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Qiao N, Villemure I, Wang Z, Petit Y, Aubin CE. Optimization of S2-alar-iliac screw (S2AI) fixation in adult spine deformity using a comprehensive genetic algorithm and finite element model personalized to patient geometry and bone mechanical properties. Spine Deform 2024; 12:595-602. [PMID: 38451404 DOI: 10.1007/s43390-024-00833-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Accepted: 01/20/2024] [Indexed: 03/08/2024]
Abstract
PURPOSE To optimize the biomechanical performance of S2AI screw fixation using a genetic algorithm (GA) and patient-specific finite element analysis integrating bone mechanical properties. METHODS Patient-specific pelvic finite element models (FEM), including one normal and one osteoporotic model, were created from bi-planar multi-energy X-rays (BMEXs). The genetic algorithm (GA) optimized screw parameters based on bone mass quality (BM method) while a comparative optimization method maximized the screw corridor radius (GEO method). Biomechanical performance was evaluated through simulations, comparing both methods using pullout and toggle tests. RESULTS The optimal screw trajectory using the BM method was more lateral and caudal with insertion angles ranging from 49° to 66° (sagittal plane) and 29° to 35° (transverse plane). In comparison, the GEO method had ranges of 44° to 54° and 24° to 30° respectively. Pullout forces (PF) using the BM method ranged from 5 to 18.4 kN, which were 2.4 times higher than the GEO method (2.1-7.7 kN). Toggle loading generated failure forces between 0.8 and 10.1 kN (BM method) and 0.9-2.9 kN (GEO method). The bone mass surrounding the screw representing the fitness score and PF of the osteoporotic case were correlated (R2 > 0.8). CONCLUSION Our study proposed a patient-specific FEM to optimize the S2AI screw size and trajectory using a robust BM approach with GA. This approach considers surgical constraints and consistently improves fixation performance.
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Affiliation(s)
- Ningxin Qiao
- Institute of Biomedical Engineering, Polytechnique Montréal, PO Box 6079, Downtown station, Montreal, QC H3C 3A7, Canada
- Sainte-Justine University Hospital Center, Montreal, Canada
| | - Isabelle Villemure
- Institute of Biomedical Engineering, Polytechnique Montréal, PO Box 6079, Downtown station, Montreal, QC H3C 3A7, Canada
- Sainte-Justine University Hospital Center, Montreal, Canada
| | - Zhi Wang
- Centre Hospitalier de l'Université de Montréal, Montreal, Canada
- Department of Surgery, Faculty of Medicine, Université de Montréal, Montreal, Canada
| | - Yvan Petit
- Department of Mechanical Engineering, Ecole de Technologie Supérieure, Montreal, Canada
| | - Carl-Eric Aubin
- Institute of Biomedical Engineering, Polytechnique Montréal, PO Box 6079, Downtown station, Montreal, QC H3C 3A7, Canada.
- Sainte-Justine University Hospital Center, Montreal, Canada.
- Department of Surgery, Faculty of Medicine, Université de Montréal, Montreal, Canada.
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Haselhuhn JJ, Soriano PBO, Grover P, Dreischarf M, Odland K, Hendrickson NR, Jones KE, Martin CT, Sembrano JN, Polly DW. Spine surgeon versus AI algorithm full-length radiographic measurements: a validation study of complex adult spinal deformity patients. Spine Deform 2024; 12:755-761. [PMID: 38336942 DOI: 10.1007/s43390-024-00825-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 01/06/2024] [Indexed: 02/12/2024]
Abstract
INTRODUCTION Spinal measurements play an integral role in surgical planning for a variety of spine procedures. Full-length imaging eliminates distortions that can occur with stitched images. However, these images take radiologists significantly longer to read than conventional radiographs. Artificial intelligence (AI) image analysis software that can make such measurements quickly and reliably would be advantageous to surgeons, radiologists, and the entire health system. MATERIALS AND METHODS Institutional Review Board approval was obtained for this study. Preoperative full-length standing anterior-posterior and lateral radiographs of patients that were previously measured by fellowship-trained spine surgeons at our institution were obtained. The measurements included lumbar lordosis (LL), greatest coronal Cobb angle (GCC), pelvic incidence (PI), coronal balance (CB), and T1-pelvic angle (T1PA). Inter-rater intra-class correlation (ICC) values were calculated based on an overlapping sample of 10 patients measured by surgeons. Full-length standing radiographs of an additional 100 patients were provided for AI software training. The AI algorithm then measured the radiographs and ICC values were calculated. RESULTS ICC values for inter-rater reliability between surgeons were excellent and calculated to 0.97 for LL (95% CI 0.88-0.99), 0.78 (0.33-0.94) for GCC, 0.86 (0.55-0.96) for PI, 0.99 for CB (0.93-0.99), and 0.95 for T1PA (0.82-0.99). The algorithm computed the five selected parameters with ICC values between 0.70 and 0.94, indicating excellent reliability. Exemplary for the comparison of AI and surgeons, the ICC for LL was 0.88 (95% CI 0.83-0.92) and 0.93 for CB (0.90-0.95). GCC, PI, and T1PA could be determined with ICC values of 0.81 (0.69-0.87), 0.70 (0.60-0.78), and 0.94 (0.91-0.96) respectively. CONCLUSIONS The AI algorithm presented here demonstrates excellent reliability for most of the parameters and good reliability for PI, with ICC values corresponding to measurements conducted by experienced surgeons. In future, it may facilitate the analysis of large data sets and aid physicians in diagnostics, pre-operative planning, and post-operative quality control.
