Successful regeneration of weight-bearing bone defects and criticalsized cartilage defects remains a major challenge in clinical orthopedics. In the past decades, biodegradable polymer materials with biomimetic chemical and physical properties have been rapidly developed as ideal candidates for bone and cartilage tissue engineering scaffolds. Due to their unique advantages over other materials of high specific-surface areas, suitable mechanical strength, and tailorable characteristics, scaffolds made of polymer fibers have been increasingly used for the repair of bone and cartilage defects. This Review summarizes the preparation and compositions of polymer fibers, as well as their characteristics. More importantly, the applications of polymer fiber scaffolds with well-designed structures or unique properties in bone, cartilage, and osteochondral tissue engineering have been comprehensively highlighted. On the whole, such a comprehensive summary affords constructive suggestions for the development of polymer fiber scaffolds in bone and cartilage tissue engineering.

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The changes that occur with disc degeneration progress from the normal state to an unstable phase with higher mobility and subsequently to an ankylosed stage. This study evaluated the contribution of different levels to the changes in overall motion that occur with degeneration.

This prospective, randomized study compared the functional outcome and complications associated with a proximal femoral nail antirotation (PFNA) device with those of a traditional extramedullary device, the dynamic hip screw (DHS), in patients with trochanteric fracture. A total of 121 patients were randomized to the PFNA group (n = 58) or the DHS group (n = 63). Perioperative information and complications were recorded, and assessments of functional outcome were made. The DHS group required a longer operative time and was associated with greater blood loss than the PFNA group. The re-operation rate was lower in the PFNA group compared with the DHS group, especially in patients with unstable fractures, although there was no statistically significant difference in the overall complication rate between the two groups. There were no significant differences in functional outcome between the PFNA and the DHS groups. In conclusion, the PFNA device is useful in the treatment of trochanteric fractures.

Comparing the clinical and radiographic outcomes in anterior cervical discectomy and fusion (ACDF) using a zero-profile anchored spacer (ROI-C) or a conventional cage-plate construct (CPC) for treating noncontiguous bilevel of cervical degenerative disc disease (CDDD).Overall, 46 patients with 2 noncontiguous segments of CDDD, treated with ACDF from January 2011 to October 2015, were included in this study. ROI-C was used in 22 patients (group A) and CPC in 24 patients (group B). The clinical and radiographic outcomes and complications were compared pre- and postoperatively. All patients were followed up for at least 24 months after surgery.No significant difference was found in fusion rate, cervical curvature, height of fused segment (FSDH), intraoperative blood loss, and Japanese Orthopaedic Association (JOA), and Neck Disability Index (NDI) scores between the 2 groups. Group A had a shorter operation time and significantly lower incidence of dysphagia (3 and 24 months postoperatively) than group B (P < .001 and P < .05, respectively). Moreover, group A had a higher loss of FSDH than group B, but with no difference between the 2 groups (P > .05). Two cages developed subsidence in group A (4.5%) and 2 adjacent levels developed degeneration in group B (2,8%).ACDF with ROI-C device was superior to CPC for noncontiguous bilevel of CDDD because it avoided postoperative dysphagia and required a shorter operation time. Moreover, the clinical outcomes were comparable. Prospective trials with larger samples and longer follow-up are required to confirm the results.

Recent studies suggest that cell therapy may be an effective way to repair intervertebral disc degeneration. As a strong immune suppressor, TGF-β1 has been shown to inhibit inflammation respond effectively. The objective of this study was to explore the effects of TGF-β1 during bone marrow mesenchymal stem cells-based therapy for disc degeneration. In vitro assays demonstrated that co-culturing of nucleus pulposus cells with bone marrow mesenchymal stem cells resulted in significantly higher levels of TGF-βl secretion. This increase inhibited IκB phosphorylation and NF-κB activation, detected by western blot analysis. Meanwhile, in a rabbit model, MRI analysis revealed significant recovery of signal intensity in the degenerative discs of rabbits receiving cells transplantation, than receiving cells treated with a TGF-β1 inhibitor or saline. These findings indicated that enhanced TGF-β1 production recovered the degeneration of intervertebral disc. And also immunohistochemical staining detected enhanced collagen II expression in the rabbits treated with cell transplantation. However, the NF-κB positive cells were significantly less than other two control groups. Thus, cell therapy promoted TGF-β1 expression in nucleus pulposus, leading to anti-inflammatory effects via the inhibition of NF-κB, and the amelioration of disc degradation due to increased expression of collagen II and aggrecan in degenerative intervertebral disc.

Ideal cartilage tissue engineering requires scaffolds featuring good biocompatibility, large pore structure, high mechanical strength, as well as minimal invasion procedure. Although significant progress has been made in the development of polymer scaffolds, the construction of smart systems with all the desired properties is still emerging as a challenge. The thermogels of stereocomplex 4‐arm poly(ethylene glycol)–polylactide (PEG–PLA) (scPLAgel) and stereocomplex cholesterol‐modified 4‐arm PEG–PLA (scPLA–Cholgel) from the equimolar enantiomeric 4‐arm PEG–PLA and 4‐arm PEG–PLA–Chol, respectively, are fabricated as scaffolds for cartilage tissue engineering. scPLA–Cholgel shows lower critical gelation temperature, higher mechanical strength, larger pore size, better chondrocyte adhesion, and slower degradation compared to scPLAgel as the benefit of cholesterol modification, which is more appropriate for cartilage regeneration. Moreover, the preservation of morphology, biomechanical property, cartilaginous specific matrix, as well as cartilaginous gene expressions of engineered cartilage mediated by scPLA–Cholgel are proven superior to those by scPLAgel. scPLA–Cholgel serves as a promising chondrocyte carrier for cartilage tissue engineering and gives an alternative solution to clinical cartilage repair.

Although degeneration of the nucleus pulposus (NP) is a major contributor to intervertebral disc degeneration (IVDD) and low back pain, the underlying molecular complexity and cellular heterogeneity remain poorly understood. Here, a comprehensive single-cell resolution transcript landscape of human NP is reported. Six novel human NP cells (NPCs) populations are identified by their distinct molecular signatures. The potential functional differences among NPC subpopulations are analyzed. Predictive transcripts, transcriptional factors, and signal pathways with respect to degeneration grades are explored. It is reported that fibroNPCs is the subpopulation for end-stage degeneration. CD90+NPCs are observed to be progenitor cells in degenerative NP tissues. NP-infiltrating immune cells comprise a previously unrecognized diversity of cell types, including granulocytic myeloid-derived suppressor cells (G-MDSCs). Integrin 𝜶M (CD11b) and oxidized low density lipoprotein receptor 1 (OLR1) as surface markers of NP-derived G-MDSCs are uncovered. The G-MDSCs are found to be enriched in mildly degenerated (grade II and III) NP tissues compared to severely degenerated (grade IV and V) NP tissues. Their immunosuppressive function and alleviation effects on NPCs' matrix degradation are revealed in vitro. Collectively, this study reveals the NPC-type complexity and phenotypic characteristics in NP, thereby providing new insights and clues for IVDD treatment.