Effect of Fenestrated Pedicle Screws with Cement Augmentation in Osteoporotic Patients Undergoing Spinal Fusion

Comparison of cement-augmented pedicle screw and conventional pedicle screw for the treatment of lumbar degenerative patients with osteoporosis

STUDY DESIGN

A retrospective cohort study.

OBJECTIVE

To compare the safety and clinical efficacy between using cement-augmented pedicle screws (CAPS) and conventional pedicle screws (CPS) for the treatment of lumbar degenerative patients with osteoporosis. Management of lumbar degenerative patients with osteoporosis undergoing spine surgery is challenging. The clinical efficacy and potential complications of the mid-term performance of the CAPS technique in the treatment of lumbar degenerative patients with osteoporosis remain to be evaluated.

PATIENTS AND METHODS

The data of 131 lumbar degenerative patients with osteoporosis who were treated with screw fixation from May 2016 to December 2019 were retrospectively analyzed in this study. The patients were divided into the following two groups according to the type of screw used: (I) the CAPS group (n = 85); and (II) the CPS group (n = 46). Relevant data were compared between two groups, including the demographics data, clinical results and complications.

RESULTS

The difference in the VAS, ODI and JOA scores at three and 6 months after the operation between the two groups was statistically significant (P < 0.05). At 12 months after surgery and the final follow-up, a significant difference in the fusion rate was found between the two groups (P < 0.05). Four cemented screws loosening were observed in the CAPS group (loosening rate 4/384, 1.04%) and 15 screws loosening were observed in the CPS group (loosening rate 15/214, 7.01%). In the CAPS group, a total of 384 augmented screws were used, and cement leakage was observed in 25 screws (25/384, 6.51%), but no obvious clinical symptoms or serious complications were observed. Adjacent vertebral fractures occurred in six patients in the CAPS group and one in the CPS group.

CONCLUSIONS

CAPS technique is an effective strategy for the treatment of lumbar degenerative patients with osteoporosis, with a higher fusion rate and lower screw loosening rate than CPS.

Design of a new detachable pedicle screw based on medical optical imaging inspection to improve osteoporosis and enhance vertebral body revision effect

Osteoporosis is a common bone disease that often leads to difficulty in vertebrae revision. Traditional pedicle screws are often complicated to operate and have poor visibility during implantation. A new detachable pedicle screw is needed to improve the revision effect. The aim of this study was to design a new detachable pedicle screw based on medical optical imaging to improve the outcome of vertebral revision in osteoporosis, and to improve operational feasibility and visibility. In this study, the parameters related to the degree of osteoporosis were obtained by optical imaging detection of the osteoporotic vertebral body. Then a new detachable pedicle screw was designed according to the test results to improve the effect of vertebral body revision. By preparing and optimizing the material and structure of the screw, it is ensured that it has sufficient mechanical strength and stability. Finally, the visibility and operability of the improved screw during implantation were verified by medical optical imaging. Compared with traditional screws, the new detachable pedicle screw can improve the vertebral body revision in the case of osteoporosis. The optical imaging test results show that the new screw has good visibility and maneuverability, providing more accurate guidance and positioning for the vertebral body revision operation.

Utilization of Antibiotic Bone Cement in Spine Surgery: Pearls, Techniques, and Case Review

Vertebral osteomyelitis (VO) encompasses a spectrum of spinal infections ranging from isolated mild vertebral osteomyelitis to severe diffuse infection with associated epidural abscess and fracture. Although patients can often be treated with an initial course of intravenous antibiotics, surgery is sometimes required in patients with sepsis, spinal instability, neurological compromise, or failed medical treatment. Antibiotic bone cement (ABC) has been widely used in orthopedic extremity surgery for more than 150 years, both for prophylaxis and treatment of bacterial infection. However, relatively little literature exists regarding its utilization in spine surgery. This article describes ABC utilization in orthopedic surgery and explains the technique of ABC utilization in spine surgery. Surgeons can choose from multiple premixed ABCs with variable viscosities, setting times, and antibiotics or can mix in antibiotics to bone cements themselves. ABC can be used to fill large defects in the vertebral body or disc space or in some cases to coat instrumentation. Surgeons should be wary of complications such as ABC extravasation as well as an increased difficulty with revision. With a thorough understanding of the properties of the cement and the methods of delivery, ABC is a powerful adjunct in the treatment of spinal infections.

