Results of Using a Novel Percutaneous Pedicle Screw Technique for Patients with Diffuse Idiopathic Skeletal Hyperostosis-The Single or Double Endplates Penetrating Screw (SEPS/DEPS) Technique

Biomechanical comparison of pedicle screw fixation strength between traditional trajectory and the single and double endplates penetrating screw trajectories in cadaver spine

PURPOSE

We have developed and reported on the usefulness of single and double endplates penetrating screw trajectories (SEPST/DEPST), which penetrate the endplates of the vertebrae to increase the fixation strength in patients with diffuse idiopathic skeletal hyperostosis (DISH). The purpose of this study is to compare the peak insertion torque (PIT) and pullout force (POF) of traditional trajectory (TT) and SEPST/DEPST using cadaveric spine.

METHODS

The eighth thoracic vertebra to the fifth lumbar vertebra from six formalin-fixed adult human cadavers (two males, four females; age at death 85.7 ± 8.8 years) were used and PIT and POF were evaluated in the following three studies. Firstly, a comparison among TT/SEPST/DEPST. Secondly, a comparison of reinsertion of screws with DEPST (re-DEPST) in vertebrae inserted with TT and removed, assuming reoperation. Lastly, a comparison between the endplate thread screw (ETS) which has a smaller pitch and the conventional cancellous thread screw (CTS) was made.

RESULTS

SEPST/DEPST had a 32-70% higher PIT and a 45-82% higher POF than TT, and DEPST was about 1.4 times higher than SEPST. Assuming reoperation, the results show that fixation with re-DEPST provided almost the same fixation strength as initial TT insertion. ETS, which was considered useful for DEPS, showed a relatively higher fixation strength than CTS, however, the difference was not significant.

CONCLUSION

The present study using cadaver demonstrated the strong fixation of SEPST/DEPST and its usefulness for revision surgery, however, there were no significant differences in the mechanical properties between ETS and CTS.

Short Fixation Using Upward/Downward Penetrating Endplate Screws and Percutaneous Vertebral Augmentation for Unstable Osteoporotic Vertebral Fractures

Introduction

Percutaneous vertebral augmentation techniques, such as balloon kyphoplasty (BKP) and vertebral body stenting (VBS), are commonly used for surgical intervention in osteoporotic vertebral fractures (OVFs). However, markedly unstable OVF cases require additional fixation procedures, prompting the exploration of combined percutaneous vertebral augmentation and posterior fixation. A novel surgical approach involving percutaneous vertebral augmentation with upward penetrating endplate screws (PES) and downward PES, complemented by a short fusion of one above one below, was developed. This study aimed to introduce and report the preliminary outcomes of this technique based on a retrospective analysis of 20 consecutive cases in the short and medium term.

Methods

Surgical indications are a vertebral wedge angle difference of 10° or more, vertebral pedicle fractures, posterior wall fractures, and diffuse low-signal changes exceeding 50% on T1-weighted magnetic resonance imaging. The procedure is reserved for highly unstable cases following a comprehensive health assessment. The surgical technique involves prone positioning, fluoroscopy-guided percutaneous vertebral augmentation, and the use of downward PES in the cranial vertebral body and upward PES for the caudal vertebral body by percutaneous technique. The fixation range is one above and one below.

Results

The case series of 20 patients, with an average follow-up period of 146.9 days, demonstrates a mean surgical time of 57 min and minimal complications. The advantages of the technique are as follows: ease of performance, minimal fixation range, and time efficiency. Risks, such as potential screw loosening and the need for prolonged follow-up, are acknowledged.

Discussion

The technique represents a promising surgical approach that balances the requirements of minimally invasive intervention and relatively robust initial fixation for elderly osteoporotic patients with unstable OVFs. While short- and medium-term results are favorable, long-term observations are needed to further assess its efficacy. This novel technique has a potential to be a valuable surgical option for unstable OVFs.

Biomechanical effects of posterior lumbar interbody fusion with vertical placement of pedicle screws compared to traditional placement

BACKGROUND

The pedicle screw technique is widely employed for vertebral body fixation in the treatment of spinal disorders. However, traditional screw placement methods require the dissection of paraspinal muscles and the insertion of pedicle screws at specific transverse section angles (TSA). Larger TSA angles require more force to pull the muscle tissue, which can increase the risk of surgical trauma and ischemic injury to the lumbar muscles.

AIM

To study the feasibility of zero-degree TSA vertical pedicle screw technique in the lumbosacral segment.

