Managing the Patient with Osteoporosis Undergoing Spinal MEDTRONIC - - PDF document

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Managing the Patient with Osteoporosis Undergoing Spinal Surgery

SHANE BURCH MD, MS, FRCSC Associate Professor in Residence UCSF Department of Orthopedic Surgery

DISCLOSURES

• MEDTRONIC
• LILLY
• MISONIX

OVERVIEW

1973 2000

LIFE IS A KYPHOSING EVENT

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OSTEOPOROSIS

• Described by the French pathologist Jean Georges Chretien

Frederic Martin Lobstein ‘the Younger’ (1777–1835)

• Greek words osteo (bone) and poros (little hole), referring to

the cavities which were observed by the pathologist in certain patients' bones

• a systemic disease characterised by low bone mass and

microarchitectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fracture

• D. Schapira, C. Schapira Osteoporosis: the evolution of a scientific term Osteoporos Int, 2 (1992), pp. 164–167

OSTEOPOROSIS

• Osteoporosis can be defined clinically by either:

– WHO - Low bone mineral density (BMD g/cm2) T-score of

• 2.5)

– A history of fragility fracture

• Fragility fracture is frequently described as a fracture
• ccurring as the result of minimal trauma or a fall from

standing height or less

NOT JUST BMD

Lumbar Vertebral Strength vs. Age

O.N. Diagnostics, Berkeley, CA

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BONE STRENGTH BONE STRENGTH

• BMD
• Morphology
• Mineralization
• Volume
• Architecture
• Turn-over rate

EULERS PRINCIPLE

16X STRONGER

VERTEBRAL COMPRESSION FRACTURES

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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

BURDEN

• 2 million fractures occur each year as a result of osteoporosis or
• steopenia, including

–300,000 hip fractures, –547,000 vertebral fractures –135,000 pelvic fractures.

• Postmenopausal white women have a 40% lifetime risk of at least one
• steoporotic fracture
• cost: $19,000,000,000 (2005)

Consequences are independent of acute fracture pain

IMPACT OF VCFS

• Impaired gait, poor balance
• Disability, reduced quality of life
• Reduced lung function
• Early satiety, gastric distress
• Future facture risk
• Excess mortality

Cauley, J. A., D. E. Thompson, et al. (2000). "Risk of mortality following clinical fractures." Osteoporos Int 11(7): 556-61.

Mortality following a VCF: RR=8.64

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UNDERTREATMENT

• 65,344 patients, mean age 65.7

year: dx - osteoporosis

• 42,033 patients (64.3%)

received no OP medication

• 23,311 patients (35.7%)

received OP treatment Substantial undertreatment among women diagnosed with

• steoporosis in a US managed care population: a

retrospective analysis." Siris, E. S., A. Modi, et al. " Curr Med Res Opin.

I have an enormous favor to ask you

ETIOLOGY

• Estrogen deficiency
• Osteoblasts proliferate
• Increase in RANKL
• Proliferation of osteoclasts
• Increase in bone turnover

CELL SIGNALLING SECONDARY OSTEOPOROSIS

• Hyperparathyroidism
• Chronic glucocorticoid use

(>3mo)

• Alcohol abuse (>3 / day)
• Smoking
• Low Ca intake
• Immobilization
• Diabetes (type I and II)
• Hypogonadism - men
• Ovarian failure

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TRENDS IN SPINE SURGERY FOR 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.

• increasing

trend to perform surgery in the elderly

INTERSECTION OF DISEASE

• steoporosis

spinal disorders

Surgical candidates

PREVALENCE OF SCOLIOSIS

• 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.

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OSTEOPOROSIS

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• 1300 cases reviewed over

age 50

• very common

– 15% males (46% with

• steopenia) vs 50%

female

PREVALENCE OF OSTEOPOROSIS IN SPINE PATIENTS

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.

Use Finite Element Analysis to Virtually Load to Failure

colored by local stiffness (red — high; blue — low) Wang JBMR 2012

CT BASED STRENGTH ASSESSMENT

FRACTURE RISK ASSESSMENT

• AGE
• HISTORY OF:

– Smoking – Prior Fracture – Family Hx – ETOH – Corticosteroid use

• BMD
• BONE TURNOVER

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Lindsay – Jama 2001

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)

PRIOR FRACTURE INCREASES RISK

Black – J Bone Min Res 1993

Increasing fracture risk with increasing deformity

FRACTURE DEFORMITY AND RISK

BONE ASSESSMENT

• DEXA - BMD
• QCT - BMD
• CT-FEA – BMD + strength
• Bone Volume – BV/TV
• Bone Formation: PINP
• Bone Resoption: CTX

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SURGICAL PERSPECTIVE

• “bone strength”

– screw pull out – adjacent fractures

• “fusion potential”

– MSCs + vascular supply – failure to fuse -

pseudarthrosis

CHANGING BIOLOGY

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

500,00 bone graft procedures performed in US /yr

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“Well we removed the growth, but the operation left you paralyzed from the neck down”

SYSTEMIC TREATMENT

• Anti-Resorptive
• Anabolic
• Bone Forming

CALCIUM / VIT D

National Osteoporosis Foundation Clinician’s guide to prevention and treatment

• f osteoporosis

National Osteoporosis Foundation, Washington, DC (2014)

BISPHOSPHONATES

• inhibition of farnesyl

pyrophosphate synthase

• interferes with

isoprenylation of small guanosine triphosphatases at ruffled border

• disrupts attachment and

promotes early apoptosis

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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

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ANTI-SCLEROSTINS

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.

• Glycoprotein secreted by
• steocytes
• Inhibits the wnt pathway
• Increases RANK-L
• Inhibits bone formation
• 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

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

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• Alendronate vs. Vit D
• N=40 randomized; osteoporosis; PEEK +

TCP + autograft

• 95% alendronate vs 65% Vit D fusion

rate

5 8

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• 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

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STIFFNESS

J Korean Neurosurg Soc. 2012 November; 52(5): 435–440.

FORTEO SPINE FUSION STUDY

• UCSF FDA trial: assessment of the use of FORTEO in patients undergoing

spinal fusion greater than two levels

• intermittent dose of PTH promotes osteoblasts over osteoclasts
• double blind randomized controlled trial

– >65; 2 or more levels; posterolateral fusion - Ct scan at 1 year – n=90; 20ug vs placebo daily injection – admin 2 weeks prior to fusion, 8 weeks after fusion

SUMMARY

• Osteoporosis is a pandemic
• Not all about BMD
• Systemic therapy – we should be part of the choice

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Thank You

THANK YOU