uniportal-full-endoscopic-posterolateral-transforaminal-lumbar

Uniportal Full Endoscopic Posterolateral Transforaminal Lumbar Interbody Fusion

Uniportal full endoscopic posterolateral lumbar interbody fusion (FE-TLIF) has recently shown promising results. However, beginners may face challenges in ...

New Taipei Municipal Tucheng Hospital

In some cases of vertebroplasty for adjacent fractures, we observed a cement bridging phenomenon, in which the injected cement flowed from the newly fractured vertebra to the previously cement-augmented vertebra through the space between the abutting anterior longitudinal ligament and the vertebral column. The purpose of this retrospective study was to investigate this phenomenon. From January 2012 to December 2014, patients who sustained new-onset adjacent vertebral compression fracture and who were again treated with vertebroplasty were enrolled. We divided the patients into two groups, the bridging group and the nonbridging group, to analyze the difference between them. Results showed that the cement bridging phenomenon occurred in 18 (22.8%) of the 79 patients. Significant differences between the bridging and nonbridging groups were identified in the following 3 imaging features: severe loss of the anterior vertebral body height at the new-onset adjacent vertebra on plain film (odds ratio [OR] = 4.46, p = 0.014), fluid accumulation (OR = 36.27, p < 0.001) and hypointense signaling (OR = 15.67, p < 0.001) around the space anterior to the abutting vertebral bodies and the corresponding intervertebral disc on MRI. After a 2-year follow-up, both the mean value of the focal kyphotic angle and anterior body height ratio were significantly better in the cement bridging group than in the nonbridging group. The cement bridging phenomenon, which has never been reported in the literature, is not rare in clinical practice. This phenomenon was associated with better maintenance of focal kyphotic angle and anterior body height ratio during the 2-year follow-up.

Cement bridging phenomenon in percutaneous vertebroplasty for adjacent vertebral compression fracture.

In cases of postoperative deep wound infection after interbody fusion with cages, it is often difficult to decide whether to preserve or remove the cages, and there is no consensus on the optimal approach for removing cages. The aim of this study was to investigate the surgical management of cage infection after lumbar interbody fusion.

The comparison between anterior and posterior approaches for removal of infected lumbar interbody cages and a proposal regarding the use of endoscope-assisted technique.

Intraoperative pedicle screw depth adjustment after initial insertion, including both forward and backward adjustments, is sometimes necessary to facilitate rod application and ensure that the screw is in the correct position, which is determined by intraoperative fluoroscopy. Adjusting the screw with forward turns has no negative influence on the screw fixation stability; however, screw turnback may weaken the fixation stability. The aim of this study is to evaluate the biomechanical properties of screw turnback and demonstrate the reduction in the fixation stability after the screw is turned 360° from its full insertion position. Commercially available synthetic closed-cell polyurethane foams with three different densities simulating various degrees of bone density were utilized as substitutes for human bone. Two different screw shapes (cylindrical and conical) together with two different pilot hole profiles (cylindrical and conical) were tested. Following specimen preparation, screw pullout tests were conducted using a material test machine. The mean maximal pullout strength between full insertion and 360-degree turnback from full insertion in each setting was statistically analyzed. The mean maximal pullout strength after 360-degree turnback from full insertion was generally lower than that at full insertion. The reduced mean maximal pullout strength after turnback increased with decreasing bone density. Conical screws had significantly lower pullout strength after 360-degree turnback than cylindrical screws. The mean maximal pullout strength was reduced by up to approximately 27% after 360-degree turnback when using a conical screw in a low bone density specimen. Additionally, specimens treated with a conical pilot hole presented a less reduction in pullout strength after screw turnback as compared to those with a cylindrical pilot hole. The strength of our study was that we systematically investigated the effects of various bone densities and screw shapes on screw stability after turnback, which has rarely been reported in the literature. Our study suggests that pedicle screw turnback after full insertion should be reduced in spinal surgeries, particularly procedures that use conical screws in osteoporotic bone. Pedicle screw secured with a conical pilot hole might be beneficial for screw adjustment.

Biomechanical evaluation of pedicle screw stability after 360-degree turnback from full insertion: effects of screw shape, pilot hole profile and bone density.

