To summarize and analyze the mid-term clinical efficacy of 360° fusion with short-segment nail-bar repositioning and “lid lift” for the treatment of isthmic spondylolisthesis. METHODS: From October 2004 to March 2008, 44 patients with grade II and III isthmic spondylolisthesis with lumbar spondylolisthesis were treated with posterior “lift-off” lumbar decompression, internal fixation with short segmental nail rods and 360° fusion of the laminae. Among them, 15 were male and 29 were female; their ages ranged from 28 to 45 years old, with an average of 38.4 years old, and according to Meyerding’s classification: 28 cases of Grade II slippage and 16 cases of Grade III slippage.
There were 18 cases of L4/5 slippage and 26 cases of L5/S1 slippage. The preoperative, postoperative and follow-up VAS scores, ODI scores, SF-36 scores, slippage rate, repositioning rate, intervertebral space and foraminal height, bone graft fusion rate and complications of all patients were statistically analyzed to evaluate the clinical and imaging treatment results. Results: All cases were followed up for 20-60 months, with an average of 42 months, and the clinical efficacy was evaluated: 32 cases were excellent, 9 cases were good, 3 cases were acceptable, and 0 cases were poor, with an excellent rate of 95.3%.
In 36 patients, anatomical repositioning was achieved, and the remaining 8 patients obtained 90%-95% repositioning, with an average repositioning rate of 97.4%, and all patients obtained bony fusion, with a fusion rate of 100%. There were 4 cases (9%) of pain in the iliac extraction area, 2 cases (4.5%) of superficial infection, 1 case (2.3%) of dural tear, 2 cases (4.5%) of degeneration in the adjacent phase of fusion, and no nerve injury in any case; there was no obvious pseudoarthrosis formation, no internal fixation failure and no postoperative canal restenosis.
Conclusion: The treatment of isthmic spondylolisthesis lumbar spondylolisthesis with 360° fusion by short-segment nail rod repositioning and “lifting the lid” is a reliable method for the treatment of LSL, with satisfactory clinical efficacy, high fusion rate and few complications in the mid-term follow-up, but the long-term efficacy needs further follow-up analysis.
The treatment of isthmic cleft lumbar spondylolisthesis is one of the common causes of low back pain in adults, and there are many treatment methods, including direct isthmic repair, Gill laminectomy, posterior posterolateral fusion, posterior instrumented repositioning with posterior posterolateral fusion, and interbody fusion, which have been commonly used recently. From October 2004 to March 2008, the authors applied short-segment nail bar repositioned “lift-the-flap” 360° fusion for isthmic cleft lumbar spondylolisthesis to treat 44 cases of adult isthmic cleft lumbar spondylolisthesis, and the clinical efficacy was satisfactory at mid-term follow-up.
1.Data and methods
1.1 Clinical data:
There were 44 cases in this group, including 15 males and 29 females; age ranged from 28 to 45 years old, with an average of 38.4 years, the longest duration of disease was 7 years, the shortest was 14 months, and the average was 38 months. All patients had different degrees of lower back pain, including 17 cases of combined bilateral lower limb pain and 27 cases of unilateral lower limb pain; the back pain was aggravated after standing and walking and relieved after lying down, and another 15 patients had intermittent claudication, and all patients were ineffective after at least 6 months of conservative treatment before surgery.
Preoperatively, lumbar ortholateral, double oblique, hyperextension, and hyperflexion films were routinely performed, and 44 cases had isthmic cleft lumbar spine slippage, including 18 cases of L4/5 slippage and 26 cases of L5/S1 slippage, according to Meyerding classification [1]: 28 cases of II degree slippage and 16 cases of III degree slippage, with a mean slippage rate of 47.5% (25%-68%).
1.2 Surgical methods:
All cases in this group were operated under general anesthesia, in prone position, with routine intraoperative evoked potential monitoring. A posterior median incision was made with the slipped vertebral body as the center, and the lesioned vertebral plate and a normal vertebral plate each above and below were revealed along the subperiosteal stripping, while the transverse processes and articular processes on both sides were revealed.
The scar tissue in the isthmus of the broken vertebral arch is removed bilaterally, the interspinous ligament, the interlaminar ligament, and the joint capsule of the bilateral inferior synovial joints are removed sequentially along the upper and lower part of this spinous process, and then the vertebral plate is lifted off intact, the hypertrophic ligamentum flavum and other soft tissues are removed and preserved (fig1.1).
