Common surgical complications in degenerative spinal surgery

The influence of lumbar vertebra and cage related factors on cage-endplate contact after lumbar interbody fusion: An in-vitro experimental study

Lumbar interbody fusion (LIF) using interbody cages is an established treatment for lumbar degenerative disc disease, but fusion results are known to be affected by risk factors such as bone mineral density (BMD), endplate geometry and cage position. At present, direct measurement of endplate-cage contact variables that affect LIF have not been fully identified. The aim of this study was to use cadaveric experiments to investigate the dependency between BMD, endplate geometry, cage parameters like type, orientation, position, and contact variables like stress and area. One vertebral body specimen from each of the five lumbar positions was harvested from five male donors. The lower half of each vertebra was potted and placed in a material testing machine (Instron 8874). A spinal cage was clamped to the machine then lowered to bring it into contact against the superior endplate. A lockable ball-joint was used to rotate the cage such that its inferior surface was congruent with the local endplate surface. A pressure sensor (Tekscan) was placed between the cage and endplate to record contact area and the peak and average contact pressures. Axial compression of 400 N was performed for five positions using a straight cage, and in one anterior position using a curved cage. The linear mixed model was utilised to perform data analyses for experimental results with statistical significance set at p < 0.05. The results indicated two trends toward significance for contact area, one for volumetric BMD (vBMD) of the vertebra (p = 0.081), and another for predicted contact area (p = 0.057). Peak contact pressure correlated significantly with vBMD (p = 0.041), and there was a trend between average contact pressure and lateral position of cage (p = 0.051). In addition, predicted contact area correlated significantly with cage orientation (p < 0.001). These results indicated that high vBMD of vertebra and a medially positioned cage led to higher contact pressures. Logically, low vBMD of vertebra and transverse cage orientation increased the contact area between the cage and endplate. In conclusion, the study identified significant influence of vBMD of vertebra, cage position and orientation on cage-endplate contact which may help to inform cage selection and design for LIF.

Pulsed Electromagnetic Fields for Cervical Spine Fusion in Patients with Risk Factors for Pseudarthrosis

Background

Certain demographics and/or risk factors contribute to complications following cervical spinal surgery including pseudarthrosis, prolonged pain, and reduced quality of life (QoL). Pulsed electromagnetic field (PEMF) stimulation is a non-invasive therapy that may enhance fusion success in at-risk patients.

Objective

To evaluate the safety and efficacy of post-operative adjunctive PEMF therapy following cervical spinal surgery in subjects at risk for pseudarthrosis.

Methods

This prospective, multicenter study investigated PEMF as an adjunctive therapy to cervical spinal fusion procedures in subjects at risk for pseudarthrosis based on having at least one of the following: prior failed fusion, multi-level fusion, nicotine use, osteoporosis, or diabetes. Radiographic fusion status and patient-reported outcomes (SF-36, EQ5D, NDI, and VAS-arm pain and VAS-neck pain) were assessed.

Results

A total of 160 subjects were assessed for fusion 12-months postoperative, and 144 subjects were successfully fused (90.0%). Fusion success for subjects with 1, 2+, or 3+ risk factors was 91.7%, 89.0%%, and 90.9%, respectively. Significant improvements in NDI, VAS-arm and VAS-neck were observed compared to baseline scores (p < 0.001) along with improvements in SF-36 and EQ5D (p < 0.001).

Conclusions

Adjunctive treatment with PEMF provides a high rate of successful fusion and significant improvements in pain, function, and quality of life despite having risk factors for pseudarthrosis.

Challenges in Contemporary Spine Surgery: A Comprehensive Review of Surgical, Technological, and Patient-Specific Issues

