Posterior Instrumentation Research Articles

Clinical Outcome of Lumbar Hybrid Surgery in a Consecutive Series of Patients with Long-term Follow-up.

This was a retrospective study combined with attempted prospective patient contact to collect current data. The purpose of this study was to investigate long-term clinical outcome of patients undergoing lumbar hybrid surgery (total disc replacement (TDR) at one level and fusion at an adjacent level. Many patients with symptomatic lumbar disc degeneration are affected at more than one level. Lumbar TDR was introduced as a fusion alternative; however, some disc levels are not amenable to TDR and fusion is preferable at such levels. Hybrid surgery was introduced as an option to fusing multiple levels. A consecutive series of 305 patients undergoing lumbar hybrid surgery was identified beginning with the first case experience in 2005. Operative and clinical outcome data including visual analog scales (VAS) assessing back and leg pain, Oswestry Disability Index (ODI), and re-operations were collected. The mean follow-up duration was 67.1 months. There were statistically significant improvements (P<0.01) in the mean values of all three clinical outcome measures: VAS back pain scores improved from 6.7 to 3.3; leg pain improved from 4.3 to 2.0; and ODI scores improved from 45.5 to 24.6. There were no significant differences in pain and function scores for patients with minimum 10-year follow-up vs. those with shorter follow-up duration. Re-operation occurred in 16.1% of patients, many of which involved removal of posterior instrumentation at the fusion level (6.2% of study group, 38.8% of re-operations). Re-operation involving the TDR level occurred in 9 patients (2.9%), only 3 of which (1.0%) involved TDR removal/revision. This study supports that for many patients with multilevel symptomatic disc degeneration, hybrid surgery is a viable surgical option. Significant improvements were demonstrated in pain and function scores with no diminished improvement in scores among patients with more than 10-year follow-up.

Patients with Hip Osteoarthritis Have a Higher Rate of Spinal Reoperation Following Lumbar Spinal Fusion.

Lumbar spinal pathology is known to affect outcomes following total hip arthroplasty (THA). However, the effect of hip osteoarthritis (OA) on outcomes following lumbar fusion has not been well studied. The purpose of this study was to determine the association between hip OA and spinal reoperation following lumbar spinal fusion. The 5% Medicare Part B claims database was queried for all patients who underwent primary elective lumbar fusion from 2005 to 2019. Patients were divided into 2 groups: those who underwent elective THA within 1 year after primary lumbar fusion, indicating that they had severe hip OA at the time of lumbar fusion, and those who underwent lumbar fusion with no diagnosed hip OA and no THA during the study period. Exclusion criteria included THA as a result of trauma, revision THA or primary THA in the 5-year period before primary lumbar fusion, <65 years of age, and no enrollment in the database for 5 years before and 1 year after primary lumbar fusion. The primary outcome was spinal reoperation within 1, 3, and 5 years. Multivariable Cox regression was performed with age, sex, diabetes, heart disease, obesity, smoking status, osteoporosis, number of levels fused, use of posterior instrumentation, use of an interbody device, use of bone graft, and surgical approach as covariates. Overall, 1,123 patients (63.4% female; 91.3% White; mean age, 76.8 ± 4.1 years) were included in the hip OA group and 8,893 patients (56.2% female; 91.3% White; mean age, 74.8 ± 4.9 years) were included in the control group. After multivariable analysis, patients with severe hip OA had significantly greater rates of revision surgery at 3 years (odds ratio [OR], 1.61; p < 0.001) and 5 years (OR, 1.87; p < 0.001) after the index lumbar fusion. Patients with severe hip OA at the time of primary lumbar fusion had a significantly increased risk of spinal reoperation at 3 and 5 years postoperatively. These data provide further evidence to support performing THA prior to lumbar fusion in the unsettled debate regarding which surgery should be prioritized for patients with simultaneous degenerative diseases of the hip and lumbar spine. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Experience and Results of Posterior Cervical Instrumentation Applied in Upper Cervical Injuries

