Severity of spinal degeneration does not affect the pain reduction under continuous epidural analgesia.

PURPOSE: To outline clinical effectiveness of continuous epidural analgesia (CEA) in patients with failed back surgery syndrome (FBSS) or lumbar spinal stenosis (LSS) depending on severity of spinal degeneration. METHODS: In this retrospective cohort study, all patients with FBSS or LSS who underwent CEA within an inpatient rehabilitation program were evaluated. The pain reduction was measured by VAS on an hourly basis. Substantial pain reduction was defined as a minimal clinically important difference (MCID) > 50%. Severity of spinal degeneration, side effects and patient-specific characteristics were documented. RESULT: We included a total of 148 patients with 105 patients suffering from FBSS and 48 with LSS. The average pain reduction was - 37.6 ± 19.2 in FBSS and - 38.1 ± 17.8 in LSS group (p < .001 and p < .001, respectively). In the FBSS group, sensory deficits (p = .047) and numbness (p = .002), and in the LSS group, a severe disability measured by ODI (38.2 ± 15.4 vs. 57.3 ± 11.3, p < .001) significantly contributed to a worse outcome. The severity of the spinal degeneration and psychological disorders did not affect the pain reduction in terms of MCID. CONCLUSIONS: This study provides new evidence about CEA in the treatment of FBSS and LSS. CEA provides a significant pain reduction even under intensified physiotherapeutic exercising in patients with severe spinal degeneration and a broad variety of secondary diagnoses. Neurologic deficits in case of FBSS and severe disability in case of LSS may be risk factors for less favorable outcome.

Feasibility of continuous epidural analgesia in patients with failed back surgery syndrome and spinal stenosis.

PURPOSE: The purpose of this study was to outline the feasibility of continuous epidural analgesia in the treatment of failed back surgery syndrome (FBSS) or spinal stenosis. METHODS: We queried our prospective collected institutional database to include all consecutive patients, who underwent continuous epidural analgesia with accompanying intensive physiotherapeutic exercise within a timeframe of 4 years. Patients suffered from FBSS or spinal stenosis; protocolled continuous epidural analgesia was planned for 4 days within the framework of an inpatient multimodal pain therapy concept. The instillation technique of the epidural catheter, the capability to attend in accompanying physiotherapy, and the peri-interventional complications were evaluated. RESULTS: 153 patients with an average age of 57.4 years (± 11.9) were enrolled in this study. 105 patients suffered from FBSS and 48 patients had spinal stenosis. Overall, 148 patients (96.7%) reported the pain reduction and were able to perform daily intensified physiotherapeutic exercise. There were no serious adverse events, neither infection nor bleeding, no cardiopulmonary complication or permanent neurological deficits. The most common side effect was neurological impairment, such as numbness, dysesthesia, or weakness of the lower limbs with complete regression after flow rate adjustment. Patients with FBSS were more likely to develop dysesthesia (p = 0.007). CONCLUSIONS: Continuous epidural analgesia is feasible in patients with FBSS or spinal stenosis. This treatment enables extensive physiotherapeutic treatment even in patients with severe pain conditions and can be considered as an alternative to epidural injections. An increased complication rate in comparison to short-term perioperative or perinatal application was not observed.

Georg Schmorl Prize of the German Spine Society (DWG) 2020: new biomechanical in vitro test method to determine subsidence risk of vertebral body replacements.

PURPOSE: Prevention of implant subsidence in osteoporotic (thoraco)lumbar spines is still a major challenge in spinal surgery. In this study, a new biomechanical in vitro test method was developed to simulate patient activities in order to determine the subsidence risk of vertebral body replacements during physiologic loading conditions. METHODS: The study included 12 (thoraco)lumbar (T11-L1, L2-L4) human specimens. After dorsal stabilisation and corpectomy, vertebral body replacements (VBR) with (a) round centrally located and (b) lateral end pieces with apophyseal support were implanted, equally distributed regarding segment, sex, mean BMD ((a) 64.2 mgCaHA/cm3, (b) 66.7 mgCaHA/cm3) and age ((a) 78 years, (b) 73.5 years). The specimens were then subjected to everyday activities (climbing stairs, tying shoes, lifting 20 kg) simulated by a custom-made dynamic loading simulator combining corresponding axial loads with flexion-extension and lateral bending movements. They were applied in oscillating waves at 0.5 Hz and raised every 100 cycles phase-shifted to each other by 50 N or 0.25°, respectively. The range of motion (ROM) of the specimens was determined in all three motion planes under pure moments of 3.75 Nm prior to and after implantation as well as subsequently following activities. Simultaneously, subsidence depth was quantified from fluoroscope films. A mixed model (significance level: 0.05) was established to relate subsidence risk to implant geometries and patients' activities. RESULTS: With this new test method, simulating everyday activities provoked clinically relevant subsidence schemes. Generally, severe everyday activities caused deeper subsidence which resulted in increased ROM. Subsidence of lateral end pieces was remarkably less pronounced which was accompanied by a smaller ROM in flexion-extension and higher motion possibilities in axial rotation (p = 0.05). CONCLUSION: In this study, a new biomechanical test method was developed that simulates physiologic activities to examine implant subsidence. It appears that the highest risk of subsidence occurs most when lifting heavy weights, and into the ventral part of the caudal vertebra. The results indicate that lateral end pieces may better prevent from implant subsidence because of the additional cortical support. Generally, patients that are treated with a VBR should avoid activities that create high loading on the spine.

