Abstract of Medical PhD thesis: Research on the treatment of thoracolumbar fracture denis type IIB by pedicle screw fixation using short configuration with interbody fusion

MINISTRY OF EDUCATION AND TRAINING MINISTRY OF DEFENCE

108 INSTITUTE OF CLINICAL MEDICAL AND PHARMACEUTICAL SCIENCES

-------------------------------------------------

NGUYEN NGOC QUYEN

RESEARCH ON THE TREATMENT OF

THORACOLUMBAR FRACTURE DENIS TYPE IIB

BY PEDICLE SCREW FIXATION USING

SHORT CONFIGURATION WITH INTERBODY FUSION

Speciality: Trauma-orthopedics and recontruction

Code: 62720129

ABSTRACT OF MEDICAL PHD THESIS

Hanoi – 2020

THE THESIS WAS DONE IN: 108 INSTITUTE OF CLINICAL

MEDICAL AND PHARMACEUTICAL SCIENCES

Supervisor:

1. PhD. Phan Trong Hau

2. Ass. Prof. PhD. Pham Hoa Binh

Reviewer:

This thesis will be presented at Institute Council at: 108 Institute of Clinical Medical and Pharmaceutical Sciences

Day Month Year

The thesis can be found at:

1. National Library of Vietnam 2. Library of 108 Institute of Clinical Medical and Pharmaceutical Sciences

1

INTRODUCTION

The thoracolumbar burst frature accounts for about 21% to 58% in all injury of thoracolumbar region, in which Denis IIB accounts for the largest percentage. The clinal signs and imaged findings of Xray and computed tomography are very diverse. The Load Sharing Classification (LSC) was introduced to make the pronosis of hardware failure after short-segment posterior pedicle screw fixation. Thus, it is worth for treatment indication, follow-up and evaluation of treatment outcomes to study about clinical features, imaged findings and LSC for the case with thoracolumbar fracture, Denis type IIB. The surgical treatment usually indicates for unstable fracture, Denis IIB to prevent the progressive spinal kyphosis and secondary neurological damage. The short-segment posterior pedicle screw fixation is the most popular. The disadvantages of this method are high rate of hardware failures and loss of kyphotic correction due to lack of anterior vertebral support. Several techniques have been introducing to reduce these problems but each method has advatages and disadvatages. It was hypothezied that the transforaminal interbody fusion could prevent the disadvantages of short fixation because the large bone defect of injured vertebral body and injured disc was fullfilled by bone chip graft. So some authors have been used this technique in treatment of thoracolumbar burst fracture. Therefore, from these issues, we carry out the topic: “Research on the treatment of thoracolumbar fracture Denis type IIB by pedicle screw fixation using short configuration with interbody fusion” with two goals:

1. Description of clinical features, the characteristiscs of conventional Xray, computed tomography and LSC in patients with thoracolumbar spinal trauma, Denis type IIB who was operated.

interbody 2. Evaluation of the results of surgical treatment for thoracolumbar spinal trauma, Denis type IIB by short-configuration fixation combined with fusion and transforaminal comparison of treatment outcomes by group of LSC score.

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CHAPTER 1: OVERVIEW

1.1. Anatomic characteristics of thoracolumbar region The thoracolumbar junction (from T11 to L2) is a transitional zone between the mobile lumbar spine and the relatively rigid thoracic spine. It also represents a transitional zone between the kyphosis of the thoracic spine and the lordosis of the lumbar spine. This results in the increased susceptibility to injury of the thoracolumbar junction.

1.2. Classification of thoracolumbar injury

1.2.1. Denis’ classification (1983)

Denis classifiedburst fracture into group II with five different types

including: Type A: Fracture of both end plates. Type B: Fracture of

superior end plate, this is the most frequent burst fracture. Type C:

Fracture of inferior end plate. Type D: Burst rotation. Type E: Burst

lateral flexion.

1.2.2. Load Sharing Classification (LSC)

McCormack introduced the load sharing classification which classified

fractures based on three factors of Xray and computed tomography: the

amount of vertebral body acctually comminuted by injury, the

apposition of the fracture fragment, the amount of kyphotic correction.

Each factor was quantified on a scale of 1 to 3 points based on

severity status. Arcoding to this classification, the best candidates for

short – segment posterior approach were the patients with LSC of six

or less. The poor candidates were the patients with LSC of seven or

more, the patients should were chosen another surgical method.

1.2.3. The other classifications

Other classifications of thoracolumbar fracture was introduced such as

AO classification, TLICS (thoracolumbar injury classification) ….

1.3. Clinical signs, diagnostic imaging methods of thoracolumbar

burst fracture.

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1.3.1. Clinical signs

Clinical findings include local spinal injury, nerve damage, and

coordination damage such as head injury, chest injury, long bone

injury...

1.3.2. Diagnostic imaging methods

X-ray is the first diagnostic imaging method for any patient with

suspected spinal injury. The common signs of vertebral burst fracture

include: the loss of anterior vertebral body height of injuried vertebra;

the enlargement of the interpedicular distance of the injuried vertebra;

the interspinous widening. The X-ray also provides the parameters of

spinal deformity after injury such as vertebral kyphotic angle, regional

kyphotic angle, the percentage of anterior vertebral body height loss.

