Pedicle screw insertion technique into a previously cement-augmented vertebral body: a technical note with a case series

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Asian Spine J. 2026;.asj.2025.0825

Publication date (electronic) : 2026 February 11

doi : https://doi.org/10.31616/asj.2025.0825

Hee Jung Son¹, Hyeongseok Kim², Hyunjin Nam², Chang-Nam Kang²

¹Department of Orthopaedic Surgery, Nowon Eulji Medical Center, Eulji University School of Medicine, Seoul, Korea

²Department of Orthopaedic Surgery, Hanyang University College of Medicine, Seoul, Korea

Corresponding author: Chang-Nam Kang, Department of Orthopaedic Surgery, Hanyang University College of Medicine, 222-1 Wangsimni-ro, Seongdong-gu, Seoul 04763, Korea, Tel: +82-2-2290-8485, Fax: +82-2-2299-3774, E-mail: cnkang65@hanyang.ac.kr

Received 2025 December 13; Revised 2026 January 26; Accepted 2026 January 26.

Abstract

Introduction

Osteoporotic vertebral compression fractures (OVCF) are becoming increasingly prevalent as the global population ages. An estimated 1.4 million individuals worldwide experience OVCF annually, with both the incidence and clinical management of OVCF varying across countries [1–3]. In South Korea, the 5-year incidence has been reported as 852 cases per 100,000 persons, and the use of bone cement augmentation procedures such as vertebroplasty (VP) and balloon kyphoplasty (BKP) continues to increase [4,5]. Consequently, clinicians are increasingly encountering patients with cement-augmented vertebrae who require additional spinal instrumentation.

Although cement augmentation stabilizes the fractured vertebra, it may alter load distribution and increase stress on adjacent levels, thereby predisposing patients to new or progressive OVCF [5–8]. Moreover, these patients often present with age-related degenerative spinal diseases. Although additional cement augmentation may be sufficient for treating adjacent-level fractures, pedicle screw insertion becomes necessary in cases of severe post-traumatic kyphotic deformity, progressive instability, motor deficit, or concomitant degenerative pathology, with or without new fractures [9,10].

Pedicle screw insertion into previously cement-augmented vertebral bodies remains technically demanding. Challenges include unpredictable cement distribution, reduced tactile feedback during cannulation, and concerns regarding screw–cement interface integrity [11]. This study aimed to describe a simple and reproducible technique for a safe and effective pedicle screw insertion into cement-augmented vertebral bodies.

Technical Notes

This study was approved by the Institutional Review Board (IRB) of Hanyang University Medical Center (IRB approval no., 2020-11-011-001). The inclusion criteria were as follows: (1) a history of VP or BKP, (2) the need for posterior instrumentation due to severe kyphotic deformity or degenerative spinal disease, and (3) at least one attempted pedicle screw insertion into a previously cement-augmented vertebra using the described technique between December 2018 and February 2023. Ten patients who met these criteria were included in the study (Table 1).

Table 1

Demographics and baseline characteristics of the patients

Surgical procedure

Selection of entry point and preparation of pilot hole

Under general anesthesia, the patient was placed in the prone position, and a standard midline posterior approach was performed. The cement-augmented vertebra was identified using fluoroscopic imaging. Several methods exist for determining the optimal pedicle entry site; however, in this technique, we adopted the intersection method, which provides a reliable and reproducible landmark for pedicle access [12]. A 3-mm high-speed burr was used to create a pilot hole at the predetermined entry point identified using the intersection method. Following burring, the pilot hole was further enlarged with an awl, and a curette was then gently advanced until it reached the cement mass to establish the initial pathway (Fig. 1).

Fig. 1

Using a high-speed burr, pilot holes are made at the entry point. The pilot hole is further enlarged using an awl, and a curette is gently advanced until it reached the cement mass (arrow).

Removal of cement by drilling

An orthopedic drill was used to partially remove the cement previously injected during VP or BKP. Drill bits of increasing diameter (2.0 mm, 2.4 mm, 3.5 mm, 4.0 mm, and 4.5 mm) were employed sequentially to gradually widen the hole. Continuous fluoroscopic monitoring was essential to prevent breach of the anterior vertebral wall (Fig. 2). This step created an adequate trajectory and space for pedicle screw placement. Copious irrigation was performed to remove cement debris and minimize the risk of thermal necrosis. The integrity of the five bony boundaries—the anterior vertebral wall and the medial, lateral, superior, and inferior pedicle walls—was confirmed using a ball-tipped probe.

Fig. 2

Drill bits of increasing diameter are employed sequentially to gradually widen the hole: 2.0 mm (A), 2.4 mm (B), 3.5 mm (C), 4.0 mm (D), and 4.5 mm (E). Drilling is observed by fluoroscopic imaging to avoid penetrating the anterior wall of the vertebral body (arrow).

Tapping and screw insertion

The prepared hole was sequentially tapped using 5.5-mm and 6.5-mm taps, corresponding to the intended pedicle screw diameter. Final pedicle screw insertion was performed under fluoroscopic guidance (Fig. 3). Screw size was determined by preoperative imaging and intraoperative anatomical assessment. In the lumbar spine, pedicle screws typically range from 5.5 to 6.5 mm in diameter and of 40 to 50 mm in length, whereas in the thoracic spine, they generally measure 5.5 mm in diameter and 30 to 40 mm in length.