A pedicle screw system and a lamina hook system provide similar primary and long-term stability: a biomechanical in vitro study with quasi-static and dynamic loading conditions.

PURPOSE: For the stabilization of the thoracolumbar spine area, various stabilization techniques have been developed in recent decades. The aim of these techniques is to immobilize the treated segment to repositioning or correct the spine and guaranty long-term stability to achieve a reliable fusion. The aim of this study was to simulate in an in vitro experiment the postoperative long-term situation in elderly osteoporotic patients to compare two different stabilization principles; a pedicle screw system and a lamina hook system. METHODS: Two comparable groups with respect to age and bone mineral density with each n = 6 fresh-frozen human, bi-segmental thoracolumbar spine specimens (T11-L1) were used. Antero-posterior and lateral radiographs were taken before the test, to assess the spinal status. Then the intact specimens were biomechanically characterized with pure moments in the three anatomical planes in different states in terms of range of motion and neutral zone. After implantation of either, a pedicle screw system or a lamina hook system, the primary stability was determined under the same conditions. Subsequently the specimens were cyclically loaded under complex loading, using a custom-made set-up in a dynamic materials testing machine with increasing moments from 3 to 66 Nm until 100,000 cycles or until one of the three defined "failure" criteria was reached. (1) A failure of a bony structure. (2) Exceeding of the threefold ROM of the primary stability after implantation in flexion plus extension. (3) Reaching of the ROM based on the intact state before implantation both in flexion plus extension. RESULTS: The results showed that the ROM was strongly reduced after instrumentation similar for both implant systems in all motion planes. The highest stabilization was found in flexion/extension. During cyclic loading with increasing moments, the ROM increased continuously for both systems. The number of load cycles until one of the failure criteria was reached varied only slightly between the two groups. In the pedicle screw group 30,000 (median) loading cycles (range 5000-80,000) with a corresponding moment of 24 Nm (range 9-54) could be reached. In the lamina hook group 32,500 load cycles (range 20,000-45,000) could be achieved with a corresponding moment of 25.5 Nm (range 18-33). There was a slight trend that the pedicle screw system is influenced more by bone mineral density. CONCLUSION: Both implant systems provide similar primary stability and similar long-term stability. In the pedicle screw group, there was a stronger correlation between bone mineral density and the reached number of load cycles.

[Interbody fusion procedures. Development from a historical perspective]. / Interkorporelle Fusionsverfahren an der Wirbelsäule. Die Entwicklung aus historischer Sicht.

BACKGROUND: The development of interbody fusion now stretches over many decades and is still not complete. DISCUSSION: Due to the lack of appropriate implants, the initial fusions were performed via decortication of the dorsal and lateral structures of the spine, followed by placement of an autograft. Despite acceptable fusion results, better primary stability and higher fusion rates were desired. In addition, it became known that the primary load-bearing of the spine is located ventrally in the area of the corpus of the vertebrae. These considerations led to the development of the PLIF technique that was introduced by Cloward in 1953 and gained significantly in popularity. After removal of the intervertebral disc, he positioned iliac crest bone blocks between the vertebral bodies. Based on this technique and these considerations, intervertebral implants were developed in the 1970s. The so-called Bagby Basket was the first intervertebral cage that was initially used in horses with wobbler syndrome. Other milestones in the improvement of the cage designs followed, resulting in the production of different implant shapes and materials. The elastic modulus of the interbody implants approached by modern materials became more and more similar to bone, so that subsidence of cages reduced and the fusion rate could be further increased. The primary stability could be further increased with screw-rod systems, so that dorsal instrumentation became the standard in the context of PLIF and TLIF procedures today. The TLIF procedure described by Harms was a new modification and minimized complications of lumbar fusions and reduced the invasiveness of the procedure. CONCLUSION: Nowadays a wide variety of implants and implantation techniques are available, making interbody fusions in PLIF and TLIF techniques safe and successful procedures.

