Observe / Operate Congenital Deformity Pedicle Screw Insertion And Salvage Techniques
2015-04-20
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Spinal Deformity Surgery Educational Continuum Challenging Pedicle Screw Insertion/Salvage Techniques Suken A. Shah, MD Alfred I. duPont Hospital for Children Division Chief, Spine and Scoliosis Center Wilmington, Delaware USA 1 10/12 DA10293A, CA9232A Pedicle Screws in Deformity Biomechanical screw performance: Hackenberg L, Spine 2002 O’Brien MF, Spine 2000 Hamill CL, et al, Spine 1996 Three column control of vertebra Improved coronal, sagittal & rotational correction Minimal loss of correction over time Lower pseudarthrosis rates Lower implant failures Earlier return to activities Avoid anterior release, thoracoplasty 2 10/12 DA10293A, CA9232A Thoracic Pedicle Screws for AIS Suk S-I, et al, Spine 1995; 20: 1399-1405 TPS for correction of adolescent idiopathic scoliosis Coronal correction Hooks Screws in a hook pattern Segmental screws Rotational correction 49% 64% 72% 19% 26% 59% Less loss of correction at 2 yrs with TPS No implant failures with TPS 3 10/12 DA10293A, CA9232A Thoracic Pedicle Screws in Deformity: Concerns Greater risk of misplaced screws Spinal cord, great vessels, viscera Truly intraosseous? Pedicle anatomy and morphology in scoliosis Thin pedicles Difficulty of placement Cost Outcomes? Vaccaro A, J Bone Joint Surg Am 1995 4 10/12 DA10293A, CA9232A Structures at Risk 5 10/12 DA10293A, CA9232A Screw Insertion Techniques Freehand Placement Pedicle gearshift / Probe Drill Fluoroscopic Assisted Funnel Technique Intraoperative Navigation Electronic Conductivity Device 6 10/12 DA10293A, CA9232A Freehand Screw Placement Safety Data: Kim Y, Lenke L, Bridwell K, et al Spine 2004 Stepwise, consistent and compulsive Accurate, reliable and safe Schizas C, Eur Spine J 2007 Safety in upper T spine (T1-T3) Equivalent to fluoro/navigation techniques 7 10/12 DA10293A, CA9232A TPS Accuracy in Deformity Belmont, Spine 2001 and Kim, Spine 2004 Accuracy in nonscoliotic spines ~ 78-99% Accuracy in deformity ~ 69-97.8% Kuklo, Lenke, O’Brien et al, Spine 2005 TPS Accuracy and Efficacy in Curves > 90° 94% of the planned screws were inserted Accuracy ~ 96.3%, Efficacy ~ 68% correction 8 10/12 DA10293A, CA9232A Dry Exposure - Visualization 9 10/12 DA10293A, CA9232A Insertion Technique: Starting Point 10 10/12 DA10293A, CA9232A Insertion Technique: Starting Point 11 10/12 DA10293A, CA9232A Assess Rotation & Adjust Trajectory 12 10/12 DA10293A, CA9232A Pedicle Morphology in the Spine with Scoliosis Parent S, et al, Spine 2004; 29: 239-248 Concave pedicles are smaller Left (concave) Pedicle Width 13 10/12 DA10293A, CA9232A Freehand Screw Placement Outward gearshift until the pedicle base Inward gearshift into vertebral body after the pedicle base Kim YJ, Lenke LG et al, Spine 20047 14 10/12 DA10293A, CA9232A Freehand Screw Placement Kim YJ, Lenke LG et al, Spine 2004 15 10/12 DA10293A, CA9232A Difficult Screw Placement Concavity of curves Main thoracic Proximal thoracic Senaran, Shah et al. J Spinal Disord 2007 T3,T4 concavity 18% sclerotic, narrow 16 10/12 DA10293A, CA9232A Pedicle Morphology Classification Watanabe, Lenke et al IMAST 2007 and under review Type A Type B Type C Type D Type A - “Large Cancellous Channel” (50%) Type B - “Small Cancellous Channel” (40%) Type C - “Cortical Channel” (7%) Type D - “Absent Pedicle Channel” (3%) 17 10/12 DA10293A, CA9232A Insertion Techniques Type A Type B Type C Type D Type A - Pedicle probe is smoothly inserted without difficulty Type B - Pedicle probe is inserted snugly with increased force Type C - Pedicle probe cannot be manually inserted but must be tapped with a mallet down into the body Type D - Necessitates a “juxtapedicular” pedicle probe insertion Watanabe, Lenke et al IMAST 2007 and under review 18 10/12 DA10293A, CA9232A 13 yo♀ AIS Lenke 3CN 85 75 19 10/12 DA10293A, CA9232A 13 yo♀ AIS Lenke 3CN PSF T4-L4 20 10/12 DA10293A, CA9232A Severe Kyphoscoliosis 21 10/12 DA10293A, CA9232A Difficult Screws Severe curves Difficult exposure: bleeding, ribs Small, narrow, sclerotic pedicles Osteoporotic bone Osteotomy stabilization 22 10/12 DA10293A, CA9232A Fluoroscopic Assisted Screw Insertion Collinear Shufflebarger, DePuy Spine Technique Guide, 2007 Carbone J, Spine 2003 Rampersaud YR, Spine 2000 23 10/12 DA10293A, CA9232A Proper AP image for Fluoro Pedicles in upper half of vertebral body Endplates parallel Spinous process equidistant 24 10/12 DA10293A, CA9232A Fluoroscopic Assisted Screw Insertion Multiplanar fluoro, Iso-C, O-arm Accuracy 78-93% Radiation exposure