Spine surgery has significantly progressed due to innovations in surgical techniques, technology, and a deeper understanding of spinal pathology. However, numerous challenges persist, complicating successful outcomes. Anatomical intricacies at transitional junctions demand precise surgical expertise to avoid complications. Technical challenges, such as underestimation of the density of fixed vertebrae, individual vertebral characteristics, and the angle of pedicle inclination, pose additional risks during surgery. Patient anatomical variability and prior surgeries add layers of difficulty, often necessitating thorough pre- and intraoperative planning. Technological challenges involve the integration of artificial intelligence (AI) and advanced visualization systems. AI offers predictive capabilities but is limited by the need for large, high-quality datasets and the "black box" nature of machine learning models, which complicates clinical decision making. Visualization technologies like augmented reality and robotic surgery enhance precision but come with operational and cost-related hurdles. Patient-specific challenges include managing postoperative complications such as adjacent segment disease, hardware failure, and neurological deficits. Effective patient outcome measurement is critical, yet existing metrics often fail to capture the full scope of patient experiences. Proper patient selection for procedures is essential to minimize risks and improve outcomes, but criteria can be inconsistent and complex. There is the need for continued technological innovation, improved patient-specific outcome measures, and enhanced surgical education through simulation-based training. Integrating AI in preoperative planning and developing comprehensive databases for spinal pathologies can aid in creating more accurate, generalizable models. A holistic approach that combines technological advancements with personalized patient care and ongoing education is essential for addressing these challenges and improving spine surgery outcomes.

Do nutritional assessment tools (PNI, CONUT, GNRI) predict adverse events after spinal surgeries? A systematic review and meta-analysis

BACKGROUND

Nutritional assessment tools are used to predict outcomes in cancer. However, their utility in patients undergoing spinal surgery is unclear. This review examined if prognostic nutritional index (PNI), controlling nutritional status (CONUT), and geriatric nutritional risk index (GNRI) can predict adverse events after spinal surgeries.

METHODS

PubMed, CENTRAL, Scopus, and Embase were screened by two reviewers for relevant studies up to 26th January 2024. The primary outcome of interest was total adverse events after spinal surgery. Secondary outcomes were surgical site infections (SSI) and mortality.

RESULTS

14 studies were included. Meta-analysis showed that while reduced PNI was not associated with an increased risk of SSI there was a significant association between PNI and higher risk of adverse events. Meta-analysis showed that high CONUT was not associated with an increased risk of complications after spinal surgeries. Pooled analysis showed that low GNRI was associated with an increased risk of both SSI and adverse events. Data on mortality was scarce.

CONCLUSIONS

The PNI and GNRI can predict adverse outcomes after spinal surgeries. Limited data shows that high CONUT is also associated with a non-significant increased risk of adverse outcomes. High GNRI was predictive of an increased risk of SSI. Data on mortality is too scarce for strong conclusions.

Impact of surgical risk factors for non-union on lumbar spinal fusion outcomes using cellular bone allograft at 24-months follow-up

BACKGROUND

The current report investigates fusion rates and patient-reported outcomes following lumbar spinal surgery using cellular bone allograft (CBA) in patients with risk factors for non-union.

METHODS

A prospective, open label study was conducted in subjects undergoing lumbar spinal fusion with CBA (NCT02969616) to assess fusion success rates and patient-reported outcomes in subjects with risk factors for non-union. Subjects were categorized into low-risk (≤ 1 risk factors) and high-risk (> 1 risk factors) groups. Radiographic fusion status was evaluated by an independent review of dynamic radiographs and CT scans. Patient-reported outcome measures included quality of life (EQ-5D), Oswestry Disability Index (ODI) and Visual Analog Scales (VAS) for back and leg pain. Adverse event reporting was conducted throughout 24-months of follow-up.

RESULTS

A total of 274 subjects were enrolled: 140 subjects (51.1%) were categorized into the high-risk group (> 1 risk factor) and 134 subjects (48.9%) into the low-risk group (≤ 1 risk factors). The overall mean age at screening was 58.8 years (SD 12.5) with a higher distribution of females (63.1%) than males (36.9%). No statistical difference in fusion rates were observed between the low-risk (90.0%) and high-risk (93.9%) groups (p > 0.05). A statistically significant improvement in patient-reported outcomes (EQ-5D, ODI and VAS) was observed at all time points (p < 0.05) in both low and high-risk groups. The low-risk group showed enhanced improvement at multiple timepoints in EQ-5D, ODI, VAS-Back pain and VAS-Leg pain scores compared to the high-risk group (p < 0.05). The number of AEs were similar among risk groups.

CONCLUSIONS

This study demonstrates high fusion rates following lumbar spinal surgery using CBA, regardless of associated risk factors. Patient reported outcomes and fusion rates were not adversely affected by risk factor profiles.