Osteoporotic Burst Fracture in a Young Male Adult as First Presentation of a Rare PLS3 Mutation: A Case Report

Low-impact spinal fractures in young patients are rare and should raise suspicion of an underlying condition, as these injuries are typically the result of high-energy trauma. We describe a case of a young male patient who sustained a burst fracture of the first lumbar vertebra (L1) following low-energy trauma. The patient underwent percutaneous posterior spinal instrumentation, yet the poor bone quality detected intraoperatively prompted further diagnostic evaluation. Subsequently, low bone mineral density (BMD) was detected, and a rare plastine-3 (PLS3) gene mutation was revealed in the genetic analysis. The patient was initiated on teriparatide therapy after the discovery of osteoporosis postoperatively. It is, therefore, imperative to investigate all young patients with low-energy spinal fractures preoperatively to discover the underlying pathology promptly.

Screw Osteointegration-Increasing Biomechanical Resistance to Pull-Out Effect

Spinal disorders cover a broad spectrum of pathologies and are among the most prevalent medical conditions. The management of these health issues was noted to be increasingly based on surgical interventions. Spinal fixation devices are often employed to improve surgery outcomes, increasing spinal stability, restoring structural integrity, and ensuring functionality. However, most of the currently used fixation tools are fabricated from materials with very different mechanical properties to native bone that are prone to pull-out effects or fail over time, requiring revision procedures. Solutions to these problems presently exploited in practice include the optimal selection of screw shape and size, modification of insertion trajectory, and utilization of bone cement to reinforce fixation constructs. Nevertheless, none of these methods are without risks and limitations. An alternative option to increasing biomechanical resistance to the pull-out effect is to tackle bone regenerative capacity and focus on screw osteointegration properties. Osteointegration was reportedly enhanced through various optimization strategies, including use of novel materials, surface modification techniques (e.g., application of coatings and topological optimization), and utilization of composites that allow synergistic effects between constituents. In this context, this paper takes a comprehensive path, starting with a brief presentation of spinal fixation devices, moving further to observations on how the pull-out strength can be enhanced with existing methods, and further focusing on techniques for implant osteointegration improvement.

Tough, Injectable Calcium Phosphate Cement Based Composite Hydrogels to Promote Osteogenesis

Osteoporosis is one of the most disabling consequences of aging, and osteoporotic fractures and a higher risk of subsequent fractures lead to substantial disability and deaths, indicating that both local fracture healing and early anti-osteoporosis therapy are of great significance. However, combining simple clinically approved materials to achieve good injection and subsequent molding and provide good mechanical support remains a challenge. To meet this challenge, bioinspired by natural bone components, we develop appropriate interactions between inorganic biological scaffolds and organic osteogenic molecules, achieving a tough hydrogel that is both firmly loaded with calcium phosphate cement (CPC) and injectable. Here, the inorganic component CPC composed of biomimetic bone composition and the organic precursor, incorporating gelatin methacryloyl (GelMA) and N-Hydroxyethyl acrylamide (HEAA), endow the system with fast polymerization and crosslinking through ultraviolet (UV) photo-initiation. The GelMA-poly (N-Hydroxyethyl acrylamide) (GelMA-PHEAA) chemical and physical network formed in situ enhances the mechanical performances and maintains the bioactive characteristics of CPC. This tough biomimetic hydrogel combined with bioactive CPC is a new promising candidate for a commercial clinical material to help patients to survive osteoporotic fracture.

