Qi-Xin Chen’s research while affiliated with Zhejiang University and other places

Stem cell-based transplantation is a promising therapeutic approach for intervertebral disc degeneration (IDD). Current limitations of stem cells include with their insufficient cell source, poor proliferation capacity, low nucleus pulposus (NP)-specific differentiation potential, and inability to avoid pyroptosis caused by the acidic IDD microenvironment after transplantation. To address these challenges, embryo-derived long-term expandable nucleus pulposus progenitor cells (NPPCs) and esterase-responsive ibuprofen nano-micelles (PEG-PIB) were prepared for synergistic transplantation. In this study, we propose a biomaterial pre-modification cell strategy; the PEG-PIB were endocytosed to pre-modify the NPPCs with adaptability in harsh IDD microenvironment through inhibiting pyroptosis. The results indicated that the PEG-PIB pre-modified NPPCs exhibited inhibition of pyroptosis in vitro; their further synergistic transplantation yielded effective functional recovery, histological regeneration, and inhibition of pyroptosis during IDD regeneration. Herein, we offer a novel biomaterial pre-modification cell strategy for synergistic transplantation with promising therapeutic effects in IDD regeneration.

Purpose Severe cervical axial deformity associated with ankylosing spondylitis (AS) is rare in clinic, and there are little concerns about surgical treatment of axial deformity associated with AS. The case study aims to show the surgical technique to perform cervical rotational osteotomy. Methods We present the case of a young AS patient whose neck was fixed in a left-rotational posture at 18°, requiring his trunk to be turned to the right to look forward visually. This made his gait appear to be limping, inconveniencing him with great difficulty. In order to correct this deformity, we performed a novel cervical rotational osteotomy through a one-stage posterior–anterior–posterior approach. Firstly, we performed laminectomies of C7 and T1, followed by a C7/T1 facetectomy with release of the bilateral C8 nerve roots. Next, we performed C7/T1 discectomy, bony resection of the lateral body and uncovertebral joints. The head of the patient was then rotated manually, so that both his face and torso were simultaneously facing frontward. Finally, rods spanning the screws from C6 to T2 were fixed. Results Postoperatively, the patient’s axial malalignment was significantly improved, and he was able to walk normally. Surgical outcomes were well maintained at a 3-year follow-up. Conclusion Through this case, we hope to draw the attention to spinal axial deformity and provide a reference point in the surgical treatment of spinal axial deformity.

Purpose To analyze the predictors for second-stage posterior direct decompression (PDD) after lateral lumbar interbody fusion (LLIF) procedure. Methods We studied patients who underwent LLIF for degenerative lumbar spinal stenosis in the last five years, from July 2016 to June 2021. All surgical levels were grouped according to Schizas’ central canal stenosis (CCS) classification, Pathria’s facet joint degeneration (FJD) classification, Bartynski’s lateral recess stenosis (LRS) classification, and Lee’s foraminal stenosis (FS) classification. Second-stage PDD rates of each subgroup and their annual change were analyzed. Evaluation of risk factors associated with PDD was investigated. Results A total of 901 segments from 557 patients were included. The overall PDD rate was 29.97%. An overall PDD rate of 75.21% for grade D CCS, 29.74% for grade C CCS, 41.67% for grade 3 FJD, 37.61% for grade 3 LRS, and 40.70% for grade 3 FS was shown. While there was a continuous decline in annual PDD rate in the past four years, the annual PDD rate for grade D remained at very high levels. Logistic regression analysis had shown grade D CCS as the utmost risk factor for PDD (OR = 17.77). And grade 3 LRS (OR = 4.63), grade 3 FS (OR = 2.42), grade C CCS (OR = 2.41), and grade 3 FJD (OR = 2.04) were also moderately correlated with PDD, which meant they only moderately increased the risk of PDD. Conclusion Extreme severe lumbar CCS (grade D) is the greatest determinant to perform the second-stage PDD procedure after LLIF.