Biomechanical comparison of different rod-to-rod connectors to a conventional titanium- and cobalt chromium posterior spinal fixation system.

Introduction: Several types of rod-to-rod connectors are available for the extension of spinal fixation systems. However, scientific literature regarding the mechanical performance of different rod-to-rod connector systems is lacking. Research question: The goal of this study was to evaluate the mechanical characteristics of axial and lateral rod connectors in comparison to a conventional pedicle screw rod (titanium and cobalt chromium) construct. Material and method: Six types of instrumentations were investigated in a standardized test model to quantify the mechanical differences: 1: titanium rod; 2: titanium rod with axial connector; 3: titanium rod with lateral connector; 4: cobalt chromium rod; 5: cobalt chromium rod with axial connector; 6: cobalt chromium rod with lateral connector. All groups were tested in static compression, static torsion and dynamic compression and statistically compared regarding failure load and stiffness. Results: In static compression loading, the use of connectors increased the construct stiffness, but unaffected the yield load. The use of a cobalt chromium rod significantly increased by approximately 40% the yield load and stiffness in comparison to the titanium rod configurations. Under dynamic compression, a similar or higher fatigue strength for all tested groups in comparison to the titanium rod configuration was evaluated, with the exception of titanium rod with axial connector. Conclusion: Biomechanically, using rod connectors is a secure way for the extension of a construct and is mechanically equal to a conventional screw rod construct. However, in clinical use, attention should be paid regarding placement of the connectors at high loaded areas.

Operative results of AO A3 and A4 traumatic injuries in the thoracic and lumbar spine. A multicenter surveillance study of 4230 patients from the German Spine Registry (DWG-Register).

BACKGROUND: The diagnosis, classification and treatment of thoracolumbar burst fractures, continue to be controversial. Surgery is generally the preferred treatment for unstable fractures while stable fractures are managed conservatively. This study aims to describe surgical procedures, outcomes, complications, demography, clinical features and differences between A3 and A4 fractures (AO classification) of the thoracolumbar region. A subgroup of patients <91 years with osteoporotic fractures is included and analyzed. METHODS: Analysis of data from the DWG-Register German spine registry on operative treatment for thoracolumbar AO A3 and A4 fractures out of 170 departments from January 2017 to May 2021. The evaluated variables included age, gender, surgical approach (posterior, anterior combined), and re-operation. RESULTS: In total, 4230 AO A3 and A4 thoracolumbar fractures were identified in the registry; 2898 A3 (group 1) and 1332 A4 (group 2). The preoperative ASIA-impairment scale score in group 1 was significantly different compared with group 2 (P=0.02). Surgical procedures such as decompression/stabilization with rod-screw system cemented/non-cemented, as well as an anterior approach, were statistically significant between the groups. Odds ratio was calculated for variables that could be influenced for the type of fracture (A3 or A4): decompression 4.89, OR time >2 hours 48.22, osteoporosis 6.46 and posterior access 9.85. CONCLUSIONS: This study provides multicenter results from a huge number of surgically treated AO A3 and A4 fractures. Anterior approaches are more often used in A4 type fractures, probably because of its inherent instability related to burst fractures, surprisingly, not associated with the occurrence of added perioperative complications. Nevertheless, A3 type fractures are presented with worse ASIA Impairment-Scale at admission, in comparison with A4 type fractures of the thoracolumbar region.

Management of Deep Spinal Wound Infections Following Instrumentation Surgery with Subfascial Negative Pressure Wound Therapy.