Aim Surgical treatment options for upper cervical trauma are few and have a very high risk. We aimed to present our experiences on the cases in which we performed surgery by eliminating the flexion restriction in the postoperative period by not including the occipital region in surgery. Materials and Method 16 cases who underwent atlantoaxial fixation with C1 mass-C2 pedicle screwing due to atlantoaxial instability after the year 2008 were retrospectively examined. Results 16 patients were included in the study. While the median surgical procedure time of the patients was calculated as 107.5 (range, 60-150) minutes; Intraoperative blood loss was measured as median 350 (range, 200-550) mL. Postoperative complications were observed in 2 patients (12.5%). 1 (6.3%) of the complications was screw revision and 1 (6.3%) was superficial infection. It was observed that the VAS scores of the patients decreased significantly in the postoperative period. Conclusion In cases where surgery is planned due to atlantoaxial instability, internal fixation with C1 lateral mass C2 pedicular screws and rod system from the posterior is recommended as an appropriate surgical method due to early and high solid fusion and no restriction in neck flexion movements.

Expandable Cages for Lumbar Interbody Fusion: A Narrative Review.

Lumbar fusion surgery for treating degenerative spinal diseases has undergone significant advancements in recent years. In addition to posterior instrumentation, anterior interbody fusion techniques have been developed along with various cages for interbody fusion. Recently, expandable cages capable of altering height, lordotic angle, and footprint within the disc space have garnered significant attention. In this manuscript, we review the current status, clinical outcomes, and future prospects of expandable cages for lumbar interbody fusion based on the existing literature. Expandable cages are suitable for minimally invasive spinal surgeries. Small-sized cages can be inserted and subsequently expanded to a larger size within the disc space. While expandable cages generally demonstrate superior clinical outcomes compared to static cages, some studies have suggested comparable or even poorer outcomes with expandable cages than static cages. Careful interpretation through additional long-term follow-ups is required to assess the utility of expandable cages. If these shortcomings are addressed and the advantages are further developed, expandable cages could become suitable surgical instruments for minimally invasive spinal surgeries.

Finite element analysis of the biomechanical effects of anterior and posterior cervical fusion surgery for bilateral cervical dislocation

Lower cervical spine injuries often manifest as lower cervical vertebral fractures and dislocations, as well as lower cervical facet joint dislocations. Especially in cases of bilateral facet joint dislocations, it is important to rapidly and effectively relieve spinal cord and nerve root compression to prevent secondary spinal cord injury, while also providing reliable and long-lasting stability to the injured segment after surgery. Combined anterior and posterior approaches have the advantages of both pure anterior or posterior approaches, but the actual situation is complex and variable, making systematic theoretical analysis crucial. This study, with bilateral facet joint dislocation of the C6 segment and cervical spinal cord injury as the research background, established a three-dimensional model of the cervical spine C3-C7 after implementing four types of anterior-posterior combined surgeries. The four surgical approaches consist of four combinations: anterior parallel or inclined screw placement combined with posterior Margel or Anderson method screw insertion. Through finite element method, a systematic comparative analysis of the theoretical effects of the four combined surgeries in treating bilateral facet joint dislocation of the cervical spine was conducted. The conclusion was that the variations in the four combined fixation methods have a certain impact on the biomechanical characteristics of the intervertebral disc nucleus. There is a clear mutual influence relationship among anterior and posterior fixation instruments. Based on the model used in this study, it is recommended to use a torque greater than 2.1 nm to tighten the locking nut of the posterior rod to ensure reliable internal fixation.