TRIAL REGISTRATION

NCT02969616 (21/11/2016).

Exploring the Thoracolumbar Interfascial Plane (TLIP) Block as a Novel Approach for Improved Pain Management After Spine Surgery: A Comparative Review

Postoperative pain management following spine surgery remains a significant challenge, often requiring multimodal approaches to achieve adequate analgesia while minimizing side effects. The thoracolumbar interfascial plane (TLIP) block has emerged as a novel regional anesthesia technique for addressing this issue. By targeting the interfascial plane between the erector spinae and quadratus lumborum muscles at the thoracolumbar junction, the TLIP block aims to provide targeted analgesia to the surgical site while reducing systemic opioid requirements. This review explores the anatomy, technique, mechanism of action, and clinical evidence supporting the TLIP block for post-spine surgery pain management. Additionally, it compares the TLIP block with traditional pain management approaches and discusses its implications for clinical practice and future research. Overall, the TLIP block shows promise as an effective and potentially safer alternative for post-spine surgery pain management, potentially improving patient outcomes and enhancing recovery. Further research is warranted to optimize its utilization and comprehensively evaluate its long-term effects.

Adjunctive Use of Bone Growth Stimulation Increases Cervical Spine Fusion Rates in Patients at Risk for Pseudarthrosis

STUDY DESIGN

A prospective multicenter clinical trial (NCT03177473) was conducted with a retrospective cohort used as a control arm.

OBJECTIVE

The purpose of this study was to evaluate cervical spine fusion rates in subjects with risk factors for pseudarthrosis who received pulsed electromagnetic field (PEMF) treatment.

SUMMARY OF BACKGROUND DATA

Certain risk factors predispose patients to pseudarthrosis, which is associated with prolonged pain, reduced function, and decreased quality of life.

METHODS

Subjects in the PEMF group were treated with PEMF for 6 months postoperatively. The primary outcome measure was fusion status at the 12-month follow-up period. Fusion status was determined using anterior/posterior, lateral, and flexion/extension radiographs and computed tomography (without contrast).

RESULTS

A total of 213 patients were evaluated (PEMF, n=160; Control, n=53). At baseline, the PEMF group had a higher percentage of subjects who used nicotine ( P =0.01), had osteoporosis ( P <0.05), multi-level disease ( P <0.0001), and were >65 years of age ( P =0.01). The PEMF group showed over two-fold higher percentage of subjects that had ≥3 risk factors (n=92/160, 57.5%) compared with the control group (n=14/53, 26.4%). At the 12-month follow-up, the PEMF group demonstrated significantly higher fusion rates compared with the control (90.0% vs. 60.4%, P <0.05). A statistically significant improvement in fusion rate was observed in PEMF subjects with multi-level surgery ( P <0.0001) and high BMI (>30 kg/m 2 ; P =0.0021) when compared with the control group. No significant safety concerns were observed.

CONCLUSIONS

Adjunctive use of PEMF stimulation provides significant improvements in cervical spine fusion rates in subjects having risk factors for pseudarthrosis. When compared with control subjects that did not use PEMF stimulation, treated subjects showed improved fusion outcomes despite being older, having more risk factors for pseudarthrosis, and undergoing more complex surgeries.

Pulsed Electromagnetic Field Stimulation in Lumbar Spine Fusion for Patients With Risk Factors for Pseudarthrosis

BACKGROUND

Lumbar spinal fusion surgeries are increasing steadily due to an aging and ever-growing population. Patients undergoing lumbar spinal fusion surgery may present with risk factors that contribute to complications, pseudarthrosis, prolonged pain, and reduced quality of life. Pulsed electromagnetic field (PEMF) stimulation represents an adjunct noninvasive treatment intervention that has been shown to improve successful fusion and patient outcomes following spinal surgery.

METHODS

A prospective, multicenter study investigated PEMF as an adjunct therapy to lumbar spinal fusion procedures in patients at risk for pseudarthrosis. Patients with at least 1 of the following risk factors were enrolled: prior failed fusion, multilevel fusion, nicotine use, osteoporosis, or diabetes. Fusion status was determined by radiographic imaging, and patient-reported outcomes were also evaluated.