BACKGROUND AND STUDY AIMS: The treatment of infections following a spine surgery continues to be a challenge. Negative pressure wound therapy (NPWT) has been an effective method in the context of infection therapy, and its use has gained popularity in recent decades. This study aims to analyze the impact of known risk factors for postoperative wound infection on the efficiency and length of NPWT therapy until healing. PATIENTS AND METHODS: We analyzed 50 cases of NPWT treatment for deep wound infection after posterior and posteroanterior spinal fusion from March 2010 to July 2014 retrospectively. We included 32 women and 18 men with a mean age of 69 years (range, 36-87 years). Individual risk factors for postoperative infection, such as age, gender, obesity, diabetes, immunosuppression, duration of surgery, intraoperative blood loss, and previous surgeries, as well as type and onset (early vs. late) of the infection were analyzed. We assessed the associations between these risk factors and the number of revisions until wound healing. RESULTS: In 42 patients (84%), bacterial pathogens were successfully detected by means of intraoperative swabs and tissue samples during first revision. A total of 19 different pathogens could be identified with a preponderance of Staphylococcus epidermidis (21.4%) and S. aureus (19.0%). Methicillin-resistant S. aureus (MRSA) was recorded in two patients (2.6%). An average of four NPWT revisions was required until the infection was cured. Patients with infections caused by mixed pathogens required a significantly higher number of revisions (5.3 vs. 3.3; p < 0.01) until definitive wound healing. For the risk factors, no significant differences in the number of revisions could be demonstrated when compared with the patients without the respective risk factor. CONCLUSION: NPWT was an effective therapy for the treatment of wound infections after spinal fusion. All patients in the study had their infections successfully cured, and all spinal implants could be retained. The number of revisions was similar to those reported in the published literature. The present study provides insights regarding the effectiveness of NPWT for the treatment of deep wound infection after spinal fusion. Further investigations on the impact of potential risk factors for postoperative wound healing disorders are required. Better knowledge on the impact of specific risk factors will contribute to a higher effectiveness of prophylaxis for postoperative wound infections considering the patient-specific situation.

Comparison of ALIF and PLIF in Isthmic Lumbosacral Spondylolisthesis. A Multicenter Surveillance Study of 602 cases from the German Spine Registry (DWG Register).

BACKGROUND: Isthmic spondylolisthesis most commonly occurs in the lumbosacral junction and can cause backpain and radicular pain as well as stiffness with progressive immobilization, with a negative impact on an individual's ability to work and quality of life. Multiple operative treatments are currently available. This study aims to compare complications, demography, and clinical features between anterior lumbar interbody fusion (ALIF) and posterior lumber body fusion (PLIF) in the operative treatment in isthmic spondylolisthesis. METHODS: An analysis of data from the German spine registry (Deutsche Wirbelsäulengesellschaft [DWG]-Register) of patients who underwent operative treatment (PLIF and ALIF) for isthmic spondylolisthesis in the sacrolumbar junction in 170 departments between January 2017 and May 2021 was performed. Age, gender, American Society of Anesthesiologists (ASA) score, surgical approach, smoker/nonsmoker, as well as severeness of the spondylolisthesis according to the Meyerding classification were evaluated. RESULTS: In total, 602 patients undergoing fusion in L5/S1 were identified in the registry, n = 570 PLIF (group 1) and n = 32 ALIF (group 2). A significant difference in the ASA score between the two groups was noted; group 1 had more patients suffering a more debilitating disease in comparison to group 2. There was no significant difference in gender, grade of spondylolisthesis, age, or smoking status. Significant differences were found in operative and postoperative variables and complications (fusion material, dura injury). CONCLUSION: No difference was found between the two procedures in terms of symptomatic benefit of patients who underwent either ALIF or PLIF. According to the DWG Register, PLIF was the preferred method to treat isthmic spondylolisthesis in the sacrolumbar junction in Germany. To compare these two spine fusion techniques, further studies with an adequate sample size and follow-up period are required.

Impact of Obesity on Perioperative Complications on Treatment of Spinal Metastases: A Multicenter Surveillance Study from the German Spine Registry (DWG-Register).

Background The spine is a common location for the development of primary and metastatic tumors, spinal metastases being the most common tumor in the spine. Spinal surgery in obesity is challenging due to difficulties with anesthesia, intravenous access, positioning, and physical access during surgery. The objective was to investigate the effect of obesity on perioperative complications by discharge in patients undergoing surgery for spinal metastases. Methods Retrospective analysis of data from the DWG-register on patients undergoing surgery for metastatic disease in the spine from January 2012 to December 2016. Preoperative variables included obesity (≥ 30 kg/m 2 ), age, gender, and smoking status. In addition, the influence of pre-existing medical comorbidity was determined, using the American Society of Anesthesiologists (ASA) score. Results In total, 528 decompressions with and without instrumentation undergoing tumor debulking, release of the neural structures, or tumor extirpation in metastatic disease of the spine were identified; 143 patients were obese (body mass index [BMI] ≥ 30 kg/m 2 ), and 385 patients had a BMI less than 30 kg/m 2 . The mean age in the group with BMI 30 kg/m 2 or higher (group 1) was 67 years (56.6%). In the group with BMI less than 30 kg/m 2 (group 2), the mean age was 64 years. Most of the patients had preoperatively an ASA score of 3 and 4 (patients with severe general disease). The likelihood of being obese in the logistic regression model seems to be protective by 47.5-fold for blood loss 500 mL or higher. Transfusions occurred in 321/528 (60.7%) patients (group 1, n = 122 and group 2, n = 299; p = 0.04). A total of 19 vertebroplasties with percutaneous stabilization (minimally invasive spine [MIS]), 6 vertebroplasties, and 31 MIS alone were identified. The variables between these groups, with exception of preoperative status (ASA-score; p = 0.02), remained nonsignificant. Conclusion Obese patients were predisposed to have blood loss more than 500 mL more often than nonobese patients undergoing surgery for spinal metastases but with perioperative blood transfusions, invasiveness, nor prolonged hospitalization. Early postoperative mobilization and a low threshold for perioperative venous thromboembolism (VTE) are important in obese patients to appropriately diagnose, treat complications, and minimize morbidity.

