses, surgical complications, Short-Form 36 (SF-36), Japanese Orthopedic Association (JOA) score, the JOA Back Pain Questionnaire (JOABPEQ), visual analog scales (VAS), and Zurich Claudication Questionnaire (ZCQ) were evaluated.

RESULTS

PLIF was observed to require significantly longer operative times and entailed greater operative blood losses than did ME-MILD (151.1 vs. 119.9 min; 202.2 vs. 6.4 mL, respectively). Surgery-related complications were identified in 3 cases in the PLIF group and 2 cases in the ME-MILD group. Seventy-eight patients (50 and 28 patients in the PLIF and ME-MILD groups, respectively) were successfully followed-up for >5 years. The follow-up rate was 67.2%. No significant differences between the groups were found in terms of preoperative and postoperative JOA scores, postoperative JOABPEQ, VAS, or ZCQ. Significant improvements in JOA scores were observed in both groups. Significant improvements in the SF-36 were observed in all subscales except in role physical, general health, vitality, and mental health in the ME-MILD group. Revision surgical procedures were performed in 2 patients in the ME-MILD group and 4 patients in the PLIF group.

CONCLUSIONS

PLIF and ME-MILD resulted in equivalent improvements in SF-36 and JOA scores. There were no differences in revision surgery rates among patients with single-level, mild DLS.

LEVEL OF EVIDENCE

Level III-a retrospective analysis.

Minimally Invasive Transforaminal Lumbar Interbody Fusion Using Banana-Shaped and Straight Cages: Radiological and Clinical Results from a Prospective Randomized Clinical Trial

BACKGROUND

In minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF), cage type and position play important roles in fusion achievement and sagittal alignment correction. However, no prospective randomized comparison of the results using different types of cage has been reported to date.

OBJECTIVE

To compare the radiological and clinical outcomes of unilateral MIS-TLIF using 2 types of cage.

METHODS

All candidates for single-level MIS-TLIF were randomized into banana-shaped cage and straight-cage groups. Plain radiographs and computed tomography scans were used for assessment of cage positions, fusion status, disc height, segmental lordotic angle, cage subsidence, and pelvic parameters. Clinical outcome was assessed using visual analog scale and Oswestry Disability Index scores.

RESULTS

Forty-four and 40 consecutive patients were operated on using banana-shaped and straight cages, respectively. Cage position was more anterior and lateral in the straight-cage group and more medial and posterior in the banana-shaped cage group. Solid fusion was achieved in 95.2% and 96.6% of the 2 groups, respectively, at 12 mo. The change in disc height and segmental lordotic angle postoperatively was significantly greater in the banana-shaped cage group. The incidence of subsidence during follow-up was significantly higher in the banana-shaped cage group (P < .04). Clinically, the visual analog scale and Oswestry Disability Index scores decreased significantly after surgery in both groups, with no significant difference between the groups.

CONCLUSION

Our preliminary outcomes suggest that the subsidence rate may be higher using banana-shaped cages in MIS-TLIF, possibly due to their more medial final position.

A Systematic Review of Complications Following Minimally Invasive Spine Surgery Including Transforaminal Lumbar Interbody Fusion

PURPOSE OF REVIEW

To assess complications after minimally invasive spinal surgeries including transforaminal lumbar interbody fusion (MI-TLIF) by reviewing the most recent literature.

RECENT FINDINGS

Current literature demonstrates that minimally invasive surgery (MIS) in spine has improved clinical outcomes and reduced complications when compared with open spinal procedures. Recent studies describing MI-TLIF primarily for degenerative disk disease, spondylolisthesis, and vertebral canal stenosis cite over 89 discrete complications, with the most common being radiculitis (ranging from 2.8 to 57.1%), screw malposition (0.3-12.7%), and incidental durotomy (0.3-8.6%). Minimally invasive spine surgery has a distinct set of complications in comparison with other spinal procedures. These complications vary based on the exact MIS procedure and indication. The most frequently documented MI-TLIF complications in current published literature were radiculitis, screw malposition, and incidental durotomy.

