L5 S1 Controversies Syllabus
2015-09-08
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Choosing Levels in Adult Scoliosis Indications to Extend Fusion to the Sacrum and Pelvis Sigurd Berven, MD Professor in Residence UC San Francisco Disclosures • Research/Institutional Support: – NIH, AO Spine, OREF, AOA • Consultancies/Scientific Advisory: – Medtronic, DePuy, Stryker, Globus • Ownership/Stock/Options: – Providence Medical, Simpirica • Royalties: Medtronic Challenges in Adult Scoliosis Surgery • Choosing Levels • Junctional Complications • When can we do less? – When should we do more? 1 How High How High How Low 2 How High When to go front and back How Low Surgical Strategies • Characterized by significant variability • Outcomes studies required for an Evidence-based approach Overview • The challenge of the lumbosacral junction: – Strain on S1 screws – Solid arthrodesis at L5-S1 • Biomechanics of the Pivot Point • Techniques and Limitations 3 Hazards of the Junctions • Thoracolumbar • Lumbosacral • Cervicothoracic The Lumbosacral Junction Two modes of failure: 1) Symptomatic degeneration below a long fusion to L4 or L5 2) Nonunion or Malunion at L5-S1 Preoperative Assessment • • • • Localization of Pain on Physical Exam Advanced Imaging- MRI or CT Dynamic Imaging Provocative testing – Facet Block – Discography 4 The Case to Fuse to L5 • • • • • • • • • • • • Better Function Less complications Good Survival of the L5-S1 motion segment Revision considerations Leaving options open for new technologies in the future The loss of range of motion resulting from spinal fusion might lead to low back pain, trunk rigidity, and a negative impact on quality of life. Nonetheless, these outcomes have not been conclusively demonstrated because lumbar mobility and LIV have not been correlated with validated outcome instruments. METHODS: Forty-one patients (mean age, 27 y) with idiopathic scoliosis treated by spinal fusion (mean time since surgery, 135 mo) were included. Patients were assigned to 3 groups according to LIV level: group 1 (fusion to T12, L1, or L2) 14 patients; group 2 (fusion to L3) 13 patients, and group 3 (fusion to L4, L5, or S1) 14 patients. At midterm follow-up, patients completed the Scoliosis Research Society (SRS)-22 Questionnaire and Quality of Life Profile for Spine Deformities to evaluate perceived TF, and rated LBPi with a numerical scale. Lumbar mobility was assessed using a dual digital inclinometer. RESULTS: Group 3 (fusion to L4, L5, or S1) showed statistically significant differences relative to the other groups, with less lumbar mobility and poorer scores for the SRS subtotal (P = 0.003) and SRS pain scale (P = 0.01). Nevertheless, LBPi and TF were similar in the 3 groups. TF correlated with SRS-22 subtotal (r = -0.38, P = 0.01) and pain scale (r = -0.42, P = 0.007) scores, and with LBPi (r = 0.43, P = 0.005). CONCLUSIONS: LIV correlated moderately with lumbar mobility, health-related quality of life (SRS-22), and spinal pain (SRS-22 pain subscale), but not with intensity of pain in the lumbar area or perceived TF. 5 6 The slippery slope of extending fusion to the sacrum • Anterior column support • Role of iliac fixation Fusion to L5 vs. S1 7 L5 vs S1 Paradox Thoracolumbar deformity arthrodesis to L5 in adults: the fate of the L5S1 disc. - Edwards, Bridwell, et al. Spine 2003 Sep 15;28(18):2122-31. • 61% developed advanced disc degeneration at L5-S1 • Associated with loss of sagittal balance, need for revision surgery and lower scores of SRS-24 • 18% loss of fixation at L5 Higher incidence of complications in patients fused to S1 Edwards, Bridwell et al, SRS 2003 Failure of Fixation at L5 The selection of L5 versus