Invasiveness has no influence on the rate of incidental durotomies in surgery for multisegmental lumbar spinal canal stenosis (≥3 levels) with and without fusion: analysis from the German Spine Registry data (DWG-Register).

BACKGROUND: Nowadays, perioperative complications as dural tear (DT) with subsequent neurological deficits are documented in independent registers. However, the relationship of these complications with the grade of invasiveness (≥3 levels) is still unclear. The aim of this study was to evaluate perioperative complications, particularly DT with subsequent neurological deficits, between patients undergoing laminotomy and decompression and decompression and fusion in ≥3 levels. METHODS: Retrospective analysis of the data pool of the DWG register based on cases described by 10 clinics between January 2012 and December 2016 was performed. Surgically treated LSS in ≥3 segments were divided into decompression with or without instrumentation and fusion. Cases with intraoperative DT in both subgroups were analysed for risk factor occurrence. The Surgical Invasive Index (SII) was used. RESULTS: DT occurred in 102/941 (10.8%) patients. Difference in DT between groups was non-significant. The likelihood of DT increased by 2.12-fold with previous spinal surgery at the same level and by 1.9-fold for BMI 30-34 and >35 in comparison with BMI 26-29, respectively. Postoperative deep wound infection was increased by 2.39-fold after DT than without. Significance in outcomes between patients with/without DT was not found. The invasiveness index explained 48% of the variation in blood loss and 51% of the variation in surgery duration. CONCLUSIONS: The rate of incidental DT during decompression for LSS with and without fusion in ≥3 levels was associated with BMI and previous surgery at the same spinal level. Invasivness (SII) is valid rather for variables proper to surgery such as bledding and Op-time but no with incidence for DT and subsequent CSF-leackage.

There is no difference in perioperative results between posterior instrumentation with and without interbody cage and debridement in primary spondylodiscitis in adults: a multicenter surveillance study from the German Spine Registry (DWG Register).

BACKGROUND: Primary spondylodiscitis is a medically challenging disease that can lead to recurrent back pain, progressive kyphotic deformity, and neurologic deficits. The incidence rate of primary non-tuberculosis spondylodiscitis has been estimated from 2.2 to 2.4 cases per 100,000 person-years, and it has been reported to be increasing because of the aging population. The objectives were to determine the safety and efficacy of posterior instrumentation (PI) with and without interbody cage, bony attachment and debridement in the treatment of primary spondylodiscitis by comparing perioperative data, functional outcomes, and overall infection-free survival. METHODS: Analysis of data from the DWG Registry on patients who have undergone posterior instrumentation with and without interbody cage, bony attachment and debridement in primary spondylodiscitis from the thoracolumbar junction to S1 (Th10-S1) at 10 institutions from January 2012 to December 2016. RESULTS: In total, 420 posterior instrumentations with and without interbody cage, bony attachment and debridement in primary spondylodiscitis in the thoracolumbar junction to S1 were identified in the registry; N.=138 were exclusively percutaneous posterior instrumented (PPI), while N.=102 underwent open posterior instrumentation (OPI) without interbody cage, bony attachment and debridement and N.=180 OPI with interbody cage, bony attachment and debridement. Clinical evaluation after surgery did not show a significant difference between groups including improvement of the mobilization and infection-free survival. However, with PPI the duration of operation and blood loss was significantly less than OPI with and without interbody cage, bony attachment and debridement. CONCLUSIONS: The results suggest interbody cage, bony attachment and debridement as not indispensable for treatment in primary spondylodiscitis. Therefore, we encourage the use of posterior stabilization alone in the treatment of spondylodiscitis as less invasive procedure reducing costs in instrumentation.

