Mingjie Yang

C1 lateral mass-C2 pedicle screws and crosslink compression fixation for unstable atlas fracture.

Study Design. Primary clinical trial of limited fixation for unstable Atlas fracture. Objectives. To clinically validate feasibility, safety and value of the C1 later-mass screw C2 pedicle screw and crosslink compression fixation technique. Summary of Background Date. In previous clinical studies, several techniques have been introduced to fix Atlas fracture. But all these treatments have intrinsic disadvantages. Now seeking a means of limited internal fixation has become a worthwhile subject of clinical study. Materials and Methods. From January 2001 to December 2004, 17 cases of atlas fracture were diagnosed consecutively, 11 cases were operated on with C1 lateral mass and C2 pedicle screws and crosslink fixation, of whom 6 patents had axial instability and rupture of transverse ligament, 1 patient had C2 laminal fracture, and the remaining 4 patients had axial instability. With the assistant of regional anatomy study and fluoroscopy C1 lateral mass screws and C2 pedicle screws were implanted in place, between which connecting rods were applied bilaterally. A crosslink compression was applied between the 2 rods to achieve realignment of C1 lateral mass fracture and C0–C1–C2 into the anatomic position. C1–C2 fusion with posterior bone grafting was performed in patients with axial instability or transverse ligament discontinuity. Results. Operative time ranged from 90 to 176 minutes with a mean of 124 minutes. Intraoperative blood loss ranged from 270 to 1200 mL with a mean of 432 mL. There were no neurologic deficits, vertebral artery related complications or other complications in all patients. No deterioration of the neurologic deficits was noticed 5 days after operation when the patients were brace fixed and began to ambulate. No cerebral hemodynamic deficit was observed in this patient. Radiograph examination showed bone fusion and stability in all patients 3 months after operation. Healing of C2 fracture was confirmed by computed tomography scan. Conclusion. Osteosynthesis of the atlas by C1 lateral mass screws C2 pedicle screws and crosslink compres- sion fixation is an ideal option for C1 burst fracture with or without rupture of the transverse ligament. The procedure allows for partially physiologic reconstruction of the C0–C1–C2 joint and shortens external fixation.

Spontaneous slip reduction of low-grade isthmic spondylolisthesis following circumferential release via bilateral minimally invasive transforaminal lumbar interbody fusion: technical note and short-term outcome.

Study Design. Retrospective clinical data analysis. Objective. To investigate and verify our philosophy of spontaneous slip reduction following circumferential release via bilateral minimally invasive transforaminal lumbar interbody fusion (Mini-TLIF) for treatment of low-grade symptomatic isthmic spondylolisthesis. Summary of Background Data. Symptomatic isthmic spondylolisthesis usually requires surgical intervention, and the most currently controversial focus is on method and degree of reduction; and Mini-TLIF is an attractive surgical procedure for isthmic spondylolisthesis. Methods. Between February 2004 and June 2008, 21 patients with low-grade isthmic spondylolisthesis underwent Mini-TLIF in our institute. Total resection of the scar around the pars interarticularis liberated the nerve roots, achieving posterior release as well. The disc was thoroughly resected, and the disc space was gradually distracted and thoroughly released with sequential disc shavers until rupture of anulus conjunct with anterior longitudinal ligament, accomplishing anterior release, so as to insert Cages. Because of circumferential release, the slipped vertebrae would tend to obtain spontaneous reduction, and with pedicle screw fixation, additional reduction would be achieved without any application of posterior translation force. Radiographs, Visual Analogue Scale, and Oswestry Disability Index were documented. All the cases were followed up for 10 to 26 months. Results. Slip percentage was reduced from 24.2% ± 6.9% to 10.5% ± 4.0%, and foraminal area percentage increased from 89.1% ± 3.0% to 93.6% ± 2.1%. Visual Analogue Scale and Oswestry Disability Index decreased from 7.8 ± 1.5 to 2.1 ± 1.1 and from 53.3 ± 16.2 to 17.0 ± 7.8, respectively. No neurologic complications were encountered. There were no signs of instrumentation failure. The fusion rate approached 100%. Conclusion. Slip reduction is based on circumferential release. The procedure can be well performed via Mini-TLIF, the outcome of which is equally gratifying to that of instrumented slip reduction and traditional midline approach. There is no need to fully reduce the slipped vertebrae. Circumferential release contributes to achieving spontaneous slip reduction partially, which aids sufficiently in the surgical treatment of low-grade isthmic spondylolisthesis.