After thorough decompression and release of the vertebral canal and nerve root canal and adequate decompression, two appropriate length lifting screws are accurately implanted in the pedicle on both sides of the slipped vertebral body, two fixation screws are implanted in the pedicle on both sides of the inferior vertebral body, a fixation rod is installed, the intervertebral space is propped open and fixed by tightening the fixation nut below, and if the intervertebral space height is <5 mm on intraoperative fluoroscopy, the intervertebral space is first removed, the intervertebral space is released, and the intervertebral space is propped open again If the intervertebral space height is <5 mm, the intervertebral disc is removed, the intervertebral space is loosened, and the intervertebral space is propped up again until the ideal height of the intervertebral space is achieved.
The intervertebral disc tissue and the posterior border of the vertebral body were completely excised through the intervertebral foraminal approach, the intervertebral spacer was inserted, the residual disc tissue and the upper and lower cartilage endplates were removed with a reamer and a spatula, the autologous iliac bone was implanted into the intervertebral space and filled into the fusion device, and one intervertebral fusion device was implanted obliquely. The intervertebral pressure was applied to open the anterior intervertebral space and restore the anterior lumbar convexity by loosening the fixation screw nut and bringing the pedicle screws together with a compression device.
The sclerotic bone of the broken end of the vertebral arch was cleared, the articular cartilage of the supra-articular synapse of the inferior vertebral body was bitten off, the articular cartilage of the inferior synapse of the posterior lamina was lifted off, and the cortex of the vertebral plate was bitten into a rough surface bone graft bed, and then the vertebral plate was replanted in situ (fig1.3), and the posterior lateral bone graft was taken from the autologous iliac bone, and if the replanted vertebral plate was unstable, the root of the spinous process was fixed to the adjacent spinous process with silk sutures. The incision was routinely placed with a drainage tube.
Fig 1.1 Fig 1.2 Fig 1.3
1.3 Perioperative treatment Antibiotics were routinely applied 30 minutes before and 5-7 days after surgery to prevent infection. The drainage tube was removed 48 h after surgery, and passive and (or active) straight leg raising exercises were started 24 h after surgery to avoid nerve root adhesions and improve nerve root compliance to adapt to the repositioned spinal structure. The brace was worn 5-7 days after surgery to gradually move down to the ground. Follow-up visits were performed every 3 months within 1 year and every 6 months after 1 year after surgery to review the lumbar spine X-ray to understand the fusion and whether the internal fixation was loosened or broken, and to perform lumbar spine CT or MRI examination if necessary.
1.4 Efficacy evaluation criteria:
1.4.1 Clinical evaluation.
Clinical efficacy evaluation was mainly evaluated from the following five aspects: ① functional evaluation using the internationally used Oswestry dysfunction score [2]; ② general condition using the SF-36 score [3]; ③ pain evaluation using the VAS score [4], ④ patient satisfaction; ⑤ patient work status. The overall clinical efficacy evaluation was based on the Morelos rating scale [5].
Table 1 Morelos clinical efficacy evaluation criteria
Excellent
Complete relief of back and leg pain
No restriction in daily life activities
No need for pain medication
Ability to squat on the floor
Good
Significant relief of low back and leg pain
Able to perform usual tasks
Mild restriction in activities of daily living
Occasional need for pain medication
Able to sit on the floor in a squatting position
Can
Partial relief of back and leg pain
Able to perform lighter or restricted work
Restricted in activities of daily living
Need to take mild pain medication regularly
Mildly restricted in squatting on the floor
Poor
Little or no relief from back and leg pain
Significant limitation in activities of daily living
Unable to perform usual work
Need to take long-term pain medication
Cannot squat on the floor
1.4.2 Imaging evaluation.
At the time of final follow-up, the lumbar spine was routinely radiographed in frontal, lateral, oblique and lateral extension and flexion positions and 3D reconstruction CT. preoperative, postoperative and at the time of final follow-up, the slip rate, intervertebral space height, foraminal height, fusion rate and nail breakage rate were measured respectively. The criteria for osseous fusion was the absence of significant transillumination between the continuous bone fragments through the bone trabeculae or bone graft material and the vertebral body.
2.Results
All 44 patients were followed up from 20 months to 60 months, with a mean of 42 months. The preoperative, postoperative and final follow-up clinical outcome scores and imaging measures were statistically analyzed for all patients (Table 2, Table 3).
