Preoperative Bone Health Assessment in Spine Fusion Surgery
Preoperative Bone Health
Assesment
Mark L Prasarn MD
Professor and Chief Division of Spine Surgery
Dept. of Orthopaedic Surgery
University of Texas, Houston
Objectives
•
At the end of the presentation the participant should:
1.
Gain some understanding of spine fusion surgery and the
potential bone related complications in older patients
2.
Become comfortable with preoperative bone health
assessment in patients undergoing spine fusion surgery
3.
Be familiar with the literature of osteoporosis drugs and
their impact on spine fusion success and complications
64 y.o. Farmer
Three main properties for fusion
•
Osteogenesis
•
Ostoconduction
•
Osteoinduction
Favorable Biomechanical Environment
Spine Fusion: Definition
•
Spine Fusion (arthrodesis):
–
A surgical procedure to provide internal stability of the spine, by
facilitating bony interconnection between two or more of the
vertebra, leading to absence of motion between these
segments.
•
Indications:
–
Degenerative diseases of the spine:
•
Instability, neurologic compression,
–
Deformity: scoliosis, kyphosis, spondylolisthesis
–
Trauma or tumor
Osteogenesis
•
Cells differentiating into osteogenic
lineage
•
Relies upon undifferentiated cells
•
Mature osteoblasts can revert to less-
differentiated cells
•
Blood vessels important source –
perivascular origin of MSCs
Osteoinduction
•
Molecules (GFs) induce MSCs to amplify
•
And to differentiate into osteoprogenitor cells
•
Most significant are TGF superfamily
•
Include well-known BMPs
Osteoconduction
•
Complementary to osteogenesis and
osteoinduction
•
Tridimensional scaffold structure of bone or
bone substitute
•
Scaffolding for cell population growth
Fusion Formation
•
Combination of Intramembranous and
Enchondral Ossification
•
Three distinct phases
–
Early (inflamation) phase
–
Middle (reparative) phase
–
Late (remodeling) phase
Boden et al. Spine 1995
Bone grafts, extenders, osteobiologics
•
Aid in fusion via:
–
Osteogenesis
–
Osteoinduction
–
Osteoconduction
–
Osteopromotion
Autograft
•
Still the gold standard!
•
First used in fusion by Hibbs 1911
•
Has all properties necessary
•
Low cost
•
No concern of disease transmission or
compatibility
•
High fusion rates (40-100%)
•
Downside is complications
Donor site pain
•
Often performed by the inexperienced
•
Higher incidence in those with persistent pain
–
Likely psychological component
–
Summers and Eisenstein JBJS 1989
•
Greater incidence in lower fusion levels
–
Delawi et al. Spine 2007
•
51% incidence of pain in those with no harvest
–
Concordant pain only 19%
–
Howard et al. TSJ 2011
Osteoinductive agents
•
BMP-2 and BMP-7
•
BMP-2 on-label for ALIF w/ LT-cage
•
BMP-7 on-label revision PLF in “compromised
host” or those not feasible for bone harvest
•
Myriad of problems and complications, in
addition to high cost!
•
DBMs
Stem cells for fusion
•
“Stem cells” – BMA, Fat, Muscle, PB, Amniotic
•
All of which may or may not have MSCs
•
May use as blood product w minimal
manipulation
•
Need osteodifferentiation
•
“Real stem cells” – need to be manipulated
•
Not approved (even autologous)
•
Clinical trial in progress
Conclusion
Spinal Stenosis
•
Narrowing of the spinal canal
DJ 4705 Rev 1
Spondylolisthesis
•
Forward translation
of one vertebral
body with respect to
another
•
Most common in
lower lumbar spine
DJ 4705 Rev 1
Listhesis vs. Lysis
•
Spondylolisthesis
–
Slippage of one
vertebral body on
another
•
Spondylolysis
–
Defect of the pars
interarticularis
DJ 4705 Rev 1
Spondylolisthesis
Operative Management
•
In situ
Non
instrumented
posterolateral fusion
•
64
%
fusion rate
DJ 4705 Rev 1
Herkowitz et al. JBJS 1991
Spondylolisthesis
Operative Management
•
Posterolateral fusion with
pedicle screws
•
87%
fusion rate
DJ 4705 Rev 1
Fritzell et al. Spine 2002
Fischgrund et al. Spine 1997
Mardjetko et al. Spine 1994
Anterior Column Support
Use anterior implant
–
Restore/maintain integrity
of anterior spinal column
DJ 4705 Rev 1
Anterior / Middle Columns
•
80% compressive
load through
anterior and middle
columns
•
90% surface area
DJ 4705 Rev 1
Interbody Fusion:
Biomechanical, Anatomic, Physiologic
•
Restoration of disc space height
•
Correction of alignment and balance
•
Prevents progression of subluxation
•
Provides load sharing
•
Prolongs life of posterior instrumentation
•
Higher fusion rate
DJ 4705 Rev 1
Spondylolisthesis
Operative Management
•
Posterposterololateral fusion with
pedicle
screws
and
interbody fusion
•
91%
fusion rate
DJ 4705 Rev 1
Lee et al. Clin Orthop Surg 2011
Anterior
Posterior
Interbody Fusion Devices
DJ 4705 Rev 1
ACRONYMS!
