Summary of doctoral thesis: Study on surgical injury characteristics and results of surgery for treatment of the lower thoracic and lumbar spinal fractures due to traumatic injury by splints and screws

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With two goals: Description of surgical injury characteristics and deformation on the image diagnosis, survey of TLICS and LSC values in lower thoracic and lumbar spinal injury. Evaluate the results of surgery for the treatment of lower thoracic and lumbar spinal fractures with posterior splints and screws.

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Nội dung Text: Summary of doctoral thesis: Study on surgical injury characteristics and results of surgery for treatment of the lower thoracic and lumbar spinal fractures due to traumatic injury by splints and screws

1 BACKGROUND A thoracic and lumbar spinal injuries account for the majority, about 90% of spinal injuries. In which, thoracolumbar spine hinge vertebra (T11 L2) and lower lumbar (L3 L5) account for about 84%, mainly with the indirect mechanism. Classification emphasizes on: the form of injury, integrity of the posterior ligamentous complex and nerve damage. The role of the posterior ligamentous system in the stable spinal structure is confirmed and appreciated by many authors. This is an issue that needs to be paid more attention to in the diagnosis and treatment of spinal injury in Vietnam when no previous research has specifically and fully mentioned before. For surgical indication,the authors based on the loss of steadiness of the injured spinal vertebra on the basis of the morphologic damage, nerve damage, and posterior ligamentous complex. However, each indication has its own advantages and disadvantages. Recent studies have been made on the validity and reliability of Vaccaro AR’s TLICS (thoracolumbar injury classification and severity score) and indicate cases where scores of 1 to 4 had to undergo surgery late after a conservative treatment period, or narrow scope of application in the multiple vertebral fracture group under the indication of McCormack and Wood KB. Posterior approaches for treatment of thoracic spinal injury is becoming more and more popular, effective and dominant. The efficiency of multiple vertebral fracture surgery has been enhanced, and demonstrated in studies by Smith JS, Ataka H., Kaminski A.. The findings of Greenberg MS about degenerative joint diseaserequired for early surgery after 3 years in long band fixations (≥ 4 bands) after 8 to 9 years in short band fixations (2 to 3 bands). Therefore, from these issues, we carry out the topic: “Study on surgical injury characteristics and results of surgery for treatment of the lower thoracic and
2 lumbar spinal fractures due to traumatic injury by splints and screws” with two goals: 1. Description of surgical injury characteristics and deformation on the image diagnosis, survey of TLICS and LSC values in lower thoracic and lumbar spinal injury. 2. Evaluate the results of surgery for the treatment of lower thoracic and lumbar spinal fractures with posterior splints and screws. CHAPTER 1. OVERVIEW 1.1. Surgery The lower thoracic and lumbar spine consists of a relatively straight, vulnerable thoraco lumbar spine hinge vertebra (T11 L2) by a longitudinal compression and a lower lumbar vertebra (L3 – L5) with a physiological curve opening backward to absorb force in the spring type so that it causes less injury. Vertebral body has weak structure in from column, stable structure in middle and back columns. Thus, injury often occurs in the front column under the vertical compression mechanism. According to Benzel E.C., the proportion of periosteum and bone marrow affects the bearing capacity and the antiscrew loosening strength. This rate is higher in the spinal stalk than in vertebral body and higher in the thoracic lumbar spine hinge vertebra than in lower lumbar vertebra. Therefore, spinal stalkis the strongest part of the vertebrae and the T11 L2 segment is stronger than the L3 L5 segment. The joint system between vertebrae is composed of two main types of joints: Cartilaginous (semimoveable) joint and the Synovial (freely moveable) joint. Of which, the Synovial (freely moveable) joint and ligament joint (rear ligament system) play an important role in steadiness, flexibility and maintaining the amplitude for movement of the spinal column.The vascular system nourishing the thoracic and lumbar marrow, including the root vascular system, spinal marrow vascular system and coronary artery network. Accordingly, Adam kiewiczcung artery provides mainly for 4/5 marrow in cross section from T8 to conus medullaris.