2.1 Operative time and bleeding volume
The operative time was 90-150 min, with an average of 115 min, intraoperative bleeding was 300-1000 ml, with an average blood loss of 600 ml, and 6 of 44 patients were transfused with 400 ml-600 ml of red blood cells.
2.2 Degree of resetting and loss
The slippage rate was measured by Tailand’s method, and the average slippage rate was 47.5% (25%-68%) before surgery, 2.6% (0%-10%) at 3 days after surgery, and 97.4% at the reset rate, and the average slippage rate was 2.6 and 97.4% at the final follow-up, with no significant loss.
2.3 Intervertebral space height and intervertebral foraminal height
The preoperative intervertebral space height was 4.5±1.3 mm and the postoperative height was 11.5±1.8 mm, an increase of 7.0 mm. The final follow-up was 11.2±1.5 mm, with a loss of 0.3 mm.
The preoperative foraminal height was 13.3 ± 2.8 mm, postoperatively it was 17.8 ± 4.1 mm, an increase of 4.5 mm. at final follow-up it was 17.4 ± 3.6 mm, a loss of 0.4 mm.
2.4 Fusion rate
In 44 cases, none of the fusion apparatus moved back or collapsed during at least 20 months of follow-up; no broken nails, broken rods or loosening occurred. x-ray and CT reconstruction showed that all patients obtained bony fusion within 1 year, with a fusion rate of 100%.
2.5 Clinical outcome assessment
① Oswestry dysfunction score: mean preoperative score (49.5±12.4), mean score (12.9±6.5) at the last follow-up;
(ii) SF-36 score was used for general condition: the mean preoperative SF-36 score was 43.2±15.8, and the mean at the last follow-up was 70.2±14.4, which was 62.4% higher than the preoperative score.
(3) VAS pain score: The mean VAS low back pain score was 7.3±2.5 before surgery, and 1.0±1.0 at the last follow-up; the mean VAS leg pain score was 8.0±3.5 before surgery, and 1.5±1.0 at the last follow-up.
④Patient satisfaction: at the last follow-up, a questionnaire was administered to the patients “How satisfied are you with the outcome of the surgery in general, and if you were to choose again, would you be treated with this surgical option again?” All patients indicated that they were satisfied with the treatment results and answered that they would be willing to undergo the surgical option again. ;
⑤ Patients’ work status: all returned to work, with 41 patients returning to their previous usual job and the remaining 3 changing to a lighter job. According to Morelos’ evaluation criteria: 32 cases were excellent, 9 cases were good, 3 cases were acceptable, and 0 cases were poor, with an excellent rate of 95.3%.
2.6 Complications
There were 4 cases of pain in the iliac bone extraction area, accounting for 9%; 2 cases of superficial infection, accounting for 4.5%; 1 case of dural tear, accounting for 2.3%; 2 cases of fusion adjacent to the stage of degeneration, accounting for 4.5%; none of the cases had nerve injury; there was no obvious pseudo-articular formation, no internal fixation failure and no postoperative spinal canal restenosis.
Table 2: Outcome information
Degree of resumption
Intervertebral space height
Intervertebral foraminal height
SF-36 score
ODI score
VAS low back pain score
VAS leg pain score
Preoperative
47.5 %
4.5±1.3
13.3±2.8
43.2±15.8
49.5±12.4
7.3±2.5
8.0±3.5
2 weeks postoperatively
97.4%
11.5±1.8
17.8±4.1
-
-
-
- –
Final follow-up
97.4%
11.2±1.5
17.4±3.6
70.2±14.4
12.9±6.5
1.0±1.0
1.5±1.0
Table 3: The occurrence of major common complications
Complications
Number of cases occurred
Occurrence rate
Perioperative complications
Infection
2
4.5%
Dural tear
1
2.3%
Nerve injury
0
0 %
Epidural hematoma
0
0 %
Complication at bone extraction
4
9 %
Distant complications
Pseudarthrosis
0
0 %
Internal fixation failure
0
0 %
Fusion adjacent to phase degeneration
2
4.5%
Postoperative spinal canal restenosis symptoms
0
0%
3. Typical cases
Fig 2.1 Fig 2.2 Fig 2.3 Fig 2.4
Fig 2.5 Fig 2.6 Fig 2.7 Fig 2.8
Fig 2.9 Fig 2.10 Fig 2.11
Patient, female, 42 years old, L5/S1 isthmic cleft lumbar spondylolisthesis, degree II, fig2.1 and fig2.2 are preoperative X-rays, fig2.3 and fig2.4 are preoperative CT, fig2.5 and fig2.6 are postoperative X-rays, fig2.7 is seen during intraoperative internal fixation, fig2.8 and fig2.9 are 2 years postoperative CT, fig2.10 and fig2.11 are 2 years postoperative CT, and fig2.11 is 2 years postoperative CT. fig2.10 and fig2.11 are postoperative X-rays after removal of the internal fixation 2 years after surgery.