•
PLF
•
TLF
•
ALIF
•
XLIF
What is the Difference???
Complications…
•
Fusion Failure (pseudoarthrosis)
•
Construct/Device failure (pedicle screw
loosening, interbody device subsistence)
•
Proximal Junctional Kyphosis due to
compression fracture of adjacent
vertebral level
Risk factors for complications
•
Old age
•
Large spondylolisthesis slip angle
•
Smoking
•
Infection
•
Excessive motion
Fusion Failure - Pseudarthrosis
Screw loosening and interbody cage subsistence are potential complications
that may be due in part to poor bone health leading to pseudarthrosis.
Pre-operative Bone Health Assessment
Prior to Elective Spine Surgery
•
Maybe women over 60? Men over 70?
•
All with diagnosis of Osteoporosis
•
Those with compression fxs from low energy
•
All patients with chronic glucocorticoid
exposure
•
Smokers
•
Major deformity surgery
Teriparatide – What does it do?
•
PTH is 84 AA protein
–
Regulates Ca++
–
1 alpha hydroxylation 25-hydroxyvitamin D
•
Receptors on osteoblasts for PTH
–
NF-kB (RANK) ligand
–
RANK on osteoclasts
Important for homeostasis and bone
remodeling
The PTH paradox – How does it work?
•
PTH – results in depletion of Ca++ from bone
•
Pattern of exposure determines skeletal
effects
•
Sustained
1° Hyperparathyroidism
•
Intermittent
paradoxical effect
•
Peak in 30 mins, and declines to non-
detectable over 3 hrs
Bone Remodeling
Osteoid
Osteoclasts -
resorption cavity
Osteoblasts –
Secrete osteod
Mineralized bone
Teriparatide Effects
Normal Homeostasis
Teriparatide Effects
Preferential stimulation
Osteoblasts
Positive Balance
When given as Forteo – Intermittent dosing
Forteo Fracture Prevention Trial
•
Prospective, random, Double Blind
•
Placebo (N=544), Forteo 20 mcg/day (N=541)
•
Duration of 18 months
•
Supplemental Ca++ and Vit D
•
Endpoints – vertebral fx, nonvertebral fx,
BMD, safety
Neer et al. NEJM 2001
Results
•
Increased L-spine BMD (Anabolic) – 9.7%
•
Risk reduction
–
Vertebral fx (RRR 65%)
–
Non-vertebral new fx (RRR 53%)
Neer et al. NEJM 2001
Anabolic Effect
After 21 months of Forteo
Neer et al. NEJM 2001
Who should get Forteo?
•
On-label = Osteoporosis at high fx risk
•
Failure on other anitresorptive tx
•
Those who continue to lose bone mass or
have very low T-scores despite tx
•
Cannot tolerate bisphosphonates
•
Glucocorticoid treated pts with fractures
Who should not get it?
•
Open epiphyses
•
Paget disease
•
Prior XRT
•
Hx of Osteosarcoma
•
Increased Alk Phos
•
Primary hyperparathyroidism
•
Pregnant or breast feeding
•
Renal impairment
Difficult Fractures
•
102 women with colles fxs
•
20 or 40 μg/kg dose
•
9.1, 7.4, 8.8 weeks to healing
•
Shorter time to healing with 20 μg/kg group
versus control (p=0.006)
•
Prospective randomized every 1/3
•
21 elderly pts with pelvic fxs 100 μg dose PTH
•
7.8 vs. 12.6 weeks (p<0.001)
•
At 8 weeks (CT) healed in 100% vs. 9.1%
•
Retrospective review of 43 pts
•
Very difficult to get to heal
•
Good results with adjunctive Forteo
•
Still need good biomechanical environment!
Spine Fusion
•
Does it help?
•
Is it cost effective?
