MRI CHANGES OF INTERVERTEBRAL DISCS AFTER CEMENT AUGMENTATION

M. A. König, S. Panzer, J Schulz, M. Bierschneider, H. Jaksche, B. M. Boszczyk

Centre for Spinal Studies and Surgery Nottingham University Hospitals Nottingham UK

Dept. of Radiology and Neurosurgery Traumacenter Murnau Germany

Centre for Spinal Studies & Surgery, Nottingham www.nottinghamspine.co.uk

Disc hydration: The intervertebral discs are the largest structures in the human body depending on diffusion The nutrition takes place mainly through endplate diffusion Cement augmentation could influence endplate diffusion

Endplate is main route of solute transport into disc Van der Werf et al. J Anat 2007

Does PMMA augmentation lead to disc degeneration?

PMMA augmented vertebral body

Patient collective Hospital record review for patients treated with KP for fractures in 2002, 2003 with in house MRI 15 patients were identified and included in the study (f/m 10/5; mean age at surgery 67.1±6.9 yrs) In total, 3 traumatic and 20 osteoporotic fractures were treated with cement augmentation 43 discs were examined. 3 discs were in-between bi-segmental cement augmentations

MRI Evaluation MRI scans were performed pre-operatively in the osteoporotic patients. All patients had a post-operative follow-up after 15.2±5.5 months. 7 patients had a long-term MRI follow-up after 85.7±10.9 months. All pre-operative and post-operative MRI scans were performed with the same MRI machine (1.0 Tesla Magnetom Expert, Siemens, Erlangen, Germany). The long-term follow-up MRI scans were perfomed with the same MRI machine (1.5 T MRT Achieva,Philips Medical Solutions, Best, The Netherlands).

Disc evaluation with two classifications: Discs with pre-op endplate injury: Oner classification grades (1-4)

Pre-op Non-injured discs and all discs at follow-up: Pfirrmann grades (1-5)

Oner et al. Spine 2002 Pfirrmann et al. Spine 2001

Results: 3 discs were in-between bi-segmental cement augmentations. Pre-op Pfirrmann grades: 3:19 (44.2%); 4: 15(34.9%); 5:5 (4.6%). 7 (16.3%) discs had injuries pre-op. Only 3 discs showed progressive degeneration at first follow-up of one Pfirrmann grade (all 3 to 4). All were located in the thoraco-lumbar region. At long-term follow-up, two further discs showed degeneration of one grade. Interestingly, none of the discs with bi-segmental cement augmentation showed degeneration.

Results for single level vertebroplasties at long-term follow-up: Patient

Age

Sex

Level

AR

66

F

L2/3 L3

BF

64

M

64

F

69

M

59

F

76

F

PfirrFU 2

3

3

3

bilat

EPs

EPi

DI

1

2 1

T12/L1

IN

3

3

4

5.5 + 5

bilat

2

1

L1/L2

IN

4

4

2

T10/11

IN

4

5

4

2.5 + 3

bilat

4

3

T11/T12

4

4

4

1

T11/12

3

3

4

1

3 +3

bilat

1

1

T12/L1

3

3

4

1

T11/12

4

4

4

1

4+4

bilat

2

1

T12/L1

4

4

4

1

L4/5

IN

4

4

2

L5 L5/S1

3+1

bilat

2 3

3

3

ALL

PLL

PLC

COR

AO

2

2

1

3

A3.1

2

2

1

2

A3.1

2

1

1

3

A3.1

1

2

1

3

A3.1

1

2

1

3

A1.2

2

1

1

3

A1.2

1

4

T11

EV

Pfirr FU 1

4

T12

PH

Pfirr pre

4

T11

MK

4+4

Access

L3/L4

L1

LM

Volume (ml)

1 1

M = male; F = female. Levels = Injured vertebral body and adjacent intervertebral discs. Volume = applied cement volume. Access: unilat = unilateral; bilat = bilateral, open uni = open unilateral. Pfirr pre = pre-operative Pfirrmann grade; PfirrFU 1 = Pfirrmann grade at first follow up; PfirrFU 2 = Pfirrmann grade long-term lollow-up. AO = fracture classification according to Magerl et al. DI; EPs; EPi; COR; ALL; PLL; PLC = spinal column injury classification according to Oner et al.“IN” in DI columns indicate injured discs. “CONS” = conservative fracture treatment. “OLD” = old traumatic fracture

Results for multi level vertebroplasties at long-term follow-up: Patient

Age

Sex

Level

CC

57

F

T8/T9 T9

Volume (ml)

4

Access

3+4

4

4

3.5 + 3.5

4

4

4

4

4

4

4

4

COR

AO

2

1

1

3

A1.2

1

A1.1 4

2 4

PLC

A1.1.

2

4

4

PLL

1 1

3

ALL

1

4

unilat

DI

1

4

bilat 4

EPi

1

1

IN 6

EPs

1

4

T12/L1 L1

4

bilat

T11/T12 T12

PfirrFU 2

4

T10/T11 T11

Pfirr FU 1

unilat

T9/T10 T10

Pfirr pre

1

2

1

1

3

A1.1

1

2

1

1

A3.1

1

2

1

2

A1.1

1

OLD

L1/L2 L2 L2/L3 L3 L3/4 L4

4+4

bilat

L4/L5 L5 L5/S1

3 IN

4+4

1

3

3

bilat

2 1

5

5

2

5

1 1

M = male; F = female. Levels = Injured vertebral body and adjacent intervertebral discs. Volume = applied cement volume. Access: unilat = unilateral; bilat = bilateral, open uni = open unilateral. Pfirr pre = pre-operative Pfirrmann grade; PfirrFU 1 = Pfirrmann grade at first follow up; PfirrFU 2 = Pfirrmann grade long-term lollow-up. AO = fracture classification according to Magerl et al. DI; EPs; EPi; COR; ALL; PLL; PLC = spinal column injury classification according to Oner et al.“IN” in DI columns indicate injured discs. “CONS” = conservative fracture treatment. “OLD” = old traumatic fracture

Example: 64 yo m traumatic # L1 A3.1, no disc degeneration at long-term follow-up

Injury

20 months postop

98 months postop (8 years)

Example: 65 yo f multiple fractures, no disc degeneration at long-term follow-up

Preop (new fractures)

17 months postop

94 months postop (7.8 yrs)

Conclusion Long-term MRI studies are useful in determining disc degeneration status. Vertebral augmentation seems not to produce accelerated disc degeneration. Prospective studies on younger trauma patients are needed if vertebroplasties are considered as treatment options in these patients. In the future, diffusion studies should be performed for detailed illustration of endplate diffusion.

Declaration of interest No benefits or funds in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this study