Device solutions for a challenging spine surgery: minimally invasive transforaminal lumbar interbody fusion (MIS TLIF)

INTRODUCTION

Lumbar interbody fusion remains a mainstay in the treatment of degenerative spinal pathology. Interbody devices are often used in an attempt to improve fusion rates and outcomes. Minimally invasive techniques lend unique advantages, but are challenging and often plagued with complications. Specifically, minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) has a steep learning curve and there is a lack of concise information on solutions to optimize outcomes.

AREAS COVERED

This review details an appropriate surgical technique of MIS TLIF and includes an overview of the components that go into a successful procedure. A thorough literature search of the PubMed database was completed to provide a comprehensive analysis of the interbody devices, posterolateral fixation, and osteobiologics.

EXPERT OPINION

MIS TLIFs have demonstrated successful clinical and radiographic outcomes and have become a mainstay for treating various degenerative lumbar pathologies. As minimally invasive techniques continue to evolve, devices and biologics will continue to expand the indications for MIS TLIFs and will optimize long-term outcomes.

Comparison of Postoperative Outcomes Between Primary MIS TLIF and MIS TLIF With Revision Decompression

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

To compare postoperative improvements in surgical and patient-reported outcomes (PROs) between patients undergoing minimally invasive laminectomy and minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) as a primary procedure to patients undergoing MIS laminectomy and TLIF as a revision to primary lumbar decompression (LD).

SUMMARY OF BACKGROUND DATA

MIS TLIF and LD have demonstrated to be effective surgical options for lumbar degenerative disease. However, some patients undergoing LD experience recurrent symptoms and eventually require a revision decompression with fusion.

METHODS

A prospectively maintained surgical database of patients who underwent a primary or revision one-level MIS TLIF for degenerative spinal pathology between 2014 and 2016 was reviewed. Consecutive patients undergoing primary MIS TLIF and revision lumbar discectomy and/or laminectomy were matched in a one-to-one fashion to primary MIS TLIF patients who had not undergone a previous LD by age and preoperative diagnosis. Differences in patient demographic, comorbidity, and perioperative characteristics between procedure groups were assessed using Pearson chi-squared analysis and Student t test for categorical and continuous variables, respectively. Improvements in PROs from preoperative values were compared between primary and revision cohorts using Student t tests. Pearson chi-squared analysis was used to compare rates of minimum clinically important difference achievement between procedure groups. Statistical significant was set at P < 0.05.

RESULTS

A total of 52 patients were included in this analysis. Twenty-six underwent primary MIS laminectomy and TLIF and 26 underwent MIS TLIF with a revision decompression. No differences in baseline or perioperative variables were observed. Revision and primary MIS TLIF patients experienced similar improvements in PROs at all postoperative time points.

CONCLUSION

The results of the present study demonstrate patients undergoing primary MIS TLIF with LD as a revision to a primary decompression experienced similar postoperative improvements in PROs as compared to primary MIS TLIF patients. This indicates a primary decompression does not compromise clinical outcomes in patients undergoing MIS TLIF. As such, patients should not be precluded from undergoing MIS TLIF based on the history of a previous LD.

LEVEL OF EVIDENCE

3.

Radiographic and Clinical Outcomes of Oblique Lateral Interbody Fusion Versus Minimally Invasive Transforaminal Lumbar Interbody Fusion for Degenerative Lumbar Disease

BACKGROUND

The effects of oblique lateral interbody fusion (OLIF) and minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) have not been compared by a meta-analysis. The present study aimed to summarize the radiographic and clinical outcomes of OLIF and MI-TLIF for degenerative lumbar disease.

METHODS

We performed a systematic review of related studies and report the outcomes of OLIF and MI-TLIF for degenerative lumbar disease. The radiographic outcomes measures included disc height, segmental lordotic angle, lumbar lordotic angle, and fusion. The clinical and functional outcomes included operative blood loss, operative time, length of hospital stay, complications, visual analog scale, and Oswestry disability index. Data pooling and meta-analysis with the random effects model were performed to evaluate the results.