Despite advancements in pedicle screw design and surgical techniques, the standard steps for inserting pedicle screws still need to follow a set of fixed procedures. The first step, known as establishing a pilot hole, also referred to as a pre-drilled hole, is crucial for ensuring screw insertion accuracy. In different surgical approaches, such as minimally invasive or traditional surgery, the method of creating pilot holes varies, resulting in different pilot hole profiles, including variations in size and shape. The aim of this study is to evaluate the biomechanical properties of different pilot hole profiles corresponding to various surgical approaches. Commercially available synthetic L4 vertebrae with a density of 0.16 g/cc were utilized as substitutes for human bone. Four different pilot hole profiles were created using a 3.0 mm cylindrical bone biopsy needle, 3.6 mm cylindrical drill, 3.2-5.0 mm conical drill, and 3.2-5.0 mm conical curette for simulating various minimally invasive and traditional spinal surgeries. Two frequently employed screw shapes, namely, cylindrical and conical, were selected. Following specimen preparation, screw pullout tests were performed using a material test machine, and statistical analysis was applied to compare the mean maximal pullout strength of each configuration. Conical and cylindrical screws in these four pilot hole configurations showed similar trends, with the mean maximal pullout strength ranking from high to low as follows: 3.0 mm cylindrical biopsy needle, 3.6 mm cylindrical drill bit, 3.2-5.0 mm conical curette, and 3.2-5.0 mm conical drill bit. Conical screws generally exhibited a greater mean maximal pullout strength than cylindrical screws in three of the four different pilot hole configurations. In the groups with conical pilot holes, created with a 3.2-5.0 mm drill bit and 3.2-5.0 mm curette, both conical screws exhibited a greater mean maximal pullout strength than did cylindrical screws. The strength of this study lies in its comprehensive comparison of the impact of various pilot hole profiles commonly used in clinical procedures on screw fixation stability, a topic rarely reported in the literature. Our results demonstrated that pilot holes created for minimally invasive surgery using image-guided techniques exhibit superior pullout strength compared to those utilized in traditional surgery. Therefore, we recommend prioritizing minimally invasive surgery when screw implantation is anticipated to be difficult or there is a specific need for stronger screw fixation. When opting for traditional surgery, image-guided methods may help establish smaller pilot holes and increase screw fixation strength.

Influence of various pilot hole profiles on pedicle screw fixation strength in minimally invasive and traditional spinal surgery: a comparative biomechanical study.

Combining oblique lumbar interbody fusion (OLIF) with posterior pedicle screw fixation (PPSF) has been proposed to reduce cage subsidence, especially in osteoporotic spines. Recently, anterolateral screw-rod fixation has gained interest as it allows direct pathology observation and avoids a posterior approach. However, controversies exist between anterolateral screw fixation systems and traditional PPSF due to variations in osteoporotic vertebral mineral density, screw fixation positions, and fixation methods (bicortical vs. unicortical). This study aimed to investigate the biomechanical impact of fixation position and method in osteoporotic spine.

Biomechanical insights into anterolateral vertebral screw fixation in osteoporotic spines: a comparative study of fixation methods and positions using porcine vertebrae.

Patients with osteoporosis experience a higher risk of pedicle screw loosening and failure, making PMMA bone cement augmentation a common recommendation to increase stability. However, there is ongoing debate about the ideal cement volume, filling pattern, and measurable increase in stability that cement provides.

Article	Year
Cement bridging phenomenon in percutaneous vertebroplasty for adjacent vertebral compression fracture. Scientific reports\| PubMed ID: 33986345	2021
The comparison between anterior and posterior approaches for removal of infected lumbar interbody cages and a proposal regarding the use of endoscope-assisted technique. Journal of orthopaedic surgery and research\| PubMed ID: 34134734	2021
Biomechanical evaluation of pedicle screw stability after 360-degree turnback from full insertion: effects of screw shape, pilot hole profile and bone density. Frontiers in bioengineering and biotechnology\| PubMed ID: 37214307	2023
Influence of various pilot hole profiles on pedicle screw fixation strength in minimally invasive and traditional spinal surgery: a comparative biomechanical study. Frontiers in bioengineering and biotechnology\| PubMed ID: 38380264	2024
Biomechanical insights into anterolateral vertebral screw fixation in osteoporotic spines: a comparative study of fixation methods and positions using porcine vertebrae. Journal of orthopaedic surgery and research\| PubMed ID: 39794854	2025
The biomechanical impact of cement volume and filling pattern for augmented pedicle screws using various density testing blocks. The spine journal : official journal of the North American Spine Society\| PubMed ID: 39894279	2025

Yun-Da Li

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