Should the pelvis be included? An analysis of distal junctional failure risk factors in correcting adult spinal deformity in women with fusion to L5.

PURPOSE: To identify the risk factors for distal junctional failure (DJF) in women treated for adult spine deformity with fusion to L5 and to highlight the significance of preoperative assessment, surgical decision-making, and postoperative care. METHODS: This is a retrospective study of data collected prospectively on the local institutional spine surgery registry (2016-2021). All patients, women older than 18 years, with a diagnosis of adult spine deformity who underwent long posterior instrumentation to L5 and had a minimum of 2-years follow-up were included in the study (two groups: with or without DJF). Demographic and radiographic data, corrective strategy, preoperative level of degeneration at L5/S1 and GAP score were compared between the two groups. RESULTS: Forty-eight patients (n = 48) satisfied eligibility criteria. At two-years follow-up, nine patients (18,7%) developed a DJF that required surgical revision. Thirty-nine patients did not present distal junctional complications. Patients with or without DJF showed significant differences in terms of preoperative spinopelvic parameters (PT: 28°± 6° vs. 23°± 9°, p-value 0.05; DJF group vs. not DJF) and degeneration of L5-S1 (Pfirmann grade L5-S1 disc 3.7 ± 1.0 vs. 2.6 ± 0.8, p-value 0.001; DJF group vs. not DJF) (L5-S1 Facet joint Osteoarthritis 3.1 ± 0.8 vs.2.4 ± 0.8, p-value 0.023; DJF group vs. not DJF). CONCLUSION: DJF following spinal deformity correction surgery is influenced by a combination of patient-related, surgical and implant-related factors. Fusion construct length, preoperative and postoperative sagittal alignment and the grade of degeneration of the distal disc have been identified as significant risk factors. Surgeons should carefully evaluate these factors and employ appropriate strategies.

Long spine fusions to the sacrum-pelvis are associated with greater post-operative proximal junctional kyphosis angle in sitting position.

STUDY DESIGN: A single-centre retrospective study. BACKGROUND AND PURPOSE: Although adult patients spend most of their time in sitting positions, the assessment of spinopelvic parameters in adult deformity surgery is commonly performed in standing X-rays. Our study compares the standing and sitting sagittal alignment parameters in subjects who underwent thoracolumbar fusion. METHODS: Patients who underwent corrective surgery for adult scoliosis with at least five instrumented vertebra were stratified according to the upper instrumented vertebra (UIV) and pelvic fixation. Group A:UIV proximal to T6 with pelvis fixation. B:UIV lower than T6 and pelvic fixation. Group C: thoracolumbar fusion without pelvic fixation. Post-operative spinopelvic sagittal parameters were measured in both standing and sitting X-rays. RESULTS: A total of 51 patients were enrolled in the study (11:Males and 40:Females). The mean age was 52.3 ± 21.7y/o. The comparison of post-operative standing and sitting X-ray within the group A and B showed that a significant change was observed in terms of JA-Junctional Angle-(Group A 6.3 ± 4.3 vs. 8.1 ± 3.3, p value = 0.03) (Group B 8.5 ± 6.4 vs. 10.9 ± 6.4, p value = 0.02). Group C showed statistically significant difference in terms of PT (15.6 ± 11.2 vs. 19.3 ± 9.2, p value = 0.04), AVA-Acetabular Version Angle-(41.1 ± 5.9 vs. 48.3 ± 6.6, p value < 0.01) and LL (- 51.3 ± 16.0 vs. - 42.6 ± 10.7, p value < 0.01). CONCLUSION: In our series, the post-operative sagittal alignment showed peculiar behaviours and adaptations in sitting position, depending on the length and the site of the instrumented area. If the pelvis is included, the JA tends to significantly increase in sitting position. These findings can improve the knowledge of pathologies as proximal junctional kyphosis or specific cases of anterior hip impingement. LEVEL OF EVIDENCE: IV.

Post-operative L5 radiculopathy after L5-S1 hyperlordotic anterior lumbar interbody fusion (HL-ALIF) is related to a greater increase of lordosis and smaller post-operative posterior disc height: results from a cohort study.

