Author: Yang Jin, Kong Qingquan, etc
Affiliation: The Affiliated Hospital of Southwest Medical University, West China Hospital of Sichuan University
Severe spondylolisthesis (HGS) refers to the displacement of the vertebral body by more than 50% compared with the adjacent vertebral body (Meyerding grade > grade II.), which is mainly manifested by symptoms such as low back pain, lower limb weakness, and paresthesia, which seriously affects the patient's life and work. According to the etiology, it can be divided into six categories: congenital, isthmus fissure, degenerative, traumatic, pathological and iatrogenic.
Severe lumbar spondylolisthesis is mostly caused by isthmus fissure spondylolisthesis, mainly at the L5 and S1 levels, and is more common in children and adolescent women, and has a genetic predisposition. In younger patients, severe spondylolisthesis is etiologically attributable to dysplasia with secondary bone changes, whereas in middle-aged and older patients, severe spondylolisthesis is caused or exacerbated by spinal degeneration. Biomechanically, kyphosis at the lumbosacral junction leads to compensatory organisms, manifested by increased lumbar lordosis, retrobolic pelvic tilt, and then hip and knee involvement, which affect posture and gait due to the anterior movement of the lines of gravity. The treatment of severe lumbar spondylolisthesis includes conservative treatment and surgical treatment, but due to the large degree of spondylolisthesis, severe deformity, nerve root compression, sacral morphology and other problems, the treatment is difficult, and the choice of treatment method is controversial in clinical practice.
This article will systematically review the current surgical treatment methods for severe lumbar spondylolisthesis, and analyze their advantages and disadvantages, so as to facilitate the selection of more appropriate treatment methods to improve the efficacy and quality of life of patients, and provide a useful reference for clinical practice.
1. Indications
Indications for surgical treatment of severe spondylolisthesis are:
(1) Slipped amplitude continues to progress, with or without symptoms. Patients with progressive spondylolisthesis often have significant lumbosacral and lower extremity pain that is ineffective to conservative management; Patients with higher Meyerding grade and larger slipped angle are more likely to have persistent slipped amplitude progression; Children and adolescents are at higher risk of persistent spondylolisthesis progression than adults due to active spinal growth.
(2) Imbalance in the sagittal plane of the spine. Severe lumbar spondylolisthesis is often associated with significant lumbosacral kyphotic deformity, which results in altered sagittal spine sequences.
(3) Neurological impairment, mainly L5 nerve root compression.
(4) Persistent and intolerable low back pain, which cannot be relieved by long-term conservative treatment.
(5) Lower limb symptoms. Conservative treatment does not respond well to lower extremity radicular pain with exact radicular compression.
2. Surgical techniques
01. Fusion method
重度腰椎滑脱手术融合方式包括经前路腰椎椎间融合（anterior lumbar interbody fusion, ALIF）、经后外侧融合（postero lateral fusion, PLF）、经椎间孔腰椎椎间融合（transforaminal lumbar interbody fusion, TLIF）伴或不伴PLF、经后路腰椎椎间融合（posterior lumbar interbody fusion, PLIF）伴或不伴PLF和环周融合。 ALIF可通过前入路植入椎体间装置来恢复椎间高度和重建节段性前凸，但该入路易造成腹部内脏器官损伤、髂血管损伤和植入物并发症。
02. Fusion segments
Although only L5 and S1 have yielded satisfactory results, most clinicians prefer to extend proximal fixation to L4 because the addition of a fixed vertebral body distributes stress, reduces stress on individual pedicle screws, and avoids implanting the fusion in an environment of excessive tension, which can cause loss of reduction or loosening of the inner plant. However, Shufflebarger et al. recommended only L5 and S1 fusion, because they could retain the active segments of L4 and 5, and believed that single-segment L5 and S1 fusion had more advantages than L4~S1 fusion.
Studies have shown that the most common internal fixation range for adult patients with severe lumbar spondylolisthesis is L4~S1; For children and adolescents with severe lumbar spondylolisthesis, circumferential fusion single-level L5, S1 internal fixed reduction and L4~S1 in situ fusion can also achieve good clinical results, no neurological complications were found and the spondylolisthesis angle was improved.
03. In situ fusion
Kasliwal et al. considered in situ fusion to be the treatment of choice for severe spondylolisthesis.