RESULTS

A total of 142 patients were included in the analysis. Fusion status was assessed at 12 months follow-up where 88.0% (n = 125/142) of patients demonstrated successful fusion. Fusion success for patients with 1, 2+, or 3+ risk factors was 88.5%, 87.5%, and 82.3%, respectively. Significant improvements in patient-reported outcomes using the Short Form 36, EuroQol 5 Dimension (EQ-5D) survey, Oswestry Disability Index, and visual analog scale for back and leg pain were also observed compared with baseline scores (P < 0.001). A favorable safety profile was observed. PEMF treatment showed a positive benefit-risk profile throughout the 6-month required use period.

CONCLUSIONS

The addition of PEMF as an adjunct treatment in patients undergoing lumbar spinal surgery provided a high rate of successful fusion with significant improvements in pain, function, and quality of life, despite having risk factors for pseudarthrosis.

CLINICAL RELEVANCE

PEMF represents a useful tool for adjunct treatment in patients who have undergone lumbar spinal surgery. Treatment with PEMF may result in improved fusion and patient-reported outcomes, regardless of risk factors.

TRIAL REGISTRATION

NCT03176303.

Influence of the geometric and material properties of lumbar endplate on lumbar interbody fusion failure: a systematic review

Background

Lumbar interbody fusion (LIF) is an established surgical intervention for patients with leg and back pain secondary to disc herniation or degeneration. Interbody fusion involves removal of the herniated or degenerated disc and insertion of interbody devices with bone grafts into the remaining cavity. Extensive research has been conducted on operative complications such as a failure of fusion or non-union of the vertebral bodies. Multiple factors including surgical, implant, and patient factors influencing the rate of complications have been identified. Patient factors include age, sex, osteoporosis, and patient anatomy. Complications can also be influenced by the interbody cage design. The geometry of the bony endplates as well as their corresponding material properties guides the design of interbody cages, which vary considerably across patients with spinal disorders. However, studies on the effects of such variations on the rate of complications are limited. Therefore, this study aimed to perform a systematic review of lumbar endplate geometry and material property factors in LIF failure.

Methods

Search keywords included ‘factor/cause for spinal fusion failure/cage subsidence/cage migration/non-union’, ‘lumbar’, and ‘interbody’ in electronic databases PubMed and Scopus with no limits on year of publication.

Results

In total, 1341 articles were reviewed, and 29 articles were deemed suitable for inclusion. Adverse events after LIF, such as cage subsidence, cage migration, and non-union, resulted in fusion failure; hence, risk factors for adverse events after LIF, notably those associated with lumbar endplate geometry and material properties, were also associated with fusion failure. Those risk factors were associated with shape, concavity, bone mineral density and stiffness of endplate, segmental disc angle, and intervertebral disc height.

Conclusions

This review demonstrated that decreased contact areas between the cage and endplate, thin and weak bony endplate as well as spinal diseases such as spondylolisthesis and osteoporosis are important causes of adverse events after LIF. These findings will facilitate the selection and design of LIF cages, including customised implants based on patient endplate properties.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-022-03091-8.

SPECT/CT in the Evaluation of Suspected Skeletal Pathology

Dedicated multi-slice single-photon emission computed tomography/computed tomography (SPECT/CT) cameras have become widely available and are becoming a mainstay of clinical practice. The integration of SPECT and CT allow for precise anatomic location of scintigraphic findings. Fusion imaging with SPECT/CT can improve both sensitivity and specificity by reducing equivocal interpretation in comparison to planar scintigraphy or SPECT alone. This review article addresses the technique, basic science principles, and applications of integrated SPECT/CT in the evaluation of musculoskeletal pathology.

True Differences in Poor Outcome Risks Between Revision and Primary Lumbar Spine Surgeries