STUDY DESIGN: A single-centre retrospective study. BACKGROUND AND PURPOSE: This study aims to investigate the rate of L5 radiculopathy, to identify imaging features associated with the complication and to evaluate the clinical outcomes in adult spine deformity patients undergoing L5-S1 ALIF with hyperlordotic cages. METHODS: Design: retrospective cohort study. A single-centre prospective database was queried to analyse patients undergoing hyperlordotic (HL) ALIF with posterior fusion to correct spinal deformity. Clinical status was evaluated by back and leg pain numeric rate scale and Oswestry Disability Index pre-operatively and at 3-, 6- and 12-month follow-up. Spinopelvic parameters, such as pelvic incidence, pelvic tilt, lumbar lordosis and L5-S1 lordosis, posterior disc height (PDH) and anterior disc height, were assessed pre-operatively and post-operatively on standardized full-spine standing EOS images. The sagittal foraminal area was measured pre- and post-operatively on a CT scan. RESULTS: Thirty-nine patients with a mean age of 63.2 ± 8.6 years underwent HL-ALIF from January 2016 to December 2019. Seven of them developed post-operative root pain (5) or weakness (2) (Group A), while thirty-two did not (Group B). Root impairment was associated with greater segmental correction magnitude, 26° ± 11.1 in Group A versus 15.1° ± 9.9 in Group B (p < 0.05), and to smaller post-operative PDH, 5.9 mm ± 2.7 in Group A versus 8.3 mm ± 2.6 (p < 0.05). CONCLUSIONS: Post-operative root problems were observed in 17.9% of patients undergoing HL-ALIF for adult spine deformity. L5 radiculopathy was associated with larger sagittal angular corrections and smaller post-operative posterior disc height. One patient (2.6%) needed L5 root decompression. At 12 months of follow-up, results were equivalent between groups. LEVEL OF EVIDENCE I: Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.

Need of vascular surgeon and comparison of value for anterior lumbar interbody fusion (ALIF) in lateral decubitus: Delphi consensus.

BACKGROUND AND PURPOSE: Anterior lumbar approaches are recommended for clinical conditions that require interbody stability, spinal deformity corrections or a large fusion area. Anterior lumbar interbody fusion in lateral decubitus position (LatALIF) has gained progressive interest in the last years. The study aims to describe the current habit, the perception of safety and the perceptions of need of vascular surgeons according to experienced spine surgeons by comparing LatALIF to the standard L5-S1 supine ALIF (SupALIF). METHODS: A two-round Delphi method study was conducted to assess the consensus, within expert spine surgeons, regarding the perception of safety, the preoperative planning, the complications management and the need for vascular surgeons by performing anterior approaches (SupALIF vs LatALIF). RESULTS: A total of 14 experts voluntary were involved in the survey. From 82 sentences voted in the first round, a consensus was reached for 38 items. This included the feasibility of safe LatALIF without systematic involvement of vascular surgeon for routine cases (while for revision cases the involvement of the vascular surgeon is an appropriate option) and the appropriateness of standard MRI to evaluate the accessibility of the vascular window. Thirteen sentences reached the final consensus in the second round, whereas no consensus was reached for the remaining 20 statements. CONCLUSIONS: The Delphi study collected the consensus on several points, such as the consolidated required experience on anterior approaches, the accurate study of vascular anatomy with MRI, the management of complications and the significant reduction of the surgical times of the LatALIF if compared to SupALIF in combined procedures. Furthermore, the study group agrees that LatALIF can be performed without the need for a vascular surgeon in routine cases.

Setting for single position surgery: survey from expert spinal surgeons.

PURPOSE: To describe a comprehensive setting of the different alternatives for performing a single position fusion surgery based on the opinion of leading surgeons in the field. METHODS: Between April and May of 2021, a specifically designed two round survey was distributed by mail to a group of leaders in the field of Single Position Surgery (SPS). The questionnaire included a variety of domains which were focused on highlighting tips and recommendations regarding improving the efficiency of the performance of SPS. This includes operation room setting, positioning, use of technology, approach, retractors specific details, intraoperative neuromonitoring and tips for inserting percutaneous pedicle screws in the lateral position. It asked questions focused on Lateral Single Position Surgery (LSPS), Lateral ALIF (LA) and Prone Lateral Surgery (PLS). Strong agreement was defined as an agreement of more than 80% of surgeons for each specific question. The number of surgeries performed in SPS by each surgeon was used as an indirect element to aid in exhibiting the expertise of the surgeons being surveyed. RESULTS: Twenty-four surgeons completed both rounds of the questionnaire. Moderate or strong agreement was found for more than 50% of the items. A definition for Single Position Surgery and a step-by-step recommendation workflow was built to create a better understanding of surgeons who are starting the learning curve in this technique. CONCLUSION: A recommendation of the setting for performing single position fusion surgery procedure (LSPS, LA and PLS) was developed based on a survey of leaders in the field.