METHODS

Finite element models of vertebral bodies and pedicle screw-rod systems were established for the L4-S1 spinal segments. A standard axial load of 500 N and a rotational torque of 10 N/m were applied. Simulated screw pull-out experiment was conducted to observe pedicle screw resistance to pull-out, maximum stress, load-displacement ratio, maximum stress in vertebral bodies, load-displacement ratio in vertebral bodies, and the stress distribution in pedicle screws and vertebral bodies. Differences between the 0-degree and 17-degree TSA were compared.

RESULTS

At 0-degree TSA, the screw pull-out force decreased by 11.35% compared to that at 17-degree TSA (P < 0.05). At 0-degree and 17-degree TSA, the stress range in the screw-rod system was 335.1-657.5 MPa and 242.8-648.5 MPa, separately, which were below the fracture threshold for the screw-rod system (924 MPa). At 0-degree and 17-degree TSA, the stress range in the vertebral bodies was 68.45-78.91 MPa and 39.08-72.73 MPa, separately, which were below the typical bone yield stress range for vertebral bodies (110-125 MPa). At 0-degree TSA, the load-displacement ratio for the vertebral bodies and pedicle screws was slightly lower compared to that at 17-degree TSA, indicating slightly lower stability (P < 0.05).

CONCLUSION

The safety and stability of 0-degree TSA are slightly lower, but the risks of screw-rod system fracture, vertebral body fracture, and rupture are within acceptable limits.

Biomechanical analysis of a trans-discal, multi-level stabilization screw (MLSS) at the upper instrumented vertebra (UIV) of long posterior thoracolumbar instrumentations

PURPOSE

To evaluate proximal junctional biomechanics of a MLSS relative to traditional pedicle screw fixation at the proximal extent of T10-pelvis posterior instrumentation constructs (T10-p PSF).

METHODS

A previously validated three-dimensional osseoligamentous spinopelvic finite element (FE) model was used to compare proximal junctional range-of-motion (ROM), vertebral body stresses, and discal biomechanics between two groups: (1) T10-p with a T10-11 MLSS ("T10-11 MLSS") and (2) T10-p with a traditional T10 pedicle screw ("Traditional T10-PS").

RESULTS

The T10-11 MLSS had a 5% decrease in T9 cortical bone stress compared to Traditional T10-PS. Conversely, the T10 and T11 bone stresses increased by 46% and 98%, respectively, with T10-11 MLSS compared to Traditional T10-PS. Annular stresses and intradiscal pressures (IDP) were similar at T9-T10 between constructs. At the T10-11 disc, T10-11 MLSS decreased annular stresses by 29% and IDP by 48% compared to Traditional T10-PS. Adjacent ROM (T8-9 & T9-10) were similar between T10-11 MLSS and Traditional T10-PS. T10-11 MLSS had 39% greater ROM at T10-11 and 23% less ROM at T11-12 compared to Traditional T10-PS.

CONCLUSIONS

In this FE analysis, a T10-11 MLSS at the proximal extent of T10-pelvis posterior instrumentation resulted in increased T10 and T11 cortical bone stresses, decreased discal annular stress and IDP and increased ROM at T10-11, and no change in ROM at the adjacent level. Given the complex and multifactorial nature of proximal junctional kyphosis, these results require additional biomechanical and clinical evaluations to determine the clinical utility of MLSS on the proximal junctions of thoracolumbar posterior instrumented fusions.

Comparison of the Fixation Strengths of Screws between the Traditional Trajectory and the Single and Double Endplate Penetrating Screw Trajectories Using Osteoporotic Vertebral Body Models Based on the Finite Element Method

STUDY DESIGN

This is a finite element (FE) study.

PURPOSE

To compare the fixation strength of traditional trajectory (TT) and single and double endplate penetrating screw trajectories (SEPST/DEPST) to the osteoporotic vertebral body model based on the FE method.

OVERVIEW OF LITERATURE

SEPST/DEPST have been developed to enhance the fixation strength in patients with diffuse idiopathic hyperostosis (DISH). This technique was also applied to patients with osteoporosis. However, determining the superiority of SEPST/ DEPST is difficult because of the heterogeneous patient backgrounds.

METHODS

Twenty vertebrae (T12 and L1) from 10 patients with osteoporosis (two males and eight females; mean age, 74.7 years) were obtained to create the 10 FE models. First, a single screw was placed with TT and SEPST/DEPST, and the fixation strength was compared by axial pullout strength (POS) and multidirectional loading tests. Second, two screws were placed on the bilateral pedicles with TT and SEPST/DEPST, and the fixation force of the vertebrae in the constructs in flexion, extension, lateral flexion, and axial rotation was examined.

