Arthroscopic-assisted uniportal spinal surgery for treatment of lumbar burst fractures complicated with neurological symptoms: a case report

Abstract

Lumbar burst fractures account for 21% to 58% of all thoracolumbar fractures. L5 lumbar burst fractures are rare, comprising 1.2% of spinal burst fractures. This report discusses the optimal treatment for an adolescent with an L5 lumbar burst fracture and neurological symptoms caused by a high-fall injury, which involved surgical decompression and spinal fixation. Complete decompression and fixation of the L5 lumbar burst fracture, complicated by neurological symptoms, were achieved using arthroscopic-assisted uniportal spinal surgery (AUSS) combined with percutaneous pedicle screw fixation (PPSF). The AUSS approach, used alongside PPSF, significantly improved the vertebral canal occupation rate, increased the anterior edge height ratio of the damaged vertebra, and alleviated the lower back pain and nerve root symptoms postoperatively. AUSS combined with PPSF is a minimally invasive technique for treating lumbar burst fractures, effectively relieving compression of the vertebral canal and nerves caused by fracture fragments.

Introduction

Thoracolumbar fractures are the most common type of spinal injury. Thoracolumbar burst fractures, caused by falls from heights, ground-level falls, and motor vehicle accidents, account for 21% to 58% of all thoracolumbar fractures.^1,2 In recent years, the incidence of thoracolumbar burst fractures has risen, leading to high mortality and disability rates that impose a significant economic burden on families. ³ Burst fractures often involve damage to the anterior and middle columns of the vertebral body. Fracture fragments may protrude into the spinal canal, compressing the spinal cord or cauda equina. Approximately 30% of thoracolumbar burst fractures are associated with nerve damage or paralysis. ⁴ Therefore, patients with thoracolumbar burst fractures should undergo surgery as early as possible to relieve nerve compression, restore the physiological curvature of the spine, and facilitate recovery. Anterior surgery effectively relieves nerve compression but carries a high risk of vascular and organ damage. By contrast, posterior surgery, while less invasive, can result in significant trauma and bleeding, with potential damage to spinal bone and ligament tissues that may lead to lumbar instability during later recovery. ⁵

In recent years, with the continuous development of minimally invasive spinal techniques, percutaneous posterior pedicle screw fixation (PPSF) has been widely used in clinical practice and has demonstrated good clinical outcomes.^6,7 However, PPSF cannot directly decompress the spinal canal or damaged nerves and has certain limitations. The rapid development of spinal endoscopy has enabled direct decompression of the spinal cord or nerves in a small area, offering the advantages of minimal trauma, small incisions, and rapid postoperative recovery. As a minimally invasive spinal endoscopy technique, unilateral biportal endoscopy (UBE) has been widely used in the treatment of lumbar degenerative diseases. ⁸ However, because of the limitations of its two fixed channels, the instruments cannot be rotated or swung freely, which may lead to operational challenges and an unstable visual field.^9–11 Wang et al. ¹² modified the UBE procedure, performing unilateral laminectomy and bilateral decompression using arthroscopic-assisted uniportal spinal surgery (AUSS) to treat lumbar degenerative diseases. This approach offers advantages such as a simple operation, shorter surgical time, smaller incision length, and reduced surgical bleeding. Although AUSS is currently used to treat patients with lumbar spinal stenosis, its application in treating thoracolumbar burst fractures has not been reported.

This report describes the first use of AUSS combined with PPSF to achieve adequate decompression and fixation in a patient with a lumbar burst fracture and neurological symptoms, demonstrating a minimally invasive approach for treating spinal fractures.