The computed tomography (CT) allows to accurately assess the bone

structure on axial and sagittal slices which helps to better detect the

vertebral fractures and more clearly describe the vertebral lesions. The

CT also provides the findings of spinal fracture as seen on X-rays.

Also assessed the degree of spinal canal encroachment (SCE).

Although MRI is an effective diagnostic imaging method for spinal

injuries, it has its disadvantages. Therefore, X-ray and CT is still the

fastest, most appropriate and effective diagnostic imaging method for

spinal injuries, especially in emergency cases.

1.4. A brief history of research on the surgery of the spinal trauma

in Vietnam.

From 2005 up to now, Vietnam's spine field has made great progress.

Modern spinal instruments have been used in spinal surgery so that

several studies have been reported about treatment of spinal injuries

using spinal fixation with modern instruments. However, until now,

there is no specelist study for thoracolumbar fracture, Denis type IIB

has been reported in Vietnam.

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1.5. Treatments of thoracolumbar burst fracture.

1.5.1. Conservative treatment

The conservative treatment is often applied to the stable thoracolumbar

burst fracture without neurological injury.

1.5.2. The surgical methods of the treatment for thoracolumbar

burst fracture

The indications for surgical treatment of the thoracolumbar burst

fracture when there is one of the following factors: (1) There are signs

of nerve damage; (2) The loss of anterior vertebral body height >50%;

(3) The fracture of three column spine; (4) The spinal canal encroachment >50%; (5) Vertebral kyphotic angle >300 or regional kyphotic angle >200. 1.5.2.1. Posterior surgical approach

This is a surgical method which is preferably chosen by many spinal

surgeons for treatment of thoracolumbar burst fracture. However, the

problem is remained that is how to perform spinal fixation should long

or short fixation was chosen? The long fixation may minimize the

hardware failure and well maintains the correction of spinal deformity.

The disadvantages are the increase in the number of un-injured

vertebrae that needs fixation, the large soft tissse lesions, the prolonged

surgery time, and an increase of treatment costs. Short fixation may

reduce the disadvantages of long fixation but has a high rate of

hardware failure and is unable to maintain the postoperative correction

of spinal deformity. Therefore, there are several methods which

combined with short fixation but, each has its own advantages and

disadvantages. Recently, transforaminal interbody fusion combined

with short fixation has been applied for treatment of thoracolumbar

burst fracture, but its effectiveness needs to be evaluated.

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1.5.2.2. Lateral-anterior surgical approach

The lateral-anterior surgical approach has the advantage which is the

spinal cord compression is decompressed directly and completely

results in creating of the favorable conditions for maximum nerve

recovery. The disadvatages which are the risk of large blood vasel

injury, is not familiar to many spinal surgeons, and therefore requires a

long learning course. In addition, the long operation time, the risk of

blood loss and complications related to the lung are also the

disadvantages of this approach. Therefore, lateral-anterior approach is

less common than the posterior approach in spinal surgery for

thoracolumbar fracture.

1.5.2.3. Other surgical methods

There are also other surgical methods for treatment of thoracolumbar

burst fracture such as a combination of anterior and posterior approach,

less invasive surgery ...

1.5.3. The treatment outcomes of posterior spinal fixation

arcoding to LSC group.

There were studies in the literature that showed that in cases with LSC

<7 can be used short fixation. In the case of LSC ≥7, there were studies

using short fixation combined with other techniques such as

vertebroplasty, kyphoplasty or insertion of pedicle screw at injured

vertebra... Although these methods have reduced the rate of hardware

failure, the loss of postoperative correction, but there has been still no

technique to completely prevent the disadvantages of short fixation.

CHAPTER 2

METERIALS AND METHODS OF THE RESEARCH

2.1. Meterials

This study was carried on the patients who diagnosed unstable

thoracolumbar fracture Denis type IIB (T11-L2), was undergone

6

surgery for decompression, transforaminal interbody fusion, deformity

correction and spinal fixation by short configuration using posterior

approach, at the Department of Spine Surgery - 108 Military Central

Hospital from January 2013 to January 2017.

2.1.1. Selection criterias

Patient was diagnosed unstable thoracolumbar fracture Denis type IIB

from T11 - L2. The patients were undergone surgery for

decompression, deformity correction, spinal fixation using short

configuration combined with transforaminal interbody fusion by

posterior approach. Regardless of gender, age was ≥18. Had a full

medical record, the image of X-ray an CT and the follow-up time of

7

Nguyen Trong Tin is 89.5%; d: permissible error = 0.1.

2.2.3. The method of data collection

The informations were collected according to the consistent form of

the medical record at 108 Military Central Hospital.

2.2.4. The content of the research

+ General characteristics: age, sex, the reasons of injury

+Clinical features: The degree of spinal pain was evaluated according

to the VAS scale. The urinated condition of the patients was asked.