S1 in long fusions for adult idiopathic scoliosis. Swamy, Berven, Bradford. Neurosurg Clin N Am 2007 Apr;18(2):281-8. Purpose Determine long-term radiographic and clinical outcome of long (>T12) fusions to L5 8 Survivorship Analysis 5 year: 75% 10 year: 70% If include pts considering revision 5 year: 70% 10 year: 65% Overall: 50% at latest FU The selection of L5 versus S1 in long fusions for adult idiopathic scoliosis. Swamy, Berven, Bradford. Neurosurg Clin N Am 2007 Apr;18(2):281-8. Conclusions • Primary long fusions to L5 associated with – 25% revision rate at 5 years – 30% revision rate at 10 years • Fusion to L5 is most reliable in patients with good sagittal balance and bone quality Indications to Extend Fusion to the Sacrum • Symptomatic degenerative changes at L5-S1 – Spondylolisthesis at L5-S1 – Stenosis requiring decompression at L5-S1 • Significant sagittal plane realignment • Osteoporosis • Fixed obliquity of the L5-S1 motion segment – Trunk translation 9 Sacral Fixation Considerations • Sacrum is a poor fixation point due to the large cancellous component • Bicortical or tricortical fixation needed • Sacrum exposed to large cantilever forces • Fixation to the sacrum eliminates most important sagittal compensatory mech. • Fixation to the sacrum alters gait Pedicle Fixation in the Sacrum Bicortical vs Tricortical Average Insertional Torque 9 Tricortical 8 Average Torque (in-lbs) • S1 pedicle screw is the strongest fixation point - unicortical fixation - bicortical fixation - tricortical fixation • S2 pedicle screw - short - weak bone 7 Bicortical 6 5 4 Linear (Tricortical) 3 2 Linear (Bicortical) 1 0 0 20 40 60 80 100 Percent Screw Length Polly, Kuklo, et al Limitations of Long Fusion to the Sacrum • Cantilever forces for long segment constructs becomes critical when sacral fusion extends to L3 or higher – Shono, et al. Spine 1998 – Cunningham, et al. Spine, 2003 • Clinical correlation with a high incidence of symptomatic pseudarthroses in long fusions to S1 •Kostuik 1983, 40% pseudarthrosis •Boachie 1991, 41% pseudarthrosis •Delvin 1991, 33% pseudarthrosis •Lenke 2004, 23% pseudarthrosis •Balderston 1986, 28% good result 10 Long fusions to the sacrum require anterior column support +/- iliac crest extension • Cantilever forces for long segment constructs becomes critical when sacral fusion extends to L3 or higher – Anterior interbody decrease S1 screw strain 30-40 % – S2 fixation decreases S1 screw strain by 15% – Iliac fixation decreases S1 screw strain by 50 to 300 % Limitations of Long Fusion to the Sacrum • Cantilever forces for long segment constructs becomes critical when sacral fusion extends to L3 or higher – Shono, et al. Spine 1998 – Cunningham, et al. Spine, 2003 • Clinical correlation with a high incidence of symptomatic pseudarthroses in long fusions to S1 •Kostuik 1983, 40% pseudarthrosis •Boachie 1991, 41% pseudarthrosis •Delvin 1991, 33% pseudarthrosis •Lenke 2004, 23% pseudarthrosis •Balderston 1986, 28% good result McCord DH et al Spine 1992 • 66 bovine specimens/10 instrumentation techniques • Established pivot point at the lumbosacral joint at the intersection of the middle osteoligamentous column (sagittal plane) and the lumbosacral intervertebral disc (transverse plane) 11 Reducing Strain on Sacral Screws in Long Fusions to the Sacrum MAXIMUM MOMENT AT FAILURE 250 Moment (Nm) 200 150 100 50 0 S1 Subla mina r Wire S1 Hook S1 Pe dicle Screw S1 Sc rew w ith S2 Hook S1 Fixation S1/S2 Fixation Chopin Block Iliosacral Screw Iliac Screw with Ga lve ston with S1 Sc rew S1 Sc rew Control Sacro-Pelvic Control S2 SCREW • “Biomechanical comparison of lumbosacral fixation Techniques in a calf spine model” PI PIVOT VOT