Case report

This study was approved by the Ethics Review Committee of the Second Hospital of Lanzhou University (approval no. 2024A-588), and written informed consent was obtained from the patient. An adolescent patient presented with a 6-hour history of pain in the lower back and right hip accompanied by numbness and weakness in both lower limbs. Six hours before admission, the patient had fallen from a height, resulting in the aforementioned symptoms but no headache, dizziness, vomiting, hematemesis, abdominal pain, or abdominal distention. Imaging revealed multiple transverse lumbar process fractures, fractures of the upper and lower ramus of the right pubic bone, comminuted fractures of the bilateral root bones, and bilateral distal fractures of the second metatarsal. The patient had no history of hypertension, diabetes, or cardiovascular disease. On admission, vital signs were as follows: temperature, 36.8°C; pulse rate, 96 beats/minute; respiratory rate, 18 breaths/minute; blood pressure, 110/74 mmHg; and weight, 60 kg. Physical examination showed a normal physiological spinal curvature without obvious deformities, tenderness from L4 to S1 with marked percussion pain, and muscle strength of grade 0 in both lower limbs. Sensation in the lower legs and soles was significantly reduced, and the patient had incontinence. The mean visual analogue scale (VAS) score for low back pain was 10. Laboratory tests revealed a white blood cell count of 7.76 × 10⁹/L, red blood cell count of 4.12 × 10¹²/L, hemoglobin concentration of 128 g/L, platelet count of 102 × 10⁹/L, and C-reactive protein concentration of 113.45 mg/L. Lumbar spine computed tomography confirmed an L5 vertebral burst fracture, spinal stenosis, and multiple transverse lumbar process fractures, while lumbar spine magnetic resonance imaging identified an L5 burst fracture with posterior compression causing spinal stenosis, cauda equina nerve compression, backward displacement, and right intervertebral foramen compression stenosis (see Figure 1).

Figure 1.

Preoperative computed tomography and magnetic resonance imaging. (a) Axial and sagittal computed tomography views of the lumbar vertebral body show bone fragments from the L5 vertebral body protruding into the center of the spinal canal, with a spinal canal occupancy rate of 82.35% and an anterior edge height ratio of the injured vertebra of 53% and (b) magnetic resonance sagittal and axial images show spinal stenosis at the L5 level caused by prominent fracture fragments.

The mass ratio of the spinal canal was calculated as follows. First, the sagittal diameters of the upper and lower adjacent spinal canals were measured and recorded as “a” and “b,” respectively. Next, the minimum middle sagittal diameter of the injured vertebral spinal canal was measured and recorded as “c.” Finally, the spinal canal occupancy rate was calculated as [1 − 2c/(a + b)] × 100%.

The height ratio of the anterior edge of the injured vertebral body was calculated as follows. First, the height of the anterior edge of the injured vertebral body was measured and recorded as “a.” Next, the heights of the anterior edges of the upper and lower adjacent vertebral bodies were measured and recorded as “b” and “c,” respectively. Finaly, the height ratio of the anterior edge of the injured vertebra was calculated as [2a/(b + c)] × 100%.

Diagnosis and surgical treatment

The patient was diagnosed with an L5 vertebral burst fracture complicated by neurological symptoms. The fracture was classified as AO Type A3, Frankel functional classification Grade B, and ASIA Grade B. The patient and their family were informed about the condition, the AUSS technology, and the associated risks and complications. AUSS technology, derived from UBE technology, combines a single-sided, two-channel approach into a single portal, allowing parallel operation of the endoscope and instruments. Compared with conventional posterior surgery, AUSS offers advantages such as a free operating space, clear vision, and compatibility with various spinal surgical instruments. ¹² After excluding contraindications and obtaining informed consent, AUSS combined with PPSF was performed on 14 July 2024, with an operation time of 150 minutes (see Figure 2).

Figure 2.

Intraoperative images of arthroscopic-assisted uniportal spinal surgery combined with percutaneous pedicle screw fixation. (a, b) Continuous saline flow provides a clear surgical field, while surgical instruments are operated, and soft tissue is dissected using a radiofrequency electrosurgical knife. (c) A grinding drill is used to smooth the root and lamina of the posterior spinous process. (d) Lamina forceps are used to relieve dorsal nerve compression. (e, f) After surgical decompression, no significant compression of the bilateral nerve roots is observed. (g) An L-shaped fracture reducer is used to reposition protruding fracture fragments and (h) intraoperative X-ray and postoperative imaging show the placement of percutaneous pedicle screws.