RESULTS

A total of 47 studies met the inclusion criteria. Similar changes in terms of disc height, segmental lordotic angle, lumbar lordotic angle, length of hospital stay, visual analog scale, Oswestry disability index, and radiological evidence of fusion of >90% were observed between the 2 groups. The OLIF group showed less operative blood loss and operative time. The incidence of intraoperative and postoperative complications was 9.5% and 19.9% for the OLIF group and 3.5% and 8.5% for the MI-TLIF group, respectively.

CONCLUSIONS

The radiographic and functional outcomes and length of hospital stay were similar between the 2 groups. The OLIF group showed advantages in operative blood loss and operative time; however, the incidence of complications in this technique was greater than that in the MI-TLIF group.

Minimally Invasive Lumbar Spinal Fusion Is More Effective Than Open Fusion: A Meta-Analysis

PURPOSE

To evaluate the efficacy of minimally invasive spinal fusion in comparison to open fusion for adult lumbar spondylolisthesis or spondylosis.

MATERIALS AND METHODS

The present study was conducted as a meta-analysis of all estimates from studies that were selected after comprehensive literature search by two independent reviewers.

RESULTS

Of 745 articles, nine prospective cohort studies were identifed. The quality of evidence was downgraded because of study design, inconsistency, imprecision, and publication bias. Greater Oswestry Disability Index score improvement [weighted mean difference (WMD), 3.2; 95% confdence interval (CI), 1.5 to 5.0; p=0.0003] and a lower infection rate (odds ratio, 0.3; 95% CI, 0.1 to 0.9; p=0.02) were observed in the minimally invasive group (low-quality evidence). The minimally invasive group had less blood loss (WMD, 269.5 mL; 95% CI, 246.2 to 292.9 mL; p<0.0001), a shorter hospital stay (WMD, 1.3 days; 95% CI, 1.1 to 1.5 days, p<0.0001), and longer operation time (WMD, 21.0 minutes; 95% CI, 15.9 to 26.2 minutes; p<0.0001) and radiation exposure time(WMD, 25.4 seconds; 95% CI, 22.0 to 28.8 seconds, p<0.0001) than the open group (low-quality evidence). There were no significant differences in pain improvement, fusion rate, complications, or subsequent surgeries between the two treatment groups (low-quality evidence).

CONCLUSION

Although present findings are limited by insufficient evidence and there is a lack of adequately powered high-quality randomized controlled trials to address this gap in evidence, our results support that minimally invasive lumbar fusion is more effective than open fusion for adult spondylolisthesis and other spondylosis in terms of functional improvement, reducing infection rate, and decreasing blood loss and hospital stay.

Spinal Biologics in Minimally Invasive Lumbar Surgery

As the use of minimally invasive spine (MIS) fusion approaches continues to grow, increased scrutiny is being placed on its outcomes and efficacies against traditional open fusion surgeries. While there are many factors that contribute to the success of achieving spinal arthrodesis, selecting the optimal fusion biologic remains a top priority. With an ever-expanding market of bone graft substitutes, it is important to evaluate each of their use as it pertains to MIS techniques. This review will summarize the important characteristics and properties of various spinal biologics used in minimally invasive lumbar surgeries and compare their fusion rates via a systematic review of published literature.

Is Body Mass Index a Risk Factor for Revision Procedures After Minimally Invasive Transforaminal Lumbar Interbody Fusion?

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To determine if an association exists between body mass index (BMI) and the rate of revision surgery after single-level minimally invasive transforaminal lumbar interbody fusion (MIS TLIF).

SUMMARY OF BACKGROUND DATA

MIS TLIF is an effective treatment for lumbar degenerative disease. Previous studies in the orthopedic literature have associated increased BMI with increased postoperative complications and need for revision. Few studies have evaluated the association between BMI and the risk for revision after minimally invasive spinal procedures.