Wang M et al, Neurosurgery 2004 Kuntz C, J Spinal Disord 2004 25 10/12 DA10293A, CA9232A Intraoperative Navigation Kotani Y et al, Spine 2007: improved accuracy over fluoro Mirza S et al, Spine 2003: multiple reference markers Kosmopoulus V et al, Spine 2007: improved accuracy over other techniques, except in thoracic spine 26 10/12 DA10293A, CA9232A Intraoperative Navigation The Challenges 10/12 Learning curve (frustration) Registration of the patient’s anatomy in the OR Non sterile expert Still need fluoro or intraop CT Tools are cumbersome 27 DA10293A, CA9232A Electronic Conductivity Device Breach anticipation (alert to surgeon) Immediate redirection if necessary Juxtapedicular technique Possible bicortical fixation 28 10/12 DA10293A, CA9232A Electronic Conductivity Device Bolger et al. Eur Spine J, in press Correctly identified intentional breaches Betz, Samdani et al. Temple J Orthop Surg 2008 Decreased rate of medial breaches by 8% 29 10/12 DA10293A, CA9232A Salvage Techniques / Alternatives Tendency is to miss lateral and/or inferior Change Trajectory [anatomic / rotational traj.] Fluoroscopic Assistance Drill / smaller or sharper probe Laminotomy / Funnel Technique Extra- or Juxtapedicular (lateral) Placement Intralaminar Screws 30 10/12 DA10293A, CA9232A Insertion Technique: Trajectory Straight Ahead Trajectory Parallels superior end plate Allows monoaxial screw Higher IT and pullout (27%) Anatomic Trajectory Along pedicle axis Requires multi-axial screw Salvage situation 62% Lehman RA, Spine 2003 31 10/12 DA10293A, CA9232A Salvage Techniques for Screw Placement Palpate the medial and inferior borders of the pedicle from the 32 canal and start 2 mm lateral 10/12 DA10293A, CA9232A Salvage Techniques for Screw Placement Palpate the lateral border of the superior articular process / TP junction Zeiller et al, Neurol India 2005 33 10/12 DA10293A, CA9232A Cannulated tap developed for screw insertion in small pedicles 34 10/12 DA10293A, CA9232A Extra/Juxtapedicular Techniques Pullout inferior than transpedicular But, acceptable (65-80%) Decent salvage alternative Maybe the only alternative (Type D pedicle) White KK, Spine 2006 Yuksel KZ, Spine 2007 35 10/12 DA10293A, CA9232A Extra/Juxtapedicular Techniques Pullout inferior than transpedicular But, acceptable (65-80%) [rib head] Decent salvage alternative Maybe the only alternative (Type D pedicle) White KK, Spine 2006 Yuksel KZ, Spine 2007 36 10/12 DA10293A, CA9232A Funnel Technique Yingsakmonkol, Karaikovic, and Gaines, J Spinal Disord 2002 37 10/12 DA10293A, CA9232A Intralaminar Screw Placement Lewis SJ et al, Spine 2009 A curved pedicle probe is directed along the axis of the lamina with the curved tip aimed dorsally. (1) The trajectory is kept slightly less than the down slope of the lamina. (2) The screw is placed entirely within the cortical bone. (3) A- Axis of the lamina, B - ideal trajectory. Biomechanics sound - Cardoso MJ J Neurosurg Spine 2009 38 10/12 DA10293A, CA9232A Screw Revision Techniques Change trajectory Pedicle dilation Clements D, pilot data – increased pullout 200Nm Larger diameter screws better than longer Polly DW et al, Spine 1998 39 10/12 DA10293A, CA9232A Other Alternatives Hooks (pedicle, laminar, TP) Cordista A, Spine 2006 “Biomechx of screws/hooks” Hook claw config was 88% stronger than TPS Coe J, Spine 1990 “Infl of BMD on fix. strength” Laminar hooks found to be the strongest 40 10/12 DA10293A, CA9232A Other Alternatives Sublaminar wires Cheng I et al Spine 2005 “Wires vs. TPS” Similar corrections, OR time, fusion length, SRS scores Wires cheaper Transverse process wires Fujita, Spine 2006 Erel, Acta Orthop Scand 2003 New materials 41 10/12 DA10293A, CA9232A Other Alternatives Sublaminar wires Cheng I et al Spine 2005 “Wires vs. TPS” Similar corrections, OR time, fusion length, SRS scores Wires cheaper Transverse process wires Fujita, Spine 2006 Erel, Acta Orthop Scand 2003 New materials Leave it out 42 10/12 DA10293A, CA9232A 14 yo ♂ AIS 43 10/12 DA10293A, CA9232A 14 yo ♂ AIS 44 10/12 DA10293A, CA9232A 14 yo ♂ AIS • Ant. Tscopic release •Ponte osteotomies •Rib head release •Combination of techniques for screw insertion 45 10/12 DA10293A, CA9232A Summary Many screw salvage techniques Severe deformities Small, narrow, sclerotic pedicles Osteoporotic bone Revision cases / fusion mass Extra- or juxtapedicular position is acceptable Fluoroscopy is helpful Segmental screw fixation is not necessary Other alternatives are available (hooks, wires) 46 10/12 DA10293A, CA9232A Thank you 47 10/12 DA10293A, CA9232A
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