Background: Previous studies have shown that the rates of complications associated with revision spine surgery are higher than those of primary spine surgery. However, there is a lack of research exploring the difference in magnitude of risk of poor outcomes between primary and revision lumbar spine surgeries. Purposes: We sought to compare the risks of poor outcomes for primary and revision lumbar spine surgeries and to analyze different measures of risk to better understand the true differences between the 2 forms of surgery. Methods: This retrospective observational study used data from the Quality Outcomes Database Lumbar Spine Surgical Registry from 2012 to 2018. We included individuals who received primary or revision surgery due to degenerative lumbar disorders. Outcome variables collected were complications within 30 days of surgery and 3 destination variables, specifically, (1) 30-day hospital readmission, (2) 30-day return to operating room, and (3) revision surgery within 3 months. Measures of risk considered were odds ratio (OR), relative risk (RR), relative risk increase (RRI), and absolute risk increase (ARI). Results: There were 31,843 individuals who received primary surgery and 7889 who received revision surgery. After controlling for baseline descriptive variables and comorbidities, revision surgery increased the odds of 4 complications and all 3 destination variables. Risk ratios reflected smaller magnitudes but similar findings as the statistically significant ORs. Conclusion: Revision surgery is related to higher overall risks than primary surgery, but the true magnitudes of these risks are very small. RRI and ARI should be included when reporting ORs to better clarify the significance.

Optimal "Low" Pedicle Screw Stimulation Threshold to Predict New Postoperative Lower-Extremity Neurologic Deficits During Lumbar Spinal Fusions

OBJECTIVE

Previous studies have shown that pedicle screw stimulation thresholds ≤6-8 mA yield a high diagnostic accuracy of detecting misplaced screws. Our objective was to determine the optimal "low" stimulation threshold to predict new postoperative neurologic deficits and identify additional risk factors associated with deficits.

METHODS

We included patients with complete pedicle screw stimulation testing who underwent posterior lumbar spinal fusion surgeries from 2010-2012. We calculated the diagnostic accuracy of pedicle screw responses of ≤4 mA, ≤6 mA, ≤8 mA, ≤10 mA, ≤12 mA, and ≤20 mA to predict new postoperative lower-extremity (LE) neurologic deficits. We used multivariate modeling to determine the best logistic regression model to predict LE deficits and identify additional risk factors. Statistics software packages used were Python3.8.5, NumPy 1.19.1, Pandas 1.1.1, and SPSS26.

RESULTS

We studied 1179 patients who underwent 8584 pedicle screw stimulations with somatosensory evoked potential and free-run electromyographic monitoring for posterior lumbar spinal fusion. Twenty-five (2.1%) patients had new LE neurologic deficits. A stimulation threshold of ≤8 mA had a sensitivity/specificity of 32%/90% and a diagnostic odds ratio/area under the curve of 4.34 [95% confidence interval: 1.83, 10.27]/0.61 [0.49, 0.74] in predicting postoperative deficit. Multivariate analysis showed that patients who had pedicle screws with stimulation thresholds ≤8 mA are 3.15 [1.26, 7.83]× more likely to have postoperative LE deficits while patients who have undergone a revision lumbar spinal fusion surgery are 3.64 [1.38, 9.61]× more likely.

CONCLUSIONS

Our results show that low thresholds are indicative of not only screw proximity to the nerve but also an increased likelihood of postoperative neurologic deficit. Thresholds ≤8 mA prove to be the optimal "low" threshold to help guide a correctly positioned pedicle screw placement and detect postoperative deficits.

Sagittal Radiographic Parameters of the Spine in Three Physiological Postures Characterized Using a Slot Scanner and Their Potential Implications on Spinal Weight-Bearing Properties

STUDY DESIGN

Prospective radiographic comparative study.

PURPOSE

To compare and understand the load-bearing properties of each functional spinal unit (FSU) using three commonly assumed, physiological, spinal postures, namely, the flexed (slump sitting), erect (standing) and extended (backward bending) postures.

OVERVIEW OF LITERATURE

Sagittal spinal alignment is posture-dependent and influences the load-bearing properties of the spine. The routine placement of intervertebral cages "as anterior as possible" to correct deformity may compromise the load-bearing capabilities of the spine, leading to complications.

METHODS

We recruited young patients with nonspecific low back pain for <3 months, who were otherwise healthy. Each patient had EOS images taken in the flexed, erect and extended positions, in random order, as well as magnetic resonance imaging to assess for disk degeneration. Angular and disk height measurements were performed and compared in all three postures using paired t-tests. Changes in disk height relative to the erect posture were caclulated to determine the alignment-specific load-bearing area of each FSU.

