Facet angle and its importance on joint violation in percutaneous pedicle screw fixation in lumbar vertebrae: A retrospective study

Influence of the facet joint angle on facet joint degeneration following pedicle screw fixation without fusion in thoracolumbar fractures

BACKGROUND

Posterior approach pedicle screw fixation without fusion is widely used in the treatment of neurologically intact type A3 thoracolumbar fractures.

OBJECTIVE

To analyze the influence of the facet joint (FJ) angle on FJ degeneration following posterior approach pedicle screw fixation without fusion in neurologically intact type A3 thoracolumbar fractures.

METHODS

Fifty-eight patients who underwent pedicle screw fixation via the traditional posterior approach (n= 28) or the Wiltse approach (n= 30) were enrolled. A CT scan was performed before fixation and before fixation removal (Within 1.5 to 2 years after fixation) to evaluate the FJs parameters, including FJ inclination (FJI), FJ tropism (FJT), FJ violation, and FJ degeneration grade (FJDG), of three fixed segments and the adjacent segment below the fixed segments.

RESULTS

There was no significant difference in FJ violation rate, FJDG deterioration, or FJ angle between the two groups (P> 0.05). FJDG deterioration showed a weak positive correlation with FJI and FJT before fixation, and the angular change in FJI (P< 0.05); and FJT before fixation and the angular change in FJI were risk factors for FJDG deterioration (P< 0.01).

CONCLUSION

The Wiltse approach did not increase the rate of FJDG deterioration and FJs angle changes. However, the FJT before fixation and the angular change in FJI were risk factors for FJDG deterioration.

Facet Joint Violation by Thoracolumbar Percutaneous Pedicle Screw and Its Effect on Progression of Facet Joint Osteoarthritis

Study Design

A retrospective study.

Purpose

This study aimed to investigate the rate and associated factors of facet violation (FV) in percutaneous pedicle screws (PPS) from the thoracic to the lumbar spine and the effect of FV on facet osteoarthritis (OA) progression.

Overview of Literature

Some reports claim PPS has a higher FV rate than conventional open surgery. However, previous reports of FV in PPS were limited to the lumbar spine; only a few reports included the thoracic spine.

Methods

The present study includes 1,028 PPS inserted from T4 to S1 in 218 patients. The rate of FV and facet OA progression after FV were assessed using computed tomography (CT) scans conducted postoperatively at 1 week and 6 months or more. To identify factors associated with FV or facet OA progression after FV, a multivariate logistic regression analysis was conducted. To investigate whether FV caused facet OA progression, we compared OA progression between patients with FV and matched controls.

Results

FV was observed in 68 (6.6%) of the 1,028 facets, and the thoracic spine was identified as an independent factor associated with FV. OA progression was detected in 48.2% of the cases with FV via CT scans conducted postoperatively at a mean duration of 22.6 months. The time between CT scans was identified as an independent factor for facet OA progression after FV. The rate of OA progression in patients with FV was significantly greater than that of the controls.

Conclusions

FV was observed in 6.6% of the patients, and the thoracic spine was identified as an independent factor associated with FV. OA progression of a violated facet occurs over time. FV is considered a complication leading to facet OA progression.

A Retrospective Analysis of Superior Facet Joint Violation Between Open and Minimally Invasive Transforaminal Lumbar Interbody Fusion and its Relation to Adjacent Segment Disease

STUDY DESIGN

A retrospective study.

OBJECTIVE

The aim was to analyze the superior facet joint violation (SFV) between open transforaminal lumbar interbody fusion (open-TLIF) and minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) and its effect on the superior and inferior adjacent segment disc height, segmental lordosis, lumbar lordosis, and facet joint degeneration.

SUMMARY OF BACKGROUND DATA

We compared SFV between open-TLIF and MIS-TLIF and its correlation with different factors as well as its effect on adjacent segment disease.

MATERIALS AND METHODS

We retrospectively studied data of patients undergoing single level TLIF surgery from January 2013 to February 2016 in single institutional hospital. Axial and coronal postoperative computed tomography scan images were used to analyze SFV. In secondary analysis patients were divided into nonfacet violation group (NSFVG) and facet violation group (SFVG) and compared the changes on the superior and inferior adjacent level disc height, segmental lordosis, lumbar lordosis, and facet joint degeneration.