3 1.2. Biological mechanisms behind injury and nerve damage in spinal injury 1.2.1. Biological mechanisms behind injury According to Benzel E.C., the force acting on the spinal column, in terms of the threedimensional space system on each coordinate axis, has two axial sliding motions and two reciprocating rotating movements that produce 12 movements around the instantaneous axis of rotation (IAR), forming up to six levels of free movement around the IAR axis in association with each other to creating forces: press – compression, cutting – shearing, twisting, stretching – tearing resulting in different forms of damages in a trauma. Instantaneous rotation axis is the imaginary point in or around the vertebrae where the spinal segment rotates under the impact force. When the impact force is noncoaxial with IAR, it generates a bending moment (M) of magnitude equal to the magnitude of the force (F) multiplying by the distance from the point of impact to the instantaneous rotation axis (D). The bending moment (M) is defined as the product of the force (F) applied to the lever arm and the length of the lever arm (D) : M = F x D. 1.2.2. Nerve damage In spinal trauma, there are four major traumatic mechanisms involved in nerve deformation in the long term: extrinsic nerve compression, diffusion, arch effect on the vertical plane, arc effect on the horizontal plane. It has two forms of lesions: primary lesions and secondary lesions. Disorders or malfunction of nerve cells due to the mechanism of: cell destruction leads to nerve cell death and cell deformation, metabolic disorders leading to temporary or permanent malfunction. Surgery removing the compression factors can prevent, overcome cell deformation and metabolic disorders. Secondary nerve damage may be prevented partially at least by medicine interventions: anticoagulant medicine therapy and corticoide therapy are recommended to use as soon as possible within the first 8 to 72 hours after injury. 1.3. Classification of injuries
4 1.3.2. Classification of Denis (1983) In 1983, Denis introduced the three column concept of spinal fractures: anterior column (the anterior vertebral body, ½ anterior annulus fibrosus, and anterior longitudinal ligament), middle column ( posterior longitudinal ligament, ½ posterior annulus fibrosus, and posterior wall of the vertebral body), the posterior column (spinal canal vein, marrow, posterior ligament system, posterior arch). Denis divides the vertebral body injury into four types: compression fracture (anterior column damage, no injury to the middle column, possible injury to the posterior column), burst fracture (injury to the middle and posterior column by the mechanism of vertical compression in combination with bending, turning, and the posterior fracture piece may press the spinal canal), distraction fracture (the fracture lies at the same level in the vertical plane, the fracture lies in two levels in the vertical plane causing injury to bones, ligaments and annulus fibrosus), dislocation fracture (severe damage to all three columns causing instability). Denis introduced the concept of “stable and unstable spinal injuries” as the basis for indications for treatment in spinal injuries. The term “stability fracture” includes mild or moderate subsidence, no injury to the middle and posterior columns, indicating conservative therapy, early movement practice. There are three types of instability based on the relationship between morphological and neurological damages: mechanical instability, neurological instability, mechanical neurological instability, and surgical indication. 1.3.3.Classification after Denis McCormack classified fractures based on three factors: the breaking degree of the vertebral body, the cohesion of fractured pieces, the kyphosis being quantified on a scale of 1 to 3 points on each factor by severity status. The higher the point, the more severe the injury. Indication for surgery in case of 6 – 9 points. VaccaroA.R., gave the TLICS classification based on three important traumatic features: injury morphology, integrity of
5 the posterior ligament system, and nerve damage. Indication: 5 10 points => surgery, 1 3 points => conservative treatment and 4 points => priority for surgery. 1.4. Medical imaging methods 3 main methods: conventional x – ray imaging, computerized tomography and MRI. 1.4.1. Conventional x – ray imaging Conventional Xray imaging has diagnostic value: position; discontinuity of three lines: inter posterior spinal cord, interjoint block, inter horizontal spinal cord; vertebral traumas, angular bending of the traumatic area and the distance between joint blocks and posterior spinal cord. The advantage of conventional xray compared to computerized tomography and magnetic resonance imaging (MRI) is that it can be investigated in a dynamic state to diagnose suspected cases of semidislocation. 