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This study aimed to investigate the incidence and risk factors for sacral fractures following lumbosacral fusion. We conducted a retrospective review of patients who underwent lumbosacral fusion for degenerative spinal stenosis with a minimum follow-up of 2 years. Patients who developed and those who did not develop a sacral fracture were categorized into the "sacral fracture" and "nonfracture" groups. The demographic and radiological data were compared between the 2 groups. A total of 65 patients were included in this study. Among them, 7 patients were categorized into the sacral fracture and 58 patients into the nonfracture groups, respectively. The incidence of sacral fracture was 10.8%. In the sacral fracture group, age and fusion levels were significantly higher (P < 0.05), while bone mineral density (BMD) T-score was significantly lower (P < 0.05) than nonfracture group. Pelvic incidence, preoperative pelvic tilt, postoperative sacral slope, and postoperative lumbar lordosis were significantly higher (P < 0.05) in the sacral fracture than the nonfracture group. Multivariable logistic regression analysis showed that BMD T-score (odds ratio [OR] 0.25, 95% confidence interval [CI] 0.08–0.79, P = 0.019), postoperative sacral slope (OR 1.14, 95% CI 1.00–1.29, P = 0.047), and changes in L4-S1 lordosis (OR 1.11, 95% CI 1.00–1.23, P = 0.049) were significant factors. The overall incidence of sacral fracture was 10.8%. In our study, advanced age, low BMD, long fusion levels, and preoperative compensatory pelvic retroversion and excessive correction of it were risk factors for sacral fractures. [ABSTRACT FROM AUTHOR]

A sacral insufficiency fracture is a rarely reported complication after lumbosacral fusion. As the majority of those undergoing surgery are elderly patients with degenerative disease, osteoporosis is usually involved along with other reported risk factors such as female, obesity, and multi-segment fusion. Through two cases experienced by the authors, this paper reports a newly found risk factor (cement-augmented pedicle screw), and the fracture treatment process with a review of the relevant literature. [ABSTRACT FROM AUTHOR]

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To investigate S2 alar screw (S2AS) accuracy and factors associated with S2AS loosening and lumbosacral nonunion. We retrospectively reviewed patients who underwent lumbosacral fusion surgery with S2AS addition under fluoroscopy. S2AS loosening and lumbosacral nonunion were analyzed using a 1-year postoperative computed tomography. S2AS insertion accuracy was originally classified as accurate, short, anterior perforation, lateral perforation, and sacroiliac joint (SIJ) deviation among lateral perforation. Clinical data including sex, age, body mass index, fused segments, fusion procedure, primary or revision surgery, Japanese Orthopedic Association scores and complications were collected. Factors associated with S2AS loosening and lumbosacral nonunion were analyzed. A total of 37 patients (74 screws, age: 63.78 ± 13.57 years, female/male: 14/23 patients, body mass index: 23.11 ± 2.53, fused segments: 1–4 levels, revision: 38%) were included. S2AS loosening and lumbosacral nonunion were observed in 18 screws (13%) and 8 patients (22%) respectively. Only 35 screws (47%) were inserted accurately in our classification. Short, lateral perforation, and anterior perforation were observed in 14 screws (19%), 22 screws (30%), and 3 screws (4.1%). SIJ deviation was seen in 15 screws (20%) Factors associated with S2AS loosening were older age (P = 0.038), fusion levels (P = 0.011), and SIJ deviation (P < 0.001). S2AS loosening affects S1 pedicle screw (S1PS) loosening (P = 0.001). Furthermore, S2AS loosening is a risk factor for lumbosacral nonunion (P = 0.046). S2AS insertion under fluoroscopy is inaccurate. S2AS loosening induces S1PS loosening and lumbosacral nonunion. Surgeons should avoid deviating to SIJ, especially in older patients and relatively longer fusion. [ABSTRACT FROM AUTHOR]

Abstract Objective There may be biomechanical changes in the adjacent hip joint after lumbosacral fusion. The literature has limited information on how these biomechanical changes may result in hip joint space. Material method Our retrospective study examined hip joint space narrowing in patients who underwent lumbosacral fusion between 2020 and 2022. In addition, spinopelvic parameters such as sacral slope, the sagittal vertical axis, pelvic incidence, lumbar lordosis, and pelvic tilt were compared in patients who underwent short-segment (up to three levels, S group) and long-segment (4 and higher levels, L group) fusions. Results Our study found no significant relationship between spinopelvic parameters and joint space narrowing in the S and L groups. In addition, it was determined that there was more narrowing in the hip joint space in the long-segment group, and there was a positive correlation between the segment length and the narrowing in the hip joint space. Conclusion After lumbosacral fusion, narrowing of the hip joint space was observed. Particularly patients with long-segment lumbosacral fusion should be followed closely regarding hip osteoarthritis risk.

Background: The study aim was to present four new well-documented cases of spontaneous improvement of olisthetic scoliosis and to analyze well-documented cases from the literature. Methods: Surgical log search and systematic review were conducted. Inclusion criteria were (1) age less than 18 years, (2) symptomatic high-grade (≥50%) spondylolisthesis, (3) scoliosis ≥20o, (4) primary surgical treatment via lumbosacral fusion, (5) complete x-rays, and (6) minimum 1-year radiographic follow-up or until curve resolution. Results: A total of 13 patients with average age of 13.9 years were included in the study, 4 from the authors' surgical logs and 9 from the literature. Slip percentage of L5-S1 ranged from 51% to 95%. Olisthetic curve magnitude averaged 34.6° (range: 20°–45°) with majority (8/13) demonstrating long thoracic curves with lateral trunk shift. All but one of these were apex right with rightward trunk shift. The remainder of the curves were isolated lumbar curves, with an apex left morphology without trunk shift. Eleven of the 13 patients showed curve improvement following isolated lumbosacral fusion. Three patients experienced a decrease in curve magnitude of 12°–28° and eight patients enjoyed complete resolution (≤10°) of their scoliosis. Conclusion: The current study summarizes 13 well-documented cases of olisthetic scoliosis (4 new cases and 9 from the literature) that associated with symptomatic high-grade spondylolisthesis. All were treated via a primary posterior lumbosacral fusion strategy. Eleven of the 13 curves showed spontaneous improvement (8 complete resolution of scoliosis) following their lumbosacral surgery. Level of evidence: Therapeutic level IV. [ABSTRACT FROM AUTHOR]