Ligamentous Augmentation to Prevent Proximal Junctional Kyphosis and Failure

Study Design: Biomechanical cadaveric study (level V). Objective: To evaluate the effectiveness of polyethylene bands looped around the supra-adjacent spinous process (SP) or spinal lamina (SL) in providing strength to the cephalad unfused segment and reducing junctional stress. Background: Proximal junctional kyphosis (PJK) is a pathologic kyphotic deformity adjacent to posterior spinal instrumentation after fusion constructs. Recent studies demonstrate a mismatch in stiffness between the instrumented construct and nonfused adjacent levels to be a causative factor in the development of PJK and proximal junction failure. To our knowledge, no biomechanical studies have addressed the effect of different methods of polyethylene band placement at the proximal junction. Materials and Methods: Twelve fresh frozen cadavers were divided into 3 groups of 4: pedicle screw-based instrumentation from T10 to L5 (“control”), T10–L5 instrumentation with a polyethylene band to the T9 “SP,” T10–L5 instrumentation with 2 polyethylene bands to the T9 “SL.” Specimens were tested with an eccentric (10 mm anterior) load at 5 mm/min for 15 mm or until failure occurred. Failure was defined by the inflection point on the load versus deformation curves. Linear regression was utilized to evaluate the effect of augmentation on the load-to-failure. Significance was set at 0.05. Results: Fractures occurred in all specimens tested. The mean peak load to failure was 2148 N (974–3322) for the SP group, and 1248 N (742–1754) for the control group (P &gt; 0.05) and 1390 N (1080–2004) for the SL group. No difference existed between the control group and the SP group in terms of fracture level (P &gt; 0.05). Net kyphotic angulation shows no differences among these 3 groups (P &gt; 0.05). Conclusion: Although statistical significance was not achieved, ligament augmentation to the SP increased mean peak load-to-failure in a cadaveric PJK model.

Single-Stage Lateral Anterior-to-Psoas Interbody Fusion and Facet Screws as a Treatment for L5–S1 Adjacent Segment Disease in a Patient With a Long-Segment Construct

Objective: Adjacent segment disease (ASD) occurs in 9% of patients with long-segment lumbar spine fusion and results from the transmission of a greater degree of stress to the segments cranial and caudal to a fused segment. The treatment of symptomatic ASD typically involves extending fusion to the involved segment. Revision and extension of posterior instrumentation bears the disadvantage of involving the exposure and modification of old hardware. Lateral interbody fusion cannot be performed at L5/S1 due to the iliac crest. Anterior lumbar interbody fusion typically still requires flipping the patient to augment the construct posteriorly. Here, we present a method to treat L5/S1 ASD using single-position anterior-to-psoas (ATP) interbody fusion combined with facet screw instrumentation.Methods: An 80-year-old man, who had undergone L2-5 fusion 27 years ago, presented with persistent lower back pain and gait dysfunction with imaging findings of L5/S1 spondylosis and ASD. Under intraoperative computed tomography navigation, left L5/S1 ATP interbody fusion was performed with simultaneous L5/S1 percutaneous facet screw fixation. Results: The abdominal incision was 4.0 cm and the single posterior incision was 1.5 cm long. Blood loss was lower than 10 mL, and the procedure lasted for less than 1.5 hours. The patient was discharged to rehabilitation after 3 days.Conclusion: ATP interbody fusion enabled the placement of an interbody device with a large footprint to promote fusion and reduce the risk of subsidence and pseudoarthrosis. The combined use of interbody fusion and facet screws obviates the need to link to the previous construct.

The Attallah screw: Where safety meets robustness in posterior subaxial cervical instrumentation.

Posterior fixation of the subaxial cervical spine (SCS) commonly relies on the application of lateral mass screws (LMS), with pedicle screws being a less prevalent alternative. The present study provides another option: A recently introduced novel approach, the Attallah screw, intended to ensure a safety profile comparable to that of LMS, combined with a strength profile similar to that of pedicle screws. The focus of the present study is the comparative analysis of peak insertion torques for these three screw types. Employing standard surgical techniques and instruments, Attallah screws were scheduled for insertion on the right side of the SCS in 15 cadavers, pedicle screws on the left side in 8 cadavers, and LMS on the left side in the remaining 7 cadavers. The peak insertion torque was recorded using an electronic torque screwdriver. The results revealed that the peak insertion torques were similar in the pedicle and the Attallah screw at C3, C4 and C7, but differed at C5 (mean ± SD; pedicle, 79.5±19.6 cNm; Attallah, 56.7±18.5 cNm; P=0.029) and C6 (pedicle, 85.4±28.7 cNm; Attallah, 49.8±17.9 cNm; P=0.004) in favor of the superior pedicle screw measurements. The peak insertion torques of the pedicle screw were superior to the corresponding data from the LMS from C4 to C7. By contrast, the peak insertion torques of the Attallah screw were only superior to those of the LMS at C7 (Attallah, 69.5±24.5 cNm; lateral mass, 40.5±21.4 cNm; P=0.030), although similar trends were observed at the other cervical levels. On the whole, the findings presented herein indicate the level-dependent superior robustness of the Attallah screw as a posterior cervical fixation method compared to the LMS. However, from a biomechanical perspective, the pedicle screw remains the preeminent choice for fixation within the C5-C6 range.

