The thoracolumbar segment fractures are the most frequent along the spine, and surgical treatment is indicated in unstable fractures. Surgical treatment has been performed through the posterior fixation pedicle fixation systems, and where necessary complemented by decompression of the spinal arthrodesis and previous channel. Surgical treatment has been performed by conventional open approach through the posterior incision on the midline, and detachment and removal of paraspinal muscles to access the posterior vertebral elements. The percutaneous minimally invasive surgery was introduced in the context of spinal surgery to reduce the morbidity associated with conventional open approach. It has been reported the lowest bleeding intra- and postoperative period, less pain, shorter hospital stay, rehabilitation and return to work faster with less use of minimally invasive percutaneous approach of the spine. However, predominates in the literature of clinical case reports and few prospective and randomized clinical trials. The performance of prospective randomized clinical trials have been required for the evaluation of the benefits of minimally invasive surgery in the treatment of the thoracolumbar spine fractures. The objective of the study is to compare the surgical treatment of fractures of the thoracolumbar spine using the conventional open approach or minimally invasive percutaneous approach to the stabilization of the vertebral segment affected, and using similar type of pedicle spinal fixation system. Patients will be evaluated in the preoperative, postoperative, 1,2,3,6,12 and 24 months by parameters related to the perioperative (intraoperative bleeding, surgery time), clinical (VAS, SF-36, HADS, EQ-5D-5L), images (radiographs and computed tomography). The study results will impact the guidelines of the surgical treatment of thoracolumbar spine fractures and may indicate the advantages or disadvantages of using surgery through conventional open approach to minimally invasive percutaneous surgery.

Introduction: Fractures of the thoracic and lumbar spine are the most frequent fractures of the axial skeleton, and correspond to about 89% of vertebral fractures. Two-thirds of these fractures occur in the thoracolumbar transition between T11 and L2 (50% of thoracic spine fractures at T12 level and 60% of lumbar spine fractures at L1 level). Surgical treatment of thoracolumbar spine fractures has been indicated in unstable fractures with the aim of stabilizing the fractured vertebral segment and allowing early rehabilitation without the use of external immobilization and rest in the bed. Conventional surgical treatment has been performed by means of fixation and posterior arthrodesis of the vertebral segment using pedicle fixation systems with or without arthrodesis The scientific challenge of the project is to carry out this method of pioneering study in our country, as no prospective randomized clinical trial has been performed in our country to compare the outcome of surgical treatment of thoracolumbar spine fractures through conventional open surgery or surgery Minimally invasive percutaneous. There are few reports of prospective and randomized trials on this subject and its implementation has been stimulated to increase the level of evidence related to the surgical treatment of thoracolumbar spine fractures.

The objective of the study will be to compare the results of treatment of thoracolumbar spine fractures through the open approach (conventional surgery) or percutaneous (minimally invasive) approach with a pedicle fixation system without vertebral arthrodesis.

The hypothesis of the study is that minimally invasive percutaneous surgery has the advantage of producing less surgical trauma with less intra- and postoperative bleeding, lower pain intensity, shorter hospitalization time and lower rate of complications, and postero-lateral arthrodesis Is not required in the treatment of thoracolumbar spine fractures.

Material and methods

After the clinical and radiographic evaluation (simple radiographs, CT and MRI if necessary) of the patients the fracture will be classified according to the classification Magerl et al., and the therapeutic planning defined. Fractures with surgical indication by means of the posterior approach will be selected for the study and the randomization process performed individually for each type of fracture (A, B and C) according to the Magerl classification. Patients will be randomized and assigned to two groups: A - conventional open surgery and B - minimally invasive percutaneous surgery.

Surgical treatment will be performed by stabilizing the fractured vertebral segment (proximal vertebra and vertebra distal to fractured vertebra and fractured vertebra) by means of a 6.5 mm or 6.5 mm diameter polyaxial pedicle screw system. In the fractured proximal and distal vertebrae, screws will be used up to the vertebral body and in fractured vertebra shorter screws that do not penetrate the vertebral body will be used. In the fractured vertebra, single or bilateral pedicle screw will be used according to the degree of involvement of the pedicle of the fractured vertebra.

The vertebral fixation system will be applied through the conventional open approach (group A) or minimally invasive percutaneous approach (group B) according to allocation after randomization.

Patients will be evaluated through perioperative, clinical, and radiographic parameters.

Perioperative parameters:

Time of surgery - time elapsed between incision and closure of the skin. Intraoperative bleeding - a measure of the amount of blood evaluated by the amount of blood drawn and blood from the compresses and gauzes used.

Postoperative bleeding - a measure of the amount of blood aspirated through the drain and measured in the postoperative gauze pads and dressings.

Time of use of fluoroscopy. Postoperative walking time Length of hospital stay Drugs used in the postoperative period

Clinical parameters:

Visual pain scale (VAS) - evaluated in the preoperative period, 1,2,3,4,5,6,7 postoperative days, 1,2,3,6,12 and 24 months.