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Affiliation(s)
- Jason J Haselhuhn
- Department of Orthopedic Surgery, University of Minnesota, 2450 Riverside Avenue South, Suite R200, Minneapolis, MN, 55454, USA
| | - Paul Brian O Soriano
- Department of Orthopedic Surgery, University of Minnesota, 2450 Riverside Avenue South, Suite R200, Minneapolis, MN, 55454, USA
| | | | | | - Kari Odland
- Department of Orthopedic Surgery, University of Minnesota, 2450 Riverside Avenue South, Suite R200, Minneapolis, MN, 55454, USA
| | - Nathan R Hendrickson
- Department of Orthopedic Surgery, University of Minnesota, 2450 Riverside Avenue South, Suite R200, Minneapolis, MN, 55454, USA
| | - Kristen E Jones
- Department of Orthopedic Surgery, University of Minnesota, 2450 Riverside Avenue South, Suite R200, Minneapolis, MN, 55454, USA
- Department of Neurosurgery, University of Minnesota, Minneapolis, MN, USA
| | - Christopher T Martin
- Department of Orthopedic Surgery, University of Minnesota, 2450 Riverside Avenue South, Suite R200, Minneapolis, MN, 55454, USA
| | - Jonathan N Sembrano
- Department of Orthopedic Surgery, University of Minnesota, 2450 Riverside Avenue South, Suite R200, Minneapolis, MN, 55454, USA
| | - David W Polly
- Department of Orthopedic Surgery, University of Minnesota, 2450 Riverside Avenue South, Suite R200, Minneapolis, MN, 55454, USA.
- Department of Neurosurgery, University of Minnesota, Minneapolis, MN, USA.
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Polly D, Mundis G, Eastlack R, Leveque JC, Elder BD, Martin C, Kent R, Snowden R, Kim HJ, Sembrano J, Herzog J, Lieberman I, Matheus V, Buchholz A, Franke J, Lee R, Shaffrey C. Randomized Trial of Augmented Pelvic Fixation in Patients Undergoing Thoracolumbar Fusion for Adult Spine Deformity: Initial Results from a Multicenter Randomized Trial. World Neurosurg 2024:S1878-8750(24)00177-3. [PMID: 38310950 DOI: 10.1016/j.wneu.2024.01.156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 01/26/2024] [Accepted: 01/27/2024] [Indexed: 02/06/2024]
Abstract
BACKGROUND The optimal configuration for spinopelvic fixation during multilevel spine fusion surgery for adult spine deformity remains unclear. Postoperative sacroiliac (SI) joint pain, S2AI screw loosening and implant breakage could be related to continued motion of the SI joint with use of only a single point of fixation across the SI joint. METHODS Prospective, international, multicenter randomized controlled trial of 222 patients with adult spine deformity scheduled for multilevel (4 or more levels) spine fusion surgery with pelvic fixation. Subjects were randomized to sacroalar (S2) iliac (S2AI) screws alone for pelvic fixation or S2AI + triangular titanium implants placed cephalad to S2AI screws. Quad rod techniques were not allowed or used. Baseline spinal deformity measures were read by an independent radiologist. Site-reported perioperative adverse events were reviewed by a clinical events committee. Quality of life questionnaires and other clinical outcomes are in process with planned 2-year follow-up. RESULTS One hundred thirteen participants were assigned to S2AI and 109 to S2AI + titanium triangular implants (TTI). 35/222 (16%) of all subjects had a history of SI joint pain or were diagnosed with SI joint pain during preoperative workup. Three-month follow-up was available in all but 4 subjects. TTI placement was successful in 106 of 109 (98%) subjects assigned to TTI. In 2 cases, TTI could not be placed due to anatomical considerations. Three TTI ventral iliac breaches were observed, all of which were managed non-surgically. One TTI subject had a transverse sacral fracture and 1 TTI subject had malposition of the implant requiring removal. CONCLUSIONS SI joint pain is common in patients with adult spinal deformity who are candidates for multilevel spine fusion surgery. Concurrent placement of TTI parallel to S2AI screws during multilevel spine fusion surgery is feasible and safe. Further follow-up will help to determine the clinical value of this approach to augment pelvic fixation.