Spine 2002, Lebwohl et al • S2 screw extends fixation distal to the pivot point thus extending lever arm and providing additional support • However, the S2 screw does not extend anterior to the pivot point and thus not as good as iliac screw fixation Long Fusion To The Sacrum in Adult Spinal Deformity: Luque Galveston vs. Iliac Screws vs. Sacral Screws Emami et al:Spine 2003 UCSF Spinal Disorders Service 12 Iliac Bolt Fixation • Bolt or screw is passed into the ilium at the PSIS • Bolt or screw is affixed directly to the spine construct • Effective in high demand construct • Failure rate half of traditional Galveston How Many Iliac Screws? 13 Study Aims and Design Goals Pelvic versus Sacral + ALIF Unilateral iliac versus bilateral iliac Methods Seven cadavers instrumented up to L1 Multi-axial bending with pure moment S1 screws modified with strain gauges for pullout force L1-S1, uni-iliac, bi-iliac… with and without ALIF at L5/S1 Multi-axial bending FLEXION/EXTENSION L5-S1 – Percent of Intact (%) 50% 40% AXIAL ROTATION * L1-S1 ** uni-iliac 60% * L1-S1 ** uni-iliac 50% 140% * L1-S1 ** ni-iliac * 120% 100% 30% 40% 20% 30% * 20% 10% ** 0% LATERAL BENDING 70% * 10% 80% * * ** 0% * * 60% 40% 20% 0% * ** ** One vs Two Iliac Screws • 100 patients with long fusions from thoracic spine to the sacrum – 53patients with 2 iliac screws – 47 patients with 1 iliac screws 14 Limitations of Iliac Fixation • Higher incidence of perioperative complications – Wound infection • Abdul-Jabbar A, et al. • Higher incidence of need for revision surgery – Screw removal • Emami A, et al. Evidence-based approach to the use of Iliac Fixation • Extension of fixation to ilium in: – Compromised anterior column support at L5-S1 • TLIF at L5-S1 – Revision fixation to the sacrum in a long construct • Above L3 – Compromised sacral fixation – Incomplete correction of sagittal and coronal balance – Pelvic obliquity/Long thoracolumbar (c-shaped) deformity corrected with cantilever maneuver – Ankylosing Spondylitis Conclusions • Fixation at the lumbosacral junction is challenging and important for stable reconstructions in deformity • High strain on the sacral screws may lead to screw loosening and nonunion • Pelvic fixation reduces strain on the sacral screws • Role of biologics and new technologies in limiting need for iliac fixation requires further investigation 15 UCSF Center for Outcomes Research 16 Spino-Pelvic Parameters: How Do They Affect My Decision to Extend a Fusion to the Sacrum/Pelvis Han Jo Kim MD Frank J. Schwab, MD Bassel G. Diebo, MD Virginie Lafage, PhD Hospital for Special Surgery New York, NY Disclosures • Consultant – K2M, Biomet, Medtronic • Speaker Bureau (not present, within last 36 months) – Depuy, Stryker • Board Membership – ASJ, HSS Journal SPINOPELVIC PARAMETERS 1 Setting Surgical Goals Regional Loss of lordosis Versus PI Global PI-LL < 10° SVA < 5cm SVA Compensatory Pelvic tilt PT < 20-25° Literature Review • 34 consecutive adult deformity patients fused from the thoracic spine to L5 • Subsequent L5-S1 DDD developed in 66% of patients after long adult fusions to L5 Literature Review • High percentage of patients subsequently degenerated the L5S1 disc • With degeneration of the L5-S1 disc, sagittal balance was frequently lost • Prevalence of breakdown of the L5-S1 disc much greater in the “long” fusions (T4-L5) vs. the “short” fusions (T10-L5) 2 Literature Review Kim YJ, Bridwell KH, Lenke LG, Cho K, Edwards II C, Rinella AS: Pseudarthrosis in adult spinal deformity following multisegmental instrumentation and arthrodesis. J Bone Joint Surg 2006;88(4):721-728 • A clinical and radiographic assessment of 232 adults • Factors found to be significantly