RESULTS

Eighty-three patients (415 lumbar intervertebral disks) were studied. Significant alignment changes were found between all three postures at L1/2, and only between erect and flexion at the other FSUs. Disk height measurements showed that the neutral axis of the spine, marked by zones where disk heights did not change, varied between postures and was level specific. The load-bearing areas were also found to be more anterior in flexion and more posterior in extension, with the erect spine resembling the extended spine to a greater extent.

CONCLUSIONS

Load-bearing areas of the lumbar spine are sagittal alignment-specific and level-specific. This may imply that, depending on the surgical realignment strategy, attention should be paid not just to placing an intervertebral cage "as anterior as possible" for generating lordosis, but also on optimizing load-bearing in the lumbar spine.

Bone SPECT/CT in Postoperative Spine

Back pain is a common problem and the diagnosis and treatment depend on the clinical presentation, yet overlap between pain syndromes is common. Imaging of patients with chronic back pain in both pre- and postoperative scenarios include radiological, radionuclide, and hybrid techniques. In general, these techniques have their own advantages and limitations. The aim of surgery is to eliminate pathologic segmental motion and accompanying symptoms, especially pain. However, surgical procedures are not without complications and localizing the cause of the pain is often challenging. Radiobisphosphonate bone SPECT/CT is reported to be useful in evaluating benign orthopedic conditions and it often provides valuable information such as accurate localization and characterization of bone abnormalities. In this review, routinely used spinal surgical techniques and procedures are discussed, as well as the acute and delayed complications related to spinal surgery, the role of conventional imaging, and the potential uses of radionuclide bone SPECT/CT to diagnose pseudoarthrosis, cage subsidence, loosening and misalignment, hardware failure, and postoperative infection.

Influence of smoking on spinal fusion after spondylodesis surgery: A comparative clinical study

BACKGROUND

Smoking is a risk factor in the process of bone healing after lumbar spondylodesis, often associated with complications that occur intraoperatively or during follow-up periods.

OBJECTIVE

To assess if smokers yield worse results concerning lumbar interbody fusion than non-smokers in a clinical comparative setting.

METHODS

Spondylodesis outcomes in 50 patients, 34 non-smokers (mean 58 years; (range 29-81) and 16 smokers (mean 47 years; range 29-75) were compared preoperatively and one year after spondylodesis surgery using Oswestry-Disability-Index (ODI), visual analogue scale (VAS) and radiological outcome analysis of fusion-success.

RESULTS

Smokers showed a comparable ODI-improvement (p = 0.9343) and pain reduction to non-smokers (p = 0.5451). The intake of opioids was only reduced in non-smokers one year after surgery. Fusion success was significantly better in non-smokers (p = 0.01).

CONCLUSIONS

The results indicate that smoking adversely effects spinal fusion. Particularly re-operations caused by pseudarthrosis occur at a higher rate in smokers than in non-smokers.

The Effect of Dynamic Hyperextension Brace on Osteoporosis and Hyperkyphosis Reduction in Postmenopausal Osteoporotic Women

BACKGROUND

Osteoporosis and hyperkyphosis could impose a considerable financial and therapeutic burden on the affected society. Thus, new strategies to prevent or manage such complications are of significant importance. Here we evaluate the effect of 'Dynamic Hyperextension Brace' (DHB) on bone density, and hyperkyphosis correction.

METHODS

Sixty postmenopausal women were randomly assigned to the case and control groups and followed for one year. DHB was applied in the case group according to the pre-designed protocol and the patients' clinical and paraclinical parameters, including bone mineral density (BMD), kyphosis angle, osteoporotic fracture, and serum alkaline phosphatase (ALP) were evaluated in two groups.

RESULTS

Despite no significant difference in basic BMD and kyphosis between the case and control groups, BMD and kyphosis were significantly improved in the DHB treated group, at the end of the study (P=0.003 and P=0.001, respectively). Serum ALP level was significantly higher in cases compared to the controls (P=0.48). The vertebral fracture rate was also lower in the case group compared to the controls.

CONCLUSION

The efficacy of bracing in osteoporosis and kyphosis management should be more emphasized. However, more detailed and controlled studies with more patients and a longer follow-up period is needed to adequately evaluate the long-term results of braces, including DHB.