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Affiliation(s)
- David Polly
- University of Minnesota, Minneapolis, Minnesota, USA.
| | - Greg Mundis
- San Diego Spine Foundation, San Diego, California, USA
| | | | | | | | | | - Roland Kent
- Axis Spine Center, Coeur D'Alene, Idaho, USA
| | - Ryan Snowden
- Tennessee Orthopaedics Associates, Nashville, Tennessee, USA
| | - Han Jo Kim
- Hospital for Special Surgery, New York, New York, USA
| | | | | | | | | | | | | | - Robert Lee
- Royal National Orthopaedic Hospital, Stanmore, UK
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Marie-Hardy L, Alvarez D, Pietton R, Mohsinaly Y, Bonaccorsi R, Pascal-Moussellard H. Kappa: Preliminary Results on a Novel Technique for Pelvic Fixation in Adult Spinal Deformity Correction. Indian J Orthop 2023; 57:1826-1832. [PMID: 37881294 PMCID: PMC10593650 DOI: 10.1007/s43465-023-00959-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 07/20/2023] [Indexed: 10/27/2023]
Abstract
Study Design Retrospective cohort study. Objectives Pelvic fixation in degenerative spinal deformation is as crucial as demanding. Several pelvic anchoring technics have been described, but loosening rates remain high for most solutions. Here is described the "Kappa" technic, combining ilio-sacral screws to S2A1 screws at 2 years of follow-up. Methods Thirteen patients that underwent a spinal deformity correction with "Kappa" fixation to the pelvis and with more than 2 years of follow-up were prospectively included in this study. The surgical technic is described, and clinical and radiographic data have been collected for all patients. Results The population exhibited an important pre-operative sagittal imbalance (mean SVA of 104,4 mm, mean PI-LL mismatch of 22,8°) that had improved significatively after surgery (mean SVA of 75,5 mm and mean PI-LL mismatch of 4,9°). No loosening of pull-out of the implants was to deplore at 2 years of follow-up. Conclusions The association of ilio-sacral screw, resistant to pull-out because of the traction axis perpendicular to the construct, to S2A1 screws, known to be effective in sagittal balance restoration seems to be an effective and safe option to pelvic fixation for adult spinal deformity correction. Level of Evidence IV.
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Affiliation(s)
- L. Marie-Hardy
- Department of Orthopaedic and Trauma Surgery, Pitié-Salpêtrière Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - D. Alvarez
- Department of Orthopaedic and Trauma Surgery, Dr. Exequiel Gonzales Cortez Hospital, Santiago, Chile
| | - R. Pietton
- Department of Orthopaedic and Trauma Surgery, Pitié-Salpêtrière Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Y. Mohsinaly
- Department of Orthopaedic and Trauma Surgery, Pitié-Salpêtrière Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - R. Bonaccorsi
- Department of Orthopaedic and Trauma Surgery, Pitié-Salpêtrière Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - H. Pascal-Moussellard
- Department of Orthopaedic and Trauma Surgery, Pitié-Salpêtrière Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
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Yang H, Pan A, Hai Y, Cheng F, Ding H, Liu Y. Biomechanical evaluation of multiple pelvic screws and multirod construct for the augmentation of lumbosacral junction in long spinal fusion surgery. Front Bioeng Biotechnol 2023; 11:1148342. [PMID: 36998811 PMCID: PMC10043192 DOI: 10.3389/fbioe.2023.1148342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 03/06/2023] [Indexed: 03/15/2023] Open
Abstract
Background: Posterior long spinal fusion was the common procedure for adult spinal deformity (ASD). Although the application of sacropelvic fixation (SPF), the incidence of pseudoarthrosis and implant failure is still high in long spinal fusion extending to lumbosacral junction (LSJ). To address these mechanical complications, advanced SPF technique by multiple pelvic screws or multirod construct has been recommended. This was the first study to compare the biomechanical performance of combining multiple pelvic screws and multirod construct to other advanced SPF constructs for the augmentation of LSJ in long spinal fusion surgery through finite element (FE) analysis.Methods: An intact lumbopelvic FE model based on computed tomography images of a healthy adult