associated were preop thoracolumbar kyphosis of >20°, age of >55 years, arthrodesis to S1 compared to L5 • Patients with a pseudarthrosis had lower total outcome scores on SRS questionnaire • Prevalence of pseudarthrosis following long arthrodesis was 17%. Close to 30% for fusions to sacrum. Literature Review Islam NC, Wood KB, Transfeldt EE, Winter RB, Denis F, Lonstein JE, Ogilvie JW. Extension of fusions to the pelvis in idiopathic scoliosis. Spine 2001;26(2):166-173. • • • • 41 patients (40 female; 1 male) 39 of 41 had combined anteroposterior fusion extension Pseudarthrosis rate was 37% (15/41) With sacral fixation only, the rate was 53% (8/15), with iliac fixation only 42% (3/7) and with both iliac and sacral fixation 21% (4/19; p<0.05) Literature Review Enami A, Deviren V, Berven S, Smith JA, Hu SS, Bradford DS. Outcome and complica-tions of long fusions to the sacrum in adult spinal deformity. Spine 2002;27:776-686. • 54 consecutive patients who underwent elective combined anterior and posterior surgical reconstruction for acute spine deformity were studied • Attention to sagittal balance is critical • Luque-Galveston fixation technique has an unacceptably high rate of pseudarthrosis. Currently, the authors are using bicortical and triangulated sacral screws with anterior interbody support • They recommend using iliac fixation, although there is a higher rate of painful implants, requiring removal 3 Literature Review McCord DH, Cunningham BW, Shono Y, Myers JJ, McAfee PC. Biomechanical analysis of lumbosacral fixation. Spine 1992;17(8S):S235-243 Long fixation points in the ilium that extend anterior to the axis of rotation of L5-S1 provide the most stable fixation of the lumbosacral joint. Literature Review Cunningham BW, Lewis SJ, Long J, Dmitriev AE, Linville DA, Bridwell KH. Biomechanical evaluation of lumbosacral reconstruction techniques for spondylo-listhesis: An in vitro porcine model. Spine 2002;27(21):2321-2327 In a spondylolisthesis model, both the iliac screws and the interbody cages at the lumbo-sacral junction protected the S1 screws, but the iliac screws were far more valuable. Factors that Dictate my Decision to Fuse to Sacrum/Ilium • Age – Bone quality – Degenerative changes in disc, foramen, canal • Deformity – – – – – – Large SVA Large Coronal Decompensation Large Curve Magnitude Rigid vs. Flexible Deformity Presence of L5/S1 Spondylolisthesis Laminectomy Defects at L5/S1 4 Factors that Dictate my Decision to Fuse to Sacrum/Ilium • Age – Bone quality – Degenerative changes in disc, foramen, canal • Deformity – – – – – – Large SVA Large Coronal Decompensation Large Curve Magnitude Rigid vs. Flexible Deformity Presence of L5/S1 Spondylolisthesis Laminectomy Defects at L5/S1 • Spino-Pelvic Parameters – High PT – High PI High PT • PT will be very difficult to correct without fusion to S1 and Iliac Fixation in Adult Spinal Deformity High PI • “Guillotine Effect” of Fusion to L5 on L5/S1 Disc Space – High shear stresses 5 Substantial sagittal imbalance, back pain, inability to ambulate PT 36 LL 20 PI 55 SVA 20cm Cantilever to “Dial In” Pelvic Anteversion PT 36 LL 20 PI 55 SVA 20 cm PT 8 LL 55 PI 55 SVA 1cm Case • 79M with bilateral leg and back pain – 10% back, 90% leg pain • 50% Left, 50% Right – Exacerbated by standing/walking – Improved with sitting, lying down (some positions) – No bowel/bladder symptoms – Subjective weakness/numbness when ambulating – Failed PT/Injections 6 Exam • • • • Marked Positive Sagittal Balance Can only stand for a short period of time Static Motor Exam intact Sensory exam normal PI 50 PT 26 LL 9 TK 27 CL 4 SVA 17 7 L1/2 L2/3 L3/4 L4/5 Questions • Osteotomy? Can you do PCOs? Or will this need a PSO? – If PSO, what level? – If PCO, what level(s)? • Is an Interbody necessary? – Lateral? Transforaminal? Anterior? • Choice for UIV? Lower or Upper Thoracic? • Iliac Fixation? • Will you need Biologics? 