RESULTS

Mean SFV grade was significantly greater in MIS-TLIF compared with open-TLIF (odds ratio: 0.638, confidence interval: 0.431-0.944; P=0.025). There was more grade 2 (10.71% vs. 5.60%) and grade 3 (4.46% vs. 1.29%) SFV in MIS-TLIF. Patient with age below 60 and body mass index (BMI) >30 kg/m2 in MIS-TLIF were more prone to high-grade SFV compared with open-TLIF. Further, logistic regression showed patients with BMI ≥30 kg/m2 has 7.137 increased odds of high-grade SFV (95% confidence interval: 3.261-15.618; P=0.000) compared with patients with BMI <30 kg/m2. Compared with NSFVG, SFVG has more SFV (0.096±0.244 vs. 0.177±0.317; P=0.012) and less improvement in lumbar visual analog scale scores -0.65±0.073 versus -0.67±0.074 (P=0.006).

CONCLUSION

MIS-TLIF has more high-grade SFV as well as overall mean SFV in comparison to open-TLIF with BMI >30 kg/m2 and location of pedicle screw as an independent risk factor for SFV and risk of adjacent segment disease increases with SFV.

LEVEL OF STUDY

Level III.

Appropriate insertion point for percutaneous pedicle screw placement in the lumbar spine using c-arm fluoroscopy: a cadaveric study

Background

We studied the characteristics and regularity of appropriate insertion points for percutaneous pedicle screw placement in the lumbar spine using C-arm X-ray fluoroscopy. The purpose of this study was to improve the accuracy of percutaneous pedicle screw placement and reduce the incidence of superior-level facet joint violation.

Methods

Six normal spinal specimens were included. Three different methods for placing percutaneous pedicle screws in the lumbar spine were applied, including the Roy-Camille method, Magerl method and Weinstein method. The relationships among the insertion point, pedicle projection and proximal facet joint on C-arm X-ray films were studied. The projection morphology of the vertebral pedicle in different segments of the lumbar spine was observed. The relationship between the outer edge of the pedicle projection and the outer edge of the cranial articular process was also studied. The distance between the insertion point and the facet joint (M1), the distance between the insertion point and outer edge of the cranial articular process (M2), and the distance between the insertion point and the projection center of the pedicle (M) were measured.

Results

In this study, we found that the projection shape of the vertebral pedicle differed across segments of the lumbar spine: the shape for L1-L3 was oval, and that for L4-L5 was round. The radiographic study showed that the outer edge of the cranial articular process was located on the lateral side of the outer edge of the pedicle projection and did not overlap with the pedicle projection. M for the Weinstein group was larger than that for the Roy-Camille group (P <  0.05). M1 for the Weinstein group was larger than that for the Roy-Camille and Magerl groups (P <  0.05). M2 for the Roy-Camille group was negative, M2 for the Magerl group was 0, and M2 for the Weinstein group was positive.

Conclusion

Under C-arm X-ray fluoroscopy, we were able to accurately identify the characteristics and regularity of the appropriate insertion point for percutaneous pedicle screw placement in the lumbar spine, which was important for improving the accuracy of percutaneous pedicle screw placement and reducing the incidence of superior-level facet joint violation.

Parafusos pediculares e violação facetária – A importância do ângulo entre a faceta e o parafuso

Objective  To verify whether, regardless of the screw placement technique, there is a safe distance or angle in relation to the facets that can prevent violation of the facet joint when the screws are placed.

Methods  Retrospective, single, comparative, non-randomized center. We evaluated by axial computed tomography: the angle of the screw/rod in relation to the midline, the angle of the center of the facets in relation to the midline, the distance between the head of the screw/rod to the midline, and the distance from the center of the facets to the midline; the violation of the facet joint will be evaluated in a gradation of 0 to 2. Also will be measured the difference between the angle os the facets and the angle of the screws (Δ Angle) and, the difference between the facet distance and the screw distance (Δ Distance).

Results  A total of 212 patients and 397 facets were analyzed (196 on the left and 201 on the right). Of these, 303 were not violated (grade 0), corresponding to 76,32%, and 94 suffered some type of violation (grade 1 and 2), corresponding to 23,68%. The mean of Δ angle was 9.87° +/− 4.66° (grade 0), and of 3.77° +/− 4.93° in facets (grade 1 and 2) ( p  < 0.001), and the Δ mean distance in cases in which there was no violation was 0.94 arbitrary units (a.u.) +/− 0.39 a.u., while the Δ distance in G1 and G2 cases was 0.56 a.u. +/− 0.25 a.u. ( p  < 0.001).