male volunteer was constructed and validated. The intact model was modified to develop five instrumented models, all of which had bilateral pedicle screw (PS) fixation from L1 to S1 with posterior lumbar interbody fusion and different SPF constructs, including No-SPF, bilateral single S2-alar-iliac (S2AI) screw and single rod (SS-SR), bilateral multiple S2AI screws and single rod (MS-SR), bilateral single S2AI screw and multiple rods (SS-MR), and bilateral multiple S2AI screws and multiple rods (MS-MR). The range of motion (ROM) and stress on instrumentation, cages, sacrum, and S1 superior endplate (SEP) in flexion (FL), extension (EX), lateral bending (LB), and axial rotation (AR) were compared among models.Results: Compared with intact model and No-SPF, the ROM of global lumbopelvis, LSJ, and sacroiliac joint (SIJ) was decreased in SS-SR, MS-SR, SS-MR, and MS-MR in all directions. Compared with SS-SR, the ROM of global lumbopelvis and LSJ of MS-SR, SS-MR, and MS-MR further decreased, while the ROM of SIJ was only decreased in MS-SR and MS-MR. The stress on instrumentation, cages, S1-SEP, and sacrum decreased in SS-SR, compared with no-SPF. Compared with SS-SR, the stress in EX and AR further decreased in SS-MR and MS-SR. The most significantly decreased ROM and stress were observed in MS-MR.Conclusion: Both multiple pelvic screws and multirod construct could increase the mechanical stability of LSJ and reduce stress on instrumentation, cages, S1-SEP, and sacrum. The MS-MR construct was the most adequate to reduce the risk of lumbosacral pseudarthrosis, implant failure, and sacrum fracture. This study may provide surgeons with important evidence for the application of MS-MR construct in the clinical settings.
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Affiliation(s)
| | | | - Yong Hai
- *Correspondence: Yong Hai, ; Yuzeng Liu,
| | | | | | - Yuzeng Liu
- *Correspondence: Yong Hai, ; Yuzeng Liu,
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Lee NJ, Marciano G, Puvanesarajah V, Park PJ, Clifton WE, Kwan K, Morrissette CR, Williams JL, Fields M, Hassan FM, Angevine PD, Mandigo CE, Lombardi JM, Sardar ZM, Lehman RA, Lenke LG. Incidence, mechanism, and protective strategies for 2-year pelvic fixation failure after adult spinal deformity surgery with a minimum six-level fusion. J Neurosurg Spine 2023; 38:208-216. [PMID: 36242579 DOI: 10.3171/2022.8.spine22755] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Accepted: 08/29/2022] [Indexed: 11/13/2022]
Abstract
OBJECTIVE The purpose of this study was to determine the incidence, mechanism, and potential protective strategies for pelvic fixation failure (PFF) within 2 years after adult spinal deformity (ASD) surgery. METHODS Data for ASD patients (age ≥ 18 years, minimum of six instrumented levels) with pelvic fixation (S2-alar-iliac [S2AI] and/or iliac screws) with a minimum 2-year follow-up were consecutively collected (2015-2019). Patients with prior pelvic fixation were excluded. PFF was defined as any revision to pelvic screws, which may include broken rods across the lumbosacral junction requiring revision to pelvic screws, pseudarthrosis across the lumbosacral junction requiring revision to pelvic screws, a broken or loose pelvic screw, or sacral/iliac fracture. Patient information including demographic data and health history (age, sex, BMI, smoking status, American Society of Anesthesiologists score, osteoporosis), operative (total instrumented levels [TIL], three-column osteotomy [3CO], interbody fusion), screw (iliac, S2AI, length, diameter), rod (diameter, kickstand), rod pattern (number crossing lumbopelvic junction, lowest instrumented vertebra [LIV] of accessory rod[s], lateral connectors, dual-headed screws), and pre- and postradiographic (lumbar lordosis, pelvic incidence, pelvic tilt, major Cobb angle, lumbosacral fractional curve, C7 coronal vertical axis [CVA], T1 pelvic angle, C7 sagittal vertical axis) parameters was collected. All rods across the lumbosacral junction were cobalt-chrome. All iliac and S2AI screws were closed-headed tulips. Both univariate and multivariate analyses were performed to determine risk factors for PFF. RESULTS Of 253 patients (mean age 58.9 years, mean TIL 13.6, 3CO 15.8%, L5-S1 interbody 74.7%, mean pelvic screw diameter/length 8.6/87 mm), the 2-year failure rate was 