Objective: There may be biomechanical changes in the adjacent hip joint after lumbosacral fusion. The literature has limited information on how these biomechanical changes may result in hip joint space. Material: method: Our retrospective study examined hip joint space narrowing in patients who underwent lumbosacral fusion between 2020 and 2022. In addition, spinopelvic parameters such as sacral slope, the sagittal vertical axis, pelvic incidence, lumbar lordosis, and pelvic tilt were compared in patients who underwent short-segment (up to three levels, S group) and long-segment (4 and higher levels, L group) fusions. Results: Our study found no significant relationship between spinopelvic parameters and joint space narrowing in the S and L groups. In addition, it was determined that there was more narrowing in the hip joint space in the long-segment group, and there was a positive correlation between the segment length and the narrowing in the hip joint space. Conclusion: After lumbosacral fusion, narrowing of the hip joint space was observed. Particularly patients with long-segment lumbosacral fusion should be followed closely regarding hip osteoarthritis risk. [ABSTRACT FROM AUTHOR]

A retrospective cohort study to evaluate the efficacy and safety of midline lumbar fusion (MIDLF) for lumbosacral fusion compared to posterior lumbar interbody fusion (PLIF). Patients who had undergone posterior lumbosacral fusion surgery were divided into a MIDLF group (n = 37) and a PLIF group (n = 42). The follow-up time was at least 12 months. The operation data, recovery condition, complications, clinical outcomes, and status of implants and fusion were compared between the 2 groups. The MIDLF group experienced significantly less blood loss, lower postoperative creatine kinase levels and total drainage volume, earlier time to ambulation, and less hospital stay times after surgery compared to the PLIF group (P < 0.05). The mean postoperative back pain visual analog scale scores in the MIDLF group were significantly lower than the PLIF group (P < 0.05). The improvement in Oswestry Disability Index scores during 3-month follow-up displayed a significant difference between the 2 groups (P < 0.05). The fusion rate tended to be higher in the MIDLF group; however, the difference was not significant (P > 0.05). There was no significant difference in respect to screw loosening and cage subsidence rate. There were 2 cases of complications both occurring in the PLIF group. MIDLF is safe and effective for lumbosacral fusion and in line with the concept of enhanced recovery after surgery. [ABSTRACT FROM AUTHOR]

The sacroiliac joint (SIJ) constitutes the predominant pain source following lumbar or lumbosacral fusion. Although studies have investigated the biomechanical patterns of SIJ behaviors after lumbosacral fusion, the relationship between ligament strain and SIJ pain following lumbosacral fusion remains unclear. The present study developed a three‐dimensional finite element model including L4, L5, sacrum, ilium, SIJ, and seven mainly ligaments. After successful validation, the model was used to investigate the biomechanics of SIJ and ligaments in simulating lumbosacral fusion process. Our results showed that small motion in a stable SIJ may significantly increases the contact pressure and stress of the SIJ, which increase the maximum contact pressure by 171%, 676%, 199%, and 203% and stress by 130%, 424%, 168%, and 241% for flexion, extension, bending, and axial rotation, respectively. An increase in contact pressure and stress in SIJ possibly causes pain at the SIJ, especially in extension and axial rotation. A comparison between the lumbosacral and intact models exhibited the maximum strain increase in the iliosacral ligament (ISL) and the ileal ligament (IL) under all loading conditions. The present study suggests that after lumbosacral fusion process, the ligament sudden increase or decrease is likely to lead sprain or strain ligament, especially ISL and IL thereby causing SIJ pain. This study may contribute to understand the relationship between SIJ ligaments and SIJ pain. [ABSTRACT FROM AUTHOR]

Background: This study aimed to evaluate the efficacy of fluoroscopy-guided percutaneous sacroplasty in patients with sacral pedicle screws loosening after instrumented spinal fusion. Methods: We retrospectively reviewed the medical records of 18 patients who underwent percutaneous sacroplasty to treat sacral pedicle screws loosening from January 2016 to December 2019. Imaging studies, visual analog scale (VAS), length of hospital stay, and complications were recorded. The clinical outcomes based on the Oswestry disability index (ODI) and the modified Brodsky's criteria (MBC) were also evaluated to determine the efficacy of percutaneous sacroplasty. Results: All patients had undergone at least 1 year of follow-up in our institute (range, 12–24 months). The average VAS score was 5.6 (range, 4–7) before surgery and decreased to 1.7 (range, 1–3) at the final visit. All patients were discharged on the next day after surgery. No patients experienced complications, such as cement leakage, deep infection, or neurologic deterioration. All patients achieved good or excellent outcomes based on the MBC. The ODI scores improved from 51.8 preoperatively to 25.6 postoperatively. Conclusion: Percutaneous sacroplasty was an effective treatment approach for relieving the patient's symptoms caused by sacral pedicle screws loosening and could be a valuable treatment alternative to extensive revision surgery. Level of clinical evidence: IV [ABSTRACT FROM AUTHOR]

Of Background Data: Pedicle screws are commonly placed with lumbar/lumbosacral fusions. Triggered electromyography (tEMG), which employs the application of electrical current between the screw and a complementary anode to determine thresholds of conduction, may be utilized to confirm the safe placement of such implants. While previous research has established clinical thresholds associated with safe screw placement, there is variability in clinical practice of anode placement which could lead to unreliable measurements.Purpose: To determine the variance in pedicle screw stimulation thresholds when using four unique anode locations (ipsilateral/contralateral and paraspinal/gluteal relative to tested pedicle screws).Study Design: Prospective cohort study. Tertiary medical center.Patient Sample: Twenty patients undergoing lumbar/lumbosacral fusion with pedicle screws using tEMG OUTCOME MEASURES: tEMG stimulation return values are used to assess varied anode locations and reproducibility based on anode placement.Methods: Measurements were assessed across node placement in ipsilateral/contralateral and paraspinal/gluteal locations relative to the screw being assessed. R2 coefficients of correlation were determined, and variances were compared with F-tests.Results: A total of 94 lumbosacral pedicle screws from 20 patients were assessed. Repeatability was verified using two stimulations at each location for a subset of the screws with an R2 of 0.96. Comparisons between the four anode locations demonstrated R2 values ranging from 0.76 to 0.87. F-tests comparing thresholds between each anode site demonstrated all groups not to be statistically different.Conclusion: The current study, a first-of-its-kind formal evaluation of anode location for pedicle screw tEMG testing, demonstrated very strong repeatability and strong correlation with different locations of anode placement. These results suggest that there is no need to change the side of the anode for testing of left versus right screws, further supporting that placing an anode electrode into gluteal muscle is sufficient and will avoid a sharp ground needle in the surgical field. [ABSTRACT FROM AUTHOR]