Intradural Cervical Disc Herniation: Report of Two Cases and Review of the Literature

Study Design. Case report and review of the literature. Objective. To report two additional cases with intradural cervical herniation and review the pertinent literature. Summary of Background Data. Intradural cervical disc herniation is rare and a total of 22 cases were reported in 2007. In searching the world literature on this topic, we found 27 cases of intradural cervical disc herniation in all. Methods. Clinical history, physical examination, and radiographic findings of two patients with intradural cervical disc herniation were described, and corpectomy was performed in both cases. A review of the literature was completed. Result. The outcome of one case was gratifying, and at a 36-month follow-up, nearly a full recovery was obtained. But the others condition was disappointing, whose postoperative MRI demonstrated high signal intensity in the spinal cord and adhesion of spinal cord to the posterior margin at C4 level. Conclusion. Intradural cervical disc herniation is relatively rare, and the two additional cases updated the number of this condition to 29. It remains difficult to definitively diagnose the disease before surgery, but some indirect signs may indicate the cases. Corpectomy under a microscope as the first option in treatment of this disease is recommended once it is highly diagnosed. The pathogenesis of intradural cervical disc herniation remains to be further investigated. We presume that biochemical factors may play an important role in the pathogenesis.

Percutaneous endoscopic lumbar discectomy for lumbar disc herniation

This study aims to compare the advantages and disadvantage of percutaneous endoscopic lumbar discectomy (PELD) and standard discectomy (SD) for the treatment of lumbar intervertebral disc herniation (LDH). We searched in MEDLINE, EMBASE, PubMed, Web of Science and Cochrane databases for relevant trials that compare PELD and SD for the treatment of LDH. The Cochrane Collaborations Revman 5.3 software was used for data analyses. This meta-analysis compiled 1301 cases from four random controlled trials and three retrospective studies. Compared with SD, PELD showed a shorter operative time (mean difference (MD)=-18.68, 95% confidence interval (CI): -24.92 to -12.43; p<0.00001), less blood loss (MD=-64.88, 95% CI: -114.51 to -15.25, p<0.0001), shorter hospital stay (MD=-3.51, 95% CI: -4.93 to -2.08, p<0.00001), and shorter mean disability period (MD=-34.34, 95% CI: -53.90 to -14.77, p<0.006). However, there were no significant differences in the visual analogue scale (VAS) scores at the final follow up (MD=-0.23, 95% CI: -0.53 to 0.07, p=0.14), Macnab criteria at the final follow up (MD=1.04, 95% CI: 0.72 to 1.50, p=0.82), complications (RR=0.76, 95% CI: 0.40 to 1.43, p=0.39), recurrence rate (risk ratio (RR)=1.00, 95% CI: 0.61 to 1.64, p=1) and reoperation rate (RR=1.40, 95% CI: 0.90 to 2.16, p=0.13). In conclusion, despite PELD showing significant benefit in short term outcomes such as hospital course and mean disability period, similar clinical efficacy and long term outcomes were observed when compared to SD. Therefore, we suggest that PELD can be a feasible alternative to the conventional posterior approach for the LDH depending on surgeon preference and indication. High-quality randomized controlled trials with sufficient large sample sizes necessary further confirm these results.

Direct Posterior C1 Lateral Mass Screws Compression Reduction and Osteosynthesis in the Treatment of Unstable Jefferson Fractures

Study Design. Technical case report. Objective. To investigate a new concept and surgical technique in the treatment of unstable Jefferson fractures, which preserves the motion of upper cervical spine, avoiding fusion. Summary of Background Data. The management of unstable Jefferson fractures remains controversial. Conservative treatment usually involves a long time of immobilization in halo vest, whereas surgical intervention generally performs fusion, eliminating the range of motion of upper cervical spine. Methods. Two patients with unstable Jefferson fractures were surgically treated via direct posterior C1 lateral mass screws compression reduction and osteosynthesis technique, aiming at restoring the C0–C2 height and maintaining the vertical ligamentous tension for C0–C1–C2 complex stability despite the incompetent transverse ligament, achieving physiologic repair instead of traditional fusion. The clinical and radiographic results were documented. Results. The postoperative CT showed that C1 lateral mass screws were well positioned. At 1-year follow-up, plain radiographs, and CT scan revealed no implant failure, good cervical alignment, and bony healing of the fractures; no C1–C2 instability was observed on the flexion-extension radiographs. The patients were completely pain-free, with full range of motion of the cervical spine. Conclusion. The ideal treatment of unstable Jefferson fractures is expected to preserve the function of C0–C1–C2. Unstable Jefferson fractures involve the concomitant failure of the vertical ligamentous tension because of the loss of C0–C2 height. Reduction of the displaced lateral masses to restore the C0–C2 height and maintain the ligamentous tension is the key to the surgery. Direct posterior C1 lateral mass screws compression reduction and osteosynthesis is a valid technique, avoiding fusion of upper cervical spine.