4.3% (n = 11). The mechanisms of failure included broken rods across the lumbosacral junction (n = 4), pseudarthrosis across the lumbosacral junction requiring revision to pelvic screws (n = 3), broken pelvic screw (n = 1), loose pelvic screw (n = 1), sacral/iliac fracture (n = 1), and painful/prominent pelvic screw (n = 1). A higher number of rods crossing the lumbopelvic junction (mean 3.8 no failure vs 2.9 failure, p = 0.009) and accessory rod LIV to S2/ilium (no failure 54.2% vs failure 18.2%, p = 0.003) were protective for failure. Multivariate analysis demonstrated that accessory rod LIV to S2/ilium versus S1 (OR 0.2, p = 0.004) and number of rods crossing the lumbar to pelvis (OR 0.15, p = 0.002) were protective, while worse postoperative CVA (OR 1.5, p = 0.028) was an independent risk factor for failure. CONCLUSIONS The 2-year PFF rate was low relative to what is reported in the literature, despite patients undergoing long fusion constructs for ASD. The number of rods crossing the lumbopelvic junction and accessory rod LIV to S2/ilium relative to S1 alone likely increase construct stiffness. Residual postoperative coronal malalignment should be avoided to reduce PFF.
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Lee NJ, Park PJ, Puvanesarajah V, Clifton WE, Kwan K, Morrissette CR, Williams JL, Fields MW, Leung E, Hassan FM, Angevine PD, Mandigo CE, Lombardi JM, Sardar ZM, Lehman RA, Lenke LG. How common is acute pelvic fixation failure after adult spine surgery? A single-center study of 358 patients. J Neurosurg Spine 2023; 38:91-97. [PMID: 36029261 DOI: 10.3171/2022.7.spine22498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 07/06/2022] [Indexed: 01/04/2023]
Abstract
OBJECTIVE There is a paucity of literature on pelvic fixation failure after adult spine surgery in the early postoperative period. The purpose of this study was to determine the incidence of acute pelvic fixation failure in a large single-center study and to describe the lessons learned. METHODS The authors performed a retrospective review of adult (≥ 18 years old) patients who underwent spinal fusion with pelvic fixation (iliac, S2-alar-iliac [S2AI] screws) at a single academic medical center between 2015 and 2020. All patients had a minimum of 3 instrumented levels. The minimum follow-up was 6 months after the index spine surgery. Patients with prior pelvic fixation were excluded. Acute pelvic fixation failure was defined as revision of the pelvic screws within 6 months of the primary surgery. Patient demographics and operative, radiographic, and rod/screw parameters were collected. All rods were cobalt-chrome. All iliac and S2AI screws were closed-headed screws. RESULTS In 358 patients, the mean age was 59.5 ± 13.6 years, and 64.0% (n = 229) were female. The mean number of instrumented levels was 11.5 ± 5.5, and 79.1% (n = 283) had ≥ 6 levels fused. Three-column osteotomies were performed in 14.2% (n = 51) of patients, and 74.6% (n = 267) had an L5-S1 interbody fusion. The mean diameter/length of pelvic screws was 8.5/86.6 mm. The mean number of pelvic screws was 2.2 ± 0.5, the mean rod diameter was 6.0 ± 0 mm, and 78.5% (n = 281) had > 2 rods crossing the lumbopelvic junction. Accessory rods extended to S1 (32.7%, n = 117) or S2/ilium (45.8%, n = 164). Acute pelvic fixation failure occurred in 1 patient (0.3%); this individual had a broken S2AI screw near the head-neck junction. This 76-year-old woman with degenerative lumbar scoliosis and chronic lumbosacral zone 1 fracture nonunion had undergone posterior instrumented fusion from T10 to pelvis with bilateral S2AI screws (8.5 × 90 mm); i.e., transforaminal lumbar interbody fusion L4-S1. The patient had persistent left buttock pain postoperatively, with radiographically confirmed breakage of the left S2AI screw 68 days after surgery. Revision included instrumentation removal at L2-pelvis and a total of 4 pelvic screws. CONCLUSIONS The acute pelvic fixation failure rate was exceedingly low in adult spine surgery. This rate may be the result of multiple factors including the preference for multirod (> 2), closed-headed pelvic screw constructs in which large-diameter long screws are used. Increasing the number of rods and screws at the lumbopelvic junction may be important factors to consider, especially for patients with high risk for nonunion.