Neurological status was assessed by ASIA scale.

+Evaluation of the X-ray and CT: the level of spinal fracture, the

regional kyphotic angle, the vertebral kyphotic angle, the anterior

vertebral body height loss (%), the widening of the pedicular distance

(%), the laminar fracture, the SCE (%) at the affected vertebra.

+ Assesment of vertebral body injuries according to LSC.

+ The surgical indications: When the patient had one of the following

signs: There are signs of nerve damage (from ASIA D to ASIA A); Regional kyphotic angle >200 or vertebral kyphotic angle >300; loss of anterior vertebral body height >50%; SCE >50%.

+ Indications for decompression: All cases were performed indirect

decompression by distraction of the pedicle screws. In the cases with

SCE ≥50% or neurological deficit, the direct and indirect

decompression was done.

+ Surgical procedure, perioperative evaluation and taking care of the

patient after surgery

* Surgical procedures: Step 1: Anesthesia, patient’s position and

determination of the location of the injured vertebra. Step 2: Exposure

of the operative field. Step 3: Examination and assessment of the injury

of the spine at injured level. Step 4: Insertion of the pedicle screws to

the above and below levels of the injured vertebral. Step 5: Open of the

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transforaminal zone, checking the spinal canal, deformity correction

and decompression. Step 6: Grafting the bones and fixing the screw

brace system. Step 7: Close the incision.

* Contents of perioperative evaluation: surgical time, the anatomical

injury, perioperative complications

* Postoperative care and treatment: wound care, post-operative

treatment and rehabilitation.

+ Evaluation the surgical results according to the following criteria: at

the time of discharge and the last follow – up.

Clinical: The degree of back pain according to VAS, nerve recovery

according to ASIA, urination status. Images: Effectiveness and

maintenance of the correction: Asseseted by the changes in the

parameters of spinal deformity on X-ray. The condition of the screws

and rods. The grade of interbody fusion according to Bridwell’s

criteria. The improvement of the SCE on CT. Work recovery was

evaluated according to Denis's classification; life quality was assessed

according to Owestry Index Disability.

2.2.5. Data processment

The data is processed by medical statictic method with SPSS 20.0

software for Window.

CHAPTER 3:

RESEARCH RESULTS

3.1. Demographic data

3.1.1. Age: The mean age was 46.6 ± 11.7 years with the age from 40

– 59 years accounting for 65%.

3.1.2. Gender: The male / female ratio was 1.2.

3.1.3. Causes of injury: The most common reason was falling down

from height, accounting for 77.5%.

3.1.4. The locaction of injuried vertebrae: The most common

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injuried vertebrae was in L1 with 60%, no cases were in T11. 3.2. Clinical characteristics of patients - The average of spinal pain according to VAS was 7.8 ± 0.7, of

which the VAS with 8 point accounts for 62.5%.

- 40 patients with thoracolumbar fracture Denis IIB, 24 patients

(60%) had normal urinary and 16 patients (40%) showed urinary

retention.

- There are 11/40 patients (27.5%) had symptoms of neurological

damage (15% ASIA C and 12.5% ASIA D), no patient had ASIA A

and ASIA B.

3.3. The characteristics of the injurid vertebrae on X-ray, CT and

classification of injuried vertebrae according to LSC

3.3.1. The imaged fidings

Table 3.5: The laminar fracture on X-ray and CT (n=40)

CT

Laminar fracture

Total

No

Yes

P(Chi-square test)

No

22 (55%)

5 (12.5%)

27 (67.5%)

X-ray

0.000 Yes

Total

0 (0.0%) 22 (55%)

13 (32.5%) 18 (45%)

13 (32.5%) 40 (100%)

Table 3.6: The features of spinal deformity on X-ray (n=40)

Parameters

≤50% >50%

Quatity (%) Minimum Maximum Average 39.3±8.4 15 (37.5%) 56.2±6.2 25 (62.5%)

49.8 73.5

19.8 50.5

Total

40 (100%)

19.8

73.5 49.9±10.9

Anterior vertebral body height loss (%) Regional kyphotic angle (0) Vertebral kyphotic angle (0)

≤200 >200 Total ≤300 >300 Total

19 (47.5%) 21 (52.5%) 40 (100%) 32 (80%) 8 (20%) 40 (100%)

-2 21 -2 11 31 11

20 33 33 29 37 37

12.5±6.2 25.1±3.1 19.1±8.1 22.5±4.4 32.6±2.0 24.5±5.8

10 -2,1 1.7

-0,7 37.9

-1.3±0.7 13.7±7.7

≤0% >0% Total

3 (7.5%) 37 (92.5%) 40 (100%)

-2.1

37.9 12.5±8.4

The distance of interpedicle (%)

Table 3.7: The SCE on CT

Parameters Quantity (%) Minimum Maximum Average

≤50% 17 (42.5%) 24.1 48.9 37.7±8.2 SCE >50% 23 (57.5%) 51.3 79.7 59.2±7.6 (%) 40 (100%) Tổng 79.7 24.1 50.1±13.3 3.3.2. The classification of injured vertebral according to Mc

Point 9 Điểm

5 Điểm Point

8 Điểm Point

6 Điểm Point

7 Điểm Point

Cormack’s LSC

Chart 3.9: Distribution of patients according to LSC score

3.2.3. The correlation between imaged findings, group of LSC

score and neurological injury.