Objective: To investigate whether anterior selective fusion (ASF) could save more distal fusion segments compared with posterior approach in the treatment of Lenke type 5 adolescent idiopathic scoliosis with long term follow-up. Methods: A retrospective cohort study. From 2008 to 2011, 22 AIS girls with Lenke type 5 who underwent ASF or posterior selective fusion (PSF) with more than 8-year follow-up, were extracted from the database. 13 girls in the ASF group had an average age of 14.3 ± 1.3 years and Risser sign of 3.3 ± 1.1; 9 PSF girls had an average age of 16.2 ± 3.6 years and Risser sign of 3.8 ± 1.5. The radiographic outcome was compared between groups preoperatively, 6-month postoperatively, 8-year postoperatively and at last follow-up (>8 years). Results: The average follow-up duration was 8.7 ± 0.4 (ASF) and 8.8 ± 0.5 (PSF) years, respectively. There was no significant difference at baseline in age, Risser sign and preoperative curve pattern in the coronal and sagittal plane between the groups (P > 0.05). The ASF group had significantly shorter fusion segments (5.1 ± 0.6 vs. 7.0 ± 1.3) and decreased upper instrumented vertebra (UIV) (T11 ± 0.8 vs. T10 ± 0.8) than the PSF (P < 0.05); while no significant difference was found in the lower instrumented vertebra (LIV) and distal reserved segments (P > 0.05), which suggested that ASF could shorten the fusion segments by lowering UIV. The distal compensatory curve in the ASF group (9.0° ± 3.9°) was significantly larger than in the PSF group (3.3° ± 2.4°, P = 0.003), despite of no significant difference in the incidence of coronal imbalance (P > 0.05), indicating that both two approaches could obtain satisfactory correction in the coronal plane. In the sagittal plane, PSF patients had significantly larger lumbar lordosis (LL, 59.1° ± 10.5°), thoracic kyphosis (TK, 37.2° ± 13.3°) and proximal junctional angle (PJA, 13.3° ± 6.1°) at the last follow-up than the ASF (LL: 43.4° ± 9.4°; TK: 20.7° ± 8.4°; PJA: 4.7° ± 3.4°; P < 0.05), but without significant difference in proximal junctional kyphosis (PJK) and sagittal vertical axis (SVA) (P > 0.05). After controlling for age, Risser sign, and radiographic parameters related to the primary curve pattern, shorter fusion segments and more distal reserved segments still remained significant in the ASF group with greater Risser sign (P < 0.05). No major intra- or post-operative complications occurred. Conclusions: Both ASF and PSF could obtain satisfactory coronal and sagittal correction for Lenke 5 AIS; compared with PSF, ASF could shorten the fusion segments by lowering UIV, and save more distal fusion segments only in patients with greater skeletal maturity.

Purpose To perform an updated and comprehensive review of LLIF; we will also introduce a new modified LLIF named as crenel lateral interbody fusion (CLIF) to reduce the approach-related complications Methods A systematic and critical review of recent literature was conducted. The sources of the data were form PubMed, MEDLINE, Embase, and Cochrane. Key search terms were "transpsoas", "interbody fusion", "LLIF", "XLIF", and “DLIF” Results Stand-alone LLIF has the risk of cage subsidence and non-union rate. LLIF has less complication compared with other approaches because of its minimal invasive, but it still has some specific complications. Conclusion LLIF is a safe, effective and lower complication rate technique when compared to other interbody fusion methods.

Background To analyze the biomechanical stability of the modified LLIF, crenel lateral interbody fusion (CLIF), and compare various methods of instrumentation of CLIF in vitro. Methods Three fresh-frozen cadaveric lumbar spines (L1-S1) were used in our study. The modified CLIF interbody cage was inserted into the L3/4 level in each specimen. Every specimen was tested under 5 conditions: intact group; stand-alone CLIF group; CLIF with lateral plate group (CLIF + LP); CLIF with lateral plate and unilateral pedicle screw group (CLIF + LP + UPS); CLIF with bilateral pedicle screw group (CLIF + BPS). Results The ROM of each CLIF group was significantly reduced when compared with intact group in all directions of loading (p< 0.05). The CLIF + LP + BPS group was the most stable in all directions of loading. CLIF + LP group has less ROM when compared with stand-alone group except for the extension condition. CLIF + BPS group has less ROM than CLIF + LP group in every condition. Conclusions CLIF combine with lateral plate and bilateral pedicel screw is the most stable supplemental fixation, and lateral plate could reduce the ROM under rotation and lateral bending conditions. For patients with good bone quality, stand-alone with or without is a alternative method to achieve a good clinical result.

The present study was to introduce a new surgical technique of cervical flexionosteotomy, with an emphasis on the clinical and radiographic outcomes. Two male patients aged 45 and 21 years presented with cervical extension deformity in ankylosing spondylitis (AS). Both patients exhibited upward deviation of the forward gaze. The chin brow vertical angle (CBVA) were 15° upward and 5° downward, respectively; and the sagittal vertical axis (SVA) were‐13.2mm and 195.7mm, respectively. Aposterior transverse release was performed at C7‐T1, exposing the theca and C8 nerve roots to facilitate closure of theosteotomy site. Then, an anterior closing‐wedgeosteotomy of C7‐T1 was performed followed with anterior internal fixation with a locking plate to prevent any translation. After closure and anterior fixation, patients were returned to the proneposition, and posterior screw‐rod instrumentation was used for further stabilization. The follow‐up periods were 20 and 10 months, respectively. At the last follow‐up, CBVA and SVA of Patient 1 were 14° downwardand ‐12.6mm; and CBVA and SVA of Patient 2 were 1° downward and 75.6mm respectively, indicating the visual angle and sagittal balance were significantly improved. No intraoperative or postoperative complications were encountered. Full‐spine radiographs of each patient at the last visit confirmed successfulbony union. The present study was the first report introducing a novel flexion osteotomy for cervical extension deformity in AS through a posterior‐anterior‐posterior approach inone‐stage. The improved forward gaze and no complications demonstrated the effectiveness and safety of the novel technique, suggesting that it might provide a more feasible method for the correction of cervical extension deformity.