Percutaneous endoscopic lumbar discectomy for recurrent lumbar disc herniation

The objective of this systematic review was to identify the effectiveness of percutaneous endoscopic lumbar discectomy (PELD) in the treatment of recurrent lumbar disc herniation (rLDH) and to present its indications and techniques. We conducted a comprehensive search in MEDLINE, EMBASE, PubMed, Web of Science and Cochrane databases, searching for relevant studies of managing rLDH with PELD up to July 2015. Only papers published in English were included. Two review authors independently selected the studies, extracted relevant data and assessed their methodological quality. The Cochrane Collaborations Revman 5.3 software was used for data analyses among the controlled studies. At last, one randomized controlled trial (RCT), two non-randomized control studies and five observational studies including a total of 579 cases were selected for this system review. The methodological quality of these studies was low to modern. The mean overall improvement of leg pain (visual analogue scale) was 66.92% (50.6%-89.87%), back pain (visual analogue scale) 54.91% (29%-67.95%), Oswestry Disability Index 60.9% (40.7%-75%), global perceived effect (MacNab/other) 75.77% (60%-95%). The mean overall of complication rate was 4.89% (0%-9.76%), dural tear rate 0.1% (0%-4.9%), recurrence rate 6.3% (4%-10%), re-operation rate 3.66% (2.33%-4.8%). We conducted a meta-analysis among the control trials. Compared with Open discectomy (OD), PELD resulted in better outcomes in terms of operative time, blood loss, lower complication rates, but with no significance differences regarding hospital stay, second recurrence rate, Macnab criteria and pain reduction. In conclusion, according to the current evidence, PELD is an effective procedure for the treatment of rLDH in terms of reducing complication and shorting hospital course, comparing with OD. Therefore, we suggested that PELD was a feasible alternative to OD in the treatment of the rLDH in the condition of proper indication. High-quality RCTs with large sample sizes are needed to further confirm these results.

Oxidative damage induces apoptosis and promotes calcification in disc cartilage endplate cell through ROS/MAPK/NF-κB pathway: Implications for disc degeneration.

Cartilage endplate (CEP) cell calcification and apoptosis play a vital role in the intervertebral disc degeneration (IVDD). Oxidative stress is a key factor in inducing programmed cell death and cartilage calcification. However, the cell death and calcification of cartilage endplate cells under oxidative stress have never been described. The present study investigated the apoptosis and calcification in the cartilage endplate cell under oxidative stress induced by H2O2 to understand the underlying mechanism of IVDD. The cartilage endplate cells isolated from human lumbar discs were subjected to different concentrations of H2O2 for various time periods. The cell viability was determined by CCK-8 assay, whereas Western blot, immunofluorescence, and Alcian blue, Alizarin red, and Von Kossa staining evaluated the apoptosis and calcification. The level of mitochondria-specific reactive oxygen species (ROS) was quantified with an oxygen radical-sensitive probe-MitoSOX. The potential signaling pathways were investigated by Western blot after the addition of N-acetyl-l-cysteine (NAC). We found that the oxidative stress induced by H2O2 increased the apoptosis and subsequently the calcification in the cartilage endplate cells through the ROS/p38/ERK/p65 pathway. The apoptosis and the calcification of the cartilage endplate cells induced by H2O2 can be abolished by NAC. These results suggested that regulating the apoptosis and the calcification in the cartilage endplate cells under oxidative stress should be advantageous for the survival of cells and might delay the process of disc degeneration.

Partial recovery of respiratory function and diaphragm reinnervation following unilateral vagus nerve to phrenic nerve anastomosis in rabbits.