MATERIALS AND METHODS

A surgical registry of patients who underwent a single-level MIS TLIF for degenerative pathology between 2005 and 2014 was reviewed. Patients were stratified based on BMI category: normal weight (BMI<25), overweight (BMI, 25-29.9), obese I (BMI, 30-34.9), and obese II-III (BMI≥35). BMI category was tested for association with demographic and procedural characteristics using 1-way analysis of variance (ANOVA) for continuous variables, and χ analysis or the Fisher exact test for categorical variables. BMI category was tested for association with undergoing a revision fusion procedure within 2 years after MIS TLIF using multivariate Cox proportional hazards survival analysis modeling.

RESULTS

In total, 274 patients were analyzed; of these, 52 (18.98%) were normal weight, 101 (36.86%) were overweight, 62 (22.63%) were obese I, and 59 (21.53%) were obese II-III. On multivariate Cox proportional hazards survival analysis modeling, BMI category was not associated with undergoing a revision procedure within 2 years after MIS TLIF (P=0.599). On multivariate analysis, younger age (P=0.004) was associated with increased risk of undergoing a revision after MIS TLIF.

CONCLUSIONS

The results of this study suggest that increasing BMI is not a risk factor for undergoing a revision procedure after MIS TLIF. As such, patients with high BMI should be counseled regarding having similar rates of needing a revision procedure after MIS TLIF as those with lower BMI.

LEVEL OF EVIDENCE

Level IV.

Minimally invasive techniques for lumbar decompressions and fusions

PURPOSE OF REVIEW

The purpose of this study is to summarize the recent literature investigating the use of minimally invasive (MIS) techniques in the treatment of lumbar degenerative stenosis, spondylolisthesis, and scoliosis.

RECENT FINDINGS

MIS lumbar decompression and fusion techniques for degenerative pathology are associated with reduced operative morbidity, shortened length of hospital stay, and reduced postoperative pain and narcotics utilization. Recent studies with long-term clinical follow-up have demonstrated equivalence in clinical outcomes between open and MIS surgical procedures. Radiographically, MIS procedures provide adequate postoperative correction of coronal alignment. Correction of sagittal alignment, however, is more variable based on current reports. MIS techniques are both safe and effective in the treatment of lumbar degenerative pathologies. While some studies have reported on long-term outcomes and costs associated with MIS procedures, more investigation into these topics is still necessary. Additionally, further work is required to analyze the training requirements and learning curves of MIS procedures to better promote adoption amongst surgeons.

Clinical outcomes after minimally invasive transforaminal lumbar interbody fusion and lateral lumbar interbody fusion for treatment of degenerative lumbar disease: a systematic review and meta-analysis

The surgical procedures used for arthrodesis in the lumbar spine for degenerative lumbar diseases remain controversial. This systematic review aims to assess and compare clinical outcomes along with the complications and fusion of each technique (minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) or minimally invasive lateral lumbar interbody fusion (MIS LLIF)) for treatment of degenerative lumbar diseases. Relevant studies were identified from Medline and Scopus from inception to July 19, 2016 that reported Oswestry Disability Index (ODI), back and leg pain visual analog score (VAS), postoperative complications, and fusion of either technique. Fifty-eight studies were included for the analysis of MIS-TLIF; 40 studies were included for analysis of LLIF, and 1 randomized controlled trial (RCT) study was included for comparison of MIS-TLIF to LLIF. Overall, there were 9506 patients (5728 in the MIS-TLIF group and 3778 in the LLIF group). Indirect meta-analysis, MIS-TLIF provided better postoperative back and leg pain (VAS), disabilities (ODI), and risk of having complications when compared to LLIF technique, but the fusion rate was not significantly different between the two techniques. However, direct meta-analysis between RCT study and pooled indirect meta-analysis of MIS-TLIF have better pain, disabilities, and complication but no statistically significant difference when compared to LLIF. In LLIF, the pooled mean ODI and VAS back pain were 2.91 (95% CI 2.49, 3.33) and 23.24 (95% CI 18.96, 27.51) in MIS approach whereas 3.14 (95% CI 2.29, 4.04) and 28.29 (95% CI 21.92, 34.67) in traditional approach. In terms of complications and fusion rate, there was no difference in both groups. In lumbar interbody fusion, MIS-TLIF had better ODI, VAS pain, and complication rate when compared to LLIF with direct and indirect meta-analysis methods. However, in terms of fusion rates, there were no differences between the two techniques.