Rapidly destructive osteoarthritis of the spine: lessons learned from the first reported case.

BACKGROUND: Rapidly Destructive Osteoarthritis (RDOA) has been described for the hip and shoulder joints and is characterized by a quickly developing bone edema followed by extensive remodeling and joint destruction. Confronted with a similarly evolving case of endplate edema and destruction of the disk space, we offer the first described case of spinal RDOA and illustrate the challenges it presented, along with the strategies we put in place to overcome them. CASE PRESENTATION: We present a case of spinal RDOA that, also due to the delay in the diagnoses, underwent multiple revisions for implant failure with consequent coronal and sagittal imbalance. A 37-years-old, otherwise healthy female presented with atraumatic low back pain: after initial conservative treatment, subsequent imaging showed rapidly progressive endplate erosion and a scoliotic deformity. After surgical treatment, the patient underwent numerous revisions for pseudoarthrosis, coronal and sagittal imbalance and junctional failure despite initially showing a correct alignement after each surgery. As a mechanic overload from insufficient correction of the alignement of the spine was ruled out, we believe that the multiple complications were caused by an impairment in the bone structure and thus, reviewing old imaging, diagnosed the patient with spinal RDOA. In case of spinal RDOA, particular care should be placed in the choice of extent and type of instrumentation in order to prevent re-intervention. CONCLUSION: Spinal RDOA is characterized by a quickly developing edema of the vertebral endplates followed by a destruction of the disk space within months from the first diagnosis. The disease progresses in the involved segment and to the adjacent disks despite surgical therapy. The surgical planning should take the impaired bone structure account and the use of large interbody cages or 4-rod constructs should be considered to obtain a stable construct.

Anterior Lumbar Interbody Fusion (ALIF) L5-S1 with overpowering of posterior lumbosacral instrumentation and fusion mass: a reliable solution in revision spine surgery.

BACKGROUND AND PURPOSE: In cases of spine surgical revisions of patients affected by sagittal malalignment, the restoration of the ideal lumbar lordosis (LL) is mandatory. ALIF procedures represent a powerful and effective approach to improve the LL in case of hypolordosis. This study evaluates the feasibility of ALIF to overpower posterior lumbar instrumentation and fusion mass in revision spine surgery and secondarily to estimate complications, clinical and radiological outcomes. METHODS: This is a single-center retrospective analysis of prospectively collected data on the use of ALIF overpowering in cases of lumbosacral instrumentation and/or fusion. Demographic, comorbidity, corrective strategy adopted, surgical data, clinical and radiological results, and intraoperative and postoperative complications were recorded. RESULTS: Twelve patients (3 male; 9 female) underwent overpowering ALIF L5-S1 were included in the study with a mean FU of 34.0 ± 13.4 months. In 10 cases, a posterior titanium instrumentation and fusion mass were present; in 2 patients, only a fusion mass was present. Indicators of pain and disability improved in all patients (p < 0.01). Sagittal realignment with the restoration of ideal spinopelvic parameters was obtained in all cases. One peritoneal lesion requiring intraoperative suture without sequelae, two cases of postoperative radiculopathy, and one posterior wound infection requiring surgical debridement and antibiotic therapy were reported. CONCLUSIONS: Anterior implant of lordotic and hyperlordotic cages with increasing segmental lordosis is possible in the presence of posterior instrumentation and/or solid fusion mass. The biomechanical strength of this corrective technique can overcome posterior instrumentation and bone fusion resistance, therefore allowing a single-staged surgery for sagittal realignment.

The use of electronic PROMs provides same outcomes as paper version in a spine surgery registry. Results from a prospective cohort study.

BACKGROUND AND PURPOSE: Patient-Reported Measured Outcomes (PROMs) are essential to gain a full understanding of a patient's condition, and in spine surgery, these questionnaires are of help when tailoring a surgical strategy. Electronic registries allow for a systematic collection and storage of PROMs, making them readily available for clinical and research purposes. This study aimed to investigate the reliability between the electronic and paper form of ODI (Oswestry Disability Index), SF-36 (Short Form Health Survey 36) and COMI-back (Core Outcome Measures Index for the back) questionnaires. METHODS: A prospective analysis was performed of ODI, SF-36 and COMI-back questionnaires collected in paper and electronic format in two patients' groups: Pre-Operatively (PO) or at follow-up (FU). All patients, in both groups, completed the three questionnaires in paper and electronic form. The correlation between both methods was assessed with the Intraclass Correlation Coefficients (ICC). RESULTS: The data from 100 non-consecutive, volunteer patients with a mean age of 55.6 ± 15.0 years were analysed. For all of the three PROMs, the reliability between paper and electronic questionnaires results was excellent (ICC: ODI = 0.96; COMI = 0.98; SF36-MCS = 0.98; SF36-PCS = 0.98. For all p < 0.001). CONCLUSIONS: This study proved an excellent reliability between the electronic and paper versions of ODI, SF-36 and COMI-back questionnaires collected using a spine registry. This validation paves the way for stronger widespread use of electronic PROMs. They offer numerous advantages in terms of accessibility, storage, and data analysis compared to paper questionnaires.

