This document summarizes a study comparing total disc replacement (TDR) to spinal fusion for treatment of degenerative disc disease. 256 patients were randomized to receive either TDR or fusion. At 24 months, 58.8% of TDR patients met all success criteria compared to 47.8% of fusion patients, demonstrating TDR was not inferior. TDR resulted in greater improvement in disability scores and higher rates of neurological success at earlier time points. Complication rates were low for both groups. The study provides evidence that TDR is a viable alternative to fusion for treating degenerative disc disease.

1. INTER-VERTEBRAL DISC
REPLACEMENT
Dr. Madhusudhan NC
Resident-Dept. of Orthopaedic Surgery
Bangalore Baptist Hospital

2. Known is a drop……….
Unknown is an ocean………..

3. Ultra-New Concept….
Campbell….. 2 paragraph.
But..,
1. Journals. Gives a lot of
2. Internet. information

4. How we’ll proceed…
1. Anatomical + Physiological aspects of Inter-vertebral
disc.
2. What is TDR?
3. TDR vs. Arthrodesis.

5. Intervertebral Disc
Function:
1. Allows spinal motion and provides stability.
2. Links adjacent vertebral bodies together.
3. Responsible for 25% of spinal column height.
Parts:
1. Annulus fibrosis.
2. Nucleus pulposes.

6. Annulus fibrosis:
1. Outer structure that encases the nucleus pulposus
2. Composed of type I collagen that is obliquely
oriented, water, and proteoglycans
3. Characterized by high tensile strength and its ability to
prevent intervertebral distraction
4. Remains flexible enough to allow for motion
5. High collagen / low proteoglycan ratio (low % dry weight
of proteoglycans)
6. Fibroblast-like cells
*Responsible for producing type I collagen and
proteoglycans

7. Nucleus pulposus:
1. Central portion of the intervertebral disc that is surrounded by the
annulus fibrosis
2. Composed of type II collagen, water, and proteoglycans
Approximately 88% water
3. Hydrophilic matrix is responsible for height of the intervertebral disc
4. Characterized by compressibility
A hydrated gel due to high polysacharide content and high
water content (88%)
Proteoglycans interact with water and resist compression
Viscoelastic matrix distributes the forces smoothly to the annulus and
the end plates
5. Low collagen / high proteoglycan ratio (high % dry weight of
proteoglycans)
6. Chondrocyte-like cells
Responsible for producing type II collagen and proteoglycans
Survive in hypoxic conditions

8. Blood supply:
1. The disk is avascular with capillaries terminating at the
end plates
2. Nutrition reaches nucleus pulposus through diffusion
through pores in the endplates
Annulus is not porous enough to allow diffusion
Innervation:
1. The dorsal root ganglion gives rise to the sinuvertebral
nerve which innervates the superficial fibers of annulus
No nerve fibers extend beyond the superficial fibers
2. Neuropeptides thought to participate in sensory
transmission include
Substance P, Calcitonin, Vip,Cpon
Fixation:
1. Attached to vertebral bodies by hyaline cartilage

9. Disc:
*Viscoelastic characteristics
Demonstrates creep which allows for deformity over time
Demonstrates hysteresis which allows for energy absorption with repetitive
axial compression
This property decreases with time
Stresses:
*Annulus fibrosus
Highest tensile stresses
*Nucleus pulposus
Highest compressive stress
*Intradiscal pressure is position dependent
Pressure is lowest when lying supine
Pressure is intermediate when standing
Pressure is highest when sitting and flexed forward with weights in the hands
When carrying weight, the closer the object is to the body the lower the
pressure
Stability:
*Following subtotal discectomy, extension is most stable loading mode

10. Pathoanatomy
Disc herniation:
 Herniated disks are associated with a spontaneous
increase in the production of :
*Osteoprotegrin (OPG)
*Interleukin-1 beta
*Receptor activator of nuclear factor-kb ligand (RANKL)
*Parathyroid hormone (PTH)

11.  Disc aging leads to an overall loss of water content
and conversion to fibrocartilage. Specifically there is
a
1. Decrease in
*Nutritional transport
*Water content
*Absolute number of viable cells
*Proteoglycans
*pH
2. Increase in
*An increase keratin sulfate to chondroitin sulfate ratio
Lactate
*Degradative enzyme activity
3. No change in
*Absolute quantity of collagen

12. With this knowledge…..
TDR will be studied under following headings!
1. What is it and why is it important?
2. What Artificial Disc Implants are Currently
Available, and What are Their Differences?
3. How is Lumbar Artificial Disc Replacement
Performed?
4. Do Artificial Disc Implants Restore Normal
Spinal Mobility?
5. Does Artificial Disc Replacement Prevent
the Development of Adjacent Segment
Disease?
6. Fusion Vs Replacement – An Article review.

13. 1. What is it and why is it important?
Answer- Yes!
Review these statistics:
Degenerative Disc Disorder - Low Back Ache
*A major public health problem
*The leading cause of disability for people < 45
*2nd leading cause for physician visits
*3rd most common cause for surgical procedures
*5th most common reason for hospitalizations
*Lifetime prevalence: 49%–80%.