Table 3.10: Distribution of patients with signs of neurological damage according to laminar fracture on CT (n=40)

Neurological damage Total No Yes P(Fisher’s Exact)

0.000 Laminar fracture Yes No Total 18 (45%) 11 (27.5%) 7 (17.5%) 22 (55%) 0 (0.0%) 22 (55%) 29 (72.5%) 11 (27.5%) 40 (100%)

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Table 3.11: Distribution of patients with signs of neurological damage

according to LSC (n=40)

Neurological damage Group Total of LSC No Yes P(Fisher’s Exact)

<7 15 (37.5%) 2 (5%) 17 (42.5%)

≥7 14 (35%) 9 (22.5%) 23 (57.5%) 0.079

Total 29 (72.5%) 11 (27.5%) 40 (100%)

Table 3.12: Comparing the average of spinal deformity parameters between the group with and without neurological injury (n=40)

Paramenters

Quantity (%) Average

Neurological damage

P(Mann- Whitney Test)

Yes

11 (27.5%)

16.3±10.5

0.248 Regional kyphotic angle (0)

No

29 (72.5%)

20.2±6.8

Yes

11 (27,5%)

24.1±6.8

0.448 Regional kyphotic angle (0)

No

29 (72,5%)

24.7±5.4

Yes

11 (27.5%)

51.3±11.1

0.904 No

29 (72.5%)

49.4±11.0

Anterior vertebral body height loss (%)

Có

11 (27,5%)

15,9±5,9

0,049

The distance of interpedicle (%)

Không

29 (72,5%)

11,3±9,0

Table 3.12: The correlation between the neurological injury and severity of SCE (n=40)

ASIA Average of SCE (%) Quantity P(Krus kal-Wallis)

C 64.4 ± 10.4 6

D 56.2 ± 8.5 5 0.001 E 45.7 ± 11.5 29

Total 50.1 ± 13.3 40

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3.4. Peri-operative characteristics

The average of surgical time was 117.6 minutes, 62.5% was underwent

indirect decompression combined directly, 10% required blood

transfusion.

3.5. The outcomes of surgical treatment

3.5.1. The results at the time of discharge

3.5.1.1. Clinical results

The mean VAS score at discharge from hospital was 1.9 ± 1.0

compared to before surgery was 7.8 ± 0.7 with an average

improvement of 5.9 ± 1.2. 14/16 patients with symptoms of urinary

retention before surgery after discharge had normal urinary. 11/40

patients with neurological damage showed improvement at least 1

degree ASIA.

3.5.1.2. The deformity correction of short fixation

Table 3.18: The correction of the anterior vertebral body height loss and

distribution according to group of LSC (n=40)

Quantity (n)

Pre-operative

Mean correction

Grou p of LSC <7 ≥7 Total

17 23 40

The average of anterior vertebral body height loss (%) Post - operation 17.1±10.5 17.8±7.8 17.5±9.0

47.3±12.3 51.8±9.6 49.9±10.9

30.2±12.6 33.9±11.1 32.4±11.7

P1 (Comparison the mean correction between the group of LSC, Mann-Whitney U) = 0.352 P2 (Pre-operation vs post – op and last follow - up, T-Test) = 0.000

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Table 3.19: The correction of the regional kyphotic angle and distribution

according to group of LSC (n=40)

The mean of regional kyphotic angle (0)

Group of LSC Quantiy (n) Pre - operation

17 23 40 <7 ≥7 Total Post- operation 9.8±5.5 7.0±4.8 8.2±5.2 Mean correction 9.2±4.6 12.4±6.1 11.0±5.7

18.9±8.0 19.3±8.3 19.1±8.1 P1 (Comparison the mean correction between the group of LSC, Mann-Whitney U) = 0.064 P2 (Pre-operation vs post – op and last follow - up, T-Test) = 0.000 Bảng 3.20: The correction of the vertebral kyphotic angle and distribution

according to group of LSC (n=40)

The mean of vertebral kyphotic angle (0)

Quantity (n) Mean correction

Group of LSC <7 ≥7 Total 17 23 40 Pre - operation 22.7±5.3 25.8±5.8 24.5±5.7 Post - operation 11.5±4.4 11.6±4.3 11.6±4.3 11.2±4.9 14.2±4.7 12.9±4.9

P1 (Comparison the mean correction between the group of LSC, Mann-Whitney U)= 0.070 P2 (Pre-operation vs post – op and last follow - up, T-Test) = 0.000

3.5.2. The surgical outcomes at the time of last follow -up

Out of 40 patients undergoing surgery, 36 patients were assessed the

results at the last follow-up. The average of follow-up time was 53.3

months.

