Biomechanical evaluation of a novel anterior transpedicular screw-plate system for anterior cervical corpectomy and fusion (ACCF): a finite element analysis

Background and objective: Cervical fusion with vertebral body screw (VBS)-plate systems frequently results in limited biomechanical stability. To address this issue, anterior transpedicular screw (ATPS) fixation has been developed and applied preliminarily to multilevel spinal fusion, osteoporosis, and three-column injury of the cervical spine. This study aimed to compare the biomechanical differences between unilateral ATPS (UATPS), bilateral ATPS (BATPS), and VBS fixation using finite element analysis. Materials and methods: A C6 corpectomy model was performed and a titanium mesh cage (TMC) and bone were implanted, followed by implantation of a novel ATPS-plate system into C5 and C7 to simulate internal fixation with UATPS, BATPS, and VBS. Internal fixation with UATPS comprises ipsilateral transpedicular screw-contralateral vertebral body screw (ITPS-CVBS) and cross transpedicular screw-vertebral body screw (CTPS-VBS) fixations. Mobility, the maximal von Mises stress on TMC, the stress distribution and maximal von Mises stress on the screws, and the maximum displacement of the screw were compared between the four groups. Results: Compared with the original model, each group had a reduced range of motion (ROM) under six loads. After ACCF, the stress was predominantly concentrated at two-thirds of the length from the tail of the screw, and it was higher on ATPS than on VBS. The stress of the ATPS from the cranial part was higher than that of the caudal part. The similar effect happened on VBS. The screw stress cloud maps did not show any red areas reflective of a concentration of the stress on VBS. Compared with VBS, ATPS can bear a greater stress from cervical spine movements, thus reducing the stress on TMC. The maximal von Mises stress was the lowest with bilateral transpedicular TMC and increased with cross ATPS and with ipsilateral ATPS. ITPS-CVBS, CTPS-VBS, and BATPS exhibited a reduction of 2.3%-22.1%, 11.9%-2.7%, and 37.9%-64.1% in the maximum displacement of screws, respectively, compared with that of VBS. Conclusion: In FEA, the comprehensive stability ranked highest for BATPS, followed by CTPS-VBS and ITPS-CVBS, with VBS demonstrating the lowest stability. Notably, utilizing ATPS for fixation has the potential to reduce the occurrence of internal fixation device loosening after ACCF when compared to VBS.

显微镜辅助微创前路融合与可动式椎间盘镜下融合治疗腰椎退变性疾病的比较研究

OBJECTIVE

To investigate the effectiveness of microscope assisted anterior lumbar discectomy and fusion (ALDF) and mobile microendoscopic discectomy assisted lumbar interbody fusion (MMED-LIF) for lumbar degenerative diseases.

METHODS

A clinical data of 163 patients with lumbar degenerative diseases who met the criteria between January 2018 and December 2020 was retrospectively analyzed. Fifty-three cases were treated with microscope assisted ALDF (ALDF group) and 110 cases with MMED-LIF (MMED-LIF group). There was no significant difference between the two groups in terms of gender, age, disease type, surgical segments, preoperative visual analogue scale (VAS) scores of low back pain and leg pain, Oswestry disability index (ODI), intervertebral space height, lordosis angle, and spondylolisthesis rate of the patients with lumbar spondylolisthesis ( P>0.05). The operation time, intraoperative blood loss, and hospital stay of the two groups were recorded. The effectiveness was evaluated by VAS scores of low back pain and leg pain and ODI. Postoperative lumbar X-ray films were taken to observe the position of Cage and measure the intervertebral space height, lordosis angle, and spondylolisthesis rate of the patients with lumbar spondylolisthesis.

RESULTS

The operations were successfully completed in both groups. The operation time, intraoperative blood loss, and hospital stay in ALDF group were less than those in MMED-LIF group ( P<0.05). The patients in both groups were followed up 12-36 months, with an average of 24 months. The VAS scores of low back pain and leg pain and ODI after operation were lower than those before operation in the two groups, and showed a continuous downward trend, with significant differences between different time points ( P<0.05). There were significant differences between two groups in VAS score of low back pain and ODI ( P<0.05) and no significant difference in VAS score of leg pain ( P>0.05) at each time point. The improvement rates of VAS score of low back pain and ODI in ALDF group were significantly higher than those in MMED-LIF group ( t=7.187, P=0.000; t=2.716, P=0.007), but there was no significant difference in the improvement rate of VAS score of leg pain ( t=0.556, P=0.579). The postoperative lumbar X-ray films showed the significant recovery of the intervertebral space height, lordosis angle, and spondylolisthesis rate at 2 days after operation when compared with preoperation ( P<0.05), and the improvements were maintained until last follow-up ( P>0.05). The improvement rates of intervertebral space height and lordosis angle in ALDF group were significantly higher than those in MMED-LIF group ( P<0.05). There was no significant difference in the reduction rate of spondylolisthesis between the two groups ( t=1.396, P=0.167). During follow-up, there was no loosening or breakage of the implant and no displacement or sinking of the Cage.