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Martin CT, Holton KJ, Elder BD, Fogelson JL, Mikula AL, Kleck CJ, Calabrese D, Burger EL, Ou-Yang D, Patel VV, Kim HJ, Lovecchio F, Hu SS, Wood KB, Harper R, Yoon ST, Ananthakrishnan D, Michael KW, Schell AJ, Lieberman IH, Kisinde S, DeWald CJ, Nolte MT, Colman MW, Phillips FM, Gelb DE, Bruckner J, Ross LB, Johnson JP, Kim TT, Anand N, Cheng JS, Plummer Z, Park P, Oppenlander ME, Sembrano JN, Jones KE, Polly DW. Catastrophic acute failure of pelvic fixation in adult spinal deformity requiring revision surgery: a multicenter review of incidence, failure mechanisms, and risk factors. J Neurosurg Spine 2023; 38:98-106. [PMID: 36057123 DOI: 10.3171/2022.6.spine211559] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 06/17/2022] [Indexed: 01/04/2023]
Abstract
OBJECTIVE There are few prior reports of acute pelvic instrumentation failure in spinal deformity surgery. The objective of this study was to determine if a previously identified mechanism and rate of pelvic fixation failure were present across multiple institutions, and to determine risk factors for these types of failures. METHODS Thirteen academic medical centers performed a retrospective review of 18 months of consecutive adult spinal fusions extending 3 or more levels, which included new pelvic screws at the time of surgery. Acute pelvic fixation failure was defined as occurring within 6 months of the index surgery and requiring surgical revision. RESULTS Failure occurred in 37 (5%) of 779 cases and consisted of either slippage of the rods or displacement of the set screws from the screw tulip head (17 cases), screw shaft fracture (9 cases), screw loosening (9 cases), and/or resultant kyphotic fracture of the sacrum (6 cases). Revision strategies involved new pelvic fixation and/or multiple rod constructs. Six patients (16%) who underwent revision with fewer than 4 rods to the pelvis sustained a second acute failure, but no secondary failures occurred when at least 4 rods were used. In the univariate analysis, the magnitude of surgical correction was higher in the failure cohort (higher preoperative T1-pelvic angle [T1PA], presence of a 3-column osteotomy; p < 0.05). Uncorrected postoperative deformity increased failure risk (pelvic incidence-lumbar lordosis mismatch > 10°, higher postoperative T1PA; p < 0.05). Use of pelvic screws less than 8.5 mm in diameter also increased the likelihood of failure (p < 0.05). In the multivariate analysis, a larger preoperative global deformity as measured by T1PA was associated with failure, male patients were more likely to experience failure than female patients, and there was a strong association with implant manufacturer (p < 0.05). Anterior column support with an L5-S1 interbody fusion was protective against failure (p < 0.05). CONCLUSIONS Acute catastrophic failures involved large-magnitude surgical corrections and likely resulted from high mechanical strain on the pelvic instrumentation. Patients with large corrections may benefit from anterior structural support placed at the most caudal motion segment and multiple rods connecting to more than 2 pelvic fixation points. If failure occurs, salvage with a minimum of 4 rods and 4 pelvic fixation points can be successful.