8 PSF T11-Ilium, PCO L1-L5, TLIF L5/S1 2 yrs post-op 2 yrs post-op PI 50 PT 8 LL 50 TK 40 SVA -5mm Do We Always Have To Go To The Sacrum? Are There Select Circumstances Where We’d Be Better Off Stopping At L5? Case following Courtesy of Dr. Keith H. Bridwell MD Frail Almost 70-Year-Old Female. Bilateral Leg Pain And Weakness, Left Greater Than Right. 10-7-05 69+11 10-7-05 69+11 56° Good Sagittal Parameters! 9 Large Calcified Disc Herniation at T11-T12 on the Left Side Stenosis at L3-L4 4 Year Follow-up Preop Postop Preop Postop 10-7-05 69+11 9-14-09 73+10 3+9 yr po 9-14-09 73+10 3+9 yr po 10-7-05 69+11 56° 10 Oswestry Scores Score Potential 100 100 100 75 46 50 14 25 0 Preop Ultimate Postop Balance Risks/Benefits • Large PI-LL mismatch • Large PT • Large PI (natural anatomy) Balance Risks/Benefits • Large PI-LL mismatch • Large PT • Large PI (natural anatomy) • Need fusions to Sacrum/Ilium • Pseudo Risk 11 9/8/2015 L5-S1 Fusion options Approach, Interbody support, & Graft Options Jason W. Savage, MD Cleveland Clinic Center for Spine Health 9/8/2015 Disclosures • Consultant: Stryker Spine • Editorial Board: JSDT • Off-label use of BMP outline • Approach – Anterior – Posterior • Interbody Support – ALIF/PLIF/TLIF/OLIF – Advantages/Disadvantages – Is it necessary ??? • Graft Options – Bone vs. PEEK vs. Metal – BMP 1 9/8/2015 Goals of surgery • Restore regional lordosis • “Fix” the fractional curve • Achieve a solid fusion Up to 25% pseudarthrosis rate at L5-S1 Anterior approach • Advantages – Access to disc space – Large structural graft – Lordosis • Disadvantages – Unfamiliar and separate approach – Complications Posterior approach • Advantages – Provides interbody support – Single approach/procedure • Disadvantages – Inferior disc “prep” – Graft extrusion – Nerve root irritation – Fusion ??? 2 9/8/2015 Anterior vs. posterior • Retrospective • 32 ALIF vs. 25 TLIF • Foraminal Height • 18.5% vs. -0.4% (p<0.01) • Segmental Lordosis • 8.3 vs. -0.1° (p<0.01) • Regional Lordosis • 6.2 °vs. -2.1° (p<0.01) Lumbar Lordosis ALIF 7 6 5 4 3 TLIF 2 1 0 -1 1 2 -2 -3 J Neurosurg Spine 2007;7:379-386. Anterior vs. posterior • • • • Retrospective ALIF vs. TLIF in ASD 42 pts in each group Segmental lordosis – 6.9°vs. -2.6° (p<0.0001) • Regional lordosis – 11.5°vs. 7.9° (p=0.29) Spine 2013;38:E755-E762. NO DIFFERENCE IN RATE OF PSEUDARTHROSIS Spine 2013;38:E755-E762. 3 9/8/2015 • Systematic Review (12 Retrospective Studies) – 609 ALIFs, 631 TLIFs • Fusion Rates – 88.6% vs. 91.9% (p=0.23) • Disc height (2.71mm) • Segmental lordosis (2.35deg) • Lumbar lordosis (6.33deg) Br J Neurosurg 2015;Early Online:1-7. Interbody graft OPTIONS • Provide structural support – Function is primarily mechanical • Require “other” bone graft substitutes to achieve bony fusion • Implant material is important – Limit subsidence and stress shielding – Bone integration Interbody graft OPTIONS • Femoral Ring Allograft – “Biological Cages” – Natural elasticity – Potential for incorporation • PEEK – Elasticity less than cortical bone – No potential for incorporation • Titanium – Elasticity is much greater than bone – Radiopaque 4 9/8/2015 • Retrospective review • ALIF with PEEK (N=27) vs. RFA (N=14) at L5-S1 • X-ray evaluation • Fusion Rates – 94.9% vs. 84.2% (p<0.05) • Improved foraminal height and segmental lordosis with PEEK J Spinal Disord Tech 2014;27:327-335. • • • • Retrospective Single level TLIF with local autograft Titanium (N=23) vs. PEEK (N=25) Fusion Rates – 100% vs. 