1.4.2 Computerized tomography (CT scan) of of spine CT scan have a accuracy rate (sensitivity) of over 98% with bone damage, which is of high value in the classification of spinal fractures. Determination of bone loss: reduction of the height of the anterior column, fracture line, separate fracture piece and compression position, joint block lesions, spinal canal, plates, bending angular deformations or dislocation, spinal canal narrow levels. However, it is difficult to assess soft tissue lesions such as ligaments, nerves. 1.4.3. MRI of spine Magnetic resonance imaging may determine the damage in marrow, soft tissue, posterior ligament complex. Marrow edema and marrow contusion without blood bleeding have same signal image or low signal on T1, high signal on T2. Acute or semiacute bleeding has low signal image on T2, in chronic phase it is a high signal image on T1 and T2. For marrow breaking, the image shows a persistent breaking of the injured segment and the marrow edema, accompanied by haemorrhage. Image of ligament injury: sudden loss of signal in a signal decreasing region on T1, increasing signal in the
6 surrounding organisms on T2. Bone damage will have an image of decreasing the signal on T1, increasing the signal on T2, can be defined the bone fracture line, fractured piece compressing the spinal column. 1.5. Brief history of the study and treatment of thoracic and lumbar spinal injury 1.5.1. In the world Surgery for treatment of thoracic and lumbar spinal injury was first supported by Gorter more than 200 years ago. Prior to 1963, the main treatment was conservative treatment, external correction, posterior arch cut operation and still have limitations. Later some authors have applied some methods for fixation in surgery such as steel string tie, hook, brace, Hartshill frame which obtained certain results. Posterior surgery actually developed as Roycamille developed, improved the surgical procedure with a screw via the spinal canal (1963 1975). This method was then modified by Margel into cluster screw with 5º15º slanted direction, which is widely used in surgery. Today, these two methods become more and more popular and effective in treatment 1.5.2. In Vietnam In Vietnam surgery began to be applied the 70s80s of the 20th century with the works of Hoang Tien Bao, Vo Van Thanh. However, in the 90s of the 20th century, spinal trauma surgery actually strongly developed in Vietnam and successfully applied both anterior and posterior surgery methods. Cho Ray Hospital, Viet Duc Hospital, 108 Military Central Hospital, Military Hospital 103 mainly applied the posterior surgery method. However, these studies have not addressed the role, conservation and restoration of the posterior ligament complex, nor have they adequately assessed the morphologic trauma on Xray and investigated the value of TLICS, LSC scales in surgery. 1.6.2. Some basic issues in posterior hardening 1.6.2.1. Configuration of foot bow screw system
7 According to Benzel E.C., the screw on the vertebral body will provide a durable traction and compression force on the vertebrae to prevent sliding deformation. This force is strongly influenced by the outer diameter of the screw, the ratio of the skeleton to the skeleton in the body and the bow, the diameter of the leg. The depth of the screws in the body of the burner is about 50% 80%. When the screw is placed in the leg screw system with adjusting force, it provides a bending and pulling torque for correcting the flexion. Corners, slides and compresses the vertical axis. At the same time, it is subjected to a bending and shearing moment in the opposite direction, especially at the beginning, end and midpoint of the screw system when the spine is subjected to a load. Therefore, system configuration is required. The foot screw must be firm enough to provide a sufficiently large force to maintain manipulation of the distal and spine. This is the theoretical basis for the construction of fixedlength configurations at two points and fixed longitudinal layers such as threepoint bending. The bending moment provided by these two fixed configurations is proportional to the length of the structure and has a lateral arm parallel to the spinal axis. This is the theoretical basis for the construction of fixedlength configurations at two points and fixed long bands such as threepoint bending. The bending moment provided by these two fixed configurations is proportional to the length of the structure and has a lever arm parallel to the spinal axis. Screw diagrams consist of a straight diagram (slanted angles down to 0º) and an anatomical diagram (slanted angles down to 20º 25º). In particular, linear diagrams provide superior mechanical biomechanics compared to bolted anatomy. We need to consider clearly the instability to make decisions and choose the optimum fixed configuration during surgery. According to Greenberg MS, joint degeneration required for surgery should usually occur after 3 years when fixing the long band and 8 – 9 years when fixing the short band. Therefore, the authors recommend that if the bone damage is not severe, fixing short band is appropriate.