The steps of AUSS surgery and PPSF surgery are briefly described as follows.

The patient was placed in the prone position, and the surgical area was marked and disinfected along the inner line of the L5–S1 pedicle and intervertebral space under C-arm fluoroscopy.

A longitudinal incision (approximately 1.5 cm) was made along the marked site. Skin, fascia, and scalene space were incised layer by layer to create longitudinal channels. The junction of the L5 spinous process root with the L5 lower plate, the S1 spinous process, and the S1 upper plate were separated using a T-shaped bone to expand the soft tissue. Fluoroscopy was repeated to confirm optimal positioning. The arthroscope was connected to the lens sheath, light source line, radiofrequency electrode, and high-speed drill, and the area was irrigated with physiological saline.

Bipolar radiofrequency plasma surgical electrodes were used to clean the soft tissue on the surface of the laminae and ligamentum flavum and to identify the lower margin of the L5 lamina. Under arthroscopic visualization, a radiofrequency ablation electrode was used for hemostasis and to reconfirm the edges of the laminar window and ligamentum flavum. Different grinding drills were used to expose the ligamentum flavum from the root of the L5 spinous process to the S1 vertebra, extending laterally to the tip of the supraspinous process. Nucleus pulposus forceps and lamina forceps were alternately used to remove the ligamentum flavum and expose the dural sac. Dorsal nerve compressors were removed using a high-speed drill, laminar forceps, or a bone knife to reveal bilateral nerve roots. Severe contusion of the contralateral nerve roots was observed, with the L5 pedicle plane bone mass protruding into the spinal canal. The bone mass was gradually reduced using an L-shaped fracture restorer. The bilateral nerve roots were explored and released under arthroscopic guidance. After complete decompression, endoscopic hemostasis was achieved, and the endoscope was withdrawn.

C-arm fluoroscopy was used to mark the bilateral pedicle body surface projections of the L4–S1 vertebrae. A puncture needle was inserted at the outer edge of the pedicle projection under fluoroscopic guidance. Once proper positioning was confirmed, the skin was incised to a length of approximately 1 cm, and pedicle screws were inserted sequentially. A guidewire and pre-bent connecting rod were used to position and secure the screws, followed by proper nut tightening. Fluoroscopy confirmed good pedicle screw positioning and vertebral reduction. The wounds were irrigated, sutured, and bandaged.

After resuscitation in the post-anesthesia care unit, the patient was stabilized and returned to the ward.

On the third day after surgery, the patient’s lumbar pain was alleviated compared with the preoperative levels. Physical examination revealed that the muscle strength of both lower limbs had improved to grade 2, and sensation in the lower legs and soles of the feet showed slight improvement. Lumbar spine computed tomography confirmed the removal of the posterior lamina of the L5 vertebral body and showed significant enlargement of the vertebral canal compared with the preoperative imaging (see Figure 3(a)). One month after the operation, the patient’s lower back pain had markedly improved compared with the preoperative levels (see Figure 3(b)). Physical examination indicated that the muscle strength of both lower limbs had increased to grade 4, sensation in the lower legs and soles of the feet had fully recovered, urination and defecation were normal, and the VAS score for low back pain had decreased to 2 points.

Figure 3.

Postoperative images. (a) Axial and sagittal computed tomography views of the lumbar vertebral body show well-reduced bone fragments of the L5 vertebral body, removal of the posterior lamina, and significant enlargement of the spinal canal. The spinal canal occupancy rate is reduced to 18.21%, and the anterior edge height ratio of the injured vertebra is 88% and (b) X-ray images taken 1 month postoperatively.