Discordance in lumbar bone mineral density measurements by quantitative computed tomography and dual-energy X-ray absorptiometry in postmenopausal women: a prospective comparative study

BACKGROUND CONTEXT

Level-specific lumbar bone mineral density (BMD) evaluation of a single vertebral body can provide useful surgical planning and osteoporosis management information. Previous comparative studies have primarily focused on detecting spinal osteoporosis but not at specific levels.

PURPOSE

To compare the detection rate of lumbar osteoporosis between quantitative computed tomography (QCT) and dual-energy X-ray absorptiometry (DXA); to explore and analyze the distribution models of QCT-derived BMD and DXA T-score at the specific levels; and to evaluate the diagnostic accuracy of level-specific BMD thresholds for the prediction of osteoporotic vertebral compression fracture (OVCF) in postmenopausal women.

STUDY DESIGN/SETTING

A comparative analysis of prospectively collected data comparing QCT-derived BMD with DXA T-score.

PATIENT SAMPLE

A total of 296 postmenopausal women who were referred to the spine service of a single academic institution were enrolled.

OUTCOME MEASURES

QCT-derived BMD and DXA T-score at specific levels, with or without osteoporotic vertebral compression fracture.

METHODS

Postmenopausal women who underwent QCT and DXA within a week of admission from May 2019 to June 2022 were enrolled. The diagnostic criteria for osteoporosis recommended by the World Health Organization and the American College of Radiology were used for lumbar osteoporotic diagnosis. To evaluate differences in lumbar BMD measurements at specific levels, a threshold of T score=-2.5 and QCT-derived BMD = 80 mg/cm³ were used to categorize level-specific lumbar BMD into low and high BMD. Disagreements in BMD categorization between DXA and QCT were classified as a minor or major discordance based on the definition by Woodson. Data between QCT and DXA were visualized in a stacked bar plot and analyzed. Correlations between DXA and QCT at the specific levels were evaluated using Pearson's linear correlation and scatter plots. Curve fitting of BMD distribution, receiver operating characteristic (ROC) and area under the curve (AUC) for each single vertebral level was performed.

RESULTS

Of the 296 patients, QCT diagnosed 61.1% as osteoporosis, 30.4% as osteopenia and 8.4% as normal. For those screened with DXA, 54.1% of the patients had osteoporosis, 29.4% had osteopenia and 16.6% had normal BMD. Diagnoses were concordant for 194 (65.5%) patients. Of the other 102 discordant patients, 5 (1.7%) were major and 97 (32.8%) were minor. Significant correlations in level-specific BMD between DXA and QCT were observed (p<.001), with Pearson's correlation coefficients ranging from 0.662 to 0.728. The correlation strength was in the order of L1 > L2 > L3 > L4. The low BMD detection rate for QCT was significantly higher than that for DXA at the L3 and L4 levels (65% vs. 47.9% and 68.1% vs 43.7, respectively, p<.001). Patients with OVCF showed significantly lower QCT-derived BMD (47.2 mg/cm³ vs. 83.2 mg/cm³, p<.001) and T-score (-3.39 vs. -1.98, p<.001) than those without OVCF. Among these patients, 82.8% (101/122) were diagnosed with osteoporosis by QCT measurement, while only 74.6% (91/122) were diagnosed by DXA. For discrimination between patients with and without OVCF, QCT-derived BMD showed better diagnosed performance (AUC range from 0.769 to 0.801) than DXA T-score (AUC range from 0.696 to 0.753).

CONCLUSION

QCT provided a more accurate evaluation of lumbar osteoporosis than DXA. The QCT-derived BMD measurements at a specific lumbar level have a high diagnostic performance for OVCF.

Surgical management of high-grade lumbar spondylolisthesis associated with Hajdu-Cheney syndrome: illustrative case

BACKGROUND

Hajdu-Cheney syndrome (HCS) is a rare connective tissue disorder characterized by severe bone demineralization. In the spine, it is associated with the early onset of severe osteoporosis and can cause spondylolisthesis. Spinal instrumentation in the setting of severe osteoporosis is challenging because of poor resistance of vertebrae to biomechanical stress.