8 . CHAPTER 2. SUBJECTS AND RESEARCH METHODS 2.1. Research subjects Study subjects included 89 patients diagnosed with thoracic and lumbar spinal injury, with single band and instability, operated to correct, fix, compress under the posterior method at Military Hospital 103 from 12/2010 to 1/2013. 2.1.1. Selection criteria Patients diagnosed with thoracic and lumbar spinal injury according to the criteria for each fracture type of the Greenberg MS, singleband lesions, c operated to correct, fix, compress by screw under the posterior method . No sex discrimination, age ≥ 18. 2.1.2. Exclusion criteria Patients have chronic diseases that affect the research results such as heart failure, liver failure, kidney failure, other cardiovascular diseases, diabetes ... Multiple injuries, fractures due to tuberculosis, cancer, mentally ill disorders, no cooperation in treatment, noncompliance with followup and reexaminaiton procedures, and lack of adequate research documentation. 2.2. Research Methodology 2.2.1. Research design A prospective research describes the clinic status with intervention, evaluates the result results on each patient before and after surgery. 2.2.2. Sample size Favorable sample selection includes all patients eligible for selection criteria and exclusion criteria during the study period. 2.2.3. Data collection method Information collected according to the unified medical records include: examination and evaluation of patients before
9 surgery; participate in surgery, follow up and treat patients after surgery, directly visit to examine patients after surgery under the medical record form of the research; check patients who return for reexamination in the Department of Neurological Surgery Military Hospital 103. 2.2.4. Research content – Determine the mechanism of injury. – Evaluate muscle strength and sensory disorders according to Greenberg M.S. criteria, applicable. – Evaluate the level of nerve damage accroding to Frankel improvement. – Evaluate via xray images: fracture position, kyphotic angle, reduction of column height in front of vertebral body, injury level of vertebral body according to McCormack, level of spinal stenosis, position pressing the spine, type of fracture, damage to the rear ligament system. – Surgery for removing, correction, fixation by the screw and plint as indicated by Greenberg M.S. – Postoperative evaluation at two points: 10 days after surgery and last examination (12 months after surgery). Criteria: Neurological rehabilitation according to Frankel; results of the correction of the kyphotic angle, the height of the column in front of the broken vertebra on the conventional x ray according to Keynal; backache, labor recovery by Denis; surgery time, blood loss during surgery, complications, condition of the screw system. 2.2.5. Data processing method Use of medical statistic software SPSS 22.0. 2.2.6. Research ethics The information about the patient’s illness status in the medical file is completely confidential and only used in the study with the consent of the Vietnam Military Medical University, Military Hospital 103.
10 CHAPTER 3 . RESEARCH RESULTS 3.1. Common features 3.1.3. Causes of injury Chart 3.3. Distribution rate of accident causes.