Respiratory dysfunction is the leading cause of mortality following upper cervical spinal cord injury (SCI). Reinnervation of the paralyzed diaphragm via an anastomosis between phrenic nerve and a donor nerve is a potential strategy to mitigate ventilatory deficits. In this study, anastomosis of vagus nerve (VN) to phrenic nerve (PN) in rabbits was performed to assess the potential capacity of the VN to compensate for lost PN inputs. At first, we compared spontaneous discharge pattern, nerve thickness and number of motor fibers between these nerves. The PN exhibited a highly rhythmic discharge while the VN exhibited a variable frequency discharge pattern. The rabbit VN had fewer motor axons (105.3±12.1 vs. 268.1±15.4). Nerve conduction and respiratory function were measured 20 weeks after left PN transection with or without left VN-PN anastomosis. Compared to rabbits subjected to unilateral phrenicotomy without VN-PN anastomosis, diaphragm muscle action potential (AP) amplitude was improved by 292%, distal latency by 695%, peak inspiratory flow (PIF) by 22.6%, peak expiratory flow (PRF) by 36.4%, and tidal volume by 21.8% in the anastomosis group. However, PIF recovery was only 28.0%, PEF 28.2%, and tidal volume 31.2% of Control. Our results suggested that VN-PN anastomosis is a promising therapeutic strategy for partial restoration of diaphragm reinnervation, but further modification and improvements are necessary to realize the full potential of this technique.

A Biomechanical Stability Study of Extraforaminal Lumbar Interbody Fusion on the Cadaveric Lumbar Spine Specimens

Background Transforaminal lumbar interbody fusion (TLIF) is an effective surgery for lumbar degenerative disease. However, this fusion technique requires resection of inferior facet joint to provide access for superior facet joint resection, which results in reduced lumbar spinal stability and unnecessary trauma. We have previously developed extraforaminal lumbar interbody fusion (ELIF) that can avoid back muscle injury with direct nerve root decompression. This study aims to show that ELIF enhances lumbar spinal stability in comparison to TLIF by comparing lumbar spinal stability of L4–L5 range of motion (ROM) on 12 cadaveric spine specimens after performing TLIF or ELIF. Methods 12 cadaveric spine specimens were randomly divided and treated in accordance with the different internal fixations, including ELIF with a unilateral pedicle screw (ELIF+UPS), TLIF with a unilateral pedicle screw (TLIF+UPS), TLIF with a bilateral pedicle screw (TLIF+BPS), ELIF with a unilateral pedicle screw and translaminar facet screw (ELIF+UPS+TLFS) and ELIF with a bilateral pedicle screw (ELIF+BPS). The treatment groups were exposed to a 400-N load and 6 N·m movement force to calculate the angular displacement of L4-L5 during anterior flexion, posterior extension, lateral flexion and rotation operation conditions. Results The ROM in ELIF+UPS group was smaller than that of TLIF+UPS group under all operating conditions, with the significant differences in left lateral flexion and right rotation by 36.15% and 25.97% respectively. The ROM in ELIF+UPS group was higher than that in TLIF+BPS group. The ROM in the ELIF+UPS+TLFS group was much smaller than that in the ELIF+UPS group, but was not significantly different than that in the TLIF+BPS group. Conclusions Despite that TLIF+BPS has great stability, which can be comparable by that of ELIF+UPS. Additionally, ELIF stability can be further improved by using translaminar facet screws without causing more tissue damage to patient.

Leptin regulates disc cartilage endplate degeneration and ossification through activation of the MAPK-ERK signalling pathway in vivo and in vitro

Recent findings demonstrate that leptin plays a significant role in chondrocyte and osteoblast differentiation. However, the mechanisms by which leptin acts on cartilage endplate (CEP) cells to give rise to calcification are still unclear. The aim of this study was to evaluate the effects of leptin that induced mineralization of CEP cells in vitro and in vivo. We constructed a rat model of lumbar disc degeneration and determined that leptin was highly expressed in the presence of CEP calcification. Rat CEP cells treated with or without leptin were used for in vitro analysis using RT‐PCR and Western blotting to examine the expression of osteocalcin (OCN) and runt‐related transcription factor 2 (Runx2). Both OCN and Runx2 expression levels were significantly increased in a dose‐ and time‐dependent manner. Leptin activated ERK1/2 and STAT3 phosphorylation in a time‐dependent manner. Inhibition of phosphorylated ERK1/2 using targeted siRNA suppressed leptin‐induced OCN and Runx2 expression and blocked the formation of mineralized nodules in CEP cells. We further demonstrated that exogenous leptin induced matrix mineralization of CEP cells in vivo. We suggest that leptin promotes the osteoblastic differentiation of CEP cells via the MAPK/ERK signal transduction pathway and may be used to investigate the mechanisms of disc degeneration.