CONCLUSION

Under appropriate indications, microscope assisted ALDF and MMED-LIF both can achieve good results for lumbar degenerative diseases. Microscope assisted ALDF was superior to MMED-LIF in the improvement of low back pain and function and the recovery of intervertebral space height and lordosis angle.

Anterior instrumentation surgery for the treatment of Lenke type 1AR curve patterns

OBJECTIVE

Previous studies have demonstrated that Lenke lumbar modifier A contains 2 distinct types (AR and AL), and the AR curve pattern is likely to develop adding-on (i.e., a progressive increase in the number of vertebrae included within the primary curve distally after posterior surgery). However, the results of anterior surgery are unknown. The purpose of this study was to present the surgical results in a cohort of patients undergoing scoliosis treatment for type 1AR curves and to compare anterior and posterior surgeries to consider the ideal indications and advantages of anterior surgery for type 1AR curves.

METHODS

Patients with a Lenke type 1 or 2 and lumbar modifier AR (L4 vertebral tilt to the right) and a minimum 2-year postoperative follow-up were included. The incidence of adding-on and radiographic data were compared between the anterior and posterior surgery groups. The numbers of levels between the end, stable, neutral, and last touching vertebra to the lower instrumented vertebra (LIV) were also evaluated.

RESULTS

Forty-four patients with a mean follow-up of 57 months were included. There were 14 patients in the anterior group and 30 patients in the posterior group. The main thoracic Cobb angle was not significantly different between the groups preoperatively and at final follow-up. At final follow-up, the anterior group had significantly less tilting of the LIV than the posterior group (-0.8° ± 4.5° vs 3° ± 4°). Distal adding-on was observed in no patient in the anterior group and in 6 patients in the posterior group at final follow-up (p = 0.025). In the anterior group, no LIV was set below the end vertebra, and all LIVs were set above last touching vertebra. The LIV was significantly more proximal in the anterior group than in the posterior surgery patients without adding-on for all reference vertebrae (p < 0.001).

CONCLUSIONS

This is the first study to investigate the surgical results of anterior surgery for Lenke type 1AR curve patterns, and it showed that anterior surgery for the curves could minimize the distal extent of the instrumented fusion without adding-on. This would leave more mobile disc space below the fusion.

[Application of small incision approach in anterior surgery of thoracic and lumbar spinal tuberculosis]

Objective

To investigate the value of small incision approach in the anterior surgery of thoracic and lumbar spinal tuberculosis.

Methods

A clinical data of 65 patients with thoracic or lumbar spinal tuberculosis treated with posterior-anterior surgery between January 2015 and January 2018 was retrospectively analyzed. The patients were divided into small incision group (group A, 29 patients) and traditional incision group (group B, 36 patients) according to the length of anterior incision. There was no significant difference in general data such as gender, age, disease duration, segment of lesion, American Spinal Cord Injury Association (ASIA) grading, preoperative pain visual analogue scale (VAS) score, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and Cobb angle of spinal kyphosis between 2 groups ( P>0.05). The length of anterior incision, operation time, intraoperative blood loss, postoperative complications, postoperative hospitalization time, ESR, and CRP were recorded and compared. The VAS score was used to evaluate the pain after operation. The Cobb angles in patients with spinal kyphosis were measured and the loss of angle and correction rate of angle were calculated. The result of bone graft fusion was assessed according to the Bridwell standard.