•
$1800-3200 per month
•
Pedicle screws can be upwards of 4K each!
•
What’s the cost of failed back –
psuedarthrosis, nonunion, future fractures?
•
Posterolateral rabbit fusion model
•
Intermittent PTH (10 μg/kg)
•
Fusion rate 81% vs 30%
•
MicroCT – 6.0 cc vs. 3.5 cc
•
Histology – twice the bone percentage area
Control vs. Teriparatide
Control
Teriparatide
Fusion Results
•
Manual biomechanical testing
–
Sagittal bending
–
Coronal bending
–
Torsion
p< .001
•
Ovariectomized osteoporotic rat model
•
30 μg/kg dose PTH
•
Higher fusion rate
•
Greater fusion bone volume
•
Higher cortical thickness
•
Faster healing time
•
20 μg/kg/day or 56.5 μg/kg/week in 29 pts
•
Mean 61 days prior, but minimum 31
•
Increased insertional torque as compared to
control
•
N
o significant difference between the daily
and the weekly teriparatide groups
•
57 women w/ 1-2 level surgery
•
29 received daily TPTD 20 mcg/d and 28 received
risedronate weekly 17.5 mg. Medications were started 2
months prior to surgery and continued for 8 months post-
operatively.
•
The rate of bone union was 82% in the TPTD group and 68%
in the risedronate group at one year
•
Symptoms were better inTPTD group as well
•
45 women with osteoporosis treated for degenerative
spondylolisthesis then short-duration TPTD, long-duration TPTD, and
bisphosphonate
•
All patients underwent PLF with a local bone graft. Fusion rate and
duration of bone union were evaluated 1.5 years after surgery.
•
Bone union rate and average duration for bone union were 92% in the
long-duration treatment group, 80% in the short-duration treatment
group, and 70% in the bisphosphonate treatment group, respectively.
•
Multicenter prospective study
–
75 female pts
–
>50 w Osteoporosis
•
Weekly TPTD for 6 months, Control
•
At 4 mos TPTD showed better fusion in cage in
center
•
Decreased bone resorption based on markers
•
62 postmenopausal women undergoing decompression and
1-2 level fusion were given either risedronate 2.5 mg/d,
TPTD 20 mcg/d or no medication for osteoporosis. OP
medications were given 2 months prior to surgery and 10
months post-operatively
•
The incidence of pedicle screw loosening in the teriparatide
(7-13%) group was significantly lower than that in the
risedronate (13-26%) or the control group (15-25%) (P <
.05)
•
76 patients treated for ASD with fusion, 43 received TPTD right
after revision surgery
•
X-rays, DEXA, CT obtained to look at UIV+1
•
H
ip-bone mineral density (BMD) increased from 0.721 to 0.771
g/cm2 in the TP group and decreased from 0.759 to 0.729 g/cm2
in the control group
•
The bone volume/tissue volume ratio increased from 46 to 54 %
in the TP group, and the trabecular bone thickness and number
increased by 14 and 5 %, respectively.
•
At the 2-year follow-up, the PJK type 2 incidence was significantly
lower in the TPTD group(4.6%) than in the control
group(15.2%;p=.02).
•
40 patients randomized to ALN
35 mg/wk vs Vit D
•
Single level PLIF with cage device
•
CT bridging across levels graded
A, B and C
•
Followed for one year
•
Also looked at vertebral
fractures and cage subsidence
Results Continued
•
There was no pedicle screw loosening reported in either arm
•
There were fewer adjacent fractures in the ALN arm zero vs 4 in Vit
D arm
•
Cage subsistence was seen in one ALN patient and 5 Vit D patients
•
No significant difference in the Oswestry scores between groups. 3
in ALN group did poorly and 4 in D group did poorly (less than 20%
improvement)…in those that did poorly pseudoarthrosis and
vertebral compression fractures were common
Conclusion: ALN in patients with OP undergoing spine fusion reduces
subsequent vertebral compression fractures and cage subsidence. The
mechanical circumstances of ALN treatment postop may overcome any
potential detrimental biological effect on bone healing.
Seventy-nine patients were randomized to
zolendronic acid (5 mg) or saline.