Major complications in extreme lateral interbody fusion access: multicentric study by Italian S.O.L.A.S. group.

PURPOSE: The eXtreme Lateral Interbody Fusion (XLIF) approach has gained increasing importance in the last decade. This multicentric retrospective cohort study aims to assess the incidence of major complications in XLIF procedures performed by experienced surgeons and any relationship between the years of experience in XLIF procedures and the surgeon's rate of severe complications. METHODS: Nine Italian members of the Society of Lateral Access Surgery (SOLAS) have taken part in this study. Each surgeon has declared how many major complications have been observed during his surgical experience and how they were managed. A major complication was defined as an injury that required reoperation, or as a complication, whose sequelae caused functional limitations to the patient after one year postoperatively. Each surgeon was finally asked about his years of experience in spine surgery and XLIF approach. Pearson correlation test was used to evaluate the association between the surgeon's years of experience in XLIF and the rate of major complications; a p-value of last than 0.05 was considered significant. RESULTS: We observed 14 major complications in 1813 XLIF procedures, performed in 1526 patients. The major complications rate was 0.7722%. Ten complications out of fourteen needed a second surgery. Neither cardiac nor respiratory nor renal complications were observed. No significant correlation was found between the surgeon's years of experience in the XLIF procedure and the number of major complications observed. CONCLUSION: XLIF revealed a safe and reliable surgical procedure, with a very low rate of major complications, when performed by an expert spine surgeon.

Prone single-position extreme lateral interbody fusion (Pro-XLIF): preliminary results.

BACKGROUND: Single-position options for combined anterior and posterior fusion in the lumbar spine have been suggested to reduce the surgical time and improve the efficiency of operating room. Previous reports have focused on lateral decubitus single-position surgery. The goal of this study is to describe and evaluate the feasibility and safety of prone single-position extreme lateral interbody fusion (XLIF) with posterior fixation. METHODS: Design Pilot prospective non-randomized controlled study. Seven patients who underwent prone single-position XLIF and posterior fixation were evaluated (Pro-XLIF). A control group (Std-XLIF) was composed of ten patients who underwent XLIF in lateral decubitus and posterior fixation in prone position. All patients underwent interbody XLIF fusion at one level and posterior procedures at one or more levels. Duration of surgery, blood loss, complications, X-ray use and clinical outcomes were recorded. RESULTS: No major complications were observed in either group. Oswestry Disability Index, back pain and leg pain were improved in the Pro-XLIF group from 48.5, 7.7 and 8.5 to 14.5, 1.71 and 2.71, respectively, and in the Std-XLIF group from 50.8, 5.7 and 7.2 to 22.5, 3.7 and 2.5. The Pro-XLIF group had a longer time of preparation before incision (39 vs 26 min, ns), equal duration of the anterior procedure (65 vs 59 min, ns), shorter duration of surgery (133 vs 182 min, ns) and longer X-ray exposure time (102 vs 92 s, ns). The surgical technique is described. CONCLUSIONS: Prone single-position XLIF is feasible and safe. In this preliminary report, the results are comparable to the standard technique. These slides can be retrieved under Electronic Supplementary Material.

Revision strategies for failed adult spinal deformity surgery.

