The nucleus pulposus (NP), a heterogeneous tissue, is an essential functional component of the intervertebral disc. However, NP cell development route and regulation mechanism in intervertebral disc degeneration (IVDD) remain unknown. Here, we performed single-cell RNA sequencing of six NP samples with normal control, mild degeneration, and severe degeneration. Based on unbiased clustering of gene expression patterns from 30,300 single-cell RNA sequencing, we identified three cell lineage families of macrophages, endothelial, and chondrocyte cells and characterized seven chondrocyte subtypes, and defined two developmental pathways of the chondrocyte cell lineage families in the process of IVDD. Additionally, CellPhoneDB analysis revealed potential interactions between chondrocyte cells and other cells in IVDD. Chondrocytes in one of the differentiated orientations interact with macrophages and endothelial cells and have an inflammatory amplification effect, which were key factors causing IVDD. Collectively, these results revealed the dynamic cell landscape of IVDD development and offered new insights into the influence of NP cells differentiation on extracellular matrix homeostasis during degeneration, providing potential treatment targets for IVDD.

Background: Percutaneous endoscopic lumbar discectomy (PELD) is an increasingly applied minimally invasive procedure that has several advantages in the treatment of lumbar disc herniation (LDH). However, recurrent LDH (rLDH) has become a concerning postoperative complication. It remains difficult to establish a consensus and draw reliable conclusions regarding the risk factors for rLDH. Purpose: This retrospective study aimed to investigate the risk factors associated with rLDH at the L4-5 level after percutaneous endoscopic transforaminal discectomy (PETD). Methods: A total of 654 patients who underwent the PETD procedure at the L4-5 level from October 2013 to January 2020 were divided into a recurrence (R) group (n=46) and a nonrecurrence (N) group (n=608). Demographic and clinical data and imaging parameters were collected and analyzed using univariate and multiple regression analyses. Results: The current study found a 7% rate of rLDH at the L4/5 level after successful PETD. Univariate analysis showed that older age, high BMI, diabetes mellitus history, smoking, large physical load intensity, moderate disc degeneration, small muscle–disc ratio (M/D), more fat infiltration, large sagittal range of motion (sROM), scoliosis, small disc height index (DHI), small intervertebral space angle (ISA), and small lumbar lordosis (LL) were potential risk factors (P < 0.10) for LDH recurrence after PETD at the L4-5 level. Multivariate analysis suggested that high BMI, large physical load intensity, moderate disc degeneration, small M/D, more fat infiltration, large sROM, small ISA, and small LL were independent significant risk factors for recurrence of LDH after PETD. Conclusion: Consideration of disc degeneration, M/D, fat infiltration of the paravertebral muscles, sROM, ISA, LL, BMI, and physical load intensity prior to surgical intervention may contribute to the prevention of rLDH following PETD and lead to a more satisfactory operative outcome and the development of a reasonable rehabilitation program after discharge.

Purpose: To compare the preliminary postoperative outcomes of percutaneous endoscopic transforaminal lumbar interbody fusion (Endo-TLIF) and minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) in the treatment of lumbar spondylolisthesis. Methods: Sixty-two patients with single-segment lumbar spondylolisthesis received Endo-TLIF and MIS-TLIF were enrolled in present study. Perioperative parameters, including operation time, estimated blood loss (EBL), interoperative fluoroscopy time, ambulation time and operative complications were recorded, respectively. The results of clinical metrics such as the Visual Analog Scale (VAS) for back and leg pain, the Oswestry Disability Index (ODI) and the Japanese Orthopaedic Association (JOA) score were obtained, respectively. Postoperative fusion rates were assessed by clinical fusion and CT at 12-month after surgery. Results: No significant differences were found in the demographic data between the two groups. Compared with MIS-TLIF group, Endo-TLIF group had similar operative time, less intraoperative blood loss and shorter ambulation time but longer duration of X-ray radiation. The postoperative VAS scores of back pain, ODI and JOA score were significantly improved comparing with the preoperative scores in two groups, but the Endo-TLIF group showed more significant improvement in the early follow-up (P < 0.05, respectively). There were no significant differences in terms of the interbody fusion rate between the two groups. Meanwhile, no serious postoperative complications were observed in the study. Conclusion: Compared with MIS-TLIF, Endo-TLIF technique showed relatively faster recovery and better outcomes in terms of early curative effect, especially in 6 months after operation. However, intraoperative repeated fluoroscopy could result in highly cumulative radiation and longer operation time.