Sacral insufficiency fractures after lumbosacral fusion continue to establish themselves as a rare complication after surgery. The diagnosis can often be missed due to inconclusive imaging and non-specific symptoms. In the literature, the treatment of sacral insufficiency fractures varies from non-operative and conservative management to surgical intervention with lumbopelvic fixation. We performed a systematic review searching the PubMed database using sacral insufficiency fracture treatment after lumbosacral fusion and sacral insufficiency fracture after posterior spinal instrumentation as keywords. This search strategy identified 32 publications from the PubMed database for literature review. After evaluating the inclusion and exclusion criteria, a total of 17 articles were included in the review. 65% of sacral insufficiency fractures were managed surgically with 35% of patients proceeding with non-operative, conservative management only. Revision surgery always involved sacropelvic fixation which typically led to immediate resolution or reduction of symptoms, with the exception of 2 cases that did not receive adequate reduction of symptoms. Five cases reported failed non-operative management that subsequently responded to revision surgery. Outcomes after non-operative management usually leads to symptom resolution; however has a slower symptom relief time as well as a higher chance of failed treatment. Operative outcomes, generally with a variation of sacropelvic fixation lead to immediate symptom resolution and very rarely failed treatment. Clinicians must always maintain a high index of suspicion of new onset lower back or sacral pain after lumbosacral surgery and order a CT scan to rule out a potential insufficiency fracture. The objective of this study was to review the literature to examine treatment options for sacral insufficiency fractures after lumbosacral fusion in order to improve clinical practice and management. This systematic review of the literature regarding treatment of sacral insufficiency fractures will assist clinicians in making the accurate diagnosis and devise a strategic treatment plan for patients with sacral insufficiency fractures after spinal instrumentation. [ABSTRACT FROM AUTHOR]

This research compared the incidence of adjacent segment pathology (ASP) between anterior interbody lumbar fusion (ALIF) treatment and transforaminal lumbar interbody fusion (TLIF) treatment. Seventy patients were included in this retrospective study: 30 patients received ALIF treatment, and 40 patients received TLIF treatment at a single medical center between 2011 and 2020 with a follow-up of at least 12 months. The outcomes were radiographic adjacent segment pathology (RASP) and clinical adjacent segment pathology (CASP). The mean follow-up period was 42.10 ± 22.61 months in the ALIF group and 56.20 ± 29.91 months in the TLIF group. Following single-level lumbosacral fusion, ALIF is superior to TLIF in maintaining lumbar lordosis, whereas the risk of adjacent instability in the ALIF group is significantly higher. Regarding ASP, the incidence of overall RASP and CASP did not differ significantly between ALIF and TLIF groups.

Study designBiomechanical, cadaveric study.ObjectiveTo compare the fixation strength of a novel S1 pedicle screw insertion technique in a revision setting to a standard S1 pedicle screw and an L5 pedicle screw.Summary of background dataFusions to the sacrum remain a difficult clinical challenge. Very few salvage techniques exist when a nonunion occurs.MethodsThe biomechanical integrity of three screw fixations, L5 pedicle screws, a standard S1 pedicle screw, and an S1 pedicle screw placed via a superior articulating process entry point (SAP S1), was characterized by performing pullout tests using cadaveric specimens including L5 and sacrum.ResultsSAP S1 constructs (735.5 ± 110.1 N/mm) were significantly stiffer than standard S1 (P = 0.005) and L5 (P = 0.02) constructs. There was no statistically significant difference between the L5 constructs and the standard S1 constructs for linear stiffness. There was no statistical difference between the three fixations for yield load, displacement at yield load, and energy absorbed to yield load.The ultimate pullout force for the SAP S1 was statistically higher than the standard S1 (1213.7 ± 579.6 vs. 478.6 ± 452.9 N; P = 0.004). Displacement at ultimate load was significantly greater for L5 screw fixation (3.3 ± 1.1 mm) compared to the other two constructs. Both the L5 (2277.4 ± 1873.3 N-mm) and SAP S1 (2628.2 ± 2054.4 N-mm) constructs had significantly greater energy absorbed to ultimate load than the standard S1 construct (811.7 ± 937.6 N-mm), but there was no statistical difference between the L5 and SAP S1 constructs.ConclusionS1 pedicle screw fixation via an SAP entry point provides biomechanical advantages compared to screws placed via the standard S1 or L5 entry point and may be a viable option for revision of a failed L5-S1 fusion with a compromised standard S1 entry point.Level of evidenceN/A.

This retrospective study aimed to evaluate the clinical outcomes of circumferential minimally invasive surgery (CMIS) using lateral lumbar interbody fusion (LLIF) and percutaneous pedicle screw (PPS) in adult spinal deformity (ASD) patients, and to clarify the conditions for achieving postoperative pelvic incidence-lumbar lordosis (PI-LL) < 10°. Demographics and other parameters of ASD patients who underwent CMIS and who were divided into groups G (achieved postoperative PI-LL < 10°) and P (PI-LL ≥ 10°) were compared. Of the 145 included ASD patients who underwent CMIS, the average fused level, bleeding volume, operative time, and number of intervertebral discs that underwent LLIF were 10.3 ± 0.5 segments, 723 ± 375 mL, 366 ± 70 min, and 4.0 segments, respectively. The rod material was titanium alloy in all the cases. The PI-LL significantly improved from 37.3 ± 17.9° to 1.2 ± 12.2° postoperatively. Pre- and postoperative PI, postoperative LL, preoperative PI-LL, PI-LL after LLIF, and postoperative PI-LL were significantly larger in group P. PI-LL after LLIF was identified as a significant risk factor of postoperative PI-LL < 10° by logistic regression, and the cut-off value on receiver operating characteristic curve analysis was 20°. Sufficient correction was achieved by CMIS. If PI-LL after LLIF was ≤20°, it was corrected to the ideal alignment by the PPS procedure. [ABSTRACT FROM AUTHOR]

Study Design Retrospective study. Purpose To determine the risk factors for S2 alar iliac (S2AI) screw loosening and its association with lumbosacral fusion in patients with adult spinal deformity (ASD). Overview of Literature S2AI screws have been widely used for ASD surgery in recent years. However, no studies have analyzed the risk factors for loosening of S2AI screws and its association with lumbosacral fusion. Methods Cases of 50 patients with ASD who underwent long spinal fusion (>9 levels) with S2AI screws were retrospectively reviewed. Loosening of S2AI screws and S1 pedicle screws and bone fusion at the level of L5–S1 at 2 years after surgery were investigated using computed tomography. In addition, risk factors for loosening of S2AI screws were determined in patients with ASD. Results At 2 years after surgery, 33 cases (66%) of S2AI screw loosening and six cases (12%) of S1 pedicle screw loosening were observed. In 40 of 47 cases (85%), bone fusion at L5–S1 was found. Pseudarthrosis at L5–S1 was not significantly associated with S2AI screw loosening (19.3% vs. 6.3%, p=0.23), but significantly higher in patients with S1 screw loosening (83.3% vs. 4.9%, p