3.5.2.1. Clinical results at the time of last follow – up

- Average VAS was 7.8 pre – operatively, reduced to 2.0 at the

discharge and at the time of last follow - up was 1.3.

- At the time of the last examination, only 1/36 of the patients showed

urinary incontinence.

- 9/36 patients with neurological damage before surgery, post-operatively

had improved at least 1 degree of ASIA and at the time of the last follow -

14

up, 8 patients were fully recovered.

3.5.2.2. The maintenance of deformity correction

Table 3.25: The maintenance of anterior vertebral body height loss and

following the group of LSC score (n=36)

The average of anterior vertebral body height loss (%)

Quantity (n)

Group of LSC

<7 ≥7 Tổng

16 20 36

Pre - operation 46.6±12,4 51.0±9.7 49.1±11.0

Post - operation 16.7±10.9 17.6±8.2 17.3±9.3

Correction loss 10.1±9.6 10.3±7.0 10.2±8.1

Last follow - up 27.0±14.1 27.9±9.1 27.5±11.4 P1 (comparison between group of LSC, Mann-Whitney U) = 0.484 P2 (the last follow-up vs pre-operation and post-operation, T-Test) = 0.000 Table 3.26: The maintenance of vertebral kyphotic angle and following

the group of LSC score (n=36)

The average of vertebral kyphotic angle (0)

Quantity (n)

Group of LSC <7 ≥7 Total

16 20 36

Pre - operation 22.4±5.3 26.4±5.4 24.6±5.7

Correction loss 3.1±2.9 2.8±2.8 2.9±2.8

Post - operation 11.1±4.4 11.8±4.3 11.5±4.3

Last follow - up 14.4±4.2 14.5±4.8 14.4±4.5 P1 (comparison between group of LSC, Mann-Whitney U) = 0.699 P2 (the last follow-up vs pre-operation and post-operation, T-Test) = 0.000 Table 3.27: The maintenance of regional kyphotic angle and following the

group of LSC score (n=36)

The average of regional kyphotic angle (0)

Quantity (n)

Group of LSC

<7 ≥7

16 20

Pre - operation 19.1±8.2 20.1±8.4

Post - operation 9.8±6.7 7.4±4.9

Last follow - up 14.2±7.2 14.0±6.4

Correction loss 4,4±4.0 6.6±5.9

15 Table

36 19.7±8.2

14.1±6.7

5.6±5.2

8.5±5.3 P1 (comparison between group of LSC, Mann-Whitney U) = 0.262 P2 (the last follow-up vs pre-operation and post-operation, T-Test) = 0.000

3.5.2.3. The improvement of SCE and grade fusion

Table 3.28: The improvement of SCE at the time of last follow-up and

following the group of LSC (n=36)

Avarage of SCE (%)

Group of LSC

Quantity (n)

Pre-operation

<7 ≥7 Tổng

16 20 36

46.4±13.1 52.7±10.8 49.9±12.1

Last follow- up 21.7±9.6 17.1±11.2 19.2±10.6

Average of improvement 24.7±8.8 35.6±13.8 30.7±12.9

P1 (Comperison between the group of LSC, Mann-Whitney U) = 0.029 P2 (preoperation vs last follow-up, T-Test) = 0,000 Table 3.29: The grade fusion according to Bridwell (n=36)

Grade fusion

I

II

III

IV

P(Fisher’s Exact)

0.001 X-ray (n,%) CT(n,%)

29 (80.6%) 23 (63.9%)

07 (19.4%) 10 (27.8%)

0 (0%) 3 (8.3%)

0 (0%) 0 (0%)

3.5.2.4 Work recovery and the quanlity of life

Table 3.29: Denis’ work scale following LSC (n=36)

Group

Denis’ work scale

of

Quantity

Grade

Grade I

Grade II

Grade III

LSC

IV

V

<7

16 (44.4%)

7 (19.4%)

5 (13.9%)

4 (11.1%)

0 (0%)

≥7

20 (55.6%)

12 (33.3%)

6 (16.7%)

2 (5.6%)

0 (0%)

Total

36 (100%)

19 (52.8%)

11 (30.6%)

6 (16.7%)

0 (0%)

0.484 P(Fisher’s Exact)

16

19,4

5,6

Grade I

Grade II

Grade V

Độ I

Độ II

Độ III Grade III

Độ IV Grade IV

Độ V

Chart 3.12: The grade of quanlity of life according to ODI

3.5.2.5. Hardware failure

Table 3.31: The rate of hardware failure following the group of LSC

(n=36).