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Affiliation(s)
| | - Kenneth J Holton
- 1Department of Orthopaedic Surgery, University of Minnesota, Minneapolis
| | - Benjamin D Elder
- 2Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota
| | - Jeremy L Fogelson
- 2Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota
| | - Anthony L Mikula
- 2Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota
| | - Christopher J Kleck
- 3Department of Orthopedics, University of Colorado, School of Medicine, Aurora, Colorado
| | - David Calabrese
- 3Department of Orthopedics, University of Colorado, School of Medicine, Aurora, Colorado
| | - Evalina L Burger
- 3Department of Orthopedics, University of Colorado, School of Medicine, Aurora, Colorado
| | - David Ou-Yang
- 3Department of Orthopedics, University of Colorado, School of Medicine, Aurora, Colorado
| | - Vikas V Patel
- 3Department of Orthopedics, University of Colorado, School of Medicine, Aurora, Colorado
| | - Han Jo Kim
- 4Department of Orthopaedic Surgery, Hospital for Special Surgery, New York, New York
| | - Francis Lovecchio
- 4Department of Orthopaedic Surgery, Hospital for Special Surgery, New York, New York
| | - Serena S Hu
- 5Department of Orthopaedic Surgery, Stanford University, Stanford, California
| | - Kirkham B Wood
- 5Department of Orthopaedic Surgery, Stanford University, Stanford, California
| | - Robert Harper
- 5Department of Orthopaedic Surgery, Stanford University, Stanford, California
| | - S Tim Yoon
- 6Department of Orthopaedics, Emory University, Atlanta, Georgia
| | | | - Keith W Michael
- 6Department of Orthopaedics, Emory University, Atlanta, Georgia
| | - Adam J Schell
- 6Department of Orthopaedics, Emory University, Atlanta, Georgia
| | | | - Stanley Kisinde
- 7Scoliosis and Spine Tumor Center, Texas Back Institute, Plano, Texas
| | - Christopher J DeWald
- 8Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, Illinois
| | - Michael T Nolte
- 8Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, Illinois
| | - Matthew W Colman
- 8Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, Illinois
| | - Frank M Phillips
- 8Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, Illinois
| | - Daniel E Gelb
- 9Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, Maryland
| | - Jacob Bruckner
- 9Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, Maryland
| | - Lindsey B Ross
- 10Department of Neurologic Surgery, Cedars-Sinai Medical Center, Los Angeles
| | - J Patrick Johnson
- 10Department of Neurologic Surgery, Cedars-Sinai Medical Center, Los Angeles
| | - Terrence T Kim
- 11Department of Orthopaedics, Cedars-Sinai Medical Center, Los Angeles, California
| | - Neel Anand
- 11Department of Orthopaedics, Cedars-Sinai Medical Center, Los Angeles, California
| | - Joseph S Cheng
- 12Department of Neurosurgery, University of Cincinnati College of Medicine, Cincinnati, Ohio; and
| | - Zach Plummer
- 12Department of Neurosurgery, University of Cincinnati College of Medicine, Cincinnati, Ohio; and
| | - Paul Park
- 13Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan
| | - Mark E Oppenlander
- 13Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan
| | | | - Kristen E Jones
- 1Department of Orthopaedic Surgery, University of Minnesota, Minneapolis
| | - David W Polly
- 1Department of Orthopaedic Surgery, University of Minnesota, Minneapolis
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Polly DW, Holton KJ, Soriano PO, Sembrano JN, Martin CT, Hendrickson NR, Jones KE. Multiple Points of Pelvic Fixation: Stacked S2-Alar-Iliac Screws (S2AI) or Concurrent S2AI and Open Sacroiliac Joint Fusion with Triangular Titanium Rod. JBJS Essent Surg Tech 2022; 12:e21.00044. [PMID: 36743282 PMCID: PMC9889296 DOI: 10.2106/jbjs.st.21.00044] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Sacropelvic fixation is a continually evolving technique in the treatment of adult spinal deformity. The 2 most widely utilized techniques are iliac screw fixation and S2-alar-iliac (S2AI) screw fixation1-3. The use of these techniques at the base of long fusion constructs, with the goal of providing a solid base to maintain surgical correction, has improved fusion rates and decreased rates of revision4. Description The procedure is performed with the patient under general anesthesia in the prone position and with use of 3D computer navigation based on intraoperative cone-beam computed tomography (CT) imaging. A standard open posterior approach with a midline incision and subperiosteal exposure of the proximal spine and sacrum is performed. Standard S2AI screw placement is performed. The S2AI starting point is on the dorsal sacrum 2 to 3 mm above the S2 foramen, aiming as caudal as possible in the teardrop. A navigated awl is utilized to establish the screw trajectory, passing through the sacrum, across the sacroiliac (SI) joint, and into the ilium. The track is serially tapped with use of navigated taps, 6.5 mm followed by 9.5 mm, under power. The screw is then placed under power with use of a navigated screwdriver.Proper placement of the caudal implant is vital as it allows for ample room for subsequent instrumentation. The additional point of pelvic fixation can be an S2AI screw or a triangular titanium rod (TTR). This additional implant is placed cephalad to the trajectory of the S2AI screw. A starting point 2 to 3 mm proximal to the S2AI