Purpose: Define the effectiveness of teriparatide (TPTD) treatment on reducing the incidence of new vertebral compression fractures (NVCFs) and back pain and improving quality of life after percutaneous kyphoplasty (PKP). Methods: Two years of clinical follow-up data from primary osteoporotic women who had experienced initial osteoporotic vertebral compression fractures (OVCFs) and received PKP plus 12-month TPTD (n=113) or basic treatment (BT) of calcium and vitamin D supplements (n=208) were retrospectively collected. The risk of NVCFs over each 6-month period in the TPTD group was evaluated and compared with the BT group using a logistic regression. Health-related quality of life (HRQoL, EQ-5D questionnaire), back pain [100 mm visual analog scale (VAS)] and bone mineral density (BMD) of the spine were analyzed using linear mixed models for repeated measures (LMMRM). Results: Logistic regression analysis adjusting for baseline characteristics showed that patients in the TPTD group had a lower risk of NVCFs compared with those receiving BT during the final three observation intervals (6–12 months, OR=0.189, 95% CI=0.030–0.681, p=0.046; 12–18 months, OR=0.009, 95% CI=0.0001–0.111, p=0.001; 18–24 months, OR=0.024, 95% CI=0.0009–0.264, p=0.009, respectively). Significant improvements in adjusted EQ-5D and back pain VAS scores were identified in the TPTD group compared with the BT group, and this improvement was sustained for at least 12 months after teriparatide treatment was discontinued (both p<0.001). The BMD of the spine also showed a higher T-value in the TPTD group compared with the BT group (p<0.001). Conclusion: In routine clinical practice, for patients with OVCFs who receive the PKP procedure, TPTD treatment may be a preferable subsequent therapy because of its ability to reduce the incidence of NVCFs and sustain a high quality of life and back pain alleviation.

Purpose: To compare the outcomes and characteristics of oblique lumbar interbody fusion stand-alone (OLIF-SA) and OLIF with posterior pedicle screw fixation (OLIF-PPS) in the treatment of Grade I or Grade II degenerative lumbar spondylolisthesis. Patients and methods: Between January 2019 and May 2022, 139 patients with degenerative spondylolisthesis were treated with OLIF-SA (n = 85) or OLIF-PPS (n = 54). The clinical and radiographic records were reviewed. Results: The clinical and radiographic outcomes were similar in both groups. The operative time and intraoperative blood loss in the OLIF-SA group were lower than those in the OLIF-PPS group (P < 0.05). However, the OLIF-PPS group had significantly better disc height (DH) and postoperative forward spondylolisthesis distance (FSD) improvement at 6 months (P < 0.05). The OLIF-PPS group had a significantly lower cage subsidence value than the OLIF-SA group (P < 0.05). Improvement of the lumbar lordotic angle (LA) and fusion segmental lordotic angle (FSA) in the OLIF-PPS group was significantly better than that in the OLIF-SA group (P < 0.05). In terms of fusion types, the OLIF-SA group tended to undergo fusion from the edge of the vertebral body. Fusion in the OLIF-PPS group began more often in the bone graft area of the central cage of the vertebral body. The fusion speed of the OLIF-SA group was faster than that of the OLIF-PPS group. Conclusion: OLIF-SA has the advantages of a short operative time, less intraoperative blood loss, and reduced financial burden, while PPS has incomparable advantages in the reduction of spondylolisthesis, restoration of lumbar physiological curvature, and long-term maintenance of intervertebral DH. In addition, the SA group had a unique vertebral edge fusion method and faster fusion speed.