4. Discussion
The isthmic fracture of the vertebral arch occurs in the lower lumbar spine, accounting for about 5% to 7% of the adult population, and is a common disease in young adults. It is a common cause of lumbar pain in adults, and surgery is required when conservative treatment is ineffective and neurological symptoms recur.
There are many surgical treatments for lumbar spondylolisthesis, which are still under debate. The main methods are: laminectomy and decompression, isthmus in situ fusion, posterior posterolateral fusion, interbody fusion, and annular fusion. Posterior posterolateral fusion has been considered the gold standard for the treatment of lumbar spondylolisthesis for a long time, and a large amount of clinical literature has reported satisfactory treatment results, with excellent clinical efficacy rates of 68%-98% and fusion rates of 80%-100%.
Molinari et al. compared PLF and ALIF+PLF in a group of patients with lumbar spondylolisthesis and showed that 39% of the PLF group developed pseudoarthrosis, while the fusion rate of the ALIF+PLF group was 100%. Patients with failed fusion often require reoperation or even multiple operations, which greatly increases the pain of patients and wastes medical resources.
In recent years, with the increasing understanding of the pathology and biomechanics of lumbar spondylolisthesis, the role of disc degeneration in the occurrence of spondylolisthesis and the role of the anterior column of the vertebral body in maintaining spinal stability have been gradually recognized by the majority of scholars, and the concept of vertebral body repositioning and annular fusion in the treatment of lumbar spondylolisthesis has been increasingly accepted by scholars. More and more reports show that annular fusion can achieve 90-100% fusion rate, especially in people who are prone to fusion failure, such as long-term smokers, diabetic patients, and those who have failed multiple fusion procedures.
Zhang Wei et al. applied annular fusion to 31 cases of lumbar spondylolisthesis with a follow-up of 5 months-3 years, with 100% fusion rate, 94% slipped repositioning rate, and 93.5% excellent clinical outcome. Sprut et al [9,10] applied annular fusion to treat mild isthmic cleft type lumbar spondylolisthesis with a mean follow-up of 2.1 years, and all patients obtained bony fusion, and then he reported a mean follow-up of 5.6 years with The fusion was well maintained, with no loosening of internal fixation or occurrence of pseudoarthrosis, and the clinical outcome was good.
In this group of cases, with an average follow-up of 42 months, all patients achieved bony fusion, and the intervertebral height, foraminal height, and slip angle basically returned to normal, with no significant loss at the final follow-up and no complications of prosthesis loosening, internal fixation failure, or aggravation of slip. The clinical efficacy evaluation was excellent in 32 cases, good in 9 cases, acceptable in 3 cases, and poor in 0 cases, with an excellent rate of 95.3% and 100% patient satisfaction.
We believe that the advantages of annular fusion are:
①The anterior, middle and posterior columns were fused with bone graft, which is a true three-dimensional three-column fixation, greatly improving the quality of spinal bone graft fusion and reducing the complications such as internal fixation fracture and reset loss;
②The combination of intervertebral bone grafting and internal fixation of the spinal arch nail can restore the mechanical structure of the spine, restore the intervertebral height and intervertebral foraminal volume, and thus play an indirect role in decompressing the nerve root canal and spinal canal;
(3) The immediate stabilizing effect of the pedicle nail can prevent complications such as Cage displacement, loosening, and sinking;
④It can avoid the complications of anterior interbody fusion such as major trauma and injury to large blood vessels and vegetative nerves, and solve the shortcomings of repositioning and nerve root decompression that cannot be performed by anterior interbody fusion;
(5) The fixed object is a short segment and the spinal motion function is preserved to the maximum extent, and the postoperative impact on the lumbar region is reduced;
(6) The nucleus pulposus is removed and the spinal canal and nerve root canal are decompressed at the same time as the intervertebral fusion is performed.