Introduction: The effect of pelvic fixation on postoperative medical complications, blood transfusion, length of hospital stay, and discharge disposition is poorly understood. Determining factors that predispose patients to increased complications after spinopelvic fusion will help surgeons to plan these complex procedures and optimize patients preoperatively. Methods: We conducted a retrospective cohort study using data from the ACS-NSQIP database between 2006 and 2016 of patients who underwent lumbar fusion with and without spinopelvic fixation. Data regarding demographics, complications, hospital stay, and discharge disposition were collected. Results: A total of 57,417 (98.5%) cases of lumbar fusion without spinopelvic fixation (LF) and 887 (1.5%) cases of lumbar fusion with spinopelvic fixation (SPF) were analyzed. The transfusion rate in the SPF group was 59.3% vs 13% in the LF group (p < 0.001). The mean length of stay (LOS) and discharge to skilled nursing facility (SNF) were significantly different (LOS: SPF 6.5 days vs LF 3.5 days p < 0.001; SNF: SPF 21.3% vs LF 10.4% p < 0.001). After controlling for demographic differences, the overall complication rates were not significantly different between the groups (p = 0.531). The odds ratio for transfusion in the SPF group was 2.9 (p < 0.001). The odds ratio for increased LOS and increased care discharge disposition were elevated in the SPF group (LOS OR: 1.3, p < 0.012, Discharge disposition OR: 1.8, p < 0.001). Conclusions: Patients who underwent SPF had increased complications, transfusion rate, LOS, and discharge to SNF or subacute rehab facilities as compared with patients who underwent LF. SPF remains an effective technique for achieving lumbosacral arthrodesis. Surgeons should consider the implications of the associated complication profile for SPF and the value of preoperative optimization in a select cohort of patients.

Study Design: Cross-sectional observational cohort study.Objective: The aim of this study was to determine the incidence and risk factors associated with the development of sacroiliac joint (SIJ) dysfunction following lumbosacral fusion.Summary Of Background Data: Adjacent segment degeneration to both proximal and distal areas of spinal fusion is a postoperative complication of lumbar fusion. Various studies examined supra-adjacent degeneration following lumbar fusion, but few focused on infra-adjacent degeneration. In lumbosacral fusion, fusion extends to the sacrum, placing increased stress on the SIJ.Methods: A total of 2069 sequential patients who underwent lumbosacral fusion surgery from 2008 to 2018 at a single academic medical center were retrospectively reviewed. Patients who subsequently developed SIJ dysfunction were identified. SIJ dysfunction was defined as patients who met the diagnostic criteria with physical examination and received an SIJ injection with clinical evidence of improvement. Controls, without subsequent SIJ dysfunction, were matched with cases based on levels of fusion, age, sex, and body mass index. Pre-and postoperative pelvic parameters were measured, including pelvic incidence, pelvic tilt (PT), sacral slope, lumbar lordosis, lumbosacral angle, L4 incidence and L5 incidence.Results: Of 2069 patients who underwent lumbosacral fusion, 81 patients (3.9%) met criteria for SIJ dysfunction. Measurements were made for 47 of 81 patients who had SIJ dysfunction, that had both pre- and post-operative imaging. Measurements for 44 matched controls were taken. Postoperative PT was significantly lower in SIJ dysfunction patients compared to controls (20.82° ± 2.19° vs. 27.28° ± 2.30°; P < 0.05), as was L5 incidence (28.64° ± 3.38° vs. 37.11° ± 3.50°; P < 0.05).Conclusion: Incidence of the SIJ dysfunction after lumbosacral fusion surgery was 3.9% and these patients had a significantly lower PT and L5 incidence compared to the control group. Significantly low PT may be derived from weak hamstring muscles, predisposing a patient to SIJ dysfunction. Therefore, hamstring muscle strengthening exercise for patients with decreased PT after lumbosacral fusion may decrease the incidence of SIJ dysfunction.Level of Evidence: 3. [ABSTRACT FROM AUTHOR]

Purpose: Various pathologies of the lumbosacral junction require fusion of the L5/S1 segment. However, pseudarthroses, which often come along with sacral screw loosening, are problematic. The aim of the present investigation was to elaborate the morphological features of the L5/S1 segment to define a so-called "safe zone" for bi- or tricortical screw placement without risking a damage of the iliac vessels. Methods: A total of one hundred computed tomographies of the pelvis were included in this investigation. On axial and sagittal slices, pedicle morphologies, the prevertebral position of the iliac vessels, the spinal canal and the area with the largest bone density were analyzed. Results: Beginning from the entry point of S1-srews iliac vessels were located at an average angle of 7° convergence, the spinal canal at 38°. Bone density was significantly higher centrally with a mean value of 276 Hounsfield Units compared to the area of the Ala ossis sacri. The largest intraosseous screw length could be achieved at an angle of 25°. The average pedicle width was 20 mm and the pedicle height 13 mm. Conclusions: A "safe-zone" for bicortical screw placement at S1 with regard to the course of the iliac vessels could be defined between 7° and 38° convergence. Regarding the area offering the largest bone density and the maximal possible screw length, a convergence of 25° is recommended at S1 to reduce the incidence of screw loosening. Screw diameter, as a further influence factor on screw holding, is limited by pedicle height not pedicle width. [ABSTRACT FROM AUTHOR]