screw tulip head on the sacral ala provides enough clearance and also helps to keep the implant low enough in the teardrop that it is likely to stay within bone. More proximal starting points should be avoided as they will result in a cephalad breach.For procedures with an additional point of pelvic fixation, the cephalad S2AI screw can be placed using the previously described method. For placement of the TTR, the starting point is marked with a burr. A navigated drill guide is utilized to first pass a drill bit to create a pilot hole, followed by a guide pin proximal to the S2AI screw in the teardrop. Drilling the tip of the guide pin into the distal, lateral iliac cortex prevents pin backout during the subsequent steps. A cannulated drill is then passed over the guide pin, traveling from the sacral ala and breaching the SI joint into the pelvis. A navigated broach is then utilized to create a track for the implant. The flat side of the triangular broach is turned toward the S2AI screw in order to help the implant sit as close as possible to the screw and to allow the implant to be as low as possible in the teardrop. The navigation system is utilized to choose the maximum possible implant length. The TTR is then passed over the guide pin and impacted to the appropriate depth. Multiplanar post-placement fluoroscopic images and an additional intraoperative CT scan of the pelvis are obtained to verify instrumentation position. Alternatives The use of spinopelvic fixation in long constructs is widely accepted, and various techniques have been described in the past1. Alternatives to stacked S2AI screws or S2AI with TTR for SI joint fusion include traditional iliac screw fixation with offset connectors, modified iliac fixation, sacral fixation alone, and single S2AI screw fixation. Rationale The lumbosacral junction is the foundation of long spinal constructs and is known to be a point of high mechanical strain5-7. Although pelvic instrumentation has been utilized to increase construct stiffness and fusion rates, pelvic fixation failure is frequently reported8,9. At our institution, we identified a 5% acute pelvic fixation failure rate over an 18-month period10. In a subsequent multicenter retrospective series, a similar 5% acute pelvic fixation failure rate was also reported11. In response to these findings, our institution changed its pelvic fixation strategies to incorporate multiple points of pelvic fixation. From our experience, utilization of multiple pelvic fixation points has decreased acute failure. In addition to preventing instrumentation failure, S2AI screws are lower-profile, which decreases the complication of implant prominence associated with traditional iliac screws. S2AI screw heads are also more in line with the pedicle screw heads, which decreases the need for excessive rod bending and connectors.The use of the techniques has been described in case reports and imaging studies12-14, but until now has not been visually represented. Here, we provide technical and visual presentation of the placement of stacked S2AI screws or open SI joint fusion with a TTR above an S2AI screw. Expected Outcomes Pelvic fixation provides increased construct stiffness compared with sacral fixation alone15-17 and has shown better rates of fusion4. However, failure rates of up to 35%8,9 have been reported, and our own institution identified a 5% acute pelvic fixation failure rate10. In response to this, the multiple pelvic fixation strategy (stacked S2AI screws or S2AI and TTR for SI joint fusion) has been more widely utilized. In our experience utilizing multiple points of pelvic fixation, we have noticed a decreased rate of pelvic fixation failure and are in the process of reporting these findings18,19. Important Tips The initial trajectory of the caudal S2AI screw needs to be as low as possible within the teardrop, just proximal to the sciatic notch.The starting point for the cephalad implant should be 2 to 3 mm proximal to the S2AI screw tulip head. This placement provides enough clearance and helps to contain the implant in bone.More proximal starting points may result in cephalad breach of the TTR.The use of a reverse-threaded Kirschner wire helps to prevent pin backout while drilling and broaching for TTR placement.If malpositioning of the TTR is found on imaging, removal and redirection is technically feasible. Acronyms and Abbreviations S2AI = S2-alar-iliacTTR = triangular titanium rodCT = computed tomographyAP = anteroposteriorOR = operating roomSI = sacroiliacDRMAS = dual rod multi-axial screwK-wire = Kirschner wireDVT = deep vein thrombosisPE = pulmonary embolism.
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Affiliation(s)
- David W. Polly
- Department of Orthopaedic Surgery, University of Minnesota, Minneapolis, Minnesota,Department of Neurosurgery, University of Minnesota, Minneapolis, Minnesota,Email for corresponding author:
| | - Kenneth J. Holton
- Department of Orthopaedic Surgery, University of Minnesota, Minneapolis, Minnesota
| | - Paul O. Soriano
- Department of Orthopaedic Surgery, University of Minnesota, Minneapolis, Minnesota
| | - Jonathan N. Sembrano
- Department of Orthopaedic Surgery, University of Minnesota, Minneapolis, Minnesota
| | | | | | - Kristen E. Jones
- Department of Neurosurgery, University of Minnesota, Minneapolis, Minnesota
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