(1) No nerve root damage or obvious appearance deformity, the main symptom is back pain;
(2) there is sufficient nerve foramen space;
and (3) a good sagittal sequence with acceptable overall sagittal balance and proximal fixed vertebral bodies. The advantages of in situ fusion are safety, low technical requirements, low rate of nerve damage, and acceptable long-term efficacy.
04. Slippage reduction
Indications for spondylolisthesis reduction are:
(1) The slippage angle > 45° or there is a serious sagittal plane imbalance;
(2) Preoperative presence of L5 radiculopathy or sacral nerve radiculopathy symptoms, requiring extensive nerve decompression;
(3) lumbar spondylolisthesis with high dysplasia;
(4) Excessive activity in L5 and S1 segments;
and (5) other anatomical deformities, such as the small transverse process, sacral dysplasia, L5 trapezoid, and sacral dome.
The advantages of slipped reduction are:
(1) It can improve spinal canal and intervertebral foraminal stenosis and directly decompress nerves.
(2) It can correct lumbosacral kyphosis, thereby improving sagittal spine-pelvic balance, gait, biomechanics and appearance, and improving patient satisfaction and quality of life.
(3) The fusion rate can be improved by reducing the tension on the inner plants, improving the biomechanical environment of the fusion segment and providing the necessary fusion time.
(4) Compared with in situ fusion, the slipped amplitude of reduction continued to progress and the incidence of pseudoarthritis was lower.
(5) It can reduce the risk of postoperative acute cauda equina syndrome.
While there are many advantages to reduction, the correlation and safety of the degree of reduction with clinical improvement are controversial, particularly in adult patients with intervertebral space stenosis. However, there are also scholars who hold a different view. From the perspective of the history of severe lumbar spondylolisthesis treatment, the main reason for the opposition to reduction is that reduction will cause a very high proportion of neurological impairment.
3. New advances in surgical treatment
In recent years, with the deepening of the concept of minimally invasive surgery, minimally invasive spine surgery has become a research hotspot. Although minimally invasive surgery has the above theoretical advantages, some studies have found that the degree of postoperative pain relief and functional recovery in the open surgery group is more obvious than that in the minimally invasive surgery group. This may be due to the difficulty of minimally invasive procedures to adequately expose the surgical site for extensive nerve decompression and adequate slipped correction, resulting in increased traction on the nerve roots and instrument misalignment.
Pu Jungang et al. reported that the Wiltse approach combined with modified TLIF can effectively reduce the destruction of paravertebral muscles and posterior bony structures and ligaments by surgical operations, and reduce the incidence of complications such as chronic low back pain after surgery, and the clinical effect is satisfactory.
In 2021, Tu et al. reported the treatment of 11 patients with severe lumbar spondylolisthesis using a combination of anterior and posterior abdominal ALIF, using the cantilever beam technique to complete the release, reduction and orthopedic intervertebral body, and the posterior uniscal fixation, and the results showed that the postoperative spondylolisthesis was partially corrected, the lumbosacral angle was significantly improved, the fusion rate was high, and the common complications were minimized.
Jiang Bin et al. described the good results of the first stage of posterior S1 osteotomy reduction and fusion. In this operation, the scar and osteophytes of the spondler of the spondylolisthesis are removed by direct vision of the posterior approach, and the L5 nerve root outside the intervertebral foramen is fully decompressed from the side, and the length of the lumbosacral spine is shortened by osteotomy to reduce the nerve root tension after reduction. This technique makes up for the shortcomings of in situ fusion that cannot correct sagittal plane imbalance and low fusion rate, and reduces the neurological complications easily caused by reduction operations, which is an ideal operation for the treatment of severe lumbar spondylolisthesis in adolescents.
The less invasive modified Delta technique under O-arm navigation is a new modified form of the traditional transvertebral disc screw fixation technique, which adopts a modified minimally invasive approach, locates the surgical incision and screw trajectory under O-arm navigation, and uses a short incision to achieve nerve root decompression while improving extensive anatomical damage, reducing operation time and bleeding, and the surgical effect is good.
Donnally et al. described overcoming the biomechanical deficiencies associated with the traditional Bohlman procedure by incorporating multi-point screw fixation. This method avoids the use of allogeneic support grafts, eliminates the need for pressurized drilling, reduces soft tissue dissection, and saves the time required for graft implantation. In addition, damage to the L5 nerve root can be reduced by avoiding intraoperative reduction. Compared with the previous spondylolisthesis reduction techniques, this surgery can significantly improve the local sequence of the spine, the percentage of spondylolisthesis and the angle of spondylolisthesis, reduce the risk of complications such as nerve injury, and have a high fusion rate and satisfactory clinical results.