Conclusion  The measurements of angle and distance between facet and screw can help in the placement of screws. These parameters can be used as safety measures with the most frequent use of surgical navigation techniques.

Risk Factors Related to Superior Facet Joint Violation During Lumbar Percutaneous Pedicle Screw Placement in Minimally Invasive Transforaminal Lumbar Interbody Fusion (MIS-TLIF)

OBJECTIVE

To investigate the incidence of superior facet joint violation (FJV) during percutaneous pedicle screw placement in minimally invasive transforaminal lumbar interbody fusion, and assess the possible risk factors for FJV.

METHODS

An analysis of 91 patients with lumbar degenerative diseases treated with percutaneous pedicle screw placement via minimally invasive transforaminal lumbar interbody fusion from 2012 to 2018 was performed. Superior FJV was evaluated and graded by 3-dimensional lumbar computed tomography reconstruction. Analysis of possible risk factors included general condition of patients, anatomical characteristics of facet joint (FJ; axial, sagittal, and coronal diameters of FJ, facet angle, lumbar lordosis angle, lumbar lordosis index, and depth of lamina), and surgical factors (pedicle screw angle, screw-superior FJ distance, cranial angle, proximal rod length, and rod contouring).

RESULTS

The overall violation rate of superior FJ was 34.07% (62/182), and high-grade violation rate was 16.06% (27/182). The logistic regression analysis revealed that body mass index ≥30 kg/m² and pedicle screw placement at L5 were independent risk factors of FJV. Anatomical factors showed that the incidence of FJV was significantly increased when axial, sagittal, and coronal diameters of FJ were all ≥12 mm or FA was ≥40°. Surgical factors showed that the FJV group had a smaller pedicle screw angle and screw-superior FJ distance compared with the non-FJV group (P < 0.05).

CONCLUSIONS

Body mass index ≥30 kg/m² and pedicle screw placement at L5 were independent risk factors of superior FJV. FJV was more likely to occur in hypertrophic FJ (axial, sagittal, and coronal diameters ≥12 mm) or coronal orientation (FA ≥40°).

Incidence and Risk Factors of Superior Facet Joint Violation in Percutaneous and Open Instrumentation Using Cortical Bone Trajectory Technique: A Comparison of Different Techniques

STUDY DESIGN

A retrospective study evaluating cranial facet joint violation (FJV) by cortical bone trajectory (CBT) screw.

OBJECTIVE

To determine the incidence and risk factors of FJV following CBT screw placement for different techniques.

SUMMARY OF BACKGROUND DATA

CBT is a novel technique for lumbar fusion, and FJV is one of the most common complications, leading to poor prognosis. No studies have investigated the incidence and risk factors of FJV for the CBT technique during different methods.

METHODS

The authors reviewed 91 consecutive patients who underwent CBT screw instrumentation from June 2015 to August 2018. In the fluoroscopic-open group (FOG), 42 patients received an open procedure. In the navigation-open group (NOG), 24 patients underwent open instrumentation. In the navigation-percutaneous group, 25 patients underwent percutaneous instrumentation. Postoperative computed tomography scans were obtained to determine the degree and incidence of FJV. Clinical and imaging data were analyzed to clarify the risk factors of FJV.

RESULTS

The incidence of FJV occurred in 35.7% of patients and 16.9% of screws in the FOG, 4.2% of patients and 3.8% of screws in the NOG, and 8.0% of patients and 8.0% of screws in the navigation-percutaneous group. Open instrumentation using navigation led to a lower risk of FJV compared with the conventional approach. There was no difference in the rate of FJV between percutaneous and open surgery with navigation assistance. Risk factors affecting FJV include: (1) left-side screw, facet angle ≥45 degrees, and scoliosis for fluoroscopy-assisted CBT instrumentation; (2) body mass index ≥30 kg/m, facet angle ≥45 degrees, and scoliosis for navigation-assisted CBT instrumentation.

CONCLUSIONS

Lumbar fusion through CBT instrumentation would reduce FJV. Computer-assisted navigation resulted in a lower incidence of FJV. Percutaneous instrumentation with navigation assistance is not a risk factor for FJV. Special care should be taken in patients with body mass index ≥30 kg/m, left-side screw, facet angle ≥45 degrees, and scoliosis.

LEVEL OF EVIDENCE

Level III.