Fig. 3

Holes are tapped with a 5.5 mm tap (A), a 6.5 mm tap (B), and a 6.5 mm pedicle screw (C) were used in this case (arrow).

Case illustration

A 74-year-old woman presented with incapacitating back pain and an inability to ambulate independently due to severe thoracolumbar kyphotic deformity. Her medical history was significant for multiple comorbidities including diabetes mellitus, rheumatoid arthritis, chronic kidney disease, and severe osteoporosis (T-score: −3.7). She had previously undergone instrumented interbody fusion at the L4–5 and L5–S1 levels, along with cement augmentation at L2 and L3 for OVCF, at another institution. Preoperative radiographs demonstrated a local kyphotic angle of +46° from T12 to L3 and a markedly increased sagittal vertical axis of +240 mm (Fig. 4A, B).

Fig. 4

A 74-year-old woman. Standing preoperative whole-spine posteroanterior (A) and lateral (B) radiographs demonstrate the thoracolumbar local kyphosis of +46° and a sagittal vertical axis of +240 mm. Standing postoperative spine anteroposterior (C) and lateral (D) radiographs show correction of the thoracolumbar local kyphosis to +18°.

Using the described technique, pedicle screws were successfully inserted into the cement-augmented L2 and L3 vertebrae. Two screws measuring 6.5 mm×45 mm were placed at L2, and one screw measuring 5.5 mm×40 mm was placed at L3. Additional pedicle screws were inserted from T10 to L1. Deformity correction was achieved without osteotomy, followed by posterolateral fusion. Postoperative radiographs demonstrated improvement of the thoracolumbar kyphosis to +18° (Fig. 4C, D).

Discussion

Polymethyl methacrylate (PMMA), commonly known as bone cement, possesses high surface hardness, tensile strength, and elastic modulus, providing strong interfacial support between implants and bone. Owing to these properties, PMMA is widely used in orthopedic surgery, including VP, BKP, and pedicle screw augmentation for osteoporotic vertebrae [13–15]. As the number of patients with prior cement augmentation grows, surgeons increasingly encounter the need for additional instrumentation across cement-augmented segments. In standard practice, the presence of cement within the vertebral body often compels surgeons to insert screws along suboptimal trajectories or select substantially shorter screws. Such compromises can weaken the screw pull-out strength, particularly in deformity correction surgeries, where screw length and trajectory are critical for the transmission of corrective forces. Therefore, avoiding short screws or suboptimal trajectories is essential for achieving secure fixation [16,17].

Despite its clinical necessity, pedicle screw insertion into previously cement-augmented vertebral bodies remains a technically challenging procedure, and few studies have described standardized techniques. A major challenge stems from the highly variable distribution patterns of cement, which may remain confined to the anterior vertebral body, extend posteriorly toward the pedicle, or form irregular distributions in the vertebral body [11]. By selectively removing cement along the planned trajectory, this technique restores tactile feedback and allows the surgeon to create a safe, controlled hole for screw insertion. It enables screws of appropriate diameter and length to be placed along the ideal trajectory, reducing the need for extended fusion levels while minimizing operative time, blood loss, and soft-tissue injury. Consequently, it can lead to improved clinical outcomes, as well as earlier ambulation and rehabilitation.

Pedicle screw insertion with cement augmentation in osteoporotic vertebrae has been shown to increase pull-out strength [15]. However, no studies have specifically evaluated whether inserting screws into a previously cement-augmented vertebra provides a similar biomechanical advantage. Nevertheless, it is reasonable to assume that the screw–cement–bone interface would retain substantial strength even when the screw is placed into an existing cement mass. Shitozawa et al. [18] reported a cement-catching technique for patients with OVCF. In this technique, a space for screw insertion is created using a bone filler during BKP, and the pedicle screw is inserted after the cement has hardened. Compared with the noncement group, the cement-catching technique was associated with significantly lower rates of screw loosening and pull-out. In the biomechanical test, deeper screw insertion into the cement mass was demonstrated to increase pull-out strength. A similar biomechanical advantage is anticipated with the technique described in this study, and our clinical experience suggests that it provides adequate screw purchase.

In this study, pedicle screws were successfully inserted into all cement-augmented vertebrae without any intraoperative complications, such as drill tip breakage, cement dislodgement, or anterior wall violation. During drilling and tapping of the cement mass, a carefully graduated, stepwise technique, which has been described previously, was meticulously employed. This approach was critical in minimizing the risk of cement dislodgement and preserving the mechanical integrity of the cement–bone interface.

Future research should aim to biomechanically validate this technique, including quantitative assessments of pedicle screw pull-out strength when inserted into previously cement-augmented vertebrae. Furthermore, prospective clinical studies with long-term follow-up periods are warranted to evaluate complication rates, particularly pedicle screw loosening, and to compare clinical outcomes with conventional strategies, such as extended fusion levels that omit screw placement in cement-augmented vertebrae.

This technical note has several limitations, including a small sample size, short follow-up, absence of clinical and radiological outcomes, and lack of biomechanical testing. Despite these limitations, pedicle screw insertion into previously cement-augmented vertebral bodies can be performed safely and reliably using this technique. This method may simplify a procedure that is traditionally regarded as technically demanding.

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