RESULTS

SEPST and DEPST had 140% and 171% higher POS values than TT, respectively, and the DEPST result was statistically significant (p =0.007). The multidirectional fixation strength was significantly higher in DEPST and SEPST than in TT in the cranial, caudal, and medial directions (p <0.05) but not in the lateral direction (p =0.05). The vertebral fracture strength at the lower instrumented vertebra of the DEPST tended to be higher than that of TT. The vertebral motion angles in SEPST and DEPST were significantly smaller in lateral bending (p =0.02) and tended to be smaller in flexion and extension than in TT (p =0.13).

CONCLUSIONS

This study may provide useful information for spine surgeons in deciding whether to choose the SEPS or DEPS technique for augmenting fixation in osteoporotic vertebral fracture surgery.

Vertebral fracture at the caudal end of diffuse idiopathic skeletal hyperostosis treated with vertebroplasty via double-endplate penetrating screw trajectory and posterior spinal fixation with a new hybrid strategy using cement-augmented fenestrated pedicle screws

Vertebral fractures in diffuse idiopathic skeletal hyperostosis (DISH) are often unstable. We encountered a case of vertebral fracture at the caudal end of DISH in which vertebroplasty was performed via a double endplate penetrating screw (DEPS) trajectory, and short posterior fixation was performed using the DEPS technique on the cranial vertebrae, including the fractured vertebra; conventional pedicle screw to the caudal vertebrae; and cement-augmented fenestrated pedicle screws to the caudal end vertebra. A 93-year-old man presented with a vertebral fracture at the caudal end of a DISH after a fall. He underwent surgery for lower back pain due to spinal instability. Vertebroplasty via DEPS trajectory can shorten the posterior fixation range. Using cement-augmented fenestrated pedicle screws to the caudal end vertebra enables balancing of the posterior fixation force. This strategy should be considered when a vertebral fracture is found at the caudal end of the DISH.

Pneumothorax by Penetrating Endplate Screw for Diffuse Idiopathic Skeletal Hyperostosis-Related Thoracolumbar Fracture

Pneumothorax is a rare surgical complication in spinal surgery with thoracic pedicle screws. The penetrating endplate screw (PES) technique has been developed as a strong alternative spinal anchor to conventional pedicle screws for diffuse idiopathic skeletal hyperostosis (DISH). We present an intraoperative pneumothorax without deviation to the thoracic during the maneuver of the PES. A 56-year-old male who presented with non-union of DISH-related T12 vertebral fracture underwent T12 kyphoplasty and T10-L2 posterior fixation using the PES technique. The left pneumothorax was developed postoperatively without screw deviation to the thorax throughout screw insertion. Postoperative CT suggested that a displaced rib head by the lateral misposition of the screw at the inserting point and the pedicle level might injure the pleura. Spine surgeons should know that the lateral insertion of PES has a potential risk for pneumothorax by the displacement of the rib head because of screw trajectory from caudal to cranial apart from conventional pedicle screw.

Downward penetrating endplate screw technique under O-arm navigation posterior fusion in patients with osteoporotic vertebral body fractures associated with diffuse idiopathic skeletal hyperostosis

Background:

A downward penetrating endplate screw (PES) technique combined with caudal anchor screws inserted in the upward direction under O-arm navigation (i.e., crossing screw technique) avoided screw backout and proximal junctional kyphosis (PJK) in three patients with osteoporotic vertebral body fractures and diffuse idiopathic skeletal hyperostosis (DISH).

Methods:

The PES techniques were utilized for patients with T12 (one patient) and L1 (two patients) spontaneous fusion across the targeted vertebrae, with minimal damage to the involved endplates/intervertebral discs. The average number of instrumented vertebrae was 5.3.

Results:

There were no perioperative complications over the mean follow-up period of 28.7 months; no screw loosening, and no PJK.

Conclusion:

The PES technique prevented screw backout, and PJK in three patients with lumbar osteoporotic vertebral fractures and DISH.

Large aortic pseudoaneurysm after fusion surgery for hyperextension-type lumbar fracture in diffuse idiopathic skeletal hyperostosis: illustrative case

BACKGROUND

This study aimed to report an aortic pseudoaneurysm, a rare but lethal complication, after a spinal fracture in ankylosing spine.