The above surgical methods are mainly minimally invasive operations on the basis of improving deformity, reducing surgical injuries and complications, optimizing the safety and effectiveness of traditional surgery, and providing a new method for the treatment of severe lumbar spondylolisthesis. Although the above studies had good surgical results and significantly improved complications, most of the studies had shortcomings such as small sample sizes and short follow-up time. Therefore, in the case of complex anatomical conditions, open surgery may still be a safer option at present, which is conducive to fully exposing the surgical field and avoiding the occurrence of serious postoperative complications, and various minimally invasive techniques need to be further improved and practiced.
4. Surgical complications and precautions
The main complications of severe spondylolisthesis include permanent or transient neurological impairment, pseudoarthrosis, failure of internal fixation, accelerated degeneration of adjacent segments, postoperative hematoma, and secondary surgery due to failure or delayed healing of internal fixation. Among them, postoperative neurological impairment is the most common complication, accounting for about 10%. Regardless of the surgical technique chosen, care needs to be taken to avoid serious complications, especially nerve damage.
Nerve damage can be largely avoided by employing the following 5 key technologies:
(1) L5 nerve root is well exposed;
(2) removal of intervertebral disc tissue or sacral protrusions that may be compressing nerve roots;
(3) to avoid excessive traction of nerve roots, which can be achieved by adequate excision of the sacral vault and the use of small intervertebral fixators;
(4) fully correct posterior sacral exversion, thereby relieving nerve root tension;
(5) Extensive laminectomy.
5. Selection and thinking of treatment plan
Ideal treatment for severe spondylolisthesis is a safe and easy way to restore normal spinal sequence while reducing iatrogenic complications.
For pediatric and adolescent patients, orthotopic fusion and long-term follow-up evaluation are recommended. In adult patients, posterior surgery for children and adolescents may not be appropriate due to poor health, possible smoking, and higher risk of secondary pseudoarthropathic comorbidities, circumferential fusion is recommended to increase the likelihood of fusion success and obtain the best clinical and radiographic results. For elderly patients, due to their sparse trabecular bones, low bone density, thin bone cortex, and the weak connection between bone and screws, it is easy to lead to intervertebral fusion failure and pseudoarthrosis formation, and the tolerance to surgery is also poor, and there is a certain difficulty in treatment.
In general, surgical treatment works well in symptomatic patients with severely impaired quality of life, but not in asymptomatic patients with relatively normal quality of life, so conservative treatment can be considered when the patient's quality of life is not severely affected.
For the choice of surgical method, due to the limited ability of patients with spine-pelvic imbalance to achieve global spinal balance through internal compensation, it is recommended for patients with postural abnormalities and pelvic imbalance, and supplementation of anterior interbody support to restore the overall spine-pelvic balance, improve the biomechanical environment of the fusion segment, and improve the shape of the lumbar spine in developmental spondylolisthesis. In patients with spine-pelvic balance, forced reduction of the deformity is not required, and simple internal fixation and fusion may be sufficient to maintain sagittal balance.
With regard to reduction surgery, since the slipped angle is an important measure of the risk related parameters of lumbosacral kyphosis and the continuous progression of spondylolisthesis, the improvement of the slipped angle is also an important clinical indicator of the success of reduction, which can bring about statistically significant positive changes, reduce the pressure on L5 nerve roots, correct sagittal deformity, and improve health-related quality of life. Therefore, improving the spondylolisthesis angle, correcting the sagittal deformity of the spine, and restoring normal spine-pelvic balance are the main goals of surgical reduction of severe lumbar spondylolisthesis, while reducing the proportion of L5 spondylolisthesis on S1 is a secondary goal, because lumbosacral kyphosis is the main cause of sagittal imbalance of the spine.
In addition, postoperative management and progressive hip extension are essential to avoid delayed neurological impairment. As for the choice of the degree of reduction, partial reduction is safer and more reliable than full reduction. Posterior fixed fusion, combined with partial deformity reduction and interbody structural support, provides satisfactory fusion rates and good clinical outcomes, especially in the absence of decompression. In some patients, anatomical limitations make it difficult to choose surgery. For patients who lack space for bone grafting due to multiple surgeries, high disc degeneration and collapse, and intervertebral space closure, transdisc screw fixation and pedicle bone grafting is a feasible option.