The status of hardware

LSC

Total

P(Fisher’s exact)

0.196 <7 ≥7 Total

Good 15 (41.7%) 15 (41.7%) 30 (83.3%)

Failure 1 (2.8%) 5 (13.9%) 6 (16.7%)

16 (44.4%) 20 (55.6%) 36 (100%)

Table 3.32: The detail of hardware failure (n=36)

Hardware failure

Numbers Percentage

Broken of 2 above screws

3 8.3%

The grade fusion of Bridwell on CT 2 patients with garde II, 1 case with grade III 2 cases with grade I

2 5.6%

1 cases with grade I

1 2.8%

Broken of 2 below screws Rod pull out of obove screw at one side

Total

6 16.7%

3 patient with grade I, 2 cases with grade II, 1 case with grade I

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CHAPTER 4: DISCUSION

4.1. Clinical features, imaged finding and classification of the

injured vertebrae according to LSC

4.1.1. Clinical features

4.1.1.1. Pain at the location of spinal injury

We found that 100% of patients showed pain in the location of spinal

injury after trauma with an average VAS score of 7.8 ranging from 6 to

9 points. Thus, pain is a common sign in spinal injuries in general and

thoracolumbar burst fracture in particular.

4.1.2.2. Urination and neurological injury

The proportion of patients with urinary disorders is 40% with signs of

urinary retention. The proportion of patients with urinary retention

after spinal injury was higher than the rate of patients with signs of

neurological damage. The proportion of patients with incomplete

neurological injury was 27.5% (ASIA C to ASIA D), 72.5% had no

signs of nerve damage (ASIA E), and no cases had signs of near

complete neurological deficit (ASIA B) or sign of complete

neurological injury (ASIA A).

4.1.2. The imaged findings

The average of the anterior vertebral body height loss was 49.9% (from 19.8% to 73.5%). The average of the regional kyphotic angle was 19.10 (from -20 to 330), the average of the vertebral kyphotic angle was 24.50 (from 110 to 370). In the same type of injury, but the severity of the deformity through the kyphotic parameters on X ray such as regional

kyphotic angle and vertebral kyphotic angle were also different in the

study because of the location of the traumatic vertebra, the severity of

the injury.

13 out of 40 patients (32.5%) had luminar frature on X-ray. But on CT

detected luminar fracture better than X-ray (45% compared to 32.5%)

18

and the difference between X-ray and CT abotu the incidence of

luminar fracture was statistically significant with p <0.05.

Research results of 40 patients with thoracolumbar fracute, Denis type

IIB showed that the mean SCE was 50.1% ± 13.3% and 23 patients

(57.5%) had SCE >50%. The correlation between the SCE and the

severity of neurological was positive, the more severe nerve damage,

the greater the SEC and the difference was statistically significant p

<0.05. This means that the higher the percentage of SCE, the greater

the risk of neurological injury.

4.1.3. The correlation between the neurological injury and the

features on Xray and CT.

We studied about the difference between the group with and without

neurological deficit in the mean value of the regional kyphotic angle,

the vertebral kyphotic angle and the anterior vertebral body height los,

we found out that the difference was no statistical significance with p>

0.05. The reason of no relationship was, the regional kyphotic angle,

the vertebral kyphotic angle, the anterior vertebral body height loss

was used as indicators to evaluate the spinal kyphotic deformation and

indirectly evaluate the degree of stability after trauma and that was not

related to neurological damage.

The correlation between the interpedicular distance and neurological

injury has been being a problem was few report in Vietnam. In this

study, the mean enlargment of the interpedicular distance in the group

with neurological injury was higher than in the group without

neurological injury (15.9% vs. 11.3%), and the difference was

statistically significant with p <0.05. Thus, the higher enlargement of

interpedicular disctance the more severity of neurological damage.

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4.1.4. The classification of the injurid vertebrae according to LSC

and clinical, imaged characteristics of the patients with LSC LSC

<7 and LSC ≥7

LSC score of patients in this study was range from 5 to 9 points, in

which the number of patients at 6, 7 and 8 points accounted for the

majority. 17/40 (42.5%) patients had LSC score <7 and 23/40 (57.5%)

had LSC score ≥7 with the mean LSC was 6.8 point. Found out about

the proportion of patients with signs of neurological damage in the

group of LSC score <7 and LSC ≥7, the proportion of patients with

signs of nerve damage in the group of LSC score ≥7 (9/23 patients)

was higher. The group of LSC score <7 (2/17 patients). However, the

difference was not statistically significant with p> 0.05. From the

results of this study, it is clear that the disadvantage of LSC

classification is that it does not imply neurological injury.

4.2.1. The surgical results at the time of discharge

4.2.1.1. The pain relief of injuried spine after surgery

In this study, 100% of patients exhibiting spinal pain with the mean

pre-operative VAS score of 7.8 ± 0.7 decreased to 1.9 ± 1.0 at the time

of discharge, the average of improvement was 5.9 ± 1.2 and the

difference was statistically significant with p <0.05. From this result, it

can be concluded that the fixaiton of injuried spine had certainly

reduced spinal pain quickly for the patient, thereby helping the patient

to recover early to quickly return to activities and work.