Obviously, the medical cost of annular fusion is significantly higher than that of other fusion methods in the short term, but we believe that in the long term, a successful one-time fusion is far less expensive than a failed fusion and reoperation, which is bound to be more expensive and cause more pain and waste of medical resources to the patient.
Soegaard R et al [11] randomized a controlled study of 146 patients treated with annular fusion or posterior posterolateral fusion with a follow-up of 4-8 years, and compared and analyzed the medical costs and clinical outcomes of the two groups, and the results showed that annular fusion was not only significantly better than the posterior posterolateral fusion group in terms of fusion rate, clinical outcomes, and reoperation, but also the average medical costs were significantly lower than those of the posterior posterolateral fusion group.
Whether or not the slip is repositioned, especially the necessity of anatomical repositioning, has been the focus of debate among many scholars. In the past, the literature reported that up to 31% of neurological injury complications were the main cause of many hair pairs, but anatomical repositioning also has many advantages, such as.
①Expanding the volume of the spinal canal and the height of the intervertebral foramen to release the nerve compression;
②Increasing the area of intervertebral bone graft fusion, eliminating the adverse shear stress on the bone graft site, and facilitating the achievement of bone graft fusion;
③ Eliminate the undesirable shear stress on the internal fixation device such as Cage, which makes the internal fixation device more stable and effectively prevents the loosening, displacement, bending and fracture of the internal fixation device;
The normal sequence and function of the spine are reconstructed, the normal biomechanical shape of the spine is restored, the lumbosacral deformity is corrected, and the excessive lumbar lordosis, pelvic tilt, and knee flexion are eliminated, thus the posture and gait are improved and the patient’s self-confidence in recovery is enhanced. In recent years, due to the improvement of the internal fixation instrumentation of the pedicle nail and the improvement of the application technology, the repositioning of the slipped vertebral rest has become possible.
Spruit et al. reported that in 12 patients with mild lumbar spondylolisthesis treated with posterior instrumentation + anterior interbody fusion, 21% of the preoperative spondylolisthesis was reduced to 7% of the postoperative spondylolisthesis, and none of the patients had neurological complications. ODI and VAS scores were significantly better than preoperatively, with good clinical outcomes.
Yizhar Floman et al. treated 12 patients with unstable lumbar spondylolisthesis using the SOCON repositioning system in combination with interbody fusion. 5 patients had anatomic repositioning, with the exception of 7 patients who achieved 90-95% repositioning, with good clinical outcomes and no neurological manifestations. A complete anatomical repositioning was achieved by combined anterior and posterior approaches for vertebral shortening, decompression, slip anatomical repositioning, and annular fusion, resulting in a good clinical outcome and a significant change in the physical appearance of the patient with no signs of neurological injury.
In this group of cases, we treated 44 cases of isthmic cleft type lumbar spondylolisthesis by using posterior “lifting lid” complete decompression, repositioning and fixation of the Fuller Vertebral Body Resurfacing System, and 360° annular fusion of the vertebral plate replantation, of which 36 patients had anatomical repositioning and the remaining 8 patients had 90%-95% repositioning, with an average repositioning rate of 97.4%, None of the patients showed nerve injury.
Unfortunately, there were no patients with Grade IV or V slippage in this group, so the occurrence of nerve injury in more severe slippage cases needs to be further observed.
We believe that the following principles need to be observed in order to pursue the repositioning of slippage and avoid nerve injury.
① Thorough decompression and release of the nerve root: Patients with isthmus cleft have obvious hypertrophy of the fibrous tissue and ligamentum flavum in the isthmus, and most of them are combined with calcification, forming an obvious “hook-like” osteophyte. After the slippage of the vertebral body, the sagittal path of the bony spinal canal is severely narrowed in the slippage plane, and the nerve root canal is more obvious.
In this group of cases, the entire vertebral plate and inferior articular eminence were lifted, the soft tissue and calcified hyperplasia in the spinal canal, isthmus and nerve root canal were completely removed, and the nerve root adhesions and compression were released. nerve roots and spinal cord strain injury.
Cadaveric [20] performed in vitro vertebral body repositioning tests and found that nerve root strain during vertebral body repositioning gradually increased with the increase in intervertebral height, but the closer the starting height of the intervertebral body was to normal, the less likely the nerve root strain injury was. Therefore, it is believed that the restoration of the intervertebral start height can significantly reduce the nerve root strain injury in the repositioning.