Intra- and postoperative complications in the treatment of spinal metastases . A multicenter surveillance study from the German Spinal Registry (DWG-Register).

BACKGROUND: The incidence of spinal column tumors is estimated to be 0.62 per 100,000 individuals in the USA. It is especially important to understand the incidence and predictive factors for adverse events of surgery in spinal oncology patients, as a single complication may be associated with morbidity, mortality, and costs. The aim of the study was to use a large national registry to evaluate the perioperative cumulative incidence and predictors of major complications, for metastatic spinal tumors. METHODS: This study is a retrospective analysis of data from the DWG registry on patients who have undergone decompression with and without instrumentation undergoing tumor debulking, release of the neural structures, spinal stabilization or tumor extirpation in metastatic disease of the spine in 124 departments from January 2017 to January 2020, as well as vertebroplasty and percutaneous instrumentation. The outcomes evaluated were major complications defined by Finkelstein et al. as: death; cerebral (new postoperative coma or stroke), cardiac, pulmonary or renal complication; symptomatic venous thromboembolism; surgical site infection. RESULTS: In total, 1617 decompressions with and without instrumentation undergoing tumor debulking, release of the neural structures, spinal stabilization or tumor extirpation in metastatic disease in the spine were identified in the registry; N.=266 developed a major complication (group 2), while N.=1351 had no complication (group 1). The mean age in group 1 was 65 years (58.5%), in group 2 69 years (63.5%). In group 2, most of the patients had preoperatively an ASA Score of 3 and 4 (patients with severe general disease): 202/266 (75.9%) being significant. The overall prevalence of a major postoperative complication was 16.5% and for an intraoperative complication remained 8%. The likelihood ratio for major complications by blood loss greater than 500 mL were as follows: cardiovascular event with a likelihood of 4.22 pulmonary insufficiency 4.18 and cerebral 5.47. CONCLUSIONS: This analysis provides predictive models for surgeons to identify patients who may benefit from transitional care programs. Preoperative status, invasiveness, blood loss >500 mL and blood transfusions are independent predictors associated with higher risk of complication.

Anterior vertebroplasty of adjacent levels after vertebral body replacement.

The aim of this study was to evaluate the feasibility of a new method, which should help to avoid cage subsidence after vertebrectomy in short fusions. After implantation of an extendable vertebral body replacement (VBR) the two adjacent endplates to the fractured or destroyed vertebra were augmented with bone cement using the anterior approach in 20 patients with short circumferential fusion. All patients were followed up for 2 years clinically and radiographically. X-rays were reviewed for kyphosis, cage subsidence, presence of a solid fusion mass and instrumentation failure. Changes in every day activities (Oswestry Disability Index-ODI) and visual analogue scale (VAS), pain score, as well as technique-related complications were examined. The mean amount of kyphosis correction was 12.8° (±6.4°) and changed by only 0.3° (±0.4°) until last follow-up. Pain (VAS) and ODI scores were significantly improved and did not change until last follow-up. In all but two cases, the authors observed solid union with incorporation of the cage. No surgery-related complications were recorded. In one case revision was advised because of non-union due to septic loosening. The augmentation of the adjacent vertebras after anterior VBR provides an enhancement of the interface between cage and vertebra in cases with poor bone quality and in revision surgery. The technique is simple and safe, as the needles can be placed under visual control. Cement augmentation of the endplates may reduce interbody device subsidence.

The effect of cement augmentation on pedicle screw fixation under various load cases : results from a combined experimental, micro-CT, and micro-finite element analysis.

AIMS: Anchorage of pedicle screw rod instrumentation in the elderly spine with poor bone quality remains challenging. Our study aims to evaluate how the screw bone anchorage is affected by screw design, bone quality, loading conditions, and cementing techniques. METHODS: Micro-finite element (µFE) models were created from micro-CT (µCT) scans of vertebrae implanted with two types of pedicle screws (L: Ennovate and R: S4). Simulations were conducted for a 10 mm radius region of interest (ROI) around each screw and for a full vertebra (FV) where different cementing scenarios were simulated around the screw tips. Stiffness was calculated in pull-out and anterior bending loads. RESULTS: Experimental pull-out strengths were excellently correlated to the µFE pull-out stiffness of the ROI (R2 > 0.87) and FV (R2 > 0.84) models. No significant difference due to screw design was observed. Cement augmentation increased pull-out stiffness by up to 94% and 48% for L and R screws, respectively, but only increased bending stiffness by up to 6.9% and 1.5%, respectively. Cementing involving only one screw tip resulted in lower stiffness increases in all tested screw designs and loading cases. The stiffening effect of cement augmentation on pull-out and bending stiffness was strongly and negatively correlated to local bone density around the screw (correlation coefficient (R) = -0.95). CONCLUSION: This combined experimental, µCT and µFE study showed that regional analyses may be sufficient to predict fixation strength in pull-out and that full analyses could show that cement augmentation around pedicle screws increased fixation stiffness in both pull-out and bending, especially for low-density bone. Cite this article: Bone Joint Res 2021;10(12):797-806.