PURPOSE: The aim of this study is to analyse the results of revision surgery for failed adult spinal deformity patients and to describe the surgical strategy selection process, based on the identification of the main clinical diagnosis responsible for failure. METHODS: We retrospectively reviewed the clinical and radiological data of 77 consecutive patients treated in a 3-year time (2016-2019) for surgical revision of long fusion (more than five levels fused) for adult spinal deformity in a high-volume spine centre, divided into four groups based on the diagnosis: rod breakage (RB) group, proximal junctional failure (PJF) group, distal junctional failure (DJF) group and loss of correction (LOC) group with symptomatic sagittal or coronal malalignment (including iatrogenic flatback). RESULTS: Seventy-seven patients met our inclusion criteria, with a female prevalence (66 F vs. 11 M). The mean age at revision surgery was 63. Fused levels before surgery were averagely 12, and revision added averagely two levels to the preexisting fusion area. Clinical status was apparently improved in ODI scores and VAS scores, while it was slightly worsened in SF36 scores. Different diagnosis groups have been addressed with different surgical strategies, according to the different surgical goals: interbody cages and multi-rod construct to improve stiffness and favour bony fusion, "kickstand" rod and "tie" rod to correct coronal and sagittal malalignment, specific rod contouring and proximal hooks in "claw" configuration to reduce mechanical stress at the proximal junctional area. Intraoperative complications occurred in 18% of patients and perioperative complications in 39%. CONCLUSION: Revision surgery in long fusions for adult spinal deformity is a challenging field. Surgical strategy should always be planned carefully. A successful treatment is a direct consequence of a correct preoperative diagnosis, and surgery should address the primary cause of failure. All the above-mentioned surgical techniques and clinical skills should be part of surgeon's expertise when managing these patients. These slides can be retrieved under Electronic Supplementary Material.

Revision surgery in distal junctional kyphosis.

BACKGROUND: Opposed to proximal junctional kyphosis and proximal junctional failure, their distal equivalents, distal junctional kyphosis and failure (DJK/DJF) have received less attention in the literature. The aim of this article is to provide an overview of the problem of DJK-DJF in different clinical scenarios such as adolescent idiopathic scoliosis (AIS), Scheuermann's kyphosis (SK) and adult deformity surgery and to suggest a strategy for prevention and treatment. METHODS: A narrative review of the literature was conducted to identify the best evidence on the risk factors of the problem. RESULTS: DJK/DJF have been described as a complication of AIS, SK and adult spine deformity (ASD). For AIS and SK, the choice of a lower instrumented vertebra more cranial than the sagittal stable vertebra has shown to increase the incidence of DJK and DJF. For ASD, constructs ending with S1 pedicle screws had a higher incidence of DJK/DJF than those ending distally with S1 pedicle plus iliac screws. CONCLUSION: The proposed strategy of treatment includes restoration of normal sagittal alignment, choice of a distal fixation point stable in the sagittal, coronal and transverse planes, balancing the fusion mass over the distal fixation point and providing solid fixation at the distal end of the construct. These slides can be retrieved under Electronic Supplementary Material.

Useful and innovative methods for the treatment of postoperative coronal malalignment in adult scoliosis: the "kickstand rod" and "tie rod" procedures.

STUDY DESIGN: Surgical technique description and case series. OBJECTIVE: To describe the use of two techniques for the correction of postoperative coronal imbalance after surgical treatment for adult spine deformity (ASD). Sagittal and coronal spinal malalignments are often present in patients with ASD or in patients who have undergone spine surgery. Surgical correction of coronal imbalance is insufficiently investigated, and the literature provides a limited spectrum of surgical options when compared to sagittal imbalance. Nevertheless, this deformity can compromise the surgical outcome and can increase the risk of hardware failure. METHODS: The kickstand (KR) and tie rod (TR) techniques utilize an accessory rod, linking the previous instrumentation to an independent iliac screw. After a proper release of the lumbar spine with anterior release or posterior osteotomies, the KR technique pushes with distraction on the concave side, whereas the TR technique pulls with compression on the convex side. Four patients (mean age, 64 years; SD 5.7) affected by severe postoperative coronal imbalance were treated. C7-PL ranges from 39 to 76 mm. The mean preoperative ODI was 70/100 (range from 55 to 82). All patients had previous spinopelvic fixation as a consequence of corrective surgery for adult spine deformity. The patients were surgically treated with the addition of supplementary rods connected to the ilium. The rods were used in the concavity or convexity of the deformity functioning as "kickstand" or "tie" or a combination of both. RESULTS: The mean surgical correction of C7-PL was 35 mm (range from 20 to 52 mm). In particular, the mean correction for kickstand rod technique was 26 mm and for tie rod technique was 43 mm. All of the patients improved their preoperative disability, and mean ODI was 30/100 (range from 10 to 60) at median 19-month follow-up. All postoperative imaging showed implants were in proper position without hardware failure. All of the patients treated demonstrated an immediate postoperative improvement in terms of coronal displacement of the spine. No complications were observed. At 1-year follow-up, all of the patients remained satisfactory in terms of clinical outcomes. CONCLUSION: The kickstand and tie rod techniques are effective in the treatment of postoperative coronal malalignment. Further studies are needed to confirm these findings. LEVEL OF EVIDENCE: V: Case report. These slides can be retrieved under Electronic Supplementary Material.