6. Limitations and prospects
At present, the research on severe lumbar spondylolisthesis is not deep enough and the quality of the evidence is low, there is a lack of prospective randomized controlled studies that can clearly indicate the best surgical approach, and most of the previous studies are retrospective studies and other non-randomized studies, which are biased; Heterogeneity between patients and surgeries can also affect the results of the study by having a small number of patients, mainly children or adolescents, with different imaging and clinical baseline status, including those with and without mature skeletal development, and with inconsistent surgical approach, degree of decompression, fusion method, and reduction ratio.
Due to the lack of specific data on severe spondylolisthesis in adults, preoperative decision-making in adult patients is still complex, so future studies of adult and pediatric patients are needed to further clarify the treatment options for severe spondylolisthesis by using standardized outcome measures and prospective data collection. In the existing studies on surgical reduction of severe lumbar spondylolisthesis, the quantitative evaluation of the impact and effect of reduction is not comprehensive, and the impact of reduction on the quality of life of patients is not clear. Current reduction techniques are also difficult to restore balance in patients with preoperative pelvic imbalance, and future research should strive to find new technologies that are effective for such patients.
In summary, the selection of treatment for severe lumbar spondylolisthesis should be comprehensively considered according to the specific situation of the patient. There is still a great deal of controversy in the treatment of severe spondylolisthesis, and further research is needed to clarify and guide the choice of surgical treatment for severe spondylolisthesis.
About the Author:
Yang Jin
Deputy Chief Physician of the Department of Spine Surgery, Affiliated Hospital of Southwest Medical University, Associate Professor, Doctor of Medicine;
Academic Appointments:
Member of the first standing committee of the Spine Surgery Branch of Sichuan Medical Communication Association; Member of the Geriatric Pain Special Committee of the Orthopedic Physician Branch of Sichuan Medical Doctor Association; Member of the Minimally Invasive Spine Group of Sichuan Orthopedic Education Base; Secretary of Osteoporosis and Bone Mineral Diseases Branch of Luzhou Medical Association; Member of the Spine and Spinal Cord Special Committee of Luzhou Association of Integrative Traditional and Western Medicine; Member of Orthopaedic Branch of Chinese Medical Association; AO Spine Member; Member of the North American Society of Spine Surgery.
主持并参与国自然、省部级课题多项，发表论文40余篇（第一作者SCI论文10篇，发表在NEJM、JNS Spine、Spine、European Spine Journal、International Orthopaedics等著名期刊），参编脊柱外科专著 5部。
Kong Qingquan
West China Hospital, Sichuan University, Chief Physician/Professor, First-level Expert, Master's/Doctoral Supervisor; Postdoctoral Rover Supervisor.
Academic and technical leader of Sichuan Provincial Department of Health; Sichuan Provincial Medical Leading Talents; President of West China Hospital, Sichuan University. "Tianfu Scholars" Distinguished Expert; Deputy Director of the "Joint Institute of Plateau Health" of West China Hospital. Overseas high-level overseas talents.
Academic Appointments:
Vice Chairman of the Basic and Clinical Research Promotion Committee of the China Medical Education Association; Leader of the Minimally Invasive Spine Group of the Sichuan Base of Orthopedic Standardized Training of China Medical Education Association; Member of the Orthopaedic Rehabilitation Group of the Orthopaedic Branch of the Chinese Medical Association; Member of the Endoscopist Branch of the Chinese Medical Doctor Association; Member of the Osteoporosis Prevention and Rehabilitation Committee of the Chinese Association of Rehabilitation Medicine; Member of the Standing Committee of the Stem Cell and Regenerative Medicine Professional Committee of the Chinese Association of Integrative Medicine; Member of the Standing Committee of the Orthopedic Professional Committee of Sichuan Medical Association and leader of the minimally invasive group; Vice President of Orthopedic Professional Committee of Sichuan Medical Doctor Association; Member of the Standing Committee of Sichuan Hospital Association; Chairman of the Special Committee of Plateau Medicine (Regional Joint) of Sichuan Association for the Promotion of International Medical Exchange; Group Leader, Sichuan Provincial Group of Orthopedics, OSOG; Deputy Head of the Orthopedic Minimally Invasive Group of the Orthopedic Physician Branch of Sichuan Medical Doctor Association; Deputy head of the Spine Group of the Orthopedic Committee of the Sichuan Geriatrics Society.
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