Radiographic bone bridging was graded A
(complete), B (bridging with 1 body),
C (
incomplete)
dy) or C (incomplete bone
bridging)
•
Review of 156 patients at Mayo (42 TPTD)
•
Revision, PJK, PJF, Pseudo, screw loosening, Fx
•
TPTD was associated with lower risk of
complications at 2 year f/u (ASD, pseudo, 30 day
readmission, related 2 year reoperations
•
Higher PJK and PJF, but more levels in TPTD
group
Conclusions
•
Teriparatide prevents future fractures in those
with osteoporosis (On-label use)
•
Off label:
–
May improve spinal fusion (need more human
studies)
–
May be useful in deformity surgery
–
May improve fx healing
Review Article
Another one
My practice
•
Always discuss things can go wrong
•
Still use ICBG or local bone for the majority of
posterior fusions (Autograft)
•
Very little BMPs
•
Allograft with DBM for long fusions
•
Some Teriparatide/Aboloparatide, All Vit
D/Ca++
Get them to quit smoking!
Thank you
This presentation by Dr. Mark L. Prasarn focuses on the importance of assessing preoperative bone health in older patients undergoing spine fusion surgery. It covers the potential bone-related complications, osteogenesis process, osteoconduction, osteoinduction, and the favorable biomechanical environment required for successful fusion. The objectives include understanding spine fusion surgery, preoperative assessment techniques, and the impact of osteoporosis drugs on surgery outcomes.
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Presentation Transcript
Preoperative Bone Health Assesment Mark L Prasarn MD Professor and Chief Division of Spine Surgery Dept. of Orthopaedic Surgery University of Texas, Houston
Objectives At the end of the presentation the participant should: 1. Gain some understanding of spine fusion surgery and the potential bone related complications in older patients 2. Become comfortable with preoperative bone health assessment in patients undergoing spine fusion surgery 3. Be familiar with the literature of osteoporosis drugs and their impact on spine fusion success and complications
Three main properties for fusion Osteogenesis Ostoconduction Osteoinduction Favorable Biomechanical Environment
Spine Fusion: Definition Spine Fusion (arthrodesis): A surgical procedure to provide internal stability of the spine, by facilitating bony interconnection between two or more of the vertebra, leading to absence of motion between these segments. Indications: Degenerative diseases of the spine: Instability, neurologic compression, Deformity: scoliosis, kyphosis, spondylolisthesis Trauma or tumor
Osteogenesis Cells differentiating into osteogenic lineage Relies upon undifferentiated cells Mature osteoblasts can revert to less- differentiated cells Blood vessels important source perivascular origin of MSCs
Osteoinduction Molecules (GFs) induce MSCs to amplify And to differentiate into osteoprogenitor cells Most significant are TGF superfamily Include well-known BMPs
Osteoconduction Complementary to osteogenesis and osteoinduction Tridimensional scaffold structure of bone or bone substitute Scaffolding for cell population growth
Fusion Formation Combination of Intramembranous and Enchondral Ossification Three distinct phases Early (inflamation) phase Middle (reparative) phase Late (remodeling) phase Boden et al. Spine 1995
Bone grafts, extenders, osteobiologics Aid in fusion via: Osteogenesis Osteoinduction Osteoconduction Osteopromotion
Autograft Still the gold standard! First used in fusion by Hibbs 1911 Has all properties necessary Low cost No concern of disease transmission or compatibility High fusion rates (40-100%) Downside is complications
Donor site pain Often performed by the inexperienced Higher incidence in those with persistent pain Likely psychological component Summers and Eisenstein JBJS 1989 Greater incidence in lower fusion levels Delawi et al. Spine 2007 51% incidence of pain in those with no harvest Concordant pain only 19% Howard et al. TSJ 2011
Osteoinductive agents BMP-2 and BMP-7 BMP-2 on-label for ALIF w/ LT-cage BMP-7 on-label revision PLF in compromised host or those not feasible for bone harvest Myriad of problems and complications, in addition to high cost! DBMs
Stem cells for fusion Stem cells BMA, Fat, Muscle, PB, Amniotic All of which may or may not have MSCs May use as blood product w minimal manipulation Need osteodifferentiation Real stem cells need to be manipulated Not approved (even autologous) Clinical trial in progress
Spinal Stenosis Narrowing of the spinal canal DJ 4705 Rev 1
Spondylolisthesis Forward translation of one vertebral body with respect to another Most common in lower lumbar spine DJ 4705 Rev 1
Listhesis vs. Lysis Spondylolisthesis Slippage of one vertebral body on another Spondylolysis Defect of the pars interarticularis DJ 4705 Rev 1
Spondylolisthesis Operative Management In situNon instrumented posterolateral fusion 64% fusion rate Herkowitz et al. JBJS 1991 DJ 4705 Rev 1
Spondylolisthesis Operative Management Posterolateral fusion with pedicle screws 87% fusion rate Fritzell et al. Spine 2002 Fischgrund et al. Spine 1997 Mardjetko et al. Spine 1994 DJ 4705 Rev 1
Anterior Column Support Use anterior implant Restore/maintain integrity of anterior spinal column DJ 4705 Rev 1
Anterior / Middle Columns 80% compressive load through anterior and middle columns 90% surface area DJ 4705 Rev 1
Interbody Fusion: Biomechanical, Anatomic, Physiologic Restoration of disc space height Correction of alignment and balance Prevents progression of subluxation Provides load sharing Prolongs life of posterior instrumentation Higher fusion rate DJ 4705 Rev 1
Spondylolisthesis Operative Management Posterposterololateral fusion with pedicle screws and interbody fusion 91% fusion rate Lee et al. Clin Orthop Surg 2011 DJ 4705 Rev 1
Interbody Fusion Devices Anterior Posterior DJ 4705 Rev 1
ACRONYMS! PLF TLF ALIF XLIF What is the Difference???