Patient-reported and radiographic outcomes of minimally invasive transforaminal lumbar interbody fusion for degenerative spondylolisthesis with or without reduction: A comparative study

This retrospective study aimed to compare the patient-reported outcomes and radiographic assessment of minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) for degenerative spondylolisthesis with reduction versus in situ fusion. Patients receiving MI-TLIF with reduction were assigned as Group A, and those without reduction were assigned as Group B. Radiographic fusion was assessed using Bridwell's grading criteria. Preoperative and postoperative patient-reported outcomes including visual analogue score (VAS), Oswestry Disability Index (ODI), Japanese Orthopedic Association (JOA) scale and improvement rate were analyzed. There were 41 patients in Group A and 37 patients in Group B. The mean follow-up was 30.78±14.15months in Group A and 28.95±10.75months in Group B (p=0.525). There were no significant differences in hospital stay (p=0.261), estimated blood loss (p=0.639), blood transfusion (p=0.336), operation time (p=0.762) and complications (p=1.00) between the two groups. Radiographic fusion rate was 92.68% (38/41) in Group A, and 81.08% (30/37) in Group B (p=0.110). Significant differences were observed in either 3-month or last follow-up JOA, VAS, and ODI compared with preoperative JOA, VAS, and ODI, respectively (p<0.05). However, there were no significant differences in JOA, VAS, and ODI between the two groups whenever preoperatively, or 3-month postoperatively, or at the last follow-up (p>0.05). According to MacNab criteria, the excellent and good rate was 85.37% in Group A and 86.49% in Group B (p=0.983). MI-TLIF is an effective and satisfactory surgical technique to manage degenerative spondylolisthesis regardless of reduction or not, so routine reduction may not be a requirement in MI-TLIF for degenerative spondylolisthesis.

Minimally Invasive Transforaminal Lumbar Interbody Fusion at L5-S1 through a Unilateral Approach: Technical Feasibility and Outcomes

Background. Minimally invasive spinal transforaminal lumbar interbody fusion (MIS-TLIF) at L5-S1 is technically more demanding than it is at other levels because of the anatomical and biomechanical traits. Objective. To determine the clinical and radiological outcomes of MIS-TLIF for treatment of single-level spinal stenosis low-grade isthmic or degenerative spondylolisthesis at L5-S1. Methods. Radiological data and electronic medical records of patients who underwent MIS-TLIF between May 2012 and December 2014 were reviewed. Fusion rate, cage position, disc height (DH), disc angle (DA), disc slope angle, segmental lordotic angle (SLA), lumbar lordotic angle (LLA), and pelvic parameters were assessed. For functional assessment, the visual analogue scale (VAS), Oswestry disability index (ODI), and patient satisfaction rate (PSR) were utilized. Results. A total of 21 levels in 21 patients were studied. DH, DA, SLA, and LLA had increased from their preoperative measures at the final follow-up. Fusion rate was 86.7% (18/21) at 12 months' follow-up. The most common cage position was anteromedial (15/21). The mean VAS scores for back and leg pain mean ODI scores improved significantly at the final follow-up. PSR was 88%. Cage subsidence was observed in 33.3% (7/21). Conclusions. The clinical and radiologic outcomes after MIS-TLIF at L5-S1 in patients with spinal stenosis or spondylolisthesis are generally favorable.

Thirty-Day Reoperation and Readmission Rates After Correction of Adult Spinal Deformity via Circumferential Minimally Invasive Surgery-Analysis of a 7-Year Experience

STUDY DESIGN

Single-center retrospective analysis of consecutive patients who have undergone circumferential minimally invasive surgery (cMIS) for correction of adult spinal deformity (ASD).

