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

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

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

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

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

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

CHAPTER 1: OVERVIEW 1.1 Anatomic characteristics of thoracolumbar region

The thoracolumbar junction (from T11 to L2) is a transitional zonebetween 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 inthe 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

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

1.5 Treatments of thoracolumbar burst fracture

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

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

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 more than 12 months postoperatively

2.1.2 Exclusion criterias

Patients with severe trauma accompanying: brain injury, abdomen injury, chest injury The patient was diagnosed other spinal diseases during the time of follow-up The patient had a mental disorder The patient did not cooperated the treatment The patient did not comply with the follow-up program and did not returned after surgery

2.2 Methods of the research

2.2.1 Study design

The prospective study with clinical describes, intervention, un-control group, evaluation of the results on each patient before - after the surgery and follow-up the treatment results

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

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

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

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)

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

(%)

≤50% 17 (42.5%) 24.1 48.9 37.7±8.2

>50% 23 (57.5%) 51.3 79.7 59.2±7.6 Tổng 40 (100%) 24.1 79.7 50.1±13.3

3.3.2 The classification of injured vertebral according to Mc Cormack’s LSC

2

5 Điể m 6 Điể m 7 Điểm 8 Điểm 9 Điểm

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)

Table 3.11: Distribution of patients with signs of neurological damage

according to LSC (n=40) Group

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)

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