Managing the Patient with Osteoporosis Undergoing Spinal MEDTRONIC - PDF document

11/4/16 DISCLOSURES Managing the Patient with Osteoporosis Undergoing Spinal • MEDTRONIC Surgery • LILLY • MISONIX SHANE BURCH MD, MS, FRCSC Associate Professor in Residence UCSF Department of Orthopedic Surgery OVERVIEW LIFE IS A KYPHOSING EVENT 2000 1973 1

11/4/16 OSTEOPOROSIS OSTEOPOROSIS • Osteoporosis can be defined clinically by either: • Described by the French pathologist Jean Georges Chretien Frederic Martin Lobstein ‘the Younger’ (1777–1835) – WHO - Low bone mineral density (BMD g/cm2) T-score of -2.5) • Greek words osteo (bone) and poros (little hole), referring to the cavities which were observed by the pathologist in certain – A history of fragility fracture patients' bones • a systemic disease characterised by low bone mass and • Fragility fracture is frequently described as a fracture microarchitectural deterioration of bone tissue, with a occurring as the result of minimal trauma or a fall from consequent increase in bone fragility and susceptibility to standing height or less fracture D. Schapira, C. Schapira Osteoporosis: the evolution of a scientific term Osteoporos Int, 2 (1992), pp. 164–167 Lumbar Vertebral Strength vs. NOT JUST BMD Age O.N. Diagnostics, Berkeley, CA 2

11/4/16 BONE STRENGTH BONE STRENGTH • BMD • Morphology • Mineralization • Volume • Architecture • Turn-over rate EULERS PRINCIPLE VERTEBRAL COMPRESSION FRACTURES 16X STRONGER 3

11/4/16 PREVALENCE OSTEOPOROSIS IN MEN • fractures occur 5–10 years later than women • men aged 50 years, the lifetime risk of any osteoporotic fracture located in the hip, the spine or the distal forearm has been estimated at 13 % compared with 40 % in Females • prevalence of vertebral fractures in men ranges from 29 % in the sixth decade to 39 % in the ninth decade • low testosterone / decreasing plasma estradiol levels IMPACT OF VCFS BURDEN • 2 million fractures occur each year as a result of osteoporosis or osteopenia, including •Impaired gait, poor balance – 300,000 hip fractures, •Disability, reduced quality of life •Reduced lung function – 547,000 vertebral fractures •Early satiety, gastric distress – 135,000 pelvic fractures. •Future facture risk • Postmenopausal white women have a 40% lifetime risk of at least one •Excess mortality osteoporotic fracture Consequences are Mortality following a VCF: • cost: $19,000,000,000 (2005) independent of acute RR=8.64 fracture pain Cauley, J. A., D. E. Thompson, et al. (2000). "Risk of mortality following clinical fractures." Osteoporos Int 11(7): 556-61. 4

11/4/16 ETIOLOGY UNDERTREATMENT Substantial undertreatment among women diagnosed with • Estrogen deficiency osteoporosis in a US managed care population: a retrospective analysis." Siris, E. S., A. Modi, et al. " • Osteoblasts proliferate Curr Med Res Opin. • Increase in RANKL • 65,344 patients, mean age 65.7 year: dx - osteoporosis • Proliferation of osteoclasts • 42,033 patients (64.3%) • Increase in bone turnover received no OP medication • 23,311 patients (35.7%) received OP treatment I have an enormous favor to ask you CELL SIGNALLING SECONDARY OSTEOPOROSIS • Hyperparathyroidism • Diabetes (type I and II) • Chronic glucocorticoid use • Hypogonadism - men (>3mo) • Ovarian failure • Alcohol abuse (>3 / day) • Smoking • Low Ca intake • Immobilization 5

11/4/16 TRENDS IN SPINE SURGERY FOR THE ELDERLY • increasing trend to perform surgery in the elderly Weinstein, J. N., J. D. Lurie, et al. (2006). "United States' trends and regional variations in lumbar spine surgery: 1992- 2003." Spine (Phila Pa 1976) 31 (23): 2707-2714. Deyo, R. A. and S. K. Mirza (2006). "Trends and variations in the use of spine surgery." Clin Orthop Relat Res 443 : 139-146. PREVALENCE OF SCOLIOSIS INTERSECTION OF DISEASE osteoporosis spinal disorders • adult degenerative scoliosis / kyphosis – up to 65% in adult volunteers – less prevalent in other studies • Schwab, F., A. Dubey, et al. (2005). "Adult scoliosis: prevalence, SF-36, and nutritional parameters in an elderly volunteer population." Spine (Phila Pa 1976) 30 (9): 1082-1085. Surgical candidates 6