(iii) Intraoperative strengthening of nerve evoked potential monitoring: intraoperative evoked potential monitoring was applied to all patients in this group of cases, and once abnormal signals appeared, the repositioning was stopped immediately, and our recommendation was to try to anatomically reposition, but not to force anatomical repositioning.
Epidural fibrosis (Epidural fibrosis) is a scar or tissue fibrosis formed within the surgical involvement of the epidural space after laminectomy, which is the body’s repair response to trauma. Although it has a positive effect on the repair of the ruptured fibrous ring, the prevention of reherniation of the residual degenerated disc, the formation of new bone, and the repair of the ligamentum flavum.
However, it is now generally believed that the adhesive contraction of the scar in the spinal canal will pull the dura and nerve roots and restrict their activities. The nerve roots encircled by the scar are subjected to abnormal pulling and squeezing, and the axoplasmic transport of nerve fibers, arterial blood supply, and venous return are affected, and the nerve roots and dorsal ganglia are sensitive to mechanical compression, which will produce a series of symptoms, such as pain, numbness, and muscle weakness. Thus, many scholars believe that epidural fibrosis is one of the important causes of post-lumbar spine surgery syndrome (FAILED BACK SURGERY SYNDROME. FBSS), which accounts for about 5%-24% of FBSS.
For the treatment of lumbar spondylolisthesis, the current treatment plan often uses the removal of the loose spinous process and lamina for spinal canal decompression, and the formation of epidural fibrosis after surgery due to laminectomy often leads to the occurrence of medical, secondary and scarring spinal stenosis in the middle and long term after surgery, i.e. FBSS. Therefore, how to reduce or prevent the formation of epidural fibrosis after spondylolisthesis is of great significance to improve the clinical outcome.
Based on this, some scholars have attempted to use different protocols to reduce local scar formation after laminar decompression, including drugs, autologous fat sheets, gelatin sponges, polymeric artificial dura and medical gels with hyaluronic acid as the main component, but the efficacy is uncertain. In recent years, some scholars have suggested that the vertebral plate is a very effective barrier to prevent the formation of epidural fibers.
Yucesoy et al. conducted an animal test using rats and replanted seven rats after laminectomy, and found that there was no significant fibrous tissue formation at the site of laminectomy. In the present case, we removed the “floating” lamina in its entirety and then replanted it, which not only fully exposed the spinal canal, but also safely and effectively repositioned the slipped vertebral body and decompressed and released the nerve roots.
At the same time, the integrity of the posterior wall of the spinal canal can be preserved by in situ replantation of the original spinous process and lamina, which can effectively prevent the postoperative neurological symptoms associated with local scar tissue growth, secondary stenosis of the spinal canal, and recompression of the dural sac due to the absence of bony structures in the posterior wall of the spinal canal.
At the same time, due to the restoration of the normal posterior structure of the spine, the fusion area of the posterior lateral implant fusion was greatly increased, which is of significance for 360° annular fusion. All 44 patients with isthmic cleft type lumbar spondylolisthesis in our group were followed up for an average of 42 months, and none of them showed clinical manifestations such as secondary and medically induced spinal stenosis. The follow-up X-rays and CT examinations showed that the reimplanted vertebral plates were well positioned, the fusion between the isthmus of the vertebral arch and the articular processes was satisfactory, and there was no stenosis of the spinal canal.
The postoperative complications of lumbar spondylolisthesis are an important cause of unsatisfactory clinical results. 7 patients had perioperative complications in this group, including 2 cases of superficial infection, which were cured by local dressing change and intravenous antibiotics, and no deep infection occurred in the intervertebral space, etc. 1 patient had severe dural adhesions, and the dura was torn in the process of lifting the plate. 4 patients had symptoms such as pain and discomfort at the bone extraction site.
However, we found that 2 patients in this group had adjacent superior segment degeneration, with an incidence of 4.5%, which may be related to the change of adjacent segment biomechanics after stable fusion, but due to the small sample size, no reliable conclusion can be drawn at this time, and further analysis is needed.
In conclusion, 360° fusion with a short segmental nail bar repositioning “lift-off” is a reliable method for the treatment of isthmic cleft lumbar spondylolisthesis, which can increase the fusion area, improve the fusion rate, maintain good interbody height and morphology and physiological anterior lumbar convexity, and reduce the formation of epidural fibrosis. The degeneration of adjacent segments deserves attention and further study.