Results

The length of anterior incision, operation time, intraoperative blood loss, and hospitalization time of group A were all significantly less than those of group B ( P<0.05). All patients in both groups were followed up 12-29 months (mean, 20 months). There were 4 cases (13.8%) and 14 cases (38.9%) of postoperative complications in groups A and B respectively, showing significant difference ( χ ²=5.050, P=0.025). The ESR and CRP in 2 groups all returned to normal at 6 months after operation, and there was no significant difference in ESR and CRP between 2 groups at 3 months, 6 months, and last follow-up ( P>0.05). At last follow-up, the neurological function of patient with neurological symptoms was significantly better than that before operation, and there was no significant difference between 2 groups ( Z=0.167, P=0.868). The VAS scores of 2 groups at each time point after operation were significantly lower than those before operation ( P<0.05); the VAS score in group A was significantly lower than that in group B ( t=-2.317, P=0.024) at 1 day after operation, but there was no significant difference between 2 groups ( t=-0.862, P=0.392) at last follow-up. Among the patients with kyphosis, the Cobb angle was significantly decreased at 1 day after operation and last follow-up when compared with preoperative angle ( P<0.05); but there was no significant difference between 1 day after operation and last follow-up ( P>0.05). There was no significant difference in Cobb angle, loss of angle, and correction rate between 2 groups after operation ( P>0.05). The bone graft healed well at last follow-up in 2 groups. There was no significant difference in bone graft fusion rate between 2 groups at 6 months after operation, 1 year after operation, and last follow-up ( P>0.05). At last follow-up, all patients cured, and no recurrence occurred.

Conclusion

In the anterior surgery of thoracic and lumbar tuberculosis, the application of small incision approach can achieve the similar effectiveness as traditional incision surgery with the advantages of minimally invasive, less complications, and quick recovery.

Closure of a giant anterior sacral meningocele with an omental flap in a patient with Marfan syndrome: case report

Anterior sacral meningoceles (ASMs) are rare lesions often associated with connective tissue disorders. These lesions are typically treated posteriorly via closure of the dural stalk. However, given their insidious nature, ASMs can be quite large on presentation, and this approach may not provide adequate decompression. In this case report, the authors describe the successful treatment of a large ASM through drainage and watertight closure of the cyst with an omental flap. A 43-year-old woman with a history of Marfan syndrome and a large ASM was referred for neurosurgical intervention. The ASM was filling the pelvic cavity and causing severe compression of the bladder. The patient underwent surgical decompression of the cyst through an anterior transabdominal approach and closure of the fistulous tract with a pedicled omental flap. This is the first reported case of successful closure of an ASM with an omental flap. At the 6-month follow-up, the ASM had not recurred on imaging and the patient's symptoms had resolved. Anterior sacral meningoceles are rare lesions that often require neurosurgical intervention. Although most can be treated posteriorly, large ASMs compressing the abdominal or pelvic organs may require a transabdominal approach. Moreover, ASMs with wide dural stalks may benefit from closure with an omental flap.

Factors predicting dysphagia after anterior cervical surgery: A multicenter retrospective study for 2 years of follow-up

A multicenter retrospective study.The purpose of this study was to explore risk factors of dysphagia after anterior cervical surgery and factors affecting rehabilitation of dysphagia 2 years after surgery.Patients who underwent anterior cervical surgery at 3 centers from January 2010 to January 2013 were included. The possible factors included 3 aspects: demographic variables-age, sex, body mass index (BMI): hypertension, diabetes, heart disease, smoking, alcohol use, diagnose (cervical spondylotic myelopathy or ossification of posterior longitudinal ligament), preoperative visual analogue scale (VAS), Oswestry Disability Index (ODI), Japanese Orthopaedic Association (JOA), surgical-related variables-surgical option (ACDF, ACCF, ACCDF, or Zero profile), operation time, blood loss, operative level, superior fusion segment, incision length, angle of C2 to C7, height of C2 to C7, cervical circumference, cervical circumference/height of C2 to C7.The results of our study indicated that the rate of dysphagia at 0, 3, 6, 12, and 24 months after surgery was 20%, 5.4%, 2.4%, 1.1%, and 0.4%, respectively. Our results showed that age (58.8 years old), BMI (27.3 kg/m), course of disease (11.6 months), operation time (103.2 min), blood loss (151.6 mL), incision length (9.1 cm), cervical circumference (46.8 cm), angle of C2 to C7 (15.3°), cervical circumference/height of C2 to C7 (4.8), preoperative VAS (7.5), and ODI (0.6) in dysphagia group were significantly higher than those (52.0, 24.6, 8.6, 88.2, 121.6, 8.6, 42.3, 12.6, 3.7, 5.6, and 0.4, respectively) in nondysphagia group; however, height of C2 to C7 (9.9 vs 11.7 cm) and preoperative JOA (8.3 vs 10.7) had opposite trend between 2 groups. We could also infer that female, smoking, diabetes, ossification of posterior longitudinal ligament, ACCDF, multilevel surgery, and superior fusion segment including C2 to C3 or C6 to C7 were the risk factors for dysphagia after surgery immediately. However, till 2 years after surgery, only 2 risk factors, smoking and diabetes, could slow rehabilitation of dysphagia.Many factors could significantly increase rate of dysphagia after anterior cervical surgery. Operation time as a vital factor markedly increases immediate postoperative dysphagia and smoking, as the most important factor, lower recovery of dysphagia. Further study is needed to prove if these factors could influence dysphagia.