Introduction: Degenerative sacroiliac (SI) joint syndrome is known to be more common after lumbosacral fusion. While this diagnosis is suspected based on various clinical criteria and diagnostic tests, it is confirmed with a diagnostic nerve block. If conservative treatment fails, SI joint fusion through a minimally invasive approach is a useful palliative approach for patients at a treatment crossroads. The aim of this study was to evaluate the clinical and functional results at 2years postoperative after minimally invasive SI joint fusion in patients with SI joint syndrome following lumbosacral fusion., Materials and Methods: We carried out a single-center retrospective study of patients operated between June 2017 and October 2020. Included were patients who had a confirmed diagnosis of SI joint syndrome after lumbosacral fusion surgery, who underwent SI joint fusion and had at least 2years' follow-up. The primary outcome was the improvement in lumbar and radicular pain on a numerical rating scale (NRS). The secondary outcomes were the functional scores (Oswestry and SF-12) along with the level of patient satisfaction. Our study population consisted of 54 patients (41 women, 13 men) with a mean age of 59years (27-88). Thirty-one of these patients were operated on both sides (85 fusions in all). The patients had undergone a mean of 3 lumbar surgeries (1-7) before the SI fusion., Results: The lumbar and radicular NRS were 8.4 (7-10) and 5.1 (2-10) preoperatively and 5.2 (0-8) and 3.0 (0-8) at 2years postoperatively, which was a reduction of 37% and 42% (p<0.001), respectively. The Oswestry score went from 69.4 (52-86) preoperatively to 45.6 (29-70) at 2years, which was a 33% improvement (p<0.001). Eighty-six percent of patients were satisfied or very satisfied with the surgery., Discussion: After minimally invasive SI joint fusion, the patients in this study had clear clinical and functional improvements. Previous publications analyzing the results of SI joint fusion found even more improvement, but those patients were relatively heterogenous; in our study, only patients who had a history of lumbosacral fusion were included., Conclusion: Minimally invasive SI joint fusion helped patients who developed SI joint syndrome after lumbosacral fusion to improve clinically and functionally., Level of Evidence: IV, retrospective study., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

The sacroiliac joint (SIJ) is a possible source of persistent or new onset pain after lumbar or lumbosacral fusion. The aim of this paper is to systematically review and analyze the available literature related to the incidence, diagnosis and management of sacroiliitis after spinal arthrodesis. The authors independently screened the titles and abstracts of all articles identified concerning sacroiliac joint pain after lumbar or lumbosacral fusion, to assess their suitability to the research focus. The average incidence of sacroiliitis after lumbar or lumbosacral arthrodesis was found to be 37 ± 28.48 (range 6-75), increasing directly to the number of fused segments involved, especially when the sacrum is included. The most accurate evaluation is the image-guided injection of anesthetic solutions in the joint. Surgery treatment may be considered when conservative therapy fails, with open surgery or with minimally invasive SIJ fusion. Although the risk of developing SIJ degeneration is unclear, the results indicate that pain and degeneration of SIJ develop more often in patients undergoing lumbosacral fusion regardless of the number of melting segments. The treatment of sacroiliitis appears to be independent of his etiology, with or without previous instrumentation on several levels. [ABSTRACT FROM AUTHOR]

Literature data on the frequency and pathogenesis of sacroiliac joint (SIJ) pain and arthropathy following lumbosacral fusion with long constructs combined with sacroiliac fixation remains scarce. From clinical experience, we noticed that many patients undergoing these surgeries develop SIJ disease postoperatively. We report a clinical observation of no occurrence or remission of SIJ pain following simultaneous SIJ fusion in cases of long-construct lumbosacral fusion and sacropelvic fixation with S2-alar-iliac screws. An illustrative case and description of the simultaneous SIJ fusion technique are discussed as well. Based on our experience, we believe that fusing the SIJ simultaneously during sacropelvic fixation in the context of a long lumbosacral fusion surgery may lead to a decline in the incidence of SIJ disease, as well as remission of SIJ pain in patients requiring revision surgeries. Future, multicenter prospective studies are needed to test and validate this observation. [ABSTRACT FROM AUTHOR]

Background: Sacral fractures and failures are uncommon after lumbosacral fusion but have received increasing attention in the surgical literature. They can be difficult to diagnose, making timely treatment difficult. No consensus has been reached on the characteristics of these complications or on optimal treatment. Questions/Purposes: The goal of this retrospective case series is to contribute additional cases of these uncommon complications of lumbosacral fusion to the surgical literature to help clinicians to anticipate, diagnose, characterize, manage, and treat sacral fractures and failures after lumbosacral fusion. Methods: The medical records of five patients who experienced a sacral fracture or failure after lumbosacral fusion between January 2012 and November 2017 were identified and reviewed retrospectively. Records were reviewed for age, sex, clinical presentation, previous management, outpatient clinical records, imaging, and post-operative course. Results: Four patients in the series experienced a sacral fracture and one experienced hardware failure. All patients presented with elevated pain and underwent revision surgery. Radiographic detection of the fracture or failure occurred at a mean of 11.2 weeks (range, 3 to 24 weeks) after initial surgery, and the mean age of patients was 68.2 years (range, 63 to 80 years). Of the five patients, four were female; two had been diagnosed with osteoporosis and two with osteopenia. In our case series, the S2–alar–iliac (S2AI) technique was used with success in all five cases. Conclusion: Fractures and failures after lumbosacral fusion can be difficult to diagnose because of delayed presentation, nonspecific presenting symptoms, and a lack of identifiable mechanism. A high index of suspicion is required to detect these uncommon complications, and patients have responded well to both conservative and surgical treatments. [ABSTRACT FROM AUTHOR]

Background Context: All currently described percutaneous iliac screw placement methods are entirely dependent on fluoroscopy.Purpose: The purpose of this study was to determine the safety and the accuracy of percutaneous and open iliac screw placement using a primarily tactile technique with adjunctive anteroposterior (AP) fluoroscopy.Study Design/context: All patients who underwent open and percutaneous iliac screw placement over a 5-year period were identified. Charts were reviewed to assess for any instances of neurologic or vascular injury associated with iliac screw placement. Screw accuracy was judged with postoperative computed tomography (CT) scans.Patient Sample: A total of 133 patients were identified who underwent open or percutaneous iliac screw placement. Computed tomography scans were available for 57 patients, and all of these patients were included in the study, with a total of 115 iliac screws.Outcome Measures: Radiographic measurements were performed, consisting of the distance of the iliac screw to the sciatic notch on postoperative radiographs and CT scans. Computed tomography scans were used to determine iliac screw accuracy.Methods: Charts were reviewed to assess for any neurologic or vascular injuries related to screw placement. The distance of the iliac screw to the sciatic notch was measured and compared on AP radiography and CT scans. Computed tomography scans were assessed for any screw violation of the iliac cortex or the sciatic notch. The accuracy of open iliac screw placement was compared with minimally invasive percutaneous placement.Results: There were no neurologic or vascular injuries related to screw placement in the 133 patients. Computed tomography scans were available for 115 iliac screws, with 3 cortical breaches, all by less than 2 mm. All 112 other screws were accurately intraosseous. There was a strong correlation between the iliac screw to the sciatic notch distance when measured by CT scan compared with AP radiography (r=0.9), thus validating the accuracy of AP fluoroscopy in guiding iliac screw placement with respect to the sciatic notch. Iliac screw accuracy was equal with the open and percutaneous insertion techniques.Conclusions: The described surgical technique represents a safe and reliable surgical option for iliac screw placement. Intraoperative AP fluoroscopy accurately reflects the distance of the iliac screw to the sciatic notch. Percutaneous iliac screws placed with this technique are as accurate as open iliac screws. [ABSTRACT FROM AUTHOR]