A new classification for coronal malalignment in adult spinal deformity: a validation and the role of lateral bending radiographs.

PURPOSE: Coronal malalignment (CM) causes pain, impairment of function and cosmetic problems for adult spinal deformity (ASD) patients in addition to sagittal malalignment. Certain types of CM are at risk of insufficient re-alignment after correction. However, CM has received minimal attention in the literature compared to sagittal malalignment. The purpose was to establish reliability for our recently published classification system of CM in ASD among spine surgeons. METHODS: Fifteen readers were assigned 28 cases for classification, who represented CM with reference to their full-length standing anteroposterior and lateral radiographs. The assignment was repeated 2 weeks later, then a third assignment was done with reference to additional side bending radiographs (SBRs). Intra-, inter-rater reliability and contribution of SBRs were determined. RESULTS: Intra-rater reliability was calculated as 0.95, 0.86 and 0.73 for main curve types, subtypes with first modifier, and subtypes with two modifiers respectively. Inter-rater reliability averaged 0.91, 0.75 and 0.52. No differences in intra-rater reliability were shown between the four expert elaborators of the classification and other readers. SBRs helped to increase the concordance rate of second modifiers or changed to appropriate grading in cases graded type A in first modifier. CONCLUSIONS: Adequate intra- and inter-rater reliability was shown in the Obeid-CM classification with reference to full spine anteroposterior and lateral radiographs. While side bending radiographs did not improve the classification reliability, they contributed to a better understanding in certain cases. Surgeons should consider both the sagittal and coronal planes, and this system may allow better surgical decision making for CM.

Pedicle screw insertion with patient-specific 3D-printed guides based on low-dose CT scan is more accurate than free-hand technique in spine deformity patients: a prospective, randomized clinical trial.

BACKGROUND: Screw misplacement incidence can be as high as 15-30% in spine deformity surgery, with possible devastating consequences. Some technical solutions to prevent misplacement require expensive devices. MySpineTM comprises a low-dose CT scan of the patient's spine to build a virtual model of the spine to plan the screw trajectories and a 3D-printed patient-specific guide system to prepare the screw trajectories and to implant the screws in the vertebrae in order to increase reproducibility and safety of the implants. The aim of this open-label, single-center, prospective randomized clinical trial with independent evaluation of outcomes was to compare the accuracy of free-hand insertion of pedicle screws to MySpineTM 3D-printed patient-specific guides. METHODS: Twenty-nine patients undergoing surgical correction for spinal deformity were randomized to Group A (pedicle screws implantation with MySpineTM) or Group B (free-hand implantation). Group A received 297 pedicle screws, and Group B 243 screws. Forty-three screws in Group A crossed over to free-hand implantation. Screw position was graded according to Gertzbein in grades 0, A, B or C, with grades 0 or A considered as "safe area." Total fluoroscopy dose and time were compared in six patients of each group. RESULTS: Comparing the two study groups, we observed a statistically significant difference between the two groups (p < 0.05), with 96.1% of screws in the "safe area" in Group A versus a 82.9% in Group B. Group-A patients had a mean effective dose of 0.23 mSv compared to 0.82 mSv in Group B. Patient-specific, 3D-printed pedicle screw guides increase safety in a wide spectrum of deformity conditions. In addition, the total radiation dose is reduced, even considering the need of a low-dose preoperative CT for surgical planning. LEVEL OF EVIDENCE: I. These slides can be retrieved under Electronic Supplementary Material.

Classification of coronal imbalance in adult scoliosis and spine deformity: a treatment-oriented guideline.

INTRODUCTION: In adult spinal deformity (ASD), sagittal imbalance and sagittal malalignment have been extensively described in the literature during the past decade, whereas coronal imbalance and coronal malalignment (CM) have been given little attention. CM can cause severe impairment in adult scoliosis and ASD patients, as compensatory mechanisms are limited. The aim of this paper is to develop a comprehensive classification of coronal spinopelvic malalignment and to suggest a treatment algorithm for this condition. METHODS: This is an expert's opinion consensus based on a retrospective review of CM cases where different patterns of CM were identified, in addition to treatment modifiers. After the identification of the subgroups for each category, surgical planning for each subgroup could be specified. RESULTS: Two main CM patterns were defined: concave CM (type 1) and convex CM (type 2), and the following modifiers were identified as potentially influencing the choice of surgical strategy: stiffness of the main coronal curve, coronal mobility of the lumbosacral junction and degeneration of the lumbosacral junction. A surgical algorithm was proposed to deal with each situation combining the different patterns and their modifiers. CONCLUSION: Coronal malalignment is a frequent condition, usually associated to sagittal malalignment, but it is often misunderstood. Its classification should help the spine surgeon to better understand the full spinal alignment of ASD patients. In concave CM, the correction should be obtained at the apex of the main curve. In convex CM, the correction should be obtained at the lumbosacral junction. These slides can be retrieved under Electronic Supplementary Material.