11 3.1.4. Mechanism of injury Chart 3.4. Distribution rate of injury mechanism. 3.2. Characteristics of vertebral injury 3.2.1. Fracture position Table 3.1. Distribution rate of fracture position. Fracture position Quantity Rate (%) P1 P2 T11 02 2.25 T12 18 20.22 L1 41 46.07 L2 15 16.85
12 3.2.6. Evaluate the fracture level of vertebral body according to McCormack Chart 3.8. Distribution rate of fracture level of fracture groups. 3.2.7. Evaluate the cohesion of fractured pieces according to McCormack Chart 3.9. Distribution rate of the cohesion of fractured pieces. 3.2.8. Evaluate the kyphotic level according to McCormack Chart 3.10. Distribution rate of the kyphotic level. 3.2.9. Evaluate the fracture types according to McCormack rating scale Chart 3.11. Distribution rate of points. 3.2.10. Evaluate the height reduction of the column in front of vertebral body Table 3.3. Height reduction of column in front of vertebral body. Reduction index Standard Smallest Biggest Mean deviation p (%) (%) (%) Fracture type (+/ %) Compression fracture 50 56 51.35 2.29 (n = 17)
13 (+/0) Fracture type Compression fracture 19 29 23.24 3.38 Burst fracture 20 40 26.37 3.89
14 Chart 3.12. Distribution rate of compression causes. 3.2.14. Spinal canal compressing positions Chart 3.14. Distribution rate of spinal canal compressing positions. 3.2.15. Fracture type and spinal decompression methods Table 3.6. Decompression method. Decompres Direct Indirect sion Quantity % Quantity % Fracture types Compression fracture 3 17.65 14 82.35 Burst fracture 34 50.75 33 49.25 Dislocation fracture 3 60.0 2 40.0 3.2.16. Decompression time Chart 3.16. Rate of decompression time.
15 3.2.17.Decompression group and deformation Table 3.7. Decompression group and deformation. Defo Smal Bigg Mea Standard deviation rmati lest est n on Quan tity Fract ure types Compressio Group 1 6 20 50 29 52 25.1 50.3 3.1 0.8 n fracture Group 2 11 19 50 29 56 22.1 51.9 3.1 2.6 Burst Group 1 37 20 25 35 50 27.7 38.5 3.2 6.9 fracture Group 2 30 20 20 40 56 24.6 32.3 3.9 6.9 Dislocation Group 1 5 22 20 35 35 28.8 27.0 5.2 5.7 fracture 3.3. Injury to the posterior ligament system 3.3.1. Fracture types and injury to the posterior ligament system Table 3.9. Determine injury to the posterior ligament system by MRI and surgery. Criteria Injury to the MRI Surgery posterior p ligament Fracture system types Quantit Quantity Quantit Rate Rate Quantit Rate y (n) y (n) (%) (%) y (n) (%) (n) Compression 17 4 23.53 4 23.53 4 23.53 fracture
16 Total 89 17 19.10 19 21.35 19 21.35 3.3.2. Evaluate fracture types according to TLICS scale Chart 3.17. Distribution according to TLICS scale. 3.4. Nerve damage 3.4.1. Nerve damage levels Table 3.14. Nerve damage levels. Frankel level A B C D1 D2 D3 E Quantity 6 3 11 1 6 8 54 3.4.3. Nerve damage and the spinal canal narrow levels in each fracture type Table 3.16. Spinal canal narrow levels and nerve damage. Narrow Not p 0.05 Burst fracture 0 8 3 23 26 7
17 Compression Group 1 6 2 12 10 16 6.6 14.6 3.3 1.5 fracture Group 2 11 2 14 10 18 4.5 15.7 3.2 1.2 Burst Group 1 37 2 4 19 15 6.9 10.5 3.2 1.2 fracture Group 2 30 2 5 33 15 8.5 10.2 7.7 2.3 Dislocation 5 8 7 10 15 9.0 10.2 1.0 3.1 Group 1 fracture 3.5.1.4. Results of neurological recovery 10 days after surgery Table 3.21. Results of neurological recovery Fra 10 Total nkel day – s Bra afte dfor r d surg leve ery l A B C D1 D2 D3 E A 6 6 B 3 3 Bef C 6 3 2 11 ore D1 1 1 surg ery D2 2 4 6 D3 3 5 8 E 54 54 Total 6 3 6 3 2 6 63 89 3.5.2. Far results 3.5.2.2. Results of deformation correction in the final examination Table 3.23. Results of deformation correction Quant Small Bigge Mean Standard deviation Defor ity est st matio n Fract ure