4.2.1.2. The recovery of neurological injury

11 out of 40 patients with signs of neurological damage were assessed

at the time of discharge, all 11 patients had improvement in

neurological damage of at least 1 degree ASIA. In which, there was 2

degree improvement in ASIA in 1 patient (1 case of ASIA C to ASIA

D), 1 degree improvement of ASIA in 10 patients. The improvement in

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signs of nerve damage at the time of discharge compared to before

surgery was statistically significant with p <0.05. Thus, after the

injuried spine was firmly fixed, the spinal canal was satisfactorily

decompressed, helping the patient to get early rehabilitation after

surgery thus the neurological injury was quite well recovered

4.2.1.3 The outcomes of kyphotic correction

All parameters of spinal deformity were significantly improved after

surgery. Specifically, the anterior vertebral body height loss was

improved with average 32.4% ± 11.7%, Pre-operation was 49.9% ± 10.9% decreased to 17.5% ± 9.0%; Regional kyphotic angle was 19.10 ± 8.10 pre – operatively, reduced to 8.20 ± 5.20 with mean correction is 11.00 ± 5.70. The mean correction of the vertebral kyphotic angle after surgery was 12.90 ± 4.90, pre – operatively the vertebral kyphotic

angle was 24.50 ± 5.70, reduced to 11.60 ± 4.30 after surgery. Thus,

from the surgical outcomes about the kyphotic correction, we believe

that it is acceptable for the short posterior pedicle screw fixation.

4.2.2. The surgical results at the last follow – up

4.2.2.1. Clinical outcomes

* The pain of the injuried spine

In this study, when assessing spinal pain at the time of final

examination of 36 patients by using the VAS scale, the patient's pain

continued to decrease.

* The recovery of the neurological deficit

36 patients were followed up at the final examination, 9 patients had

signs of nerve damage before surgery, after surgery all improved at

least 1 degree ASIA and at the time of the last follow – up, 8 patients

fully recovered. This result showed that after the injuried vertebrae was

firmly fixed by pedicular screws, the neurological organization was

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released by good decompression, which would help facilitate the

process of neurological recovery.

4.2.2.2. The work ability and the quantify disability of the patients.

Research results show that 83.3% of patients have been able to return to

work as before the injury. We evaluated the impact of spinal injuries on

the patient's quality of life according to the ODI. The results showed that

75% of patients had no effect or little effect on the quality of life (grade I);

but there is 5.6% seriously affect the quality of life (grade III).

4.2.2.3. The maintenance of kyphotic correction and limitation of

hardware failure

The study results showed that the average of the spinal kyphotic

parameters at the time of final examination were better than before

surgery. However, compared with the post-operative time, these

parameters were increased. The loss of spinal kyphotic correcction:

The average loss of anterior vertebral body heigh was 10.2% ± 8.1%;

the vertebral kyphotic angle is 2.90 ± 2.80 and the regional kyphotic

angle is 5.60 ± 5.20. This shows that transforaminal interbody fusion

using the bone cheep grafting could prevent but not completely the loss

of kyphotic correction after surgery. One of the purposes of

transforaminal interbody fusion was to reduce the rate of hardware

failure. As a result, 6 patients (16.7%) had hardware failures. In which,

there were 3 patients with 2 upper screws broken, 2 patients with

broken of 2 lower screws, 1 patient with the rod breaking out of the upper 1 side screw, and there was no case with correction loss ≥100 without hardware failure. However, in no case of instrument failures,

surgical intervention is required.

4.2.2.4. Bone union and the dimension of spinal canal at the last

follow-up.

According to Bridwell’s grade of bone union, on X-ray images showed

22

80.6% of grade I and 19.4% of grade II bone healing, there was no

case of grade III and IV. However, when evaluating by CT images, the

grade of bone healing has changed in 8.3% of patients with grade III,

very good bone union 63.9% (degree I) and good bone union 27.8%

(degree II). The difference in bone healing when assessed through X-

ray and CT images had statistical meanings with p <0.05. The reason is

that CT image gives a detailed and clear image of the bone structure

and is not affected by other structures such as the chest, lungs ...

Research results show that the average of pre-operative spinal canal

stenosis was 49, 9% decreased to 19.2% at the time of last follow-up,

the improvement was 30.7%. This result shows that the indirect

decompression technique related to distraction of the posterior

longitudinal ligament and or combination with the direct

decompression was an effective technique.

4.2.3. Surgical outcomes according to group of LSC

The improvement of spinal pain at the time of discharge from hospital

and the time of last follow - up showed no difference between the two

groups of LSC scores with p> 0.05. This shows that after operation, the

injuried vertebral body was fixed by pediclar screw so that the patient

was reduce spinal pain, regardless of the severity of the injuried

vertebral body. The level of improvement of signs of neurological

damage in the two groups of LSC scores was not statistically

significant with p> 0.05. This result can suggest that the recovery of

neurological deficit does not depend on the severity of the preoperative

vertebrae. The labor recovery of the patient between 2 groups of LSC

points also had no statistically significant difference with p> 0.05. This

shows that surgery helps restore working capacity for patients

regardless of the LSC score before surgery.

The degree of spinal kyphotic correction in the LSC ≥7 group was

23

higher than the LSC group <7 in all three parameters. However, this

difference between the two groups in this study was not statistically

significant with p> 0.05. This shows that the effect of the surgical

method does not depend on the severity of injury. We also found that

there was no statistically significant difference with p> 0.05 about the

correction loss after surgery in the group with LSC score ≥7 and LSC

<7. The group with LSC score ≥7 had a higher instrument failure rate

than the group <7 points, but the difference was not statistically

significant with p> 0.05.