Discussion

Lumbar burst fractures often result in alterations to the physiological curvature of the spine, instability of adjacent segments, and, in severe cases, neurological damage or symptoms that significantly impair patients’ quality of life. ¹³ Advances in surgical instruments and techniques have made endoscopic spine surgery a reliable option, allowing precise identification of vertebral body anatomy and enhancing the safety of procedures. ¹⁴ Compared with traditional posterior decompression and fixation surgery, the minimally invasive decompression and fixation approach for spinal fractures described in this study may be preferred by surgeons because of its advantages. In this study, AUSS technology combined with PPSF was employed to treat a patient with a lumbar burst fracture and neurological symptoms. This approach minimized damage to the paravertebral muscles and significantly enhanced spinal stability. Postoperative outcomes demonstrated effective fracture reduction, complete spinal canal decompression, and significant improvement in neurological symptoms.

For unstable thoracolumbar fractures, short-segment pedicle screw fixation is an effective method to restore anterior vertebral height and provide reliable support. ¹⁵ Previous studies have demonstrated that percutaneous pedicle screw fixation offers a superior minimally invasive surgical option compared with traditional open pedicle screw fixation. It effectively restores vertebral body height, improves the sagittal Cobb angle, and has additional advantages, including reduced trauma, faster recovery, less bleeding, and enhanced safety and reliability.^16,17 In this case, percutaneous pedicle screw implantation was performed, which minimized muscle dissection, preserved the structural integrity of the posterior ligament complex, intermittently reduced displaced bone mass, restored the physiological curvature of the spine, and provided reliable structural support.

UBE is a well-established spinal endoscopic technique widely used for treating various spinal degenerative diseases by inserting optical instruments, irrigation systems, and surgical tools through independent channels.^18–20 Tang et al. ²¹ found that UBE in the treatment of lumbar spinal stenosis provides a shorter operation time and better preservation of facet joints. Similarly, Kaneko et al. ²² reported that UBE-assisted treatment of spinal canal stenosis caused by osteoporotic vertebral compression fractures achieved decompression while avoiding the risk of small joint resection and yielded good follow-up results. UBE technology has independent observation and operation channels; however, because of the limitation of fixed channels, the instruments cannot rotate or swing freely, which may lead to complex operations, an unstable field of vision, and a long learning curve. The modified AUSS technique, based on UBE, has demonstrated good surgery-related outcomes in the treatment of lumbar degenerative diseases. ¹² AUSS technology allows free switching between observation and operation channels through a single small incision, providing a reliable field of vision, significantly improving surgical efficiency, and reducing the learning curve for surgeons. In patients with lumbar burst fractures, it is important to note that bleeding from the fracture site is continuous, with particularly severe bleeding at the broken end of the fracture during decompression, which can result in blurred surgical vision. AUSS technology, under appropriate pressure, uses normal saline as a medium to control bleeding at the fracture site, clarify the surgical field, and improve the safety and accuracy of surgery. AUSS also minimizes damage to structures such as facet joints, paravertebral muscles, and posterior ligament complexes, reducing the impact on the biomechanical stability of the spine. In this case, the posterior lamina was completely decompressed using a grinding drill, the posterior ligamentum flavum was alternately removed with nucleus pulposus forceps and lamina forceps to expose the bilateral nerve roots, and the spinal bone fragment was reduced using an L-shaped reducer.

In this case, we used AUSS combined with percutaneous pedicle screw fixation to treat a lumbar vertebral burst fracture, achieving satisfactory results. The spinal canal invasion rate, postoperative anterior edge height ratio of the injured vertebra, and VAS score all improved compared to preoperative values. We believe that AUSS technology effectively achieves spinal canal decompression and fracture reduction through small incisions, offering the advantages of reduced trauma, minimal disruption to spinal structures, and faster postoperative recovery. However, this study only involved one patient with a lumbar burst fracture, and the follow-up period was short. Therefore, further studies with a longer follow-up period and more patients are needed to evaluate the efficacy and safety of AUSS in treating lumbar burst fractures.

Conclusion

AUSS combined with PPSF is a minimally invasive technique for treating lumbar burst fractures, effectively relieving vertebral canal and nerve compression caused by fracture fragments.