Predictive factors relating to prognosis of anterior decompressive surgery for proximal-type cervical spondylotic amyotrophy

BACKGROUND AND OBJECTIVE

Cervical spondylotic amyotrophy (CSA) is a relatively rare disorder. This study was conducted to elucidate the prognosis of proximal-type CSA after anterior decompressive surgery by evaluating clinical factors and imaging findings.

METHODS

Anterior decompressive surgery was performed in 40 patients with proximal-type CSA between March 2000 and December 2011. Patients were classified into 2 categories based on axial T2-weighted magnetic resonance imaging (MRI) findings: "nerve root compression (NRC)", with nerve root compressed at the intervertebral foramen, and "spinal cord compression (SCC)" with spinal cord compressed at the medial or paramedial site of spinal canal. Manual muscle testing (MMT) was used to evaluate the surgical effect. Scapular, deltoid, and biceps brachii muscles of the affected side were tested and the sum scores were calculated. Clinical factors and imaging findings, such as age, duration of disease, preoperative MMT grade, number of affected levels and signal intensity changes of spinal cord, were collected to analyze prognostic factors.

RESULTS

After anterior decompressive surgery, 30 patients (75%) showed an improvement. NRC was observed in 6 patients and SCC in the rest 34 patients based on MRI findings. All patients (100%) with NRC had an improvement, while only 24 patients (70.6%) with SCC improved. In patients with SCC, there was a significant difference in duration of disease between patients who had an improvement and those who had not (P< 0.01).

CONCLUSIONS

Anterior decompressive surgery is effective in the treatment of most patients with CSA. NRC on MRI may indicate a good surgical outcome. In patients with SCC, a long duration of disease is a risk factor for poor prognosis.

Anterior surgical treatment of cervical spondylotic myelopathy: review article

BACKGROUND

Cervical spondylotic myelopathy (CSM) is a common indication for cervical spine surgery. Surgical options include anterior, posterior, or combined procedures each with specific advantages and disadvantages.

QUESTIONS/PURPOSES

This article will provide a description of the various anterior alternatives and discuss the available evidence used in guiding the surgical decision making process with the aim of answering the following questions: (1) What anatomical/disease related factors favor anterior over posterior surgeries? (2) What are the common anterior procedures and how safe and effective are they? (3) What are the most effective options for multilevel CSM? (4) Is there a role for motion preservation? An additional objective is to discuss technical advances that have improved success rates for anterior procedures.

METHODS

The PubMed database was searched. Keywords were CSM and anterior surgery. Three hundred eighty two articles were found one hundred three were reviewed. Articles describing anterior cervical techniques were selected along with studies describing the various anterior techniques or comparisons of anterior to posterior techniques.

RESULTS

Anterior decompression and fusion procedures are more effective than posterior procedures for patients with primarily ventrally located compression especially in the presence of cervical kyphosis. ACDF, ACCF, and hybrid combinations are safe and effective treatment options for multilevel CSM. Anterior procedures may be more cost effective and result in significantly improved postoperative quality of life and health-related quality of life measures compared to posterior procedures.

CONCLUSION

Anterior cervical decompression techniques are safe and effective in the treatment of CSM. Anterior surgeries may be preferable to posterior approaches, when considering health-related quality of life measures and cost effectiveness.

Anterior decompression for cervical spondylotic myelopathy

Cervical spondylotic myelopathy is a clinical entity that manifests itself due to compression and ischemia of the spinal cord. The goal of treatment is to decompress the spinal cord and stabilize the spine in neutral, anatomical position. Since the obstruction and compression of the cord are localized in front of the cord, it is obvious that an anterior surgical approach is the preferred one. The different surgical procedures, complications, and outcome are discussed here.