Background Context: Pelvic incidence (PI)=pelvic tilt (PT)+sacral slope (SS) is an established trigonometric equation which can be expanded from studying the fixed pelvis with the spine to a fixed spinopelvic complex with the remnant spine, in scenarios of spinopelvic fusion or ankylosis. For a fixed spinopelvic complex, we propose the equation termed: lumbar incidence (LI)=lumbar tilt (LT)+lumbar slope (LS).Purpose: This study aimed to establish reference values for LI, LT, and LS at each lumbar vertebral level, and to show how LI can be used to determine residual lumbar lordosis (rLL).Study Design: This is a cross-sectional study of prospectively collected data, conducted at a single academic tertiary health-care center.Patient Sample: The study included 53 healthy patients aged 19-35 with first episode mechanical low back pain for a period of <3 months. Patients with previous spinal intervention, those with known or suspected spinal pathologies, and those who were pregnant, were excluded.Outcome Measures: Radiological measurements of LI, LT, LS, and rLL.Methods: All patients had full-body lateral standing radiographs obtained via a slot scanner. Basic global and regional radiographic parameters, spinopelvic parameters, and the aforementioned new parameters were measured. LI was correlated with rLL at each level by plotting LI against rLL on scatter plots and drawing lines-of-best-fit through the datapoints.Results: The mean value of L5I was 22.82°, L4I was 6.52°, L3I was -0.92°, L2I was -5.56°, and L1I was -5.95°. LI turns negative at L3, LS turns negative at the L3/L4 apex, and LT remains positive throughout the lumbar spine. We found that the relationship of LI with its corresponding rLL follows a parabolic trend. Thus, rLL can be determined from the linear equations of the tangents to the parabolic lumbar spine. We propose the LI-rLL method for determining rLL as the LI recalibrates via spinopelvic compensation post instrumentation, and thus the predicted rLL will be based on this new equilibrium, promoting restoration of harmonized lordosis. The rLL-to-LI ratio is a simplified, but less accurate, method of deriving rLL from LI.Conclusions: This study demonstrates the extended use of PI=PT+SS proposed as LI=LT+LS. These new spinopelvic reference values help us better understand the position of each vertebra relative to the hip. In situations when lumbar vertebrae are fused or ankylosed to the sacrum to form a single spinopelvic complex, LI can be used to determine rLL, to preserve spinal harmony within the limits of compensated body balance. [ABSTRACT FROM AUTHOR]

Spondylolysis and spondylolisthesis usually affect the lumbosacral junction and are the most common causes of back pain in children and adolescents. In severe forms the deformity may be progressive and produce neurological deficits, sagittal imbalance and physical disability. The mainstay of treatment in early stages is conservative, while surgery is offered in persistently symptomatic patients or progressive deformities. Severe forms of spondylolisthesis require spinal stabilization and deformity correction; however there is lack of consensus regarding the optimal operative management. The aim of this article is to present the current concepts on the development, progression and classification of this condition, to illustrate the clinical and imaging diagnostic approaches and describe the principles of surgical treatment in all stages of the disease. [ABSTRACT FROM AUTHOR]

Study Design: A retrospective analysis of two consecutive patients who underwent a novel surgical technique.Objective: A report of a novel surgical technique utilizing an electronic conductivity device guidance to aide placement of S2-Alar-Iliac (S2-AI) instrumentation. Electronic conductivity guidance for instrumentation of the thoracolumbar spine is an accepted means of improving intraoperative accuracy. Although commercially available for percutaneous techniques, there is a paucity of literature regarding its use. Percutaneous implantation of S2-AI screws has been previously described as another technique surgeons can avail, primarily employing fluoroscopy as a means of intraoperative feedback. We describe a novel technique that utilizes electronic conductivity as an added feedback measure to increase accuracy of percutaneous S2-AI fixation.Methods: Two patients were treated by the senior author (FAS) who underwent surgery employing S2-AI fixation utilizing an electronic conductivity device (Pediguard cannulated probe, Spineguard, Paris, France). The surgical technique, case illustrations, and radiographic outcomes are discussed.Results: Stable and accurate fixation was attained in both patients. There were no peri-operative complications related to hardware placement.Conclusion: To the authors' knowledge, this is the first reported literature combining S2-AI screws with electronic conductivity for immediate intraoperative feedback. This technique has the opportunity to provide surgeons with increased accuracy for placement of S2-AI screws while improving overall radiation safety. This feedback can be particularly helpful when surgeons are learning new techniques such as placement of S2AI screws. [ABSTRACT FROM AUTHOR]

Study Design: A retrospective study.Objective: We investigated the prevalence of iliac screw loosening and determined risk factors after adult spinal deformity surgery.Summary Of Background Data: Lumbosacral fixation is crucial to maintain optimal sagittal alignment. Iliac screws are commonly placed to provide protection for sacral pedicle screws. Radiolucent areas around the screws indicate fixation loss and pseudarthrosis.Methods: Seventy-two patients with adult spinal deformity (13 men, 59 women; mean age, 69.0 yr) who underwent spinal deformity surgeries using bilateral iliac screws with at least 2 years follow-up were studied. Iliac and S1 screw loosening were assessed by postoperative radiograph. The period of loosening appearance and the relations between loosening and the following items were investigated: (1) upper instrumented vertebra, (2) L5/S interbody fusion, (3) iliac screw placement, (4) spinopelvic parameters (T1 pelvic angle, sagittal vertical axis, pelvic tilt, pelvic incidence-lumbar lordosis [LL]). Oswestry Disability Index scores were obtained preoperatively and 2 years postoperatively.Results: Iliac and S1 screw loosening was found in 20 (27.8%) and 7 patients (9.7%), respectively. Iliac screw loosening appeared at 5.2 months (range, 3-12) on average. Compared with nonloosening, loosening had significantly higher upper thoracic fusion rates (above T6), lower L5/S interbody fusion rate, higher misplacement rate, and higher insufficient correction rate (PI-LL >10°). Oswestry Disability Index significantly improved in nonloosening, whereas no significant difference was observed in loosening. Multiple regression analysis showed that misplacement (odds ratio = 10.8) and insufficient correction (odds ratio = 7.5) affected loosening.Conclusion: Iliac screw loosening indicated instability of the lumbosacral junction, resulting in sagittal malalignment and poor outcomes. Accurate screw insertion and restoration of optimal LL were necessary to prevent complications.Level Of Evidence: 4. [ABSTRACT FROM AUTHOR]