Complications Fusion Failure (pseudoarthrosis) Construct/Device failure (pedicle screw loosening, interbody device subsistence) Proximal Junctional Kyphosis due to compression fracture of adjacent vertebral level
Risk factors for complications Old age Large spondylolisthesis slip angle Smoking Infection Excessive motion
Fusion Failure - Pseudarthrosis Screw loosening and interbody cage subsistence are potential complications that may be due in part to poor bone health leading to pseudarthrosis.
Pre-operative Bone Health Assessment Prior to Elective Spine Surgery Maybe women over 60? Men over 70? All with diagnosis of Osteoporosis Those with compression fxs from low energy All patients with chronic glucocorticoid exposure Smokers Major deformity surgery
Teriparatide What does it do? PTH is 84 AA protein Regulates Ca++ 1 alpha hydroxylation 25-hydroxyvitamin D Receptors on osteoblasts for PTH NF-kB (RANK) ligand RANK on osteoclasts Important for homeostasis and bone remodeling
The PTH paradox How does it work? PTH results in depletion of Ca++ from bone Pattern of exposure determines skeletal effects Sustained 1 Hyperparathyroidism Intermittent paradoxical effect Peak in 30 mins, and declines to non- detectable over 3 hrs
Bone Remodeling Osteoclasts - resorption cavity Osteoblasts Secrete osteod Osteoid Mineralized bone
Teriparatide Effects Normal Homeostasis
Teriparatide Effects When given as Forteo Intermittent dosing Preferential stimulation Osteoblasts Positive Balance
Forteo Fracture Prevention Trial Prospective, random, Double Blind Placebo (N=544), Forteo 20 mcg/day (N=541) Duration of 18 months Supplemental Ca++ and Vit D Endpoints vertebral fx, nonvertebral fx, BMD, safety Neer et al. NEJM 2001
Results Increased L-spine BMD (Anabolic) 9.7% Risk reduction Vertebral fx (RRR 65%) Non-vertebral new fx (RRR 53%) Neer et al. NEJM 2001
Anabolic Effect After 21 months of Forteo Neer et al. NEJM 2001
Who should get Forteo? On-label = Osteoporosis at high fx risk Failure on other anitresorptive tx Those who continue to lose bone mass or have very low T-scores despite tx Cannot tolerate bisphosphonates Glucocorticoid treated pts with fractures
Who should not get it? Open epiphyses Paget disease Prior XRT Hx of Osteosarcoma Increased Alk Phos Primary hyperparathyroidism Pregnant or breast feeding Renal impairment
102 women with colles fxs 20 or 40 g/kg dose 9.1, 7.4, 8.8 weeks to healing Shorter time to healing with 20 g/kg group versus control (p=0.006)
Prospective randomized every 1/3 21 elderly pts with pelvic fxs 100 g dose PTH 7.8 vs. 12.6 weeks (p<0.001) At 8 weeks (CT) healed in 100% vs. 9.1%
Retrospective review of 43 pts Very difficult to get to heal Good results with adjunctive Forteo Still need good biomechanical environment!
Spine Fusion Does it help? Is it cost effective? $1800-3200 per month Pedicle screws can be upwards of 4K each! What s the cost of failed back psuedarthrosis, nonunion, future fractures?
Posterolateral rabbit fusion model Intermittent PTH (10 g/kg) Fusion rate 81% vs 30% MicroCT 6.0 cc vs. 3.5 cc Histology twice the bone percentage area
Control vs. Teriparatide Control Teriparatide
