Disclosures. Outline. General Guideline 6/4/2011. Consultant Medtronic, Stryker, Depuy. Osteotomy Planning and the Impact of Reciprocal Changes

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1 Disclosures Consultant Medtronic, Stryker, Depuy Osteotomy Planning and the Impact of Reciprocal Changes Christopher Ames MD Associate Professor Director of Spine Tumor and Deformity Surgery UCSF Department of Neurosurgery Outline Planning considerations in Sagittal Plane Favorable and Unfavorable Reciprocal Changes General Guideline so you just make the spine look like the model! Problem is, which one? 1

2 PI and Lumbar Lordosis 100 degrees total lordosis/72 degrees of which come from terminal segments 75% Jackson SRS 1994 Normal L5-S1 disc 41% of total lumbar lordosis L4-5 disc 27% C1-C2 75% cervical tilt PT 68% LL=PI+9 degrees (Duval-Beaupere) Normal Conus of Economy Background Loss of lumbar lordosis is especially poorly tolerated and has direct effect on disability 2

3 Compensation ODI and Sagittal Plane ESJ Article ASD and LL/SS Combined Assessment of Pelvic Tilt, Lumbar Lordosis/Pelvic Incidence Mismatch and Sagittal Vertical Axis Predicts Disability in Adult Spinal Deformity: A Prospective Analysis 492 ASD patients enrolled in multicenter database OP vs non Op ODI 41.4 vs 23.9 Radiographic parameters demonstrating highest correlation with HRQOL values were evaluated using Pearson analysis to determine a threshold of severe disability based on ODI=40. Threshold values for severe disability included: PT=22, SVA =46mm, and LL-PI=-11. ASD Incidence worsens with increased pelvic tilt and positive sagittal balance Group A. 8% Group B. 48% Group C. 50% Group D. 53% 3

4 Decompensation Angular changes at base of spine Ondra Technique for PSO planning Ondra Spine 2006 Ondra Formula Example Reciprocal Changes of Pelvis 4

5 Sagittal Imbalance and Gait Importance of the Pelvis in Sagittal Plane Outcomes Normal gait requires forward flexion of pelvis If high PT is maintaining SVA this forward tilt may decompensate pt Sagittal Imbalance results in abnormal gait External Rotation of Hip Internal Rotation of Knee Short stride Accelerated arthritis? Diagnosis-can a pt with a normal sva and high PT have symptomatic imbalance? Case Example Gait Totally Flat ODI M U S C U L preop A R ODI WE 33 post op 6 months 16 5

6 PT and planning Location of Osteotomy and Impact Location of Osteotomy and Impact PSO level correlated to PT correction but not to SVA correction PSO degree correlated to LL change, TK change and PT change 6

7 Results Entire group Changes in Thoracic Kyphosis Negatively Impact Sagittal Alignment Following Lumbar Pedicle Subtraction Osteotomy Virginie Lafage PhD, Eric Klineberg MD, Frank Schwab MD, Behrooz Akbarnia MD, Christopher Ames MD, Oheneba Boachie-Adjei MD, Douglas Burton MD, Robert Hart MD, Richard Hostin MD, Christopher Shaffrey MD, Kirkham Wood MD, Shay Bess MD. International Spine Study Group SRS 2010 Kyoto Patients 34 lumbar PSO 24F:10M Age: 54.4 years (SD = 12) BMI: 25.5 kg/m 2 (SD = 5.2) 26 revision Surgery Most common PSO Site: L3 Focal resection: 26 (SD = 9) Levels fused: 6.4 Radiographic Changes LL: 17 to 48 p<0.001 TK: 22 to 35 p<0.001 T1SPI: 5 to -3 p<0.001 SVA: 14 to 4cm p<0.001 PT: 33 to 25 p<0.001 PSO site Group distribution Neutral RC change in thoracic kyphosis less than 5 Favorable RC increase in thoracic kyphosis countered excessive negative SVA excessive decrease of PT Unfavorable RC increase in thoracic kyphosis led to post-operative SVA > 4cm post-operative PT>20 Demographic Analysis of unfavorable RC Older 59 y vs. 49 years p=0.01 Larger Pre-op imbalance Worse SVA 17.5 vs 10.3cm p=0.002 Worse T1SPI 7 vs. 2 p=0.004 Pelvic retroversion 36 vs. 28 p=0.024 Loss of lordosis 11 vs. 24 p=0.04 Morphology Pre-operative parameters PI : LL mismatch Larger PI 61 vs. 54 p=0.04 Significant difference in terms of patient pre-operative profiles 7