14. What made us to think about Replacement when
we already had a procedure for that?
The draw-backs of Arthrodesis:
1. Alters the biomechanics of the spine.
2. Loss of motion and overall shift in the sagittal
alignment.
3. Induces degenerative changes in the nearby
spinal motion segments.

15. 2nd Reason:
The draw-backs of Arthrodesis:
1. Alters the biomechanics of the spine.
2. Loss of motion and overall shift in the sagittal
alignment.
3. Induces degenerative changes in the nearby
spinal motion segments.

16. 1. Disc removal , assuming it to be the main source of pain
2. Restoration of disc height (increase the foraminal diameter,
relieve loads across the facet joints and improve the pattern of
load bearing between vertebrae)
3. Segmental stability
4. Preservation or improvement of segmental motion
5. Lordosis curve (rebalance the spine - preserves the motion,
protect adjacent segment from accelerated degeneration.)
6. Limit disability & early return to work.

17. 2. What Artificial Disc Implants are Currently
Available, and What are Their Differences?
1. Charite artificial disc (Depuy Spine) was the first
implant approved for lumbar disc replacement
in the USA. It received approval by the Food and
Drug Administration (FDA) for use in October of
2004.
2. The Prodisc-L (Synthes Spine) has just recently
received FDA approval (August 2006) and is just
now being used clinically outside of the FDA
research study.

21. Pro Disc L allowing movement during flexion and extension

22. Lateral views of Lumbar spine of a 38 yr old treated with ProDisc L Total Disc
Replacement at L3 -4 and L4-5 level made at end of 24 month follow up .
X Rays are taken in Neutral , Flexion and in Extension of lumbar spine.

23. Pro Disc L Maverick disc

24. 3. How is lumbar artificial disc replacement
performed?
1. Placed into the disc space from the front and
center position.
1. The surgical approach…… Incision.
2. Major blood vessels

25. 4. Do artificial disc implants restore normal
Spinal mobility?
1. Does not replicate "normal" spinal motion per
se.
2. There have been some reports that patients who
have had artificial disc replacement surgery have
accelerated posterior facet joint degeneration.

26. 5. Does Artificial Disc Replacement Prevent the
Development of Adjacent Segment Disease?
1. Theoretical benefit.
2. Needs longer follow-up and studies.

27. 6. Fusion Vs. Replacement – An Article review.
The Journal of Bone & Joint Surgery. 2011; 93:705-
715 doi:10.2106/JBJS.I.00680

28. MATERIAL & METHOD
• From January 2002 to June 2004, a total of 256 patients
were randomized by 38 spine surgeons at 16 sites
across the United States.
• Blocked randomization was performed in a controlled
design
• with use of a 2:1 ratio of total disc arthroplasty to
circumferential arthrodesis
• Overall, 237 patients (165 in the total disc replacement
group & 72 in the arthrodesis group) were treated.
• At the end of the study of 24 months a total of 203
patients (including 143 in the total disc replacement
group and 60 in the arthrodesis group were available.

29. FLOW CHART of STUDY PATTERN

30. STUDY DESIGN
Inclusion criteria
• With degenrative disc
disease at two levels from
L3 to S1.
• Patients who had minimum
of 6 months of unsuccessful
nonoperative treatment
• +/- Leg pain
• With a minimum oswestry
disability index ODI score of
>_ 40
Exclusion criteria
• Spondylolisthesis >grade I,
• Degenerative disc disease
at more than two levels,
• Previous arthrodesis
• Inability to comply with the
study protocol.

31. Degenerative Disc Disease includes :
• Lumbar spine instability,
• loss of intervertebral disc height,
• scarring of the annulus fibrosus,
• herniated nucleus pulposus,
• vaccum phenomenon of disc
Investigation modes :
• Flexion-extension Radiographs,
• Computed Tomography (CT),
• Magnetic Resonance Imaging (MRI),
• Discography,
• Myelography

32. STUDY PATTERN
• Study approval was obtained from each site's institutional
review board prior to the start of the study. Patient
randomization was performed with use of a 2:1 ratio of TDR
to circumferential arthrodesis.
• Patients in the investigational group were managed with TDR
at both levels.
• The control group was managed with a two-level anterior
lumbar interbody arthrodesis with use of a commercially
available femoral ring allograft and posterolateral
arthrodesis with autogenous iliac crest bone graft in
combination with pedicle screw instrumentation.