75% at 2 years (p=0.016) • Vertebral osteolysis was seen in 60% of PEEK non-unions Eur Spine J 2014;23:2150-2155. Interbody graft OPTIONS • Expandable Cages • “Surface Enhanced” • Silicone Nitrate • Tantalum • 3D Printing • Nanotechnology 5 9/8/2015 The world of biologics MSC Efficacy Allograft Safety Autograft DBM BMP Cost Regulatory Ceramics Courtesy of Wellington K. Hsu, MD ICBG Local Autograft Allograft alone BMA BMP - 2 Ceramics DBM1 PRP # Studies 23 8 4 2 3 16 3 4 # Patients 1389 714 269 40 213 697 192 209 # Fused 1103 637 141 34 201 603 171 154 Rate (%) 79% 89% 52% 85% 94% 87% 89% 74% • Retrospective Study • ALIF in ASD – ICBG (N=32) vs. BMP (N=23) • Fusion Rates – 71.9% vs. 95.7% (p=0.057) • Follow-up – 4.9 vs. 2.7 years Spine 2009;34:2205-2212. 6 9/8/2015 • Retrospective Case Series • L5-S1 Interbody fusion vs. PLF – IF (N=35) vs. PLF (N=26) • Average BMP – 4.1mg in IF vs. 3.2mg in PLF • Fusion Rates – 97% vs. 96% (p=1.0) Spine 2015;11:E634-E639. My algorithm at L5-S1 • ALIF – Sagittal plane deformity (mostly from L4-L5 and/or L5-S1) – Adjacent segment pathology below a previous fusion (i.e. AIS) • TLIF – De novo scoliosis with “tall” disc or spondy – Fractional curve • PLF alone – De novo scoliosis with collapsed disc Case example Courtesy of Doug Orr, MD 7 9/8/2015 Case example Conclusions • Historically high rate of pseudarthrosis at L5-S1 • Iliac Fixation, 360°, and Biologics have improved fusion rates • ALIF improves disc height, segmental lordosis, and LL better than TLIF • Likely no difference in fusion • Still a lot of questions ??? Thank you 8 Sacroplevic Fixation Options, Techniques and Complications Khaled M. Kebaish, M.D., FRCSC Professor of Orthopedic & Neurosurgery Department of Orthopedic Surgery Johns Hopkins University DISCLOSURE Depuy Spine Consultant, Royalty K2M Consultant Orthofix Consultant WHY PELVIC FIXATION? S1 Pedicles capacious & short Sacrum bone is osteopenic Failure rate of S1 Screws Up to 44% Inadequate as the only means of fixation in long fusion Camp et al, Spine 1990 1 INDICATIONS FOR PELVIC FIXATION Expected significant biomechanical stresses Long fusions to the sacrum Definition: > 4 levels Osteoporosis Sacral Fracture 2 Sacro-Pelvic Fixation Options Casting and bracing Sacral Sublaminar devices Wires Cables Hooks Sacral pedicle screws S1 pedicle screws S2 Pedicle screws S1 Alar screws S1 and Alar screw blocks Dunn-McCarthy SRod Jackson intra-sacral rod Kostuik sacral bar Galveston technique Iliac Screws Sacral Alar Iliac screws (S2AI) LUMBO-SACRAL PIVOT POINT “Axis about which the lumbosacral region rotates” Middle of osteo-ligamentous column at L5-S1 Implants ventral to this point provide an effective moment arm to resist flexion & improve fixation strength McCord et al, Spine, 1992. LUMBO-SACRAL PIVOT POINT McCord et al, Spine, 1992. 3 GALVESTON TECHNIQUE Most commonly used in NM Spinal deformities Inexpensive Difficult to get the correct angle Loss of correction Windshield wiper effect Broom MJ, et al, JBJS (A), 1989. Gau Y, et al, J Spinal Disord, 1991. Moseley C, et al, Orthop Trans, 1986. Jackson Technique S1 pedicle screws Rod placed in S1 screw and into sacral ala Not crossing the SI joint Technically difficult Biomechanically weaker than iliac fixation Jackson RP, et al, Spine, 1993. Lebwohl NH, Spine, 2002. Iliac Screws Commonly used Fixation with screws Implants easier to place Reduction in LS motion More Protective of S1 than IB cages Cunningham BW, et al, Spine, 2002. 4 67 patients ( 81 initial Cohort) 5 years Follow-up Iliac screws removed in 23 pts 7 broken screws Screws halos in 29 pts No SI joint arthritis Woojin et Al. paper 46, IMAST 2011 67 of 190 patients Iliac screws Minimum 2 ys follow-up 34.3 % failure 11.9 Major failure S2 Alar –Iliac S2AI “SAI” 5 Surgical Technique How it all started? Surgical Technique How it all started? Surgical Technique How it all started? 