OBSERVATIONS

An 83-year-old obese woman presented with dementia and was nonambulatory after a fall. She was transported to the hospital, and imaging showed a hyperextension-type L1 fracture with diffuse idiopathic skeletal hyperostosis (DISH). After posterior fusion surgery using percutaneous pedicle screws, screw loosening was detected 10 days postoperatively. Fracture dislocation was reduced by changing to transdiscal screws and rodding while in the lateral position. However, the anterior opening persisted. Enhanced computed tomography performed at 6 weeks postoperatively showed a large aortic pseudoaneurysm extending into the vertebral fracture site without screw loosening. Neither endovascular aortic repair nor open surgery was applicable. The patient was transferred to a sanatorium and died of pneumonia 5 months postoperatively without aortic aneurysm rupture.

LESSONS

An aortic pseudoaneurysm can occur in hyperextension-type spinal fractures in DISH, even after fusion surgery, when the edge of the fracture is in contact with the aortic wall. The anterior opening dislocation should be reduced as much as possible.

Urinary Retention as the Presenting Clinical Manifestation of Unstable Thoracic Spinal Fracture with Diffuse Idiopathic Skeletal Hyperostosis

Patients with diffuse idiopathic skeletal hyperostosis (DISH) are at high risk for unstable vertebral fracture, which can be frequently missed. An 80-year-old man with pre-existing muscle lower limb weakness due to frailty was referred from another hospital, presenting with progressive urinary retention and its related symptoms, which had been treated as a urinary tract infection at previous hospital. One week prior to our visit, he had fallen. On arrival, he appeared lethargic and unable to follow commands. He denied any back pain. Computed tomography identified a T10 fracture and dislocation associated with DISH. Although immediate surgical fixation was performed, the patient did not recover from the neurological deficits. Diagnostic delay of DISH-associated vertebral fracture can occur due to both patients' and clinicians' delayed action. We believe this case report can help clinicians recognize this potentially devastating condition.

Differentiation between thyroid-associated orbitopathy and Graves' disease by iTRAQ-based quantitative proteomic analysis

Graves' ophthalmopathy, also known as thyroid-associated orbitopathy (TAO), is the most common inflammatory eye disease in adults. The most common etiology for TAO is Graves' disease (GD); however, proteomic research focusing on differences between GD and TAO is limited. This study aimed to identify differentially expressed proteins between thyroid-associated orbitopathy (TAO) and GD. Furthermore, we sought to explore the pathogenesis of TAO and elucidate the differentiation process via specific markers. Serum samples of three patients with TAO, GD, and healthy controls, respectively, were collected. These samples were measured using the iTRAQ technique coupled with mass spectrometry. Differentially expressed proteins in TAO and GD were identified by proteomics; 3172 quantified proteins were identified. Compared with TAO, we identified 110 differential proteins (27 proteins were upregulated and 83 were downregulated). In addition, these differentially expressed proteins were closely associated with cellular processes, metabolic processes, macromolecular complexes, signal transduction, and the immune system. The corresponding functions were protein, calcium ion, and nucleic acid binding. Among the differential proteins, MYH11, P4HB, and C4A were markedly upregulated in TAO patients and have been reported to participate in apoptosis, autophagy, the inflammatory response, and the immune system. A protein-protein interaction network analysis was performed. Proteomics demonstrated valuable large-scale protein-related information for expounding the pathogenic mechanism underlying TAO. This research provides new insights and potential targets for studying GD with TAO.

What Trajectory Is Safe for Double Penetrating Endplate Screw Posterior Spinal Fusion Surgery in the Thoracolumbar Region?

BACKGROUND

The penetrating end plate screw (PES) technique improved the fixation strength of the pedicle screw by penetrating the end plate in posterior fusion. The "double" PES, which is a trajectory that penetrates both the upper end plate of the corresponding vertebra and the lower end plate of the upper adjacent vertebral body, provides a stronger tricortical fixation but requires a stricter trajectory. The purpose of this study was to measure the cephalad angles from T7-L5 that would allow a safe trajectory for "double" PES.

METHODS

We analyzed 1078 pedicles of 539 vertebral bodies of 50 consecutive cases (27 males and 23 females, mean age, 63.3 years) who underwent computed tomography (CT) myelography for evaluation of spinal disorders. The mean cephalad angle to obtain the double PES trajectory of each vertebra was examined, except for cases in which the appropriate trajectory would perforate the pedicles.

RESULTS

The cephalad angle for the appropriate trajectory of "double" PES ranged from 23.4 to 37.6 degrees in the thoracic spine and 34.8 to 40.8 degrees in the lumbar spine. The ratio of pedicle perforation was significantly higher at T7 (16%), L4 (26%), and L5 (52%).

CONCLUSIONS

It is important to measure the optimal cephalad angle by preoperative computed tomography imaging according to the vertebral level. In L4 and L5, "double" PES should be avoided because it is often unsafe.