OBSERVATIONS

A 59-year-old woman with known idiopathic HCS presented with a grade 4 L5-S1 spondylolisthesis and right L5 pedicle fracture associated with a left L5 pars fracture, causing a progressive L5 radiculopathy that was worse on the left side than the right side and bilateral foot drop. The authors performed decompressive lumbar surgery, which included a complete L5 laminectomy and resection of the left L5 pedicle. This was followed by multilevel lumbosacral instrumentation using cement-augmented fenestrated pedicle screws as well as transdiscal sacral screws and bilateral alar-iliac fixation. Postoperatively, the radicular pain resolved, and the left foot drop partially recovered.

LESSONS

Stabilization of high-grade spondylolisthesis in the setting of bone demineralization disorders is challenging. The use of different instrumentation techniques is important because it increases biomechanical stability of the overall instrumentation construct.

Does augmentation increase the pull-out force of symphyseal screws? A biomechanical cadaver study

Purpose

Open reduction and internal fixation using anterior plate osteosynthesis currently represents the gold standard for the treatment of symphyseal disruptions. Since postoperative screw loosening with consequent implant failure is frequently observed, this study aims to evaluate if and to what extent augmentation can increase the pull-out force of symphyseal screws to improve the constructs stability.

Methods

Twelve human cadaveric anterior pelvic rings were separated at the symphyseal joint for bilateral testing, consequently achieving comparable sites. First, one non-augmented screw was drilled into the superior pubic ramus, whereas the contralateral side was primarily augmented. The screws were then withdrawn with a constant speed of 10 mm/min and the fixation strengths determined by the force (N) displacement (mm) curve. Finally, the primary non-augmented site was secondary augmented, representing revision surgery after initial implant failure, and the corresponding fixation strength was measured again.

Results

Augmentation compared to non-augmented screws displayed significantly higher pull-out forces with an increase in pull-out force by 377% for primary and 353% for secondary augmentation (p < 0.01). There was no significant difference in the pull-out force comparing primary and secondary augmentation (p = 0.74).

Conclusions

Primary and secondary augmentation significantly increases the stability of symphyseal screws and, therefore, potentially decreases rates of implant failure.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00068-022-01963-6.

Postoperative and Intraoperative Cement Augmentation for Spinal Fusion

OBJECTIVE

To review outcomes of patients undergoing spinal fusion with prophylactic cement augmentation (CA) of pedicle screws and adjacent levels.

METHODS

In a retrospective case-control study, 59 patients underwent CA of pedicle screws for spinal fusion between 2003 and 2018. Most patients (83%) underwent postoperative CA, while 17% underwent intraoperative CA. Outcomes of CA techniques were compared, and patients undergoing CA for a thoracolumbar fusion (n = 51) were compared with a cohort not undergoing CA (n = 39). Mean follow-up was 3 years.

RESULTS

In patients receiving CA, survivorship free of proximal junctional kyphosis (PJK) was 94%, 60%, and 20% at 2, 5, and 10 years postoperatively. Survivorship free of revision was 95%, 83%, and 83% at 2, 5, and 10 years postoperatively. Development of PJK (P = 0.02, odds ratio [OR] 24.44) was associated with revision surgery. There were 4 (7%) cardiopulmonary complications. Patients who received CA for thoracolumbar fusion were older (70 years vs. 65 years) and were more likely to have osteoporosis (53% vs. 5%) than patients who did not receive CA. CA was associated with a decreased risk of PJK (P = 0.009, OR 0.16), while osteoporosis (P = 0.05, OR 4.10) and fusion length ≥8 levels (P = 0.06, OR 2.65) were associated with PJK. PJK was associated with revision surgery (P = 0.006, OR 12.65).

CONCLUSIONS

CA allows for substantial rates of radiographic PJK; however, this typically does not result in a need for revision surgery and leads to revision and PJK rates that are comparable to patients undergoing long segment fusions without osteoporosis.