6 Surgical Technique How it all started? Surgical Technique S2AI Starting point: Midway between S1 & S2 foramina 2.5 mm drill from pelvic set Trajectory: 45o to floor 20-30o caudal “Varies w. pelvic obliquity & Sacral tilt” Aim for the AIIS Confirm bony end point with a probe 7 Surgical Technique S2AI Surgical Technique S2AI 8 Surgical Technique S2AI Screw path just above sciatic notch Fluoroscopy is helpful Iliac oblique, Tear drop 9 Surgical Technique S2AI Screw path just above sciatic notch Fluoroscopy is helpful Iliac oblique, Tear drop Diameter 8-10 mm Length 80-100 Biomechanics Biomechanical properties equivalent to Iliac screws Stress-strain & load to failure 200 150 100 50 0 S1+S2 Screw S1+S2 Portal S1+Iliac Screw 10 Outcomes and Complications of Sacro-Pelvic Fixation Using S2 Alar-Iliac (S2AI) Fixation in Adult Deformity patients: A prospective Study with 2-Year Follow-Up Khaled Kebaish, MD Mostafa El Dafrawy,,M.D Hamid Hassanzadeh, M.D Philip Neubauer, M.D Roosevelt Offoha, BS Eric Tan, M.D Paul Sponseller, MD Department of Orthopaedic Surgery Johns Hopkins University RESULTS 146 patients were included 2 year clinical & radiographic F/U 2 patient were lost to follow up Average age: 59 ys (21-80) 35% of patients had > one comorbidity S2AI Fixation specific complications Screw Breakage Screw Misplacement Minimal Screw loosening (<2mm) 13 patients Reoperation 8 (5 pts) 2 16 screws (6%) 4 11 Sacropelvic Fixation Using the S2 Alar-Iliac (S2AI) Screw in Adult Deformity Surgery: A Prospective Study with Minimum 5-Year Follow-Up Sophia A. Strike, MD; Hamid Hassanzadeh, MD; Floreana Naef, MD; John Carrino, MD; Paul D. Sponseller, MD; Richard Skolasky, ScD; Khaled M. Kebaish, MD S2AI FIXATION COMPLICATIONS 109 S2AI screws placed Six broken screws (four patients) > 2 mm lucency: 20 screws No pseudoarthrosis at L5-S1 No SI joint degeneration Effect on the SI Joint There was no evidence of SI joint fusion No significant change in joint space No significant SI joint area pain Corlett EN, Bishop RP. Ergonomics 1976 12 Concerns of Fusion Across SI Joint Anatomic studies Minimal motion in pediatric cadavers No motion in adult cadavers 75% auto fused in adults over 50 years Asher MA, et al, CORR, 1986. Kostuik JP, et al, CORR, 1986. White AA, et al, Surgery of Musculoskeletal System, 1990. Adult Scoliosis 71 YO M Retired Physician Severe Back Pain and Rt Buttock Used to be very active now Limited by his symptoms No Prior Rx 13 62 y.o. Female Degenerative on Idiopathic Spondylolithesis 14 Spondylolithesis Spondylolithesis 15 Spondylolithesis Sacral Fracture 16 Bone Graft Harvest! 17 Bone Graft Harvest! DISCUSSION Implant fractures were only seen with smaller diameter screws (7mm) Recommend using Larger screws (>8mm) Loosening > 2mm very rare Reoperation and removal are infrequent 18 S2AI Technique Relatively easy and safe Minimal offset from the axis of spine Less prominent One rod no connectors Better control of the pelvis S2AI Technique Relatively easy and safe Minimal offset from the axis of spine Less prominent One rod no connectors Better control of the pelvis EASIER TO PERFORM RECONSTRUCTIVE PROCEDURES AT THE LS JUNCTION Conclusion Many techniques for PELVIC FIXATION High Rate of implant related problems S2 Alar Iliac (SAI) technique easy & safe Lower Complications Effective in distal LS corrective procedures No effect on the SI joint at 5 ys! Can be done through an MIS approach 19 THANK YOU 20
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