Should the level of the posterior instrumentation combined with the intermediate screw be a short segment or a long segment in thoracolumbar fractures with fusion to the fractured segment?

It was aimed to compare the results of long segment posterior instrumentation with intermediate pedicular screw + fusion at the level of the fractured segment including one vertebra above and one below the fractured vertebra (LSPI) and short segment posterior instrumentation with intermediate pedicular screw + fusion at the level of the fractured segment including one vertebra above and one below the fractured vertebra (SSPI) in the surgical treatment of thoracolumbar vertebral fractures. Ninety patients with thoracolumbar vertebral (T11-L2) fractures operated between March 2015 and February 2022 were included in this retrospective study. The patients were divided into two groups as those who underwent LSPI (n, 54; age, 40.3) and those who underwent SSPI (n, 36; age, 39.7). Radiological evaluations like vertebral compression angle (VCA), vertebral corpus heights (VCH), intraoperative parameters, and complications were compared between the groups. Correction in early postoperative VCA was statistically significantly better in LSPI (p = 0.003). At 1-year follow-up, postoperative VCA correction was significantly more successful in LSPI (p = 0.001). There was no difference between the two groups in terms of correction loss in VCA measured at 1-year follow-up. There was no statistically significant difference between the two groups in terms of postoperative VCH, VCH at 1-year follow-up, and correction loss in VCH. LSPI provides better postoperative kyphosis correction of the fractured vertebra than SSPI. Regarding the segment level of posterior instrumentation, there was no difference between the two groups in terms of the loss of achieved correction of VCA, ABH, and PBH at 1-year follow-up. Operating a thoracolumbar fracture with LSPI will lengthen the operation and increase the number of intraoperative fluoroscopies compared to SSPI.

A Rare Case of Osteogenesis Imperfecta Type V

Osteogenesis imperfecta (OI) is a hereditary bone condition characterised by fragile bones to be more susceptible to fracture. We reported a rare case of a 6-year-old girl with OI Type V and hyperplastic callus formation. She presented with recurrent fractures since birth with no family history of a similar condition. Clinically, her height and weight were lower than the 5th percentile for her age. She had deformities with limitation of movement of elbows, kyphoscoliosis, a more extensive right thigh, and anterior bowing of both legs. Radiographic examination revealed interosseous membrane of forearm ossification, dislocation of the right radial head and hyper-callosity of both femurs during fracture healing. She was treated with intravenous pamidronate and had posterior instrumentation and fusion for scoliosis and intramedullary rodding for her femur fracture. On a recent follow-up at the age of 16 years, she was ambulating well with no progression of the spinal deformity.

Biphasic Calcium Phosphate Bone Graft With a Unique Surface Topography: A Single-Center Ambispective Study for Degenerative Disease of the Lumbar Spine.

This study is an ambispective evaluation and analysis of a single-center cohort. This study aimed to evaluate the performance of a novel biphasic calcium phosphate (BCP) bone graft with submicron-sized needle-shaped surface topography (BCP<µm) in interbody arthrodesis of the lumbar spine. This study was a single-center ambispective assessment of adult patients receiving BCP<µm as part of their lumbar interbody fusion surgery. The primary outcome was a fusion status on computed tomography (CT) 12months postoperative. The secondary outcomes included postoperative changes in the visual analogscale (VAS), Oswestry Disability Index (ODI), Short Form 12 (SF-12), and length of stay (LOS). Sixty-three patients with one- to three-level anterior (48, 76%) and lateral (15, 24%) interbody fusions with posterior instrumentation were analyzed. Thirty-one participants (49%) had three or more comorbidities, including heart disease (43 participants, 68%), obesity (31 participants, 49%), and previous lumbar surgery (23 participants, 37%). The mean ODI decreased by 24. The mean SF-12 physical health and SF-12 mental health improved by a mean of 11.5 and 6.3, respectively. The mean VAS for the left leg, right leg, and back improved by a mean of 25.75, 22.07, and 37.87, respectively. Of 101 levels, 91 (90%) demonstrated complete bridging trabecular bone fusion with no evidence of supplemental fixation failure. The data of BCP<µm in interbody fusions for degenerative disease of the lumbar spine provides evidence of fusion in a complicated cohort of patients.