Background: Lumbar/lumbosacral fusion supplemented with topping-off devices has been proposed with the aim of avoiding adjacent segment degeneration proximal to the fusion construct. However, it remains unclear how the biomechanics of the sacroiliac joint (SIJ) are altered after topping-off surgery. The objective of this study was to investigate the biomechanical effects of topping-off instrumentation on SIJ after lumbosacral fusion., Methods: The validated finite element model of an intact lumbar spine-pelvis segment was modified to simulate L5-S1 interbody fusion fixed with a pedicle screw system. An interspinous spacer, Device for Intervertebral Assisted Motion (DIAM), was used as a topping-off device and placed between interspinous processes of the L4 and L5 segments. Range of motion (ROM), von-Mises stress distribution, and ligament strain at SIJ were compared between fusion (without DIAM) and topping-off (fusion with DIAM) models under moments of four physiological motions., Results: ROM at the left and right SIJs in the topping-off model was higher by 26.9% and 27.5% in flexion, 16.8% and 16.1% in extension, 18.8% and 15.8% in lateral bending, and 3.7% and 7.4% in axial rotation, respectively, compared to those in the fusion model. The predicted stress and strain data showed that under all physiological loads, the topping-off model exhibited higher stress and ligament strain at the SIJs than the fusion model., Conclusions: Motion, stress, and ligament strain at SIJ increase when supplementing lumbosacral fusion with topping-off devices, suggesting that topping-off surgery may be associated with higher risks of SIJ degeneration and pain than fusion alone., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Study Design: Biomechanical, cadaveric study.Objective: To compare the fixation strength of a novel S1 pedicle screw insertion technique in a revision setting to a standard S1 pedicle screw and an L5 pedicle screw.Summary Of Background Data: Fusions to the sacrum remain a difficult clinical challenge. Very few salvage techniques exist when a nonunion occurs.Methods: The biomechanical integrity of three screw fixations, L5 pedicle screws, a standard S1 pedicle screw, and an S1 pedicle screw placed via a superior articulating process entry point (SAP S1), was characterized by performing pullout tests using cadaveric specimens including L5 and sacrum.Results: SAP S1 constructs (735.5 ± 110.1 N/mm) were significantly stiffer than standard S1 (P = 0.005) and L5 (P = 0.02) constructs. There was no statistically significant difference between the L5 constructs and the standard S1 constructs for linear stiffness. There was no statistical difference between the three fixations for yield load, displacement at yield load, and energy absorbed to yield load.The ultimate pullout force for the SAP S1 was statistically higher than the standard S1 (1213.7 ± 579.6 vs. 478.6 ± 452.9 N; P = 0.004). Displacement at ultimate load was significantly greater for L5 screw fixation (3.3 ± 1.1 mm) compared to the other two constructs. Both the L5 (2277.4 ± 1873.3 N-mm) and SAP S1 (2628.2 ± 2054.4 N-mm) constructs had significantly greater energy absorbed to ultimate load than the standard S1 construct (811.7 ± 937.6 N-mm), but there was no statistical difference between the L5 and SAP S1 constructs.Conclusion: S1 pedicle screw fixation via an SAP entry point provides biomechanical advantages compared to screws placed via the standard S1 or L5 entry point and may be a viable option for revision of a failed L5-S1 fusion with a compromised standard S1 entry point.Level Of Evidence: N/A. [ABSTRACT FROM AUTHOR]

Background The proper anchoring zone at the anterior sacral cortex is vital for the stability of S1 bicortical pedicle screw. During implantation, de-orbiting S1 bicortical pedicle screw is encountered occasionally and immediate correction is biomechanically required, especially in osteoporotic condition. Nevertheless, the biomechanical changes of the de-orbiting S1 bicortical pedicle screw after correction in different bone qualities remain unclear. The purpose of this study was thus to evaluate the biomechanical changes of the de-orbiting S1 bicortical pedicle screw after correction. Methods 18 fresh-frozen human sacra were divided into the normal and osteoporotic groups. The control and de-orbiting S1 bicortical pedicle screws were established randomly on either side of the sacrum. Following fatigue loading test, the subsidence displacement and axial pull-out strength were measured and analyzed. Findings In normal group, the subsidence displacement of the de-orbiting screw was increased significantly by comparison with the control one (median 0.37 vs. 0.36 mm) ( P = 0.009); but no significant difference of the maximum pull-out strength between the two screws (median 359 vs. 353 N) ( P = 0.262) was observed. In osteoporotic group, when compared with the control screw, the subsidence of the de-orbiting screw increased significantly (median 1.14 vs. 0.74 mm) ( P = 0.012) and the maximum pull-out strength decreased obviously (median 151 vs. 252 N) ( P = 0.012). Interpretation For normal bone quality, comparable stability could be achieved in the de-orbiting S1 bicortical pedicle screw after correction. Nevertheless, in osteoporotic condition, the correction procedure could not effectively prevent the loss of anchoring strength, and hence additional immediate augmentation fixation should be considered. [ABSTRACT FROM AUTHOR]

Study Design: A retrospective study.Objective: To determine the risk factors for sacroiliac joint pain (SIJP) after lumbar or lumbosacral fusion.Summary Of Background Data: Recently, the sacroiliac joint has gained increased attention as a source of pain after lumbar or lumbosacral fusion. We examined the factors related to the development of SIJP after lumbar or lumbosacral fusion.Methods: In total, 262 patients who underwent lumbar or lumbosacral fusion from June 2006 to June 2009 were included in this study. All patients who did not show SIJP clinically in the preoperative screening period were considered. Of these patients, 28 newly developed SIJP. We investigated whether development of SIJP after lumbar or lumbosacral fusion is related to the presence of fusion involving the sacrum (floating fusion vs. fixed fusion) and the number of fused segments.Results: The incidence of SIJP was higher with fixed fusion (13.1%) than with floating fusion (10.0%). With regard to the number of fused segments, the incidence of SIJP was 5.8% for one fused segment, 10.0% for two segments, 20.0% for three segments, 22.5% for at least four segments. Thus, the incidence was significantly higher when at least three segments were fused. Logistic regression analysis was performed to determine if the development of SIJP was related to the presence of fusion involving the sacrum or the number of fused segments. The analysis revealed that the number of fused segments was significantly associated with the development of SIJP.Conclusion: SIJP is a potential cause of low back pain after lumbar or lumbosacral fusion surgeries. Our study indicated that fusion of multiple segments (at least three) can increase the incidence of SIJP after lumbar or lumbosacral fusion.Level Of Evidence: Level 3. [ABSTRACT FROM AUTHOR]

