This retrospective cohort study was exempt from informed consent requirements. This study was approved by the Institutional Review Board (IRB) of Hunan Provincial People’s Hospital (the First Affiliated Hospital of Hunan Normal University; IRB no.,2025114). We reviewed patients with single-segment LBFs who underwent surgical treatment at the Department of Spine Surgery, Hunan Provincial People’s Hospital (the First Affiliated Hospital of Hunan Normal University), between January 2019 and December 2021. After screening, 64 patients met the inclusion criteria and were enrolled in the study. Patients were divided into two groups based on the surgical approach: the long-segment group (n=38), which received posterior long-segment pedicle screw-rod fixation, and the short-segment group (n=26), which underwent posterior short-segment pedicle screw-rod fixation.

The long-segment group consisted of 28 males and 10 females, with a mean age of 44.8 years (range, 25–65 years). The distribution of fractured vertebrae in this group was as follows: L1 (19 cases), L2 (13 cases), L3 (four cases), and L4 (two cases). The short-segment group comprised 19 males and seven females, with a mean age of 43.1 years (range, 27–64 years). The distribution of fractured vertebrae in this group was as follows: L1 (18 cases), L2 (two cases), L3 (three cases), and L4 (three cases). Preoperative informed consent was obtained from all patients, and relevant examinations were completed prior to surgery.

Long-segment fixation involves fixing the fractured vertebra and at least two adjacent vertebrae above and below it. Short-segment fixation only involves fixing the fractured vertebra and one adjacent vertebra above and below it.

The inclusion criteria were as follows: (1) single-segment traumatic LBF (Thoracolumbar Injury Classification and Severity [TLICS] score >4 points, Load Sharing score 5–8 points); (2) both sides of the pedicle of the injured vertebra intact; (3) age between 18 and 65 years.

The exclusion criteria were as follows: (1) pathological fractures; (2) history of spinal surgery; (3) severe fractures or serious organ injuries in other parts; (4) osteoporosis (T score <−2.5); (5) pregnancy; (6) loss to follow-up; and (7) cases with deep incision infection.

Under general anesthesia, patients were positioned prone with the abdomen suspended. C-arm fluoroscopy was used to confirm the location of the injured vertebra, and precise markings were made on the skin. A midline posterior incision centered over the injured vertebra was then made, exposing the injured vertebra and one or two adjacent vertebrae. Pedicle screws were implanted under fluoroscopic guidance to ensure accurate placement. In the long-segment fixation, the injured vertebra and two adjacent vertebrae above and below were fixed, whereas in the short-segment fixation, only the injured vertebra and one adjacent vertebra above and below were fixed. Lateral fluoroscopic views were used to verify that the lengths and positions of the screws were satisfactory. Appropriately sized pre-bent rods were then selected, and a vertebral distractor was used to distract the two sets of pedicle screws in a parallel manner. This allowed for reduction and fixation to restore vertebral height and physiological spine curvature. After the surgery, fluoroscopy was repeated to check for any displacement of the screws and the recovery of the height of the injured vertebra. Once satisfactory reduction was achieved, a drain was placed and the incision was sutured. Prophylactic antibiotics were administered for at least 3 days. Postoperative rehabilitation instructions emphasized the importance of ambulation with the protection of an external immobilization brace, while strictly avoiding bending or twisting movements of the waist. The immobilization period was maintained for at least 3 months or longer. Notably, at the commencement of the study, none of the patients had undergone removal of their internal fixation screws. Additionally, fusion procedure was not performed during the initial surgery for any patient.

Data pertaining to surgical duration (minutes), intraoperative blood loss (mL), postoperative drainage volume (mL), and length of hospital stay (days) were obtained from anesthesia records, postoperative nursing records, and the hospital’s inpatient information system.