Bioceramic vertebral augmentation with a calcium sulphate/hydroxyapatite composite (Cerament SpineSupport): in vertebral compression fractures due to osteoporosis.

A prospective, non-randomized multicenter study was initiated to study efficacy and safety of a partly resorbable composite of calcium sulphate and hydroxyapatite (Cerament SpineSupport), a novel, injectable bioceramic, in osteoporotic patients with vertebral compression fractures during 18-month follow-up. Fifteen patients with low-energy trauma and 1-2 vertebral compression fractures verified by magnetic resonance imaging were recruited to undergo percutaneous bioceramic vertebral augmentation under fluoroscopy. The patients were treated with a highly flowable bioceramic containing calcium sulphate, hydroxyapatite and the non-ionic radiocontrast agent iohexol, with final setting time within 1 h. After the procedure, the patients were allowed to mobilize after 2 h. Pain (VAS), occurrence of remote and adjacent fractures, and Quality of Life (QoL; SF-36 and EQ-5D) was recorded during 18 months. The injected volume of the composite material ranged from 2.8 to 9 mL (mean 4.2 mL). Pre-operative VAS score was mean 70.3 (CI95% +/-8.7) with an immediate post-operative pain relief, which was maintained at the 4-week visit (mean 26.4 with CI95% +/-16.1) and 8-week visit (mean 18.0 with CI95% +/-13.5 pain relief). Eighty percent of the patients demonstrated a clinical improvement. The pain relief was maintained over 18 months and no adjacent fractures were observed. There was a statistically significant improvement of physical components in the QoL assessment. No extra-vertebral leakage or neurological deficits were reported in this series. This first prospective multicenter study on a partly resorbable bioceramic material indicate that fracture healing can be achieved with sustained pain relief over a follow-up period of 18 months in an osteoporotic patient population with vertebral compression fractures.

Reduction of radiation dose during radiofrequency denervation of the lumbar facet joints using the new targeting system SabreSource: a prospective study in 20 patients.

BACKGROUND AND AIMS: Facet joint denervation is a frequently performed technique to treat facet joint syndrome. Most often this technique is used under fluoroscopic guidance implicating high radiation doses for both patients and surgeons. This prospective study was performed to evaluate the effectiveness in reducing radiation dose during radiofrequency ablation therapy of the lumbar facet joints and to evaluate the feasibility and possibilities of the new real time image guidance system SabreSource. MATERIALS AND METHODS: As much as 20 consecutive patients with radiofrequency ablation therapy of the facet joints L4 to S1 were included. Ten patients were treated by fluoroscopic control alone; the following 10 patients were treated with the SabreSource image guidance system. A total of 40 thermal ablations to the facet joints were performed. Each patient was given one thermal ablation on both sides of the vertebral segment, either to the facet joints of L4-L5 or of L5-S1. Pain, according to the visual analogue scale (VAS), was documented before and 6 h after the intervention. Radiation dose, time of radiation and the number of shots needed to place the radiofrequency cannula were recorded. RESULTS: No complications occurred. Before therapy, the mean VAS in all patients was 7.6 (range 6-10). After therapy the mean VAS in all patients was 3.4 (range 0-5). Compared to the fluoroscopy-guided thermal ablation therapy the SabreSource system significantly reduced the number of fluoroscopy exposures (reduction 23.53%, p = 0.02), the time of radiation exposure (reduction 21.2%, p = 0.03) and the mean entrance surface dose (reduction 30.46%, p = 0.01). CONCLUSION: The SabreSource System reduces radiation exposure and radiation dose in the radiofrequency denervation therapy of the lumbar facet joints and can be applied for other minimally invasive techniques.

A Prospective, Randomized Study Evaluating Clinical and Radiographic Efficacy of Lumbar Interbody Fusion Performed Using a Truss Technology-Based Interbody Fusion Device With Homologous Bone or Bone Marrow Aspirate.