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

PurposeTo 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).MethodsA 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”).ResultsThe 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.ConclusionsIn 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.

Surgical management of lower limb radiculopathy following acute singe-level osteoporotic vertebral fracture of lower lumbar spine in geriatric patient: a retrospective study

BackgroundRadiculopathy of the lower limb after acute osteoporotic vertebral fractures (OVFs) in the lower lumbar spine is uncommon in geriatric patients. Moreover, surgical intervention is generally recommended in patients who are irresponsive to conservative treatment. Determining an optimum surgical strategy is challenging considering the poor general condition of this population. Thus, herein, we established an algorithm for surgically managing this clinical scenario, hoping to provide a reference for making a surgical decision.MethodsWe retrospectively studied patients who suffered from new-onset radiculopathy of the lower limb after acute single-level OVFs in the lower lumbar spine and eventually underwent surgical intervention at our department. Information on the demographics, bone quality, AO spine classification of the vertebral fracture, pre-existing degenerative changes, including foraminal stenosis and lumbar disc herniation, and surgical intervention type was collected. Additionally, clinical outcomes, including preoperative and postoperative visual analog scale (VAS) scores for back and leg pain, Oswestry disability index (ODI), and MacNab criterion for response to surgery, were evaluated.ResultsFrom September 2019 to December 2021, a total of 22 patients with a mean age of 68.59 ± 9.74 years were analyzed. The most involved vertebra was L5 (54.5%), followed by L4 (27.3%) and L3 (18.2%). Among the 22 patients, 15 (68.2%) were diagnosed with the A1 type fracture of AO classification, and among them, 11 (73.3%) were characterized by the collapse of the inferior end plate (IEP). Three patients (13.6%) suffered from A2-type fractures, whereas four patients (18.2%) suffered from A3-type fractures. Pre-existing degenerative changes were observed in 12 patients (54.5%) of the patients. A total of 16 patients (72.7%) were treated by percutaneous kyphoplasty (PKP). Additionally, three patients underwent posterior instrumentation and fusion, two patients underwent a secondary endoscopic foraminoplasty, and one patient underwent a secondary radiofrequency ablation. The mean follow-up period was 17.42 ± 9.62 months. The mean VAS scores for leg and back pain and ODI decreased significantly after the surgery (P < 0.05). The total satisfaction rate at the last follow-up was 90.9% per the Macnab criterion.ConclusionPatients with OVFs in the IEP are predisposed to suffer from radiculopathy of the lower limb. PKP alone or in combination with other minimally invasive surgical strategies is safe and effective in treating stable fractures. Additionally, aggressive surgical intervention should be considered in patients with unstable fractures or severe foraminal encroachment.

474 Comparing the Reciprocal Changes of Single Level Transforaminal Interbody Fusions Versus Lateral Interbody Fusions: A Radiographic Analysis for Sagittal Alignment and Spinopelvic Parameters