11/4/16 OSTEOPOROSIS 7

11/4/16 PREVALENCE OF OSTEOPOROSIS IN SPINE PATIENTS • 1300 cases reviewed over age 50 • very common – 15% males (46% with osteopenia) vs 50% female Chin, D. K., J. Y. Park, et al. (2007). "Prevalence of osteoporosis in patients requiring spine surgery: incidence and significance of osteoporosis in spine disease." Osteoporos Int 18 (9): 1219-1224. FRACTURE RISK ASSESSMENT CT BASED STRENGTH ASSESSMENT • AGE Use Finite Element Analysis to Virtually Load to Failure • HISTORY OF: – Smoking – Prior Fracture – Family Hx – ETOH – Corticosteroid use • BMD colored by local stiffness • BONE TURNOVER (red — high; blue — low) Wang JBMR 2012 8

11/4/16 PRIOR FRACTURE INCREASES RISK PRIOR FRACTURE INCREASES FUTURE FRACTURE RISK • Lindsay 2001 analyzed VCF risk within one year in patients with 0, 1 or 2 or more prior VCFs. (JAMA 2001) • Lindsay 2005 used the same patient cohort to analyze VCF risk within one year in patients with 0, 1, 2, 3, 4, 5, 6, 7, or 8 prior VCFs. (Osteoporos Int 2005) Lindsay – Jama 2001 BONE ASSESSMENT FRACTURE DEFORMITY AND RISK • DEXA - BMD Increasing fracture risk with increasing deformity • QCT - BMD • CT-FEA – BMD + strength • Bone Volume – BV/TV • Bone Formation: PINP • Bone Resoption: CTX Black – J Bone Min Res 1993 9

11/4/16 SURGICAL PERSPECTIVE CHANGING BIOLOGY • “bone strength” 500,00 bone graft procedures performed in US /yr – screw pull out – adjacent fractures • “fusion potential” – MSCs + vascular supply Caplan, A. I. (2007), Adult mesenchymal stem cells for tissue engineering versus regenerative medicine. Journal of Cellular Physiology, 213: 341–347. doi: 10.1002/jcp.21200 – failure to fuse - pseudarthrosis 10

11/4/16 SYSTEMIC TREATMENT • Anti-Resorptive • Anabolic • Bone Forming “Well we removed the growth, but the operation left you paralyzed from the neck down” CALCIUM / VIT D BISPHOSPHONATES • inhibition of farnesyl pyrophosphate synthase • interferes with isoprenylation of small guanosine triphosphatases at ruffled border • disrupts attachment and National Osteoporosis Foundation Clinician’s guide to prevention and treatment promotes early apoptosis of osteoporosis National Osteoporosis Foundation, Washington, DC (2014) 11

11/4/16 Treatment with 10 mg of alendronate daily for 10 years produced mean increases in bone mineral density of 13.7 percent at the lumbar spine (95 percent confidence interval, 12.0 to 15.5 percent), 10.3 percent at the trochanter (95 percent confidence interval, 8.1 to 12.4 percent), 5.4 percent at the femoral neck (95 percent confidence interval, 3.5 to 7.4 percent), and 6.7 percent at the total proximal femur (95 percent confidence interval, 4.4 to 9.1 percent) as compared with base-line values Cohen, A., E. M. Stein, et al. "Teriparatide for idiopathic osteoporosis in premenopausal women: a pilot study." J Clin Endocrinol Metab 98 (5): 1971-81. BMD increased at the spine (10.8 +/- 8.3% [SD]), 71% increase in trabecular bone stiffness 12

11/4/16 ANTI-SCLEROSTINS • Glycoprotein secreted by osteocytes • Inhibits the wnt pathway • Increases RANK-L • Inhibits bone formation McClung, M. R., A. Grauer, S. Boonen, M. A. Bolognese, J. P. Brown, A. Diez-Perez, B. L. Langdahl, J. Y. Reginster, J. R. Zanchetta, S. M. Wasserman, L. Katz, J. Maddox, Y. C. Yang, C. Libanati and H. G. Bone (2014). "Romosozumab in postmenopausal women with low bone mineral density." N Engl J Med 370( 370(5) 5): 412 412-420. 420. • overall initial mean graft volume was 6251 mm3 • decreased to 2842 mm3 by 18 months after surgery (P < 0.001) • more than one half of the initial graft bone volume was being absorbed during the consolidation processes of the graft bone 13

11/4/16 Spine (Phila Pa 1976). 2013 Apr 15;38(8):696-702. 54 55 56 14

11/4/16 • Alendronate vs. Vit D • N=40 randomized; osteoporosis; PEEK + TCP + autograft • 95% alendronate vs 65% Vit D fusion rate 5 8 15

11/4/16 • Animal studies show that bisphosphonates impede fusion maturation • Unclear effect on mechanical strength • Not demonstrated in one human paper INTRA-OP CONSIDERATIONS • maximize pull-out strength of pedicle screws - optimal trajectory (fit and fill pedicle) • augment UIV+1 (increases stiffness - prevents creep) • augment UIV - increases pull out strength of prox screws • maintain posterior ligamentous structure intact - prevent lig failure • multiple osteotomies to generate a harmonious and balanced curve across the TL junction (dont end in kyphosis) • bilateral S2-alar-iliac bolts • optimal choice of bonegraft / bonegraft substitute 16