BACKGROUND: Our group used vertebral bone marrow aspirate (BMA) with an anterior truss-based interbody implant to promote fusion. This implant has biomechanical characteristics that may enhance bone on-growth and through-growth and allow for the use of BMA clot alone. The primary end point was comparison of the proportion of patients who achieved fusion with the implant packed with either crushed cancellous homologous bone chips (CCB) alone or with BMA clot alone. METHODS: Patients were randomized to receive either BMA clot or CCB in the implant. Both groups also had supplemental fixation. Clinical assessments were performed preoperatively and postoperatively at 3, 6, and 12 months, including for the Oswestry Disability Index, leg and back visual analog scale, EQ5-D, reoperations, complications, and adverse events. Radiographs were obtained prior to discharge and at 3, 6, and 12 months postoperatively. A computed tomography scan was performed 3 months postoperatively. Radiographs were assessed by an independent radiologist to determine fusion status and evidence of subsidence. RESULTS: Between January 2015 and February 2016, 42 consecutive patients were randomized into 1 of the 2 study groups. There were significant postoperative changes within both groups in pain improvement across all outcome scales. There were no significant differences between groups in change scores from preoperative to assessments at any follow-up time point, with the exception of the change in EQ-5D and visual analog scale at 6 months; however, there was no difference at 3 or 12 months. There were no device-related adverse events in either group. All patients achieved grade II fusion at 3 months postoperatively. There was no significant difference in implant subsidence between groups or smokers versus nonsmokers. CONCLUSIONS: The clinical outcomes of this study suggest that reliable fusion can be obtained using an anterior truss-based implant with either CCB or BMA alone. LEVEL OF EVIDENCE: 2.

Carbon fiber-reinforced pedicle screws reduce artifacts in magnetic resonance imaging of patients with lumbar spondylodesis.

The study investigated whether the use of carbon fiber-reinforced PEEK screw material (CF-PEEK) can reduce magnetic resonance imaging (MRI) artifact formation. Two consecutive groups of patients were treated for degenerative spinal disorders of the lumbar spine with dorsal transpedicular spinal fusion. The first group (n = 27) received titanium pedicle screws. The second group (n = 20) received CF-PEEK screws. All patients underwent an MRI assessment within the first four postoperative weeks. For each operated segment, the surface of the artifact-free vertebral body area was calculated as percentage of the total vertebral body. For each implanted segment, the assessability of the spinal canal, the neuroforamina, and the pedicle screws, as well as the surrounding bony and soft-tissue structures was graded from 1 to 5. A mean artifact-free vertebral body area of 48.3 ± 5.0% was found in the in the titanium group and of 67.1 ± 5.6% in the CF-PEEK group (p ≤ 0.01). Assessability of the lumbar spine was significantly improved for CF-PEEK screws (p ≤ 0.01) for all measurements. CF-PEEK pedicle screws exhibit smaller artifact areas on vertebral body surfaces and their surrounding tissues, which improves the radiographic assessability. Hence, CF-PEEK may provide a diagnostic benefit.

Radiological evaluation of kyphoplasty with an intravertebral expander after osteoporotic vertebral fracture.

Spinal deformities due to osteoporotic vertebral compression fractures can be reduced by balloon kyphoplasty, but the correction may be partly lost when the balloon is deflated. The present study aimed to evaluate an intravertebral expander developed to reduce and maintain vertebral body height while cement is injected to correct spinal deformities due to osteoporotic vertebral fractures. The study included 31 osteoporotic vertebral body fractures in 31 patients, classified as A1 according to the AO classification, who underwent kyphoplasty using an intravertebral expander. The kyphosis angle was significantly corrected from 13.4 degrees prior to kyphoplasty to 10.8 degrees (p < 0.01) after surgery, but this correction was lost at 12 months (13.3 degrees). The correction of the kyphosis angle best correlated with the pre-operative mobility of the fracture (r = 0.59, p < 0.01), and the loss of the kyphosis improvement correlated with the amount of correction (r = 0.49, p = 0.01). All patients, except for six with adjacent vertebral fractures, experienced significant pain reduction (VAS 8.7 pre-operatively and 2.0 at 12 months; p < 0.01), and the pain was not affected by the correction of the spinal deformity or the loss of correction in the follow-up period. These results suggest that the mobility of the fracture mainly determines the extent of deformity correction rather the device used for reduction, and greater corrections are at increased risk for losing the improvement. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:457-465, 2019.