Rate and Risk Factors of Superior Facet Joint Violation during Cortical Bone Trajectory Screw Placement: A Comparison of Robot-Assisted Approach with a Conventional Technique

Objective

To compare the incidence and risk factors of superior facet joint violation (FJV) during cortical bone trajectory screw placement in robot‐assisted approach versus conventional technique.

Methods

A retrospective study, including 69 patients having cortical bone trajectory (CBT) screw instrumentation for symptomatic degenerated diseases or trauma, was conducted between June 2015 to January 2019. All patients underwent CBT surgery performed by the same team of experienced surgeons. Patients were randomly divided into two groups: a conventional group (CG, 46 cases) and a robot group (RG, 23 cases). The surgical robotic system was used for screw instrumentation in the robot group and the traditional screw instrumentation with fluoroscopic guidance was used in the conventional group. Cortical screws followed a medio‐to‐lateral path in the transverse plane and a caudal‐to‐cephalad path in the sagittal plane. Preoperative and postoperative computed tomography (CT) scans were obtained to determine the degree and incidence of FJV. The violation status of facet joint was evaluated according to the modified classification: grade 0, no violation; grade 1, screw shaft, screw head or rod within 1 mm of or abutting the facet joint, but did not enter the articular facet joint; grade 2, screw shaft, screw head or rod clearly in the facet joint. The following factors that may contribute to the occurrence of FJV were analyzed: age, sex, body mass index (BMI), proximal fusion level, fusion length, the side of screw, preoperative vertebral slip, superior facet angle, and degenerative scoliosis. The chi‐squared test and Student's t‐test were used for analysis of the variables for significance (P < 0.05).

Results

FJV occurred in 41.3% of patients in CG and 17.3% of patients in RG. A chi‐squared analysis revealed a significantly lower rate of FJV for RG compared with CG (P = 0.04). In the CG, 17 of the 109 cephalad screws were grade 1 (15.6%), and five were grade 2 (4.6%). In the RG, three of the 46 cephalad screws were grade 1 (6.5%), and three were grade 2 (6.5%). There was a statistically significant difference in the incidence of FJV between the left and right screw with fluoroscopy‐assisted CBT screw instrumentation (P < 0.05). A significant correlation between scoliosis with the FJV was found in CG (P < 0.05) and in RG (P < 0.05). With regard to superior facet angle, a measurement ≥45° was a significant risk factor of FJV in CG (P < 0.05) and in RG (P < 0.05).

Conclusions

A robot‐assisted approach could reduce the incidence of FJV compared with the conventional approach in CBT technique.

Superior Facet Joint Violations in Single Level Minimally Invasive and Open Transforaminal Lumbar Interbody Fusion: A Comparative Study

Study Design

Prospective comparative study.

Purpose

To compare the incidence of iatrogenic superior facet joint violation (SFV) in minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) and open TLIF (OPEN-TLIF) at a single lower lumbar fusion level and to evaluate the patient and surgical factors influencing the outcome.

Overview of Literature

Iatrogenic SFV is a significant risk factor for adjacent segment disease (ASD). Blind screw placement technique in MIS-TLIF contributes to the increasing incidence of iatrogenic SFV which can be influenced by several other potential factors. There are only limited studies comparing the incidence of iatrogenic SFV in MIS-TLIF and OPEN-TLIF.

Methods

In total, 225 cases (450 top screws; MIS-TIFL, 120; OPEN-TILF, 105) undergoing single-level lower lumbar fusion were included in the study. Postoperative computed tomography grading system was used to evaluate iatrogenic SFV. Patient and surgical factors such as age, body mass index, top-screw level, side of the top screw, depth of the spine, and superior facet joint angle (SFA) were analyzed in iatrogenic SFV and non-violation groups to determine their influence on iatrogenic SFV. The clinical outcomes in both groups were assessed preoperatively and postoperatively.

Results

The overall incidence of iatrogenic SFV and high-grade violations was higher in MIS-TLIF (41.25%) than in OPEN-TLIF (30.4%). In both groups, bivariate analysis showed a significantly greater incidence of the iatrogenic SFV in patients aged <60 years and those with obesity, top pedicle screws at L4, right-sided top screws, SFA >35°, and depth of the spine >50 mm.

Conclusions

This study demonstrated that the incidence of iatrogenic SFV is greater in MIS-TLIF than in OPEN-TLIF at a single lower lumbar level. MIS-TLIF is effective for lumbar degenerative disease; however, the incidence of iatrogenic SFV was higher. Patient and surgical factors must be considered to protect the facet joints in both TLIF methods to avoid ASD.