INTRODUCTION: Transforaminal lumbar interbody fusion (TLIF) and lateral lumbar interbody fusion (LLIF) are two techniques that are widely used to treat single-level pathology at L4-5. To date, no studies have compared the two techniques in terms of their ability to address disc space pathology, such as loss of height and spondylolisthesis, and achieve spinopelvic alignment goals. METHODS: After IRB approval, this study retrospectively reviewed the records of 203 patients who underwent single-level L4-L5 TLIFs and single-level L4-L5 LLIFs between 2017 to 2022. Preoperative and postoperative scoliosis films were collected and analyzed using an automated calibrated radiographic tool to measure pre-postoperative SA and SPs. Two blinded readers measured the pre-postoperative variables. Independent Sample T-tests were used to analyze the radiographic outcomes between the two groups. RESULTS: This study evaluated the results of 203 single-level TLIFs and LLIFs (109 L4-L5 TLIFs, and 94 L4-L5 LLIFs). Among the surgeries analyzed, 90 were MIS TLIFs, 19 open TLIFs, 16 standalone LLIs, and 78 LLIFs with posterior instrumentation. Postoperative scoliosis films were taken at a median of 0.28 (± 0.4) months. The analysis focused on comparing the reciprocal changes between both procedures. Significant statistical differences was found for ΔGTilt (p = 0.036), ΔLPA (p = 0.12), ΔADH (p = 0.03), ΔPDH (p = 0.04), ΔFH (p = 0.001), and ΔS% (p = 0.01) in the LLIF group, among all the variables included in the analysis. CONCLUSIONS: L4-5 LLIF and TLIF resulted in statistically similar amounts of lordosis restoration and reciprocal change at proximal and distal lumbar levels. LLIF was found to be superior in restoration of anterior disc height, posterior disc height, and foraminal height compared to TLIF. LLIF was also superior in percentage reduction of spondylolisthesis.

1073 Prone Transpsoas (PTP)-LLIF Approach Versus Standard LLIF in Patients Undergoing Surgical Revision Following Adult Spinal Deformity Correction Surgery

INTRODUCTION: Both the prone transpsoas (PTP) and standard LLIF have been developed to facilitate minimally invasive (MIS) indirect decompression, alignment correction, and posterior instrumentation. METHODS: A multi-center cohort of all patients was identified and all relevant data were retrospectively collected. Preoperative standing 36” scoliosis radiographs were retrospectively reviewed for pelvic incidence (PI), lumbar lordosis (LL), and PI minus LL (PI-LL mismatch). Postoperative regional sagittal alignment parameters were measured using the first postoperative standing 36” scoliosis radiographs. Finally, multivariable analysis was performed to assess the primary outcome measure: postoperative change in regional sagittal alignment (PI-LL mismatch). RESULTS: Two-hundred and two (n = 202) patients were retrospectively identified and included for formal analysis. One-hundred and fifty one (n = 151, 74.8%) of the patients underwent PTP revision while 51 (25.2%) underwent standard LLIF revision. Univariate analysis demonstrated a greater value for baseline mean pre-operative PI-LL mismatch in the PTP versus standard LLIF cohort (21.4 vs. 10.45°; p = 0.0001). Furthermore, multiple linear regression demonstrated that the PTP approach enabled significantly greater PI-LL mismatch change (p = 0.0017) and that this change was associated with the number of levels fused (p = 0.0481) as well as percutaneous (vs. open) screw placement (p = 0.0193). Finally, multiple logistic regression identified standard LLIF (p = 0.0378), female sex (p &lt; 0.0001), non-osteoporotic bone density (p &lt; 0.0001), and younger age (p &lt; 0.0001) as predictive of postoperative PI-LL mismatch &lt; 10° (the threshold under which such mismatch is no longer regarded as clinically significant deformity). CONCLUSIONS: Ultimately, PTP-LLIF was associated with greater net improvement in postoperative PI-LL mismatch, the primary outcome measure of this study. The present retrospective analysis therefore corroborated results of previous studies in suggesting that the utility of PTP-LLIF is translatable to ASD revision surgery.