Improved Accuracy of Minimally Invasive Transpedicular Screw Placement in the Lumbar Spine With 3-Dimensional Stereotactic Image Guidance: A Comparative Meta-Analysis

STUDY DESIGN

This study compares the accuracy rates of lumbar percutaneous pedicle screw placement (PPSP) using either 2-dimensional (2-D) fluoroscopic guidance or 3-dimensional (3-D) stereotactic navigation in the setting of minimally invasive spine surgery (MISS). This represents the largest single-operator study of its kind and first comprehensive review of 3-D stereotactic navigation in the setting of MISS.

OBJECTIVE

To examine differences in accuracy of lumbar pedicle screw placement using 2-D fluoroscopic navigation and 3-D stereotaxis in the setting of MISS.

SUMMARY OF BACKGROUND DATA

Surgeons increasingly rely upon advanced image guidance systems to guide minimally invasive PPSP. Three-dimensional stereotactic navigation with intraoperative computed tomography offers well-documented benefit in open surgical approaches. However, the utility of 3-D stereotaxis in the setting of MISS remains incompletely explored by few studies with limited patient numbers.

MATERIALS AND METHODS

A total of 599 consecutive patients underwent minimally invasive lumbar PPSP aided by 3-D stereotactic navigation. Postoperative imaging and medical records were analyzed for patient demographics, incidence and degree of pedicle breach, and other surgical complications. A total of 2132 screw were reviewed and compared with a meta-analysis created from published data regarding the placement of 4248 fluoroscopically navigated pedicle screws in the setting of MISS.

RESULTS

In the 3-D navigation group, a total of 7 pedicle breaches occurred in 6 patients, corresponding to a per-person breach rate of 1.15% (6/518) and a per-screw breach rate of 0.33% (7/2132). Meta-analysis comprised of data from 10 independent studies showed overall breach risk of 13.1% when 2-D fluoroscopic navigation was utilized in MISS. This translates to a 99% decrease in odds of breach in the 3-D navigation technique versus the traditional 2-D-guided technique, with an odds ratio of 0.01, (95% confidence interval, 0.01-0.03), P<0.001.

CONCLUSIONS

Three-dimensional stereotactic navigation based upon intraoperative computed tomography imaging offers markedly improved accuracy of percutaneous lumbar pedicle screw placement when used in the setting of MISS.

Correlation of reduction and clinical outcome in patients with degenerative spondylolisthesis

STUDY DESIGN

Prospective cohort study.

INTRODUCTION

Operative treatment is increasingly implemented for the treatment of degenerative lumbar listhesis, with lumbar fusion the most common intervention. Prediction of clinical outcomes after such procedures is of ongoing relevance, and the correlation of radiologic parameters with clinical outcome remains controversial. In particular, clinical studies have not determined conclusively whether reduction of slipped vertebrae is beneficial.

METHODS

We performed a monocenter prospective analysis of a comprehensive set of quality of life scores (QLS) (Core Outcome Measure Index, Oswestry Low Back Pain Disability Index, SF-36) of 40 patients, who underwent a standardized PLIF procedure for symptomatic, Spondylolisthesis. Follow-up was 24 months. The correlations between the radiologic parameters (degree of slippage, sagittal rotation) and the clinical scores before surgery as well as 12 and 24 months post-operatively were examined.

RESULTS

All QLS showed a statistically significant improvement after 12 and 24 months post-operatively (p < 0.05). The mean amount of the anterior slippage was 34.2 ± 14.7 % (minimum 12 %, maximum 78 %). After 12 months, there was an average 19.1 % decrease to 15.1 ± 8.3 % (minimum 2 %, maximum 38 %, p < 0.000) and after 24 months it was decreased by 18.0-16.2 ± 9.0 % (minimum 2.9 %, maximum 40 %, p < 0.000). Average sagittal rotation measured 67.3° ± 16.6° initially (minimum 35°, maximum 118) and decreased by 4.3° to an average of 63.0° ± 15.2° at 12 months post-surgery (minimum 15°, maximum 101°, p = 0.065,), and by 5.7° to an average of 61.6° ± 13.0° at 24 months (minimum 15°, maximum 90°, p = 0.044). The data show positive correlations between the amount of reduction of the slipped vertebra as well as the amount of correction of the sagittal rotation and the improvement of the clinical outcomes(r = 0.31-0.54, p < 0.05).

CONCLUSION

The current study indicates a modest advantage for the best possible reposition in respect of the clinical outcome.