Supplementary delta-rod configurations provide superior stiffness and reduced rod stress compared to traditional multiple-rod configurations after pedicle subtraction osteotomy: a finite element study.

PURPOSE: The biomechanical performance of conventional multi-rod configurations (satellite rods and accessory rods) in pedicle subtraction osteotomies has been previously studied in vitro and using finite element models (FEM). Delta and delta-cross rods are innovative multi-rod configurations where the rod bends were placed only in its proximal and distal extremities in order to obtain a dorsal translation of the central part of the rod respect to the most angulated area of the main rods. However, the biomechanical properties of the delta and delta-cross rods have not been investigated. This study used FEM to analyze the effect of delta-rod configurations on the stiffness and primary rod stress reduction in multiple-rod constructs after pedicle subtraction osteotomy. METHODS: The global range of motion in the spine and the magnitude and distribution of the von Mises stress in the rods were studied using a spine finite element model described previously. A follower load of 400 N along with moments of 7.5 N in flexion/extension, lateral bending, and axial rotation were tested on the spine model. Initial breakage was created on the rod based on the maximum stress location. The post-breakage models were tested under flexion. RESULTS: Delta and delta-cross rods reduced more range of motion (up to 45% more reduction) and reduced more primary rod stress than other previously tested rod configurations (up to 48% more reduction). After initial rod fracture occurred, delta and delta-cross rods also had less range of motion (up to 23.6% less) and less rod von Mises stress (up to 81.2% less) than other rod configurations did. CONCLUSIONS: Delta and delta-cross rods have better biomechanical performance than satellite rods and accessory rods in pedicle subtraction osteotomies in terms of construct stiffness and rod stress reduction. After the initial rod breakage occurred, the delta and delta-cross rods could minimize the loss of fixation, which have less rod stress and greater residual stiffness than other rod configurations do. Based on this FEA study, delta-rod configurations show more favorable biomechanical behavior than previously described multi-rod configurations. These slides can be retrieved under Electronic Supplementary Material.

Hypercomplex pedicle subtraction osteotomies: definition, early clinical and radiological results and complications.

PURPOSE: To describe hypercomplex pedicle subtraction osteotomies (HyC-PSO) for adult spine deformity with sagittal imbalance in terms of preoperative, intraoperative and postoperative outcomes and complications. METHODS: From a prospective single centre database, patients undergoing PSO between January 2016 and May 2017 were reviewed. HyC-PSO were defined as those in patients with one of the following conditions: sagittal correction > 45° needed at a single level or at 1-3 consecutive vertebrae, more than 60° of total sagittal correction needed and PSO on segments of the spine with congenital deformities. RESULTS: 22 patients were included, 14 had standard PSO (group A) and 8 had HyC-PSO (group B). Significant correction of lumbar lordosis (LL) and pelvic (PT) was noted in both groups (p < 0.01). Operative time was longer in HyC-PSO, 604 min compared to standard PSO, 478 min. A trend versus greater intraoperative blood loss (3837 vs 2285 ml) and greater intraoperative blood infusion (from cell saver plus homologous, 2306 vs 1280 ml) was recorded in HyC-PSO (ns). Patients in group B received significantly more blood units intra and postoperatively (8.25 vs 4.71 units, p = 0.006). Sagittal correction at the PSO level (54.7°-30° to 85°-vs 26.8°-8° to 39°-, p = 0.000) and total sagittal correction (64.5°-50 to 95°-vs 39.8°-20° to 51°-, p = 0.000) were greater in HyC-PSO. PROMs at the last available follow-up did not show significant differences between groups for any of the outcomes analyzed. Complications were similar in both groups. CONCLUSION: This is the first report on hypercomplex pedicle subtraction osteotomies. Hypercomplex PSO describes a subset of clinical scenarios with increased surgical effort that can be measured as longer surgical time and greater blood transfusion requirements. Successful correction of misalignment can be achieved in this specific group of patients, and clinical results and complications profile could be similar to standard PSO procedures.