Key Clinical Message Transforaminal lumbar interbody fusion ( TLIF) is a popular posterior spinal fusion technique, but sometimes require salvage surgery when implant failure occurs, which involves possible neural damage due to postoperative adhesion. The current report deals with successful anterior transperitoneal salvage surgery for failed L5-S TLIF with less neural invasiveness. [ABSTRACT FROM AUTHOR]

Introduction: Spinal fusion is a surgical procedure that has been successfully conducted for many years. It is applied for various indications, such as degeneration, deformity, instability, spinal stenosis, trauma, tumor, and infection. This study aims to determine the effects of this procedure on daily life and sleep quality by examining postoperative symptoms and refractory complaints of patients who underwent lumbosacral fusion for various indications., Methods: The files of the patients who underwent only posterolateral lumbosacral fusion for various indications between June 2021 and July 2022 were reviewed retrospectively. Patients who had had regular clinical follow-ups for at least six months postoperatively were included in the study. Preoperative and postoperative Visual Analog Scale (VAS), Oswestry Disability Index (ODI), and Pittsburgh Sleep Quality Index (PSQI) scores were compared using the Wilcoxon Ordinal Signs test. A p-value of <0.05 was considered statistically significant., Results: Twenty patients were included in the study. The mean age of the patients was 68.2 ± 7.5 (54-79). Three (15%) of the patients were males, and seventeen (85%) were females. Improvement was observed in all three scores, i.e., VAS, ODI, and PSQI assessments. No correlation was found between the number of segments undergoing fusion, body mass index (BMI), and clinical outcomes., Conclusion: Spinal fusion surgery is still viewed as the gold standard treatment method for many indications. Posterolateral fusion provides adequate stabilization in many cases when applied correctly. However, the possibility of persistent or newly developing low back pain in the postoperative period as a result of mechanical reasons should not be forgotten, and patients should be informed about the same. Postoperative expectations should, thus, be shaped accordingly., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Bozduman et al.)

Study Design: Biomechanical Laboratory Study.Objective: Analysis of the biomechanical characteristics of a novel sacral constrained dual-screw fixation device (S1-PALA), combining a S1-pedicle screw and a S1-ala screw, compared to a standard bicortical S1-pedicle screw (S1-PS) fixation.Summary Of Background Data: Instrumented fusions to the sacrum are biomechanically challenging and plagued by a high risk of nonunion when S1-PS is used as the sole means of fixation. Thus, lumbopelvic fixation is increasingly selected instead, although associated with a reasonable number of instrumentation-related complications.Methods: Around 30 fresh-frozen human sacral bones were harvested and embedded after CT scans. Instrumentation was conducted in alternating order with bicortical 7.0 mm S1-PS and with the S1-PALA including a S1-PS screw and a S1-ala screw, of 7.0 and 6.0 mm diameter, respectively. Specimens were subjected to cyclic loading with increasing loads (25-250 N) until a maximum of 2000 cycles or displacement >2 mm occurred. All implant sacral units (ISUs) were subject to coaxial pullout tests. Failure load, number of ISUs surpassing 2000 cycles, number of cycles, and loads at failure were recorded and compared.Results: Donors' age averaged 77 ± 14.2 years, and BMD was 115 ± 64.8 mgCA-HA/ml. Total working length of screws implanted was 90 ± 8.6 mm in the S1-PALA group and 46 ± 5 mm in the S1-PS group (P = 0.0002). In the S1-PALA group, displacement >2 mm occurred after 845 ± 325 cycles at 149 ± 41 N compared to 512 ± 281 cycles at 106 ± 36 N in the S1-PS group (P = 0.004; P = 0.002). In coaxial pull-out testing, failure load was 2118.1 ± 1166 N at a displacement of 2.5 ± 1 mm in the S1-PALA group compared to 1375.6 ± 750.1 N at a displacement of 1.6 ± 0.5 mm in the S1-PS group (P = 0.0007; P = 0.0003).Conclusion: The novel sacral constrained dual-screw anchorage (S1-PALA) significantly improved holding strength after cyclic loading compared to S1-PS. The S1-PALA demonstrated mechanical potential as a useful adjunct in the armamentarium of lumbosacral fixations indicated in cases that need advanced construct stability, but where instrumentation to the ilium or distal dissection to S2 should be avoided.Level Of Evidence: N/A. [ABSTRACT FROM AUTHOR]

Introduction: Sagittal balance is an independent predictor of outcomes in spinal care and several authors focused their attention on the lumbar lordosis restoration as the key point to prevent secondary sacroiliac joint dysfunction (SIJD) after fusion. On the other hand, lumbar disc arthroplasty allows preservation of motion avoiding increased stress on the spinopelvic junction and preventing iatrogenic sagittal imbalance. Methods: We analyze the incidence of a secondary SIJD and the spinopelvic alignment on a series of 31 consecutive lumbar disc prosthesis with a 10-year follow-up. Results: Sagittal balance assessment showed no significant variation of preoperative spinopelvic parameters. Four patients (12 %) presented a symptomatic SIJD. Only two of them required a percutaneous SIJ fixation. Both of them presented a fused L5-S1 prosthesis. Conclusions: The low rate of SIJD 10 years after lumbar arthroplasty might be explained by the preservation of the spinopelvic balance. [ABSTRACT FROM AUTHOR]

Purpose: This paper reports the authors' 19 years experience with pediatric intrasacral rod fixation. Methods: After insertion of two cannulated screws in S1 with and an original template guiding them into the anterior third of the endplate, two short fusion rods were inserted into the sacrum according to Jackson's technique distally to S3. In neuromuscular scoliosis, pelvic obliquity was reduced by connecting the proximal and distal constructs, distraction or compression, and in situ rod bending. In children with high-grade spondylolisthesis, lumbosacral kyphosis was reduced by rotation of the sacrum and in situ bending. Results: There were no direct neurological or vascular injuries. The main complication was infection (7 %). No pseudarthrosis or significant loss of correction at the lumbosacral junction was observed during follow-up. Conclusions: Intrasacral rod fixation appears to be safe and reliable for lumbopelvic fusion in pediatric patients. [ABSTRACT FROM AUTHOR]