Medical Outcomes Study 36 - Item Short - Form Health Survey (SF-36) HADS - Hospital Anxiety Depression Scale EQ-5D-5L Dennis Pain and Work Scale Pain Assessment Scale (Dennis) P1: absence of pain P2: minimal occasional pain; No need for medication. P3: Moderate pain, occasional medication and no interruption of professional or daily activities.

P4: moderate or severe pain, occasional absence of work, significant change in daily activities.

P5: constant, severe pain, use of chronic analgesic medication

Work ability assessment scale (Dennis) W1: return to previous work (heavy arm activity) or heavy physical activities W2: return to previous work (sedentary) or heavy physical labor with restrictions W3: unable to return previous plus works full time in another activity W4: unable to return full time to work W5: does not work, totally disabled They were evaluated in the immediate postoperative period, 1,2,3,6,12 and 24 months.

Radiographic Parameters Simple radiographs in AP and profile - location, fracture classification, assessment of vertebral body height, evaluation of Farcy's sagittal index, fractured kyphosis, fractured vertebral kyphosis, intervertebral disc height above and below fractured vertebra, alignment in AP, (preoperative, immediate postoperative, 1,2,3,6,12 and 24 months).

Alignment in the coronal plane will be performed by measuring the angle of Cobb between the line parallel to the proximal vertebral plaque of the vertebra above the fractured vertebra and distal vertebral plate below the fractured vertebra.

The height of the vertebral body will be evaluated by means of the percentage of compression of the vertebral body in relation to the adjacent segments. The height of the vertebral body above (V1) and below (V2) of the fractured vertebra (V3) is considered using the following formula:% compression = [(A1 + A3) / 2-A2] / (A1 + A3) / 2

The kyphosis of the fractured segment will be assessed by the angle formed by the line parallel to the superior vertebral plate of the vertebra proximal to the fractured vertebra and by the line of the inferior vertebral plate of the vertebra distal to the fractured vertebra The sagittal index of the fractured segment (Farcy Index) will be calculated using the height of the proximal vertebra (A1), height of the fractured vertebra (A2) and height of the distal vertebra. Sagittal index of the fractured segment = (A3): 100- (2xA2 / A1 + A3) x100.

Computed tomography - morphology and type of fracture, percentage of compression of the vertebral canal, positioning of the screws (preoperative and immediate postoperative).

Compression of the vertebral canal will be evaluated by measuring the sagittal diameter of the vertebral canal (Fig. 8) and the direct measurement of the cross-sectional area of the vertebral canal using scanning to delimit its perimeter.

The positioning of the screws inside the pedicles will be evaluated by means of tomographic cuts of 2mm. Correct positioning will be considered when the pedicle screw is fully encircled by the vertebral pedicle and the cortical vertebra is not perforated. The perforation will be classified as small (≤2mm), medium (2.1-4mm) and severe (> 4mm), and the perforation site: medial, lateral, superior, posterior will also be evaluated.

Evaluation of implant release, implant breakage and fracture consolidation, loss of reduction.

Computed tomography - evaluation of the paravertebral musculature - Evaluation of the transverse sectional area and fat infiltration in the paravertebral musculature by computed tomography (CT).

The CT examinations performed to evaluate the position of the metallic implants, fracture type and the evolution of the morphology of the vertebral body will also be used to evaluate the paravertebral musculature. In this way it will be possible to compare the effect of each of the fixation techniques on the musculature trophism.

The evaluation will be performed by a senior radiologist with more than fifteen years of experience in musculoskeletal radiology and with experience in evaluation using quantitative techniques.

Patient images will be anonymized and presented to the radiologist through the Osirix imaging software at random. The observer will not be aware of the clinical and surgical information at the time of the measurements to be performed.

Two other researchers, a radiologist and a spine surgeon will perform this classification independently, so as to enable the analysis of Interobserver reproducibility of the classification.

General risks, local and adverse effects - risks will be defined as any incident, change in treatment or normal progress regardless of whether or not it is associated with the treatment being evaluated. The predicted risks related to thoracolumbar spine fractures and their surgical treatment are superficial infection, deep infection, epidural hematoma, duramater injury, inadequate position of pedicle screws, radiculopathy, fractured vertebral segment kyphosis, instability, pain uncontrollable to treatment , Failure of implants, degeneration of adjacent segments, pressure ulcers and reoperation.

The adverse effects will be considered as any undesirable medical event that the study participant presents (death, deep venous thrombosis, septicemia, pulmonary embolism, pneumonia, urinary tract infection, acute respiratory failure, multiple organ failures, hospitalization, prolonged failure of the implants Or intraoperative adverse effects).

Inclusion Criteria:

• Single level fracture
• Fracture T11-L5
• Posterior Stabilization Indication

Exclusion Criteria:

• Fracture in more than 1 level
• Osteoporotic fracture
• Pathological fracture
• Previous history of surgery
• Deformity
• Mental disease
• TCE
• Posterior vertebral canal open decompression