18 types Compressio Group 1 6 3 15 12 19 7.8 17.3 3.5 1.5 n fracture Group 2 11 3 17 11 20 5.4 18.0 3.2 1.0 Burst Group 1 37 3 5 20 17 8.4 12.4 5.1 2.5 fracture Group 2 30 3 7 34 17 9.8 11.8 7.6 2.4 Dislocation 5 9 10 12 20 10.8 13.2 1.3 3.9 Group 1 fracture 3.5.2.3. Results of neurological recovery in the final examination Table 3.24. Results of neurological recovery. Fran Final Total kel – exa Brad mina ford tion level A B C D1 D2 D3 E s A 4 2 6 B 2 1 3 Befo C 2 3 2 2 2 11 re D1 1 1 surg D2 6 6 ery D3 8 8 E 54 54 Total 4 4 3 3 2 2 71 89 3.5.2.4. Back pain
19 Chart 3.19. Distribution rate of backache levels. 3.5.2.5 Labor recovery Chart 3.20. Distribution rate of labor recovery levels. 3.5.2.6. Number of fixed bands and the broken rate of screws Chart 3.21. Number of fixed bands and the broken rate of screws. CHAPTER 4. DISCUSSION 4.2. Characteristics of vertebral fractures 4.2.1. Position of vertebral body injury The fracture rate at the thoracolumbar spine hinge vertebra and vertebra L1 is the highest. This result is consistent with the anatomical characteristics of the spine segment (which is considered straight, kyphotic angle of the region 0⁰ 10⁰), with the injury mechanism of longitudinal compression type and consistent with the study results of the local and foreign authors. 4.2.2. Fracture types In our study, burst fracture accounts for 74,16%; compression fracture of 19,10%. This rate is consistent with indirect trauma and thoracolumbar spine hinge vertebra injury accounts for the majority with the rate of 94,38% and 85,39%, respectively. According to Benzel E. C., the traumatic force acting
20 in the direction of the vertical axis will be coaxial with IAR on the thoracolumbar spine hinge vertebra, therefore burst fracture, compression fracture are more commonly seen. 4.2.3. Vertebral fracture level, the cohesion of fractured pieces, height reduction of front column and kyphotic angle in the injured area in terms of each fracture type In our research, deformation was studied and evaluated for each fracture group and found that it depended on: the degree of height reduction in vertebral body, breaking degree of vertebral body, cohesion of fractured pieces, especially injury in the middle column. This is consistent with McCormack's judgment. However, there are other related factors such as the integrity of the posterior ligament complex, joint block lesions. Thus, a full evaluation of the correlations between the factors in each fracture group has given us a more comprehensive view of deformation in spinal injuries as a basis for selecting an appropriate method for stabilizing and maintaining a stable structure in surgery. To overcome the possible kyphotic complications, besides the correction, restoration of kyphotic angle of the area and height of the vertebral body, the restoration and conservation of the posterior ligament complex is necessary. 4.2.4 Spinal canal narrow levels, causes and compressing positions Through the computerized tomography image of the fractured vertebra, we have realized that: compression fracture with low spinal canal narrows rate accounts for 17.65%; of which 100% of the spinal canal narrow is < 50% due to the posterior bending angle of the vertebral body at the ½ above position. Burst fractures of spinal canal narrows group accounts for the majority, about 88.06%; of which narrow level ≥ 50% is about 49.25%; the reason is that fractured pieces accounts for the majority (96.6%) and compression at the position of ½ above accounts for the majority (84.7%). Group