Regular follow-ups were conducted postoperatively, including assessments at baseline, 1 week, 3 months, and 24 months post-surgery. The following parameters were evaluated: Visual Analog Scale (VAS) pain scores, Oswestry Disability Index (ODI), neurological function based on the American Spinal Injury Association (ASIA) classification, anterior edge height of the fractured vertebra, and conditions related to screw-rod loosening, fracture, and displacement. Two researchers, blinded to the research protocol and grouping, independently completed the follow-ups, with the average of their assessments used as the final study result.

Complete encapsulation type, where osteophytes connect the two adjacent vertebrae above and below the fractured vertebra, completely covering both sides and the front of the vertebra, scored 3 points. The bridged osteophyte type, where osteophytes connect the two adjacent vertebrae but only cover the sides or the front of the vertebra, scored 2 points. Incomplete type osteophyte formation characterized by localized osteophyte formation without bridging, scored 1 point. Lastly, the no osteophyte type, indicating an absence of osteophyte formation, scored 0 points (Fig. 1).

The vacuum sign is a radiographic finding that occurs when the intervertebral disc undergoes degeneration, leading to shrinkage and necrosis of the nucleus pulposus. This creates gaps within the disc, resulting in negative pressure that allows gases from surrounding blood or tissue, such as nitrogen or carbon dioxide, to enter and produce low-density images visible on X-rays or CT scans. The vacuum sign is scored as follows: (1) Complete: Both adjacent intervertebral discs exhibit the vacuum sign, scoring 2 points. (2) Partial: Only one of the adjacent intervertebral discs exhibits the vacuum sign, scoring 1 point. (3) None: Neither of the adjacent intervertebral discs exhibits the vacuum sign, scoring 0 points (Fig. 2).

The intervertebral height was measured at 1 week, 3 months, and 24 months post-surgery (Fig. 3). This measurement specifically refers to the distance between the lower endplate of the upper vertebra and the upper endplate of the lower vertebra at the fractured site. The intervertebral height loss rate was calculated using the following formula:

To calculate the intervertebral space height, the following steps were taken: The four corners of the intervertebral discs above and below the injured vertebra were identified. The two points along the direction parallel to the end plates were connected, and the distances between the two consecutive midpoints were measured and denoted as (a) and (b). The intervertebral space height was then calculated using the following formula: (a+b)/2.

Data analyses were conducted using IBM SPSS ver. 26.0 (IBM Corp., Armonk, NY, USA). Normally distributed continuous variables were expressed as mean±standard deviation and analyzed using the independent samples t-test. Multi-group comparisons were performed using analysis of variance. Non-normally distributed continuous variables were analyzed using the rank-sum test, while categorical variables were analyzed using the chi-square test. All p-values of less than 0.05 were considered indicative of statistical significance.

At baseline, there were no significant differences between the two groups with respect to sex, age, disease duration or load-sharing score (p>0.05).

The surgical duration, intraoperative blood loss, and postoperative drainage volume were significantly higher in the long-segment group compared to the short-segment group (p<0.05) (Fig. 4).

Fig. 6 shows CT of long-segment fixation (A–E correspond to preoperative, 1 week postoperative, 3 months postoperative, 2 years postoperative, and 2 years postoperative [three-dimensional reconstruction] images, respectively). The osteophyte score was 0 at 1 week and 3 months postoperative, and 2 at 2 years postoperative; the vacuum sign score was 0 at 3 months and 1 at 2 years; the intervertebral height loss rate was 6.73% at 3 months and 8.79% at 2 years.

Fig. 7 shows typical CT changes in short-segment fixation (A–E correspond to preoperative, 1 week postoperative, 3 months postoperative, 2 years postoperative, and 2 years postoperative [three-dimensional reconstruction] images, respectively). As shown in Fig. 7A, the preoperative CT image is presented. The bone spur score was 0 at 3 months and 3 at 2 years; the vacuum sign score was 0 at both 3 months and 2 years; the intervertebral height loss rate was 6.84% at 3 months and 9.29% at 2 years (Fig. 7B).