CONCLUSION

1. Clinical features, image findings, and classification of vertebral

body fracture according to LSC.

- Average age was 46.6 ± 11.7 years, with 55% male and 45% female.

The main reason was falling down from hight, accounting for 77.5%.

The most common vertebral fracture was L1 (60%). The mean VAS of

spinal pain was 7.8 ± 0.7 points. 29/40 patients (72.5%) had no signs

of neurological injury, 11/40 patients had signs of incomplete

neurological deficit. Urinary retention was found in 16/40 patients

(40%). There were 92.5% of patients with widening of interpedicular

distance of the injuried vertebra with an average rate of 12.5%. The

parameters of spinal deformity: Average of the anterior vertebral body height loss was 49.9% ± 10.9%; the regional kyphotic angle was 19.10 ± 8.10; the vertebral kyphotic angle was 24.50 ± 5.70. The average of the spinal canal enroarchment was 50.1%, there was postive colleration

between spinal canal enroarchment and the severity of neurological

deficit.

- The LSC point of the vertebral body injury were from 5 to 9, of

which 23 cases (57.5%) with LSC score ≥7 and 17 patients with LSC

score <7 (42.5%)

24

2. Results of surgical treatment and comparison of the surgical

outcomes between both group of LSC score.

* Surgical results

- Clinical outcomes: After surgery, the spinal pain was significantly

reduced (average VAS was 7.8 at preoperatively and was 1.9 at

discharge). 11/11 patients with incomplete neurological injury was

recovered at least 1 grade of ASIA. Work recovery according to Denis

classification has 83.3% returning to work as before the injury (52.7%

of grade I, 30.6% of grade II). The quality of life according to ODI was

75% of grade I; 16.7% of grade II and 8.3% of grade III.

- Radiological results: Spinal fixation with short configuration also

gained the good correction of spinal deformity with the average of

correction of the vertebral body height loss was 32.4% ± 11.7%; the regional kyphotic angle was 110 ± 5.70; the vertebral kyphotic angle was 12.90 ± 5.70. Transforaminal interbody fusion well maintained the postoperative correction of spinal deformity with an average loss of

correction: the percentage of anterior vertebral body height was 10.2% ± 8.1%; the regional kyphotic angle was 2.90 ± 2.80; the vertebral kyphotic angle was 5.60 ± 5.20. The good improvement of spinal canal enroarchment with the mean of improvement was 30.7% ± 12.9%. The

good interbody fusion was 91.7%. Hardware failures were reduced

when compared with short fixation without fusion and the rate of

hardware failure was 16.7%.

* Comparison of the surgical results between both group of LSC: LSC

score did not affect the clinical results, the loss of correction, the

maintenance of correction which were achieved after surgery.

- Clinically, there was no significant difference between the two

groups of LSC scores in terms of improvement in pain, the recovery of

neurological deficit and working ability.

25

- The correction was achieved between two groups of LSC scores is

not significant difference. The average correction of the parametes of

spinal deformities included the regional kyphotic angle, the vertebral

kyphotic angle, the anterior body height loss of the groop with LSC score <7 were 9.20, 11.20 and 30.2% compared to group with LSC score ≥7 is 12.40, 14.20 and 33.9% (respectively). The group with LSC score ≥7 (average 35.6%) improved the cannal enroarchment better

than the group with LSC score <7 (mean 24.7%), the difference was

significant.

- There were no significant differences of the postoperative correction

loss, the rate of hardware failure in the group with LSC scores <7 and

group with LSC cscore ≥7 (the average correction loss of the anterior

vertebral body height was 10.1% and 10.3%; the regional kyphotic angle was 3.10 and 2.80; the vertebral kyphotic angle was 4.40 and 6.60; the rate of hardware failure was 1/16 and 5/20; respectively).

LIST OF PUBLISHED ARTICLE RELATING TO THESIS

1. Nguyen Ngoc Quyen, Phan Trong Hau, Pham Hoa Binh, Le

Hung Truong (2018), “The surgical outcomes of short fixation

combination with transforaminal interbody fusion in treatment

of unstable thoracolumbar burst fracture”, Jounal of 108 –

Clinical Medicine and Pharmacy, special issue, pp. 111 - 117.

2. Nguyen Ngoc Quyen, Phan Trong Hau, Pham Hoa Binh (2020),

“Clinical features and radiological findings of patients with

thoracolumbar burst fracture, Denis IIB”, Vietnam Medical

Jounal, 2(494), pp. 9-12.

3. Nguyen Ngoc Quyen, Phan Trong Hau, Pham Hoa Binh (2020),

“The long-term results of short segment pedicle screw fixation

with transforaminal interbody fusion in treatment of

thoracolumbar burst fracture Denis IIB”, Jounal of 108 –

Clinical Medicine and Pharmacy, 6(15), pp. 113-119.