OBJECTIVES

To study the rates of reoperations and readmissions within the first 30 days following cMIS for correction of ASD.

BACKGROUND

Hospital readmission and reoperation rates have been emphasized as an important measure of quality and cost-effectiveness of care. However, there is little information about the readmission rates following cMIS correction of ASD.

METHODS

This is a retrospective cohort study of 214 consecutive patients with ASD who underwent correction using cMIS involving at least 2 levels. Major complications encountered during surgery or within 30 days following the index procedure that needed reoperation or readmission were recorded. The primary outcomes measured were early readmission, and early reoperation.

RESULTS

An average of 4 levels were fused. Nineteen complications were noted in the 30-day period following the index surgery, giving an early complication rate of 8.9%. Twelve of those complications occurred during the initial hospitalization and 7 complications occurred after the patient had been discharged home. Forty-seven percent of the complications occurred within the first 3 years of our experience, 37% in the next 2 years, and only 16% in the following 3 years. The 30-day readmission rate was 3.3%, which showed no statistically significant difference based on the number of levels fused.

CONCLUSIONS

Our study delivers significant evidence that efforts to reduce hospital readmissions for ASD patients should begin by concentrating on the postoperative complications. Although minimally invasive approaches will not eliminate all complications, they may have an effect on reducing the rate of major complications, most notably the rate of postoperative infection. This in turn can lead to a substantially lower readmission and reoperation rate as is reported in our study.

LEVEL OF EVIDENCE

Level IV, case series.

Minimally Invasive Transforaminal Lumbar Interbody Fusion for Spondylolisthesis: Comparison Between Isthmic and Degenerative Spondylolisthesis

INTRODUCTION

Minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) is a common surgical option for degenerative spondylolisthesis (DS). However, its effectiveness for isthmic spondylolisthesis (IS) is still controversial. No current studies have directly compared perioperative and postoperative results including various radiological parameters between IS and DS after MIS TLIF.

PURPOSE

The purpose of this study is to compare the clinical and radiological results between isthmic and degenerative spondylolisthesis after MIS TLIF.

METHODS

This is a retrospective study of 41 patients who underwent MIS TLIF for single-segment, grade 1 or 2 IS (n = 18) and DS (n = 23). The same surgical techniques and procedure were applied to both groups. Perioperative outcomes (operation time, blood loss, hospital stay, complications); clinical outcomes (visual analog scale [VAS], Oswestry Disability Index [ODI]); radiological parameters (disk height, degree of spondylolisthesis, slip angle, lumbar lordosis, segmental lordosis, sacropelvic parameters: pelvic incidence, sacral slope, pelvic tile); and fusion rates using computed tomography scanning were compared between groups at 1 year postoperatively.

RESULTS

There were no significantly different perioperative results between groups. Mean VAS and ODI scores improved significantly postoperatively in both groups but were not significantly different between groups at each follow-up point. Radiological parameters were not significantly different between groups except disk height and degree of spondylolisthesis. The disk heights were increased postoperatively (IS: 6.79-9.22 mm; DS: 8.18-8.97 mm) in both groups, and there were significant differences preoperatively. In addition, disk height restoration was greater for IS than DS (2.43 mm vs. 0.79 mm, P = 0.01). However, postoperative disk heights were not significantly different between groups. The degree of spondylolisthesis was significantly different between groups both preoperatively (16.77% vs. 11.33%, P < 0.01) and postoperatively (9.79% vs. 3.78%, P < 0.01). However, slip reduction was no different between groups (6.97 vs. 7.56%, P = 0.74). Fusion rates were not significantly different between groups.

CONCLUSIONS

MIS TLIF resulted in similar clinical outcomes when used to treat both isthmic and degenerative spondylolisthesis. Although disk height restoration was more effective for IS than DS, other radiological parameters including fusion rate were no different between groups. For both isthmic and degenerative spondylolisthesis, MIS TLIF can be a safe and effective surgical option.