Spinopelvic parameter changes and low back pain improvement due to femoral neck anteversion in patients with severe unilateral primary hip osteoarthritis undergoing total hip replacement.

PURPOSE: The study of the interrelation between hip and spine disorders is gaining increasing importance in the last years, but the link between Hip Osteoarthritis (HOA) and Low Back Pain (LBP) remains still unclear. Aim of the study is to assess the relationship between Femoral Neck Anteversion (FNA), LBP, and spinopelvic parameters in patients undergoing Total Hip Replacement (THR) for unilateral severe primary HOA. MATERIALS AND METHODS: 91 patients were recruited. Inclusion criteria were: grade 5 or 6 unilateral HOA, according to Turmezei, and Harris Hip score (HHS) <60. Exclusion criteria were: secondary hip osteoarthritis (dysplasia of the hip, rheumatoid arthritis, and ankylosing spondylitis); previous surgery of the spine, hip or knee; scoliosis with a Cobb angle greater than 10°; spondylolisthesis; history of spine fractures; previous bone tuberculosis or any spine infections; any contraindications to CT; BMI >30. Patients were divided into two homogeneous Groups according to the presence (Group-A) or not of concomitant LBP (Group-B). All patients underwent preoperatively a hip CT scan to evaluate FNA, Acetabular Anteversion (AA), and Combined Anteversion (CA = FNA + AA). ΔFNA, ΔAA and ΔCA were calculated as the differences between the arthritic hip and the normal hip angles in each Group. Full spinal X-rays in upstanding position were performed before (baseline) and 6 months after THR (follow-up) to calculate spinopelvic parameters. The health-related quality of life (HRQoL) was evaluated at baseline and at follow-up using Visual Analogue Scale (VAS), HHS, Oswestry Disability Index (ODI), Roland-Morris Disability Questionnaire (RM), and Short-Form Health Survey (SF-36). The intra-group and inter-group variability were assessed using, respectively, paired and unpaired t tests. At baseline, the association between HRQoL scores and ΔFNA, ΔAA, and ΔCA was analysed by the Pearson correlation test. RESULTS: At baseline, in Group-A, there was a significant difference between arthritic FNA and normal hip FNA, while no differences were found in AA between the two hips. A close correlation was observed between ΔFNA and Spine-VAS (r = 0.788), ODI (r = 0.824), and RM (r = 0.775). In Group-B, there was not a significant difference in FNA and AA between the two hips. At recruitment, in Group-A patients, we recorded a higher LL, SS, PI, SVA(C7), and a lower PT and T1-SPI compared with Group-B subjects. Six months after THR, in Group-A, an improvement of all clinical scores was recorded, as well as, a significant reduction of SS, LL, T1PA, and SVA(C7) and an increment of PT. In Group-B, at follow-up, an improvement of HHS, Hip-VAS, and SF-36 was recorded, while the changes in spinopelvic parameters were not significant. CONCLUSIONS: Patients with concomitant unilateral HOA and LBP showed a marked anteverted FNA in the arthritic hip and a spinopelvic misalignment. After THR, a relief of both hip and low back pain and a change in spinopelvic parameters is observed.

The effect of case-based discussion of topics with experts on learners' opinions: implications for spinal education and training.

PURPOSE: This investigation aimed to examine the extent to which case-based discussion with experts could influence the audience's opinions on the treatment of patients during a continuing medical education event for spine surgeons. METHODS: We conducted a prospective controlled crossover study of 90 surgeons. During a continuing medical education activity using case-based discussion, quiz questions were used which asked participants (attendants and faculty group) their opinions on the best choices about diagnosis and treatment in a number of cases. No answer was considered correct, but we evaluated the number of participants choosing each specific answer among a number of valid options. Quiz questions were collected with an automated response system at the entry and at the end of each case discussion. Change in participant's opinions was estimated from the change in the preferred answers between the entry and exit quizzes. Chi-square analysis was performed to determine significance. RESULTS: Sixty-two attendants out of eighty three (75%) and six faculties out of twelve (50%) responded to the survey. After the case discussion, 68.2% (p < 0.04, Chi-square test) of the attendants changed their opinion on the appropriate treatment. The faculty answers, however, showed no significant change in opinions regarding the identification of the appropriate treatment. CONCLUSIONS: On the basis of our results, case-based discussion driven by experts, as a form of teaching, has a measurable effect in terms of changes in the learners' opinions.