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Introduction to Spine Arthroplasty Ira Fedder, MD Scoliosis and Spine Center Towson, MD. DePuy Spine confidential information. Do not duplicate. Do not distribute. Spine Surgery at the Millennium. Posterolateral +/- Instrumentation Circumferential (“360°”)
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Introduction to Spine Arthroplasty Ira Fedder, MDScoliosis and Spine Center Towson, MD DePuy Spine confidential information. Do not duplicate. Do not distribute.
Spine Surgery at the Millennium • Posterolateral +/- Instrumentation • Circumferential (“360°”) • PLIF (Posterior Lumbar Interbody Fusion) • ALIF (Anterior Lumbar Interbody Fusion) • TLIF (Transforaminal Lumbar Interbody Fusion)
Paradox Can the same problem (discogenic pain) be treated effectively using interventions with the exact opposite technical goals?
Biomechanics 80%Anterior 20%Posterior The 80-20 rule of Spine loading
History of Lumbar TDR Fernström – 1960’s
History of Lumbar TDR Synthes™ PRODISC®I - 1987 PRODISC®II - 1999
History of Lumbar TDR Medtronic™ Maverick™ - 2001
History Karin Büttner-Janz INVENTOR DePuy Spine confidential information. Do not duplicate. Do not distribute.
History of Lumbar TDR SB CHARITÉ™ I - 1984 II - 1985 III - 1987
HistoryDesign Iterations Experimental PrototypesNever Commercially Available • Inventors Drs. Schellnack and Büttner-Janz • SB Charité™ I • 1984 • 13 patients, 14 Implants • SB Charité ™ II • 1985 • 36 patients, 44 Implants • Non-forged stainless steel • No special instrumentation Data from The Artificial Disc, Buttner-Janz, 2003
History - Current Design CHARITÉ Artificial Disc • Refined design by Waldemar Link • Cast Cobalt Chrome Endplates • Ultra High Molecular Weight Polyethylene (UHMWPE) Sliding Core • Design unchanged since 1987 • First released 1987 • Thousands of implantations worldwide • Same design used in U.S. IDE clinical study • 17-year track record
Importance of Sizing Bone Density Proper Endplate Size Dr. Wolfgang Raushning - Uppsala University, Sweden 2000
David, TJ. “Lumbar Disc Prosthesis: Five Years Follow-up Study on 147 Patients with 163 SB Charité Prosthesis.” EuroSpine 2003 Results related to surgeon experience • 1989 - 1991 • 43 patients: 63% excellent/good • 1992 - 1994 • 57 patients: 82% excellent/good • 1995 - 1997 • 44 patients: 93% excellent/good
European Experience: Lessons Learned • Sizing • Positioning • Patient selection • Controlled distraction
Learning Objectives • Patient Selection • Patient Selection • Patient Selection
Radiographic Evaluation We ARE treating discogenic pain with TDR • Biggest challenge is to identify the pain generator • Start with plain x-rays, MRI • Studies have shown high false positive rate of MRIs • Discography can help distinguish between asymptomatic “dark discs” on MRI and those that are pain generators
Clinical pain provocation test Radiographic images Test is positive only if: The disc is abnormal in appearance AND Patient’s clinical pain is provoked during injection Discography
Clinical Indications • Chronic low back pain +/- leg pain • Persisting > 6 months • Associated with degenerative disc changes • Leg pain • Radicular • Pseudoradicular • Foraminal stenosis • Secondary to disc space height loss • may be relieved indirectly by disc height restoration
Contraindications Osteoporosis or Osteopenia • Dexa-scan patients > age 50 or with more than 1 risk factor • T< -1.0 is contraindicated
Contraindications Scoliosis >11º sagital deformity
Contraindications Instability including • isthmic spondylolysis • spondylolisthesis • retro or anteriolisthesis > 3mm
Contraindications • Poor psychometric evaluation • Abnormal pain discogram • Hz of Schizophrenia • Bi-polar condition • Severe depression • Inability to comprehend procedure and risks
Facet Disease Mild Moderate Severe • Contraindication: • Advanced Facet Disease • Severe Spinal Stenosis (canal space < 8mm) • Use CT Myelogram to evaluate
Central Stenosis Tumor Arachnoiditis History of chronic steroid use Advanced facet disease Facet joint ankylosis Metal allergies Pregnancy Single or bilateral leg pain (due to nerve compression) Non-contained herniated nucleus pulposus Infection/neoplasm Autoimmune disorders Contraindications
Approach Related Contraindications • Anterior Vascular Calcification • Previous major vessel surgery • Obesity: BMI > 40 or 100lbs over ideal body weight • Previous retroperitoneal procedures
Effectiveness Results (All Randomized) Primary Hypothesis: Overall Success Rate • Small P-value indicates high degree of certainty Conclusion: The CHARITÉ Artificial Disc is at least equivalent in overall success to the BAK cage in treatment of DDD at one level (L4-S1).
Effectiveness Results (All Randomized) Primary Effectiveness Endpoints * re-operation, revision, removal or additional fixation ** major vessel injury, neurological damage or nerve root injury
Implant Lateral X-Ray Final Center of rotation 2mm dorsal sagital midlinemaximum footprint coverage – proper lordotic angles
Implant A/P X-Ray Final Center spike positioned on A/P midline