8 Taking Thoracic Change into Account? Can Different Surgical Strategies Result in Optimal Post Operative Alignment ISSG PSO Sites 77pts with SVA<5cm included No sig differences in preop parameters Can Different Surgical Strategies Result in Optimal Post Operative Alignment Can Different Surgical Strategies Result in Optimal Post Operative Alignment Ave T9 termination with largest PSO (site 3) had greatest increase in TK 8

9 Critical Analysis of Preoperative 5 Planning Techniques Critical Analysis of Preoperative 5 Planning Techniques Retropective analysis of mathematical formulas used to predict SVA after PSO 147 PSO patients ISSG database 47 had post op SVA>5cm Differences noted in good vs poor prediction accuracies Best formula included PI, TK and PT *PTpo = (PI) -.52 (LLm) -.19(TKm) *Lafage 2011 Over-correction Over-correction-why does it happen? 183 PSO patients in multicenter database Divided into 3 groups Well corrected SVA 0-5cm Overcorrected SVA<0 Undercorrected SVA>5cm Over-corrected pts were younger Over-corrected pts had lower PI (53 vs 62), lower PT (30 vs 36) and SVA (94 vs 185mm) Over-corrected pts had less gain in TK (5 vs 12) No differences in degree of PSO or instrumented levels Changes in LL were not different Change in Pelvic Tilt 9

10 TVCR-Reciprocal Lumbar and Pelvic Changes Pelvic Reciprocal Change after Thoracic TCO VCR Radiographic Assessment of Alignment Failure Unfavorable Lumbar Reciprocal Change C and T Spine Reciprocal Changes 10

11 Lumbar PSO and Cervical Spine A pilot study to determine if significant reciprocal changes may also occur in the mobile cervical spine after a global alignment change To begin to characterize these changes Identify parameters that may help predict these changes as candidates for further study in large multicenter PSO database ( ISSG) Methods Multicenter retrospective study (UCSF, UVA, USC, Howell Allen Clinic 25 adult deformity patients with preoperative positive sagittal balance of at least 50 mm Lumbar osteotomy Films allowed accurate cervical and T/L/Pelvic measurement Maintained horizontal gaze Measurements between 3-6 months post op Example Case Correction of Cervical Hyperlordosis with Lumbar PSO Sample Case Measurement 11

12 Results Concept CT Incidence -T1 slope C2- C3< C2- C7< SVA C7- S1 Pelvic Tilt Sacral Slope T2- T9< C2-C7 SVA Pre-Op Post- Op P-value 0.08 < < < < =0.14 T1 T1 Pre-operative and post-operative angles with P-values PSO Correction and T spine changes combine to change T1 slope-pi of C spine The Impact of Positive Cervical Sagittal Balance in Adult Cervical Surgery 12

13 Measurements of Cervical SVA Red arrow: C2- C7 plumb line Yellow arrow: CGH-C7 plumb line *CGH measured from anterior margin of external auditory canal NDI Score Correlation between C2-C7 Plumb Line and NDI Scores < C2-C7 Plumb Line (mm) Conclusions Reciprocal changes are frequent occurrences in spinal rebalancing surgery General trends may be predicted Knowledge of these changes should be incorporated into preoperative planning strategies for optimal results These changes extend from the pelvis to occiput and may impact outcomes and pain scores Thank you Acknowledgements Virginie Lafage PhD Frank Schwab MD Shay Bess MD Vedat Deviren MD 13