269 Risk Factors for Fusion Failure in Children Undergoing Occipital to C2 Rigid Instrumentation and Fusion

INTRODUCTION: Studies of pediatric occipital-cervical fusions have been limited, and there is substantial variation among surgical constructs with reported failure rates as high as 20%. METHODS: The Pediatric Spine Study Group (PSSG) registry was queried to identify patients &lt;/= 21-years-old who had: (1) O-C2 posterior rigid instrumentation and fusion, (2) 2-year clinical and radiographic follow-up, and (3) available post-operative lateral cervical radiograph or CT. Failure was defined as hardware revision surgery &gt;30 days following the index procedure or the presence of screw haloing or breakage on the most recent imaging study. Univariate comparisons were made using Mann-Whitney U-tests, Chi-square tests, and Fisher’s Exact tests followed by multivariable logistic regression. RESULTS: 76 patients were included. The median age at surgery was 9 years (range, 0.2 to 17.2 years), and 51% of the cohort was male. 55% percent of patients had syndromic etiology (41/75), and the most frequent diagnosis was Down Syndrome (28%). Of the 74 patients with complete information, 28/74 (38%) had fusion failure (95% CI, 27%-50%). Rib autographs were used more frequently in patients with successful fusions compared to failures (52% vs 25%; p = 0.04). Multivariable logistic regression determined that patients with rib autograft have a 75% decrease in the odds of failure compared to those without rib autograft (OR = 0.25; 95% CI = 0.08-0.75; p = 0.01). Other variables did not influence the risk for failure. CONCLUSIONS: In this multicenter, international registry study of children undergoing O-C2 rigid instrumentation, fusion failure was seen in 38% of patients, a higher rate than previously reported. Based on this study, the use of structural rib autograft should be considered to reduce fusion failure.

466 Primary Anterior Lumbar Interbody Fusion, With and Without Posterior Instrumentation: A 1377 Patient Cohort From a Multicenter Spine Registry

INTRODUCTION: Anterior lumbar interbody fusion (ALIF) is a versatile and powerful technique for a variety of lumbar degenerative pathologies. Adding posterior supplementary fixation to ALIF (ALIF+PSF) is common and may confer benefits in terms of higher fusion rate but could contribute to adjacent segment disease (ASD) due to additional rigidity. METHODS: Adult patients who underwent primary ALIF for lumbar degenerative pathology between levels L4-S1 over a 12-year period were included. Cases of trauma, cancer, infection, supplemental decompression, noncontiguous fusions, prior lumbar fusions, and other interbody devices were excluded. Primary outcomes included reoperation for nonunion and ASD. Multivariable Cox proportional hazard regression was used to evaluate risks adjusting for patient characteristics. RESULTS: The study consisted of 1377 cases; 307 ALIF alone and 1070 ALIF+PSF. Mean follow-up time was 5.6-years. 5-year crude nonunion incidence was 2.4% for ALIF only and 0.5% for ALIF+PSF; after adjustment for covariates, a lower operative nonunion risk was observed for ALIF+PSF (HR = 0.22, 95% CI = 0.07-0.70). Of patients deemed potentially suitable for ALIF alone, one would need to add PSF in 53-patients to prevent one case of operative nonunion at a 5-year follow-up (number needed to treat). Five-year operative ASD incidence was 4.3% for ALIF only and 6.2% for ALIF+PSF; with adjustments, no difference was observed between the cohorts (HR = 0.96, 95% CI = 0.53-1.74). CONCLUSIONS: While addition of posterior instrumentation in ALIFs is associated with lower risk of operative nonunion compared to ALIF alone, it is rare in both techniques (&lt;5%). Accordingly, surgeons should evaluate added risks associated with addition of PSF, and rather reserve PSF for patients at higher risk for operative nonunion. Rates of operative ASD were not statistically higher with addition of PSF suggesting concern regarding future ASD may be less supported.

Intraoperative Cone-Beam Computed Tomography Navigation Versus 2-Dimensional Fluoroscopy in Single-Level Lumbar Spinal Fusion: A Comparative Analysis.

Several studies have advocated for the higher accuracy of transpedicular screw placement under cone-beam computed tomography (CBCT) compared to conventional 2-dimensional (2D) fluoroscopy. The superiority of navigation systems in perioperative and postoperative outcomes remains a topic of debate. This study aimed to compare operative time, screw placement time and accuracy, total radiation dose, perioperative and postoperative outcomes in patients who underwent transpedicular screw fixation for degenerative lumbar spondylolisthesis (DLS) using intraoperative CBCT navigation versus 2D fluoroscopy. A retrospective analysis was conducted on patients affected by single-level DLS who underwent posterior lumbar instrumentation with transpedicular screw fixation using surgical CBCT navigation (NV group) or 2D fluoroscopy-assisted freehand technique (FH group). Demographics, screw placement time and accuracy, operative time, total radiation dose, intraoperative blood loss, screw revision rate, complications, and length of stay (LOS) were assessed. The study included a total of 30 patients (NV group: n = 15; FH group: n = 15). The mean screw placement time, operative time, and LOS were significantly reduced in the NV group compared to the FH group (p < 0.05). The total radiation dose was significantly higher in the NV group (p < 0.0001). No significant difference was found in terms of blood loss and postoperative complications. This study suggests that intraoperative CBCT-navigated single-level lumbar transpedicular screw fixation is superior in terms of mean screw placement time, operative time, and LOS compared to 2D fluoroscopy, despite a higher intraoperative radiation exposure.

