Materials and methods

Study design and setting

This was a prospective, single-arm, hospital-based interventional study conducted over an 18-month period from October 2019 to March 2021 at a tertiary care center. The study was approved by the Institutional Ethics Committee, and written informed consent was obtained from all patients or their legally authorized representatives. There was no concurrent open-surgery comparison group.

Sample size

Taking the proportion of satisfactory outcomes after PPSF as 86.1% from Ni et al. [11], a sample size of 46 was calculated for a margin of error of 10% at a 5% level of significance using the formula n≥p(1−p)/(ME/Zα)².

Participants

Patients aged 18-50 years of either sex with AO Spine type A3 or A4 thoracolumbar fractures or type B1/B2 flexion-distraction (Chance) injuries and intact neurology (American Spinal Injury Association (ASIA) Impairment Scale grade E) were included in the study. Patients with any neurological deficit, fracture types other than those specified, spinal tumors or suspected pathological fractures, severe osteoporosis, or spinal tuberculosis were excluded.

Preoperative assessment

Plain anteroposterior and lateral radiographs were used to measure the sagittal Cobb angle and anterior vertebral body height (AVBH). The sagittal Cobb angle was measured between the superior endplate of the vertebra above and the inferior endplate of the vertebra below the fractured vertebra, while AVBH was calculated as the percentage of the anterior height of the fractured vertebral body relative to the estimated normal height derived from the adjacent vertebrae. Computed tomography (CT) was used to assess fracture comminution and fragment apposition, whereas magnetic resonance imaging (MRI) was used to evaluate the posterior ligamentous complex and spinal cord. Neurological status was documented using the ASIA Impairment Scale [12-14].

Surgical technique

After induction of general anesthesia, patients were carefully positioned prone on a radiolucent operating table with chest and pelvic bolsters to promote lordosis, with appropriate padding and meticulous protection of the abdomen, external genitalia, pressure points, and endotracheal tube. Short-segment percutaneous fixation was performed using pedicle screws inserted one level above and one level below the fractured vertebra, connected with contoured rods under fluoroscopic guidance using a conventional C-arm. A single conventional C-arm was used to obtain true anteroposterior and lateral projections aligned with the vertebral endplates. Skin entry points were marked 1-2 cm lateral to the target pedicle (2-3 o'clock on the right and 9-10 o'clock on the left) to permit a convergent trajectory (Figure 1).

Figure 1: (a) Skin incision. (b) Entry point of the Jamshidi needle

A Jamshidi needle was advanced to the base of the pedicle under intermittent fluoroscopic guidance. A guidewire was then passed into the vertebral body, taking care not to breach the anterior cortex (Figure 2).

Figure 2: (a) Tip of the Jamshidi needle at the center of the pedicle. (b) Tip of the Jamshidi needle approaching the posterior wall of the vertebral body

After sequential dilation and cannulated tapping, cannulated pedicle screws were inserted over the guidewires, followed by placement of the contoured rods (Figure 3). The wounds were closed in layers (Figure 4).

Figure 3: (a) Guidewire inserted. (b) Pedicle screw insertion over the guidewire

Figure 4: (a) Skin closure. (b) Final position of the pedicle screws

Postoperative assessment and outcomes

Postoperative radiographs were obtained to remeasure the Cobb angle and AVBH, and CT was performed to grade screw placement using the Gertzbein-Robbins classification with 2-mm pedicle breach increments (grade A, fully contained; grade B, 0-2 mm; grade C, 2-4 mm; grade D, 4-6 mm) [15]. Pain was assessed using a 0-10 visual analog scale (VAS) on the day of surgery and on postoperative day 3. Operative time, intraoperative blood loss, length of hospital stay, and complications (neurological injury, infection, implant failure, and revision surgery) were recorded. All patients received the institutional postoperative protocol, including early mobilization as tolerated, appropriate analgesia, brace support when indicated, and physiotherapy before discharge.

Statistical analysis

Statistical analysis was performed using SPSS Statistics version 21.0 (IBM Corp., Armonk, NY, USA). Continuous variables were expressed as mean±standard deviation (SD) and range, while categorical variables were presented as frequencies and percentages. Normality of continuous variables was assessed using the Shapiro-Wilk test. Normally distributed paired variables were compared using the paired Student's t-test, whereas non-normally distributed paired variables were compared using the Wilcoxon signed-rank test. Categorical variables were summarized descriptively without inferential testing because the study lacked a comparison group. A p-value <0.05 was considered statistically significant.