A variety of procedures have been proposed for the optimal surgical management of a retropulsed posterior wall fragment from an osteoporotic vertebral fracture (OVF) protruding into the spinal canal and compressing the neural elements; however, it remains a matter of serious deliberation [1,2]. Pedicle screw (PS) pullout is a frequent concern in short-segment posterior fixation in elderly patients with OVFs. To prevent this complication, several techniques have been developed, including endplate-penetrating (pedicular transvertebral) screw fixation [3] and fenestrated hollow screws that allow polymethyl methacrylate (PMMA) injection through the screw lumen to enhance screw anchorage [4]. However, even with penetrating endplate screws (PES), problems such as screw loosening and pullout are not completely resolved [5].

To address this, we devised a simple technique to combine PES with PMMA augmentation. In this technique, the tip of a hollow PS is intentionally filled with disc tissue to act as a biological “plug” before cement injection to enhance screw fixation while preventing cement leakage into the intervertebral disc space. Herein, we present two illustrative cases detailing the surgical technique and outcomes. This technical report does not establish a new standard technique, but rather describes a preliminary salvage approach applicable in select cases.

Many patients with OVFs, where a retropulsed posterior wall fragment protrudes into the spinal canal and directly compresses neural tissue, or where instability of the fractured vertebra leads to neurological deficits, are elderly and have severe osteoporosis [1,2]. Consequently, the optimal surgical approach in this population remains a matter of debate. Anterior surgery is often difficult because of the patient’s age and poor bone quality; therefore, posterior indirect decompression and posterior fusion are generally preferred. However, in such cases, because of a kyphotic deformity at the fracture level, decompression alone is frequently insufficient to improve neurological symptoms, necessitating posterior fixation [6]. Although short-segment fixation is preferred to preserve motion segments, PS pullout remains a major concern in osteoporotic vertebrae.

PES fixation or pedicular transvertebral screw fixation was first described by Abdu et al. [3]. It has since evolved into the single or double-endplate penetrating screw (SEPS/DEPS) technique, in which the screw penetrates the endplates of adjacent vertebrae [7]. This technique involves intentional puncture of the intervertebral disc, and therefore long-term adjacent segment degeneration and instability are potential concerns. However, from a biomechanical standpoint, disc violation and local cement augmentation may increase stiffness at the treated level and shift motion and load to adjacent segments, potentially predisposing to adjacent segments to degeneration or junctional fractures, especially within a short fusion construct. As summarized in the Table 1, previous reports have shown acceptable short- to mid-term outcomes [5,7–9]; however, at present, this technique should probably be limited to cases in which conventional PS fixation is expected to fail, such as very elderly patients with osteoporotic vertebrae in whom intraoperative loosening is anticipated. A previous report noted that at the 1-year follow-up, cases treated with the one-above/one-below short fusion using PESs without cement for OVFs showed radiolucent zones around screws (n=3/11; 27.3%), screw loosening or nonunion (n=1/11; 9.1%), and adjacent vertebral fracture (n=1/11; 9.1%) [5]. Thus, even when PESs were used, problems such as screw loosening and pullout were not completely resolved.

Cement augmentation through fenestrated PSs is a widely used technique to increase pullout strength in osteoporotic vertebrae [4,10]. However, when PMMA is simply injected through a PES, the cement can leak from the screw tip into the intervertebral disc space, potentially increasing the risk of adjacent vertebral fractures and accelerating disc degeneration [11]. In addition, once cement has leaked into the disc, it becomes difficult to create a sufficient cement mass within the vertebral body, and the expected improvement in PS fixation may not be achieved.

To address these issues, we used to intentionally draw the disc tissue into the hollow PS tip to act as a “plug” before PMMA injection. This maneuver helped prevent intradiscal cement leakage from the screw tip while allowing cement to distribute from the side holes of the PS into the cancellous bone of the vertebral body. As a result, the contact area between the vertebral body and the PS was increased, and stronger fixation could be obtained. In both illustrative cases, the cement was injected in a highly viscous state under continuous fluoroscopic monitoring, and injection was immediately stopped when the cement front approached the posterior wall, which may have ensured the absence of clinically relevant leakage [4,10].

Nevertheless, great caution is always required regarding cement leakage outside the vertebral body. In particular, when the distance between the screw tip and the posterior vertebral wall is small, cement leakage in this region is difficult to detect on lateral fluoroscopy. In such cases, the injection volume should be kept to a minimum as a safety measure, as shown in Case 2.

This report has several limitations. First, there were only two patients, with a short follow-up and no control group; hence, we could not provide definitive data on long-term safety, durability, or superiority over conventional cement-augmented screws. Second, no biomechanical testing or animal model was used to validate the behavior of the disc-tissue “plug,” the cement distribution, and its effectiveness in markedly degenerated or nearly empty discs. Intraoperatively, resistance faced by the guidewire at the screw tip suggested a mechanical barrier of disc and endplate tissue (Fig. 3D), but this cannot substitute for formal biomechanical evidence. Third, the long-term effects of intentional disc puncture and localized cement augmentation in terms of adjacent disc degeneration, fracture risk, and implant stress within a short-fusion construct are unknown. Notably, the two cases presented here, as well as previous case series reporting the short- to mid-term outcomes of cementless endplate-penetrating short fusions, have not shown screw breakage or catastrophic construct failure. Accordingly, this technique is not presented as a superior method, but as a preliminary salvage option when PES alone are judged insufficient and conventional cement injection would likely cause intradiscal leakage. Wider clinical application of this technique can only be recommended after adequate biomechanical and longer-term clinical studies have been conducted using larger patient cohorts.