Abstract Background Extreme lumbar spinal stenosis was thought to be a relative contraindication for lateral lumbar interbody fusion (LLIF) and was excluded in most studies. This is a retrospective study to analyze the radiographic and clinical outcome of LLIF for extreme lumbar spinal stenosis of Schizas grade D. Methods For radiographic analysis, we included 181 segments from 110 patients who underwent LLIF between June 2017 and December 2018. Lumbar spinal stenosis was graded according to Schizas’ classification. Anterior and posterior disc heights, disc angle, foramen height, spinal canal diameter and central canal area were measured on CT and MRI. For clinical analysis, 18 patients with at least one segment of grade D were included. Visual analogue scale (VAS) and Oswestry disability index (ODI) scores were used to evaluate clinical outcome. Continuous variables were compared using Student’s t-test, with P-values

To analyze the biomechanical stability of a redesigned cage, a new lateral plate and the effect of length of cage in CLIF, an L4-L5 finite element model was performed. Six different internal fixation methods were designed and operated under six conditions (Stand-alone CLIF; CLIF with unilateral pedicle screws (CLIF + UPS); CLIF with bilateral pedicle screws (CLIF + BPS); CLIF with lateral plate (CLIF + LP); CLIF with lateral plate and unilateral pedicle screws (CLIF + LP + UPS); CLIF with lateral plate and bilateral pedicle screws (CLIF + LP + BPS)). Ranges of motion (ROM) and stress distribution were evaluated. The effect of the length of cage was analyzed. The ROMs of stand-alone CLIF group and other internal fixation groups were decreased by >90% compared with the intact group. The CLIF + LP + BPS group has the minimum ROM. The CLIF + LP group has smaller ROM than stand-alone group. The stand-alone group has the minimum stress except for extension condition. The CLIF + LP model has less ROM, but a greater stress load was observed in the lateral plate. As for the length of cage, the largest stress is located at the junction between cage and distal end plate, especially in the epiphyseal ring and cortical compact. We conduct a new ‘cylinder wall theory’ that the cage should be placed to cover the epiphyseal ring. We recommend the length of cage should cover the epiphyseal ring to reduce the subsidence of cage.

Background: Extreme lumbar spinal stenosis was thought to be a relative contraindication for lumbar lateral interbody fusion (LLIF) and was excluded in most studies. This is a retrospective study to analyze the radiographic and clinical outcome of LLIF for extreme lumbar spinal stenosis of Schizas grade D. Methods: For radiographic analysis, we included 202 segments from 124 patients who underwent LLIF between June 2017 and December 2018. Lumbar spinal stenosis was graded according to Schizas’ classification. Anterior and posterior disc heights, disc angle, foramen height, spinal canal diameter and central canal area were measured on CT and MRI. For clinical analysis, 18 patients with at least one segment of grade D were included. Visual analogue scale (VAS) and Oswestry disability index (ODI) scores were used to evaluate clinical outcome. Continuous variables were confronted by using Student's t-test, obtaining a statistically significant difference for values inferior to 0.05. Results: Among the 202 segments included for radiological evaluation, there were 42 grade A segments, 41 grade B segments, 101 grade C segments and 18 grade D segments. Postoperatively, the average change of midsagittal canal diameter of grade D was significantly greater than that of grade A, and not significantly different compared to grades B and C. As to the average changes of disc height, bilateral foraminal height, disc angle and central canal area (CCA), grade D was not significantly different from the others. The average postoperative CCA of grade D was significantly smaller than the average preoperative CCA of grade C. Eighteen patients with grade D stenosis were followed up for an average of 19.61 ± 6.32 months. Clinical evaluation revealed an average improvement in the ODI and VAS scores for back and leg pain by 20.77%, 3.67 and 4.15 points, respectively. Sixteen of 18 segments with grade D underwent posterior decompression. Conclusion: The radiographic decompression effect of LLIF for Schizas grade D segments were comparable with that of other grades. Posterior decompression was necessary for LLIF to achieve a satisfactory clinical outcome for extreme lumbar spinal stenosis of Schizas grade D.