Establishing case volume benchmarks for ACGME-accredited orthopedic surgery of the spine fellowship training

BACKGROUND CONTEXTThere has been increasing scrutiny on the standardization of surgical training in the US. PURPOSEThis study provides case volume benchmarks for Accreditation Council for Graduate Medical Education (ACGME)-accredited orthopedic spine surgery fellowship training. STUDY DESIGN/SETTINGThis was a retrospective cross-sectional study of fellows at ACGME-accredited orthopedic spine surgery fellowships (2017–2022). PATIENT SAMPLEN/A. OUTCOME MEASURESReported case volume during fellowship training. METHODSCase volume percentiles were calculated across ACGME-defined case categories and temporal changes assessed via linear regression. Variability between the highest and lowest deciles by case volume was calculated as fold-differences (90th percentile/10th percentile). Sensitivity analyses were performed to identify potential targets for case minimum requirements. RESULTSA total of 163 spine surgery fellows were included in this study. Total mean reported spine surgery case volume increased from 313.2±122 in 2017 to 382.0±164 in 2022 (p=.19). Most cases were classified as adult (range, 97.2%–98.0%) over pediatric cases (range, 2.0%–2.8%). An average of 322.0 cases were reported and most were classified as laminectomy (32%), posterior arthrodesis (29%), and anterior arthrodesis (20%). Overall variability in total case volume was 2.4 and the greatest variability existed for posterior instrumentation (38.1), application of cage (34.6), anterior instrumentation (20.8), and fractures and dislocations (17.3). If case minimum requirements for total reported cases was assumed at 200 cases, then all spine fellows included in this study would achieve this requirement. However, if case minimum requirements were assumed at 250 total cases, then approximately thirty percent of fellows (n=49) would not achieve this requirement for graduation. CONCLUSIONSIncreasingly, national societies and accrediting bodies for surgical education recognize the need for standardized training. This study provides benchmarks to inform potential case minimum requirements and help reduce variability during spine fellowship training. Future studies are needed to establish case minimum requirements for spine surgery fellowship training across comprehensive and granular case categories that cover the full gamut of orthopedic spine surgery.

Vertebral Hemangiomas: Yucesoy-Yilmaz Classification System with Corresponding Therapeutic Options

Vertebral hemangiomas (VHs) are relatively common, symptomatic benign tumors of the spine with a reported estimated incidence up to 11%. They usually appear in the body of the vertebrae; however, they can extend into pedicles, laminae, and epidural space. They may cause pain, neurologic deficits. and fractures. In this retrospective, single-center study, we reviewed our cases with VH and we propose the novel classification system that evaluates these lesions per their views on magnetic resonance imaging and clinical findings under 4 main categories. Our novel classification system proposes that grade I lesions occupy less than 50% of the vertebral body, whereas grade II lesions occupy more than 50% and grade III lesions occupy the whole corpus. Grade IV lesions show an epidural and pedicular extension. We propose that grade I lesions may not be worthwhile for follow-up, whereas asymptomatic grade II (a) lesions to be worthy for a biannual imaging and symptomatic thoracolumbar grade II (b) and thoracolumbar grade III lesions to be considered for percutaneous vertebroplasty. We imply that decompression, posterior spinal instrumentation, and open vertebroplasty may be performed for thoracolumbar grade IV lesions. We further consider cervical grade IIb, III, and grade IV lesions as operable because of the disadvantages of percutaneous vertebroplasty. We suggest that our novel classification system may be useful for the determination of diagnostic and therapeutic procedures in the management of VH. Further multicentric trials on larger series are warranted to validate this system and popularize its utility in larger populations.