Spinal fractures are common clinical injuries, especially prevalent in the thoracolumbar region. This area, transitioning between thoracic kyphosis and lumbar lordosis, experiences high vertebral mobility and concentrated stress, making it prone to fractures. Under axial loading, fractured vertebrae can further compress and deform, potentially leading to sagittal spinal imbalance, i.e., kyphotic deformity, during healing. Therefore, for patients requiring surgery, strong fixation of the fracture site is essential to achieve maximum bone healing and maintain good spinal balance. The intermuscular approach minimizes muscle fiber damage and causes relatively less injury to the posterior longitudinal ligament complex, reducing postoperative low back pain [1]. It also involves less blood loss during surgery and shorter postoperative bed rest [2]. Offering comparable internal fixation efficacy with these advantages, it has become an ideal minimally invasive treatment option. Literature suggests that bone grafting into the fractured vertebra is considered a beneficial surgical method to promote bone healing and reduce the occurrence of the "cavity phenomenon" or "vacuum sign"[3,4]. Vertebral body bone grafting can more effectively reduce the fractured vertebra, restore physiological curvature, and prevent the loss of central vertebral height and spinal instability caused by stress concentration. Studies investigating postoperative fracture morphology have revealed an average bone resorption rate of −15.29 % at mid-term follow-up in patients with mandibular condylar head fractures [5]. Furthermore, in patients with proximal humeral fractures, non-reduction of the greater tuberosity or insufficient medial support increases the risk of bone resorption in the consolidated greater tuberosity fragment post-reduction; an increased number of fracture fragments, smaller fragment size, and reduced bone mineral density also contribute to this risk [6]. It is evident that the bone remodeling phase following a fracture is accompanied by bone resorption phenomena, which may adversely affect the patient's bone quality. Therefore, bone grafting at the fracture site is necessary. However, conventional bone funnels often present common issues: unidirectional bone material delivery from the tip can be obstructed by irregular fracture surfaces within the vertebral body, limiting the graft volume and leading to insufficient filling of bone defects. Moreover, the smooth outer wall and relatively large diameter of some funnels may lead to insufficient screw purchase if screws are placed in the injured vertebra after its use. Distraction between screws might cause pedicle cutting injuries, increasing the risk of screw loosening and failure. Thus, a user-friendly, efficient, and safe tool for transpedicular bone grafting that also preserves screw purchase in the injured vertebra is highly desirable in clinical practice.

This study utilized a self-developed tappable bone grafting tool with a variable-angle lateral window for treating thoracolumbar fractures. By retrospectively analyzing relevant cases, we aimed to investigate the impact of the choice of this novel bone grafting tool and the decision to place screws in the injured vertebra on surgical outcomes.