33. STUDY GROUP V/S CONTROL GROUP

34. Demographic characteristics Total Disc
Replacement
(N = 165)
Arthrodesis
(N= 72)
P Value *
Sex No. of patients 0.6701
Male 95 39
Female 70 33
Age (yrs) 41.8+_ 7.73 41.8 +- 7.81 0.9745
Body mass Index (kg/m2) 27+-4.52 27.1+_4.05 0.8723
Smoking status 0.1373
Never 86 29
Former 31 21
Current 47 22

35. Demographic characteristics Total Disc
Replacement
(N = 165)
Arthrodesis
(N= 72)
P Value *
Previous surgical treatment 0.8864
None 96 43
Any 69 29
Discectomy 32 13
Intradiscal electrothermic theraphy 17 7
Laminectomy 31 9
Laminotomy 4 2
other 12 8

36. Demographic characteristics Total Disc Replacement
(N = 165)
Arthrodesis
(N= 72)
P Value*
Previous conservative treatment 0.9436
injection 127 52
Physical therapy 135 61
Corset/Brace 68 28
chiropractic 60 28
other 35 12
Duration of pain in the Back / leg 0.6145
< 6 months 1 0
6 months to 1 year 16 4
> 1 year 148 68

37. Components of Composite End Point at 24 Months
1. >_ 15% improvement in ODI compared with baseline
2. Improvement in SF-36 PCS compared with baseline
3. Neurological status improved or maintained from baseline
4. No secondary surgical procedures to remove or modify the total disc
replacement implant or arthrodesis implant/site
Radiographic success
5. No subsidence >3 mm
6. No migration >3 mm
7. No radiolucency/loosening
8. No loss of disc height >3 mm
Motion status
9. Total disc replacement: range of motion improved or maintained
from baseline
10.Arthrodesis: no motion (<10° angulation, total for two levels
combined) on flexion and extension radiographs

38. OSWESTRY DISABILITY INDEX - ODI
 Pain intensity
 Personal care
 Lifting
Walking
 Sitting
 Standing
 Sleeping
 Sex life
 Social life
 Travelling
 0 to 20 % Minimal disability
 21 to 40 % Moderate
disability
 41 to 60 % Severe disability
 61 to 80% crippled
 81 to 100 % Bed bound

39. Clinical Outcome Measurements
1. Patient was clinically evaluated preoperatively, at 6 weeks
postoperatively, and at 3,6,12,18,24 months postoperatively.
2. Every visit included physical and neurological examinations,
radiographic evaluation, determination of medication use,
work and recreation status, and completion of self-assessment
questionnaires (including the odi, short form of the medical
outcomes study [sf-36], and visual analog scales [vas] for pain
and satisfaction.
3. Physical and neurological examinations were performed to
assess nerve root tension, reflexes, muscle strength, and
sensory deficits. Radiographic evaluation consisted of neutral
anteroposterior and lateral views, flexion-extension views, and
lateral bending views.

40. Radiographic Outcomes
1. The radiographic outcomes that were assessed included
2. Device migration ( 1 anterior migration of the superior
arthroplasty implant)
3. Device subsidence(3 patients in TDR of > 3 mm-clinically
insignificant),
4. Disc height,
5. Radiolucency around the implant,
6. Fusion status in the arthrodesis group
*Flexion-extension range of motion in the tdr group averaged
 7.8° ± 5.3° at the level of the superior disc
 6.2° ± 4.1° at the level of the inferior disc

41. Outcome:
1. At twenty-four months, eighty-seven (58.8%) of 148
patients in the total disc replacement group and thirty-two
(47.8%) of sixty-seven patients in the arthrodesis group met
all ten criteria and were considered a study succes
2. At six months, the percentage of patients with
neurological success was significantly higher in the tdr
group (87.3%; 131 of 150) than in the arthrodesis group
(71.6%; forty-eight of sixty-seven) (p = 0.0068).
3. Overall, four (2.4%) of 165 patients in the total disc
replacement group and six (8.3%) of seventy-two patients in
the arthrodesis group required a secondary surgical
procedure at the index level or levels.

42. Outcome: (cont.)
4. The total disc replacement group demonstrated
significantly greater improvement than the
arthrodesis group did at all follow-up time points

43. Complications
1. Major surgery-related complications included one dural tear
in the total disc replacement group (0.6%; 1/165) and 3 dural
tears in the arthrodesis group (4.2%; 3/72).
2. Blood loss of >1500 ml occurred in 2/165 (1.2%) of patients
in the TDR group and 2/72(2.8%) of patients in the arthrodesis
group.
3. One of the two patients in the total disc replacement group
sustained an iliac artery tear
4. One patient in the total disc replacement group and the 2
patients in the arthrodesis group had excessive oozing from the
decompression, decorticated bone, and graft sites.
5. Postoperatively dvt was reported in 2/165 (1.2%) .Of
patients in the tdr group and 2/72 (2.8%) of in the arthrodesis
group

44. RESULTS:
1. At twenty-four months, 58.8% (87/ 148 )patients in the
TDR group were classified as a statistical success, compared
with 47.8% (32/67)patients in the arthrodesis group; non-inferiority
was demonstrated.
CONCLUSION:
1. Despite the relatively short duration of follow-up and
design limitations, the present study suggests that two-level
lumbar disc arthroplasty is an alternative to and offers
clinical advantages in terms of pain relief and functional
recovery in comparison with arthrodesis.
2. Longer-term follow-up is needed to determine the risks for
implant wear and/or degenerative segment changes.

45. THANK YOU