Chunxi Yang

The healing of the tendon-bone interface remains a significant challenge due to the lack of suitable bioactive materials for promoting interface regeneration. To address this, we developed a photosensitive hydrogel system designed to mimic the extracellular matrix. This system is based on light-induced imine crosslinking between type I collagen (Col I) and o-nitrobenzyl alcohol (NB)-modified hyaluronic acid (HANB). Experimental results demonstrate that the hydrogel (Col I-HANB) exhibits excellent controllability, low swelling rate, biodegradability, and tissue-adhesive properties. Using a fluorescent dye (8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt, HPTS) as a model molecule, we confirmed that the hydrogel enables localized and sustained release, high-lighting its potential as a drug-delivery platform for tissue engineering. To further enhance tendon-bone interface repair, the hydrogel was functionalized with two key components: (I) The E7 peptide, known for its stem cell-homing properties, was covalently immobilized into the hydrogel network via conjugation to bovine serum albumin (BSA) and followed by imine-ligation between UV-triggered aldehyde generation from HANB and BSA's amino groups; and (II) Kartogenin (KGN)-loaded nanoparticles (KGN-NPs) were incorporated to potentially promote chondrogenic differentiation, with release assays confirming sustained KGN delivery over 21 days. The composite hydrogel demonstrated excellent biocompatibility in cytotoxicity and live/dead assays. Importantly, in a rabbit rotator cuff tear model, it effectively promoted fibrocartilage regeneration and significantly improved tendon-bone healing, creating a favorable microenvironment for repair. The results above indicate that the hydrogel system provides a good microenvironment for rotator cuff injury repair and is a promising scaffold applied in treatment of rotator cuff injury.

The on-demand delivery and release of chemotherapeutic drugs have attracted great attentions, among which photoresponsive prodrug systems have shown specific advantages for effective cancer treatment due to its spatiotemporal control, non-invasive nature and easy operation. Unlike the traditional strategy of physical encapsulation of drugs in liposomes, we herein report a biomimetic and photoresponsive drug delivery system (DDS) based on a lipid prodrug liposomal formulation (LNC), which combines the features of prodrug and nanomedicines, and can realize photocontrollable release of anticancer drugs. The lipid prodrug comprises three functional moieties: a single-arm phospholipid (Lyso PC), an o-nitrobenzyl alcohol (NB) and a chlorambucil (CBL). Before irradiation, LNC formed liposomal assemblies in water with an average size of about 200 nm, and upon light irradiation, the efficient photocleavage reaction of NB facilitated the disintegration of liposomal assemblies and the release of drug CBL. Photolysis analysis showed that LNC exhibited accurate and controllable drug release in response to UV 365 nm irradiation. Cell viability assays showed that LNC liposomes demonstrated very low cytotoxicity in dark and high cellular toxicity upon light irradiation, with toxicity even higher than free CBL. Our results suggest that our photoresponsive lipid prodrug represents a promising strategy to construct controlled DDS for cancer therapy.

The study of neuroimmune crosstalk and the involvement of neurotransmitters in inflammation and bone health has illustrated their significance in joint-related conditions. One important mode of cell-to-cell communication in the synovial fluid (SF) is through extracellular vesicles (EVs) carrying microRNAs (miRNAs). The role of neurotransmitter receptors in the pathogenesis of inflammatory joint diseases, and whether there are specific miRNAs regulating differentially expressed HTR2A, contributing to the inflammatory processes and bone metabolism is unclear. Expression of neurotransmitter receptors and their correlated inflammatory molecules were identified in rheumatoid arthritis (RA) and osteoarthritis (OA) synovium from a scRNA-seq dataset. Immunohistochemistry staining of synovial tissue (ST) from RA and OA patients was performed for validation. Expression of miRNAs targeting HTR2A carried by SF EVs was screened in low- and high-grade inflammation RA from a public dataset and validated by qPCR. HTR2A reduction by target miRNAs was verified by miRNAs mimics transfection into RA fibroblasts. HTR2A was found to be highly expressed in fibroblasts derived from RA synovial tissue. Its expression showed a positive correlation with the degree of inflammation observed. 5 miRNAs targeting HTR2A were decreased in RA SF EVs compared to OA, three of which, miR-214-3p, miR-3120-5p and miR-615-3p, mainly derived from monocytes in the SF, were validated as regulators of HTR2A expression. The findings suggest that fibroblast HTR2A may play a contributory role in inflammation and the pathogenesis of RA. Additionally, targeting miRNAs that act upon HTR2A could present novel therapeutic strategies for alleviating inflammation in RA.

Discoid lateral meniscus (DLM) is the most common congenital variant of the lateral meniscus, which is prone to degeneration and lesions, and often leads to knee osteoarthritis. At present, there is no consensus on the clinical practice of DLM, and this expert consensus and practice guidelines on DLM was developed and approved by Chinese Society of Sports Medicine according to the Delphi method. Among 32 statements drafted, 14 statements were excluded for redundant information, and 18 statements achieved consensus. This expert consensus focused on the definition, epidemiology, etiology, classification, clinical manifestations, diagnosis, treatment, prognosis, and rehabilitation of DLM. Restoring the normal shape, retaining appropriate width and thickness, and ensuring the stability of the remnant meniscus is critical to sustaining the physiological function of the meniscus and preserving the knee. The partial meniscectomy with or without repair should be the first‐line treatment when possible, given that the clinical and radiological long‐term outcomes of total or subtotal meniscectomy are worse.

Introduction: Suture passer needle, as one of commonly used instrument in the arthroscopic rotator cuff repair, often breaks at the notch of the needle, which originally was designed to facilitate suture with thread. Our study aimed to evaluate the suture failure rate and stitch success rate between intact suture needle and broken needle and explore the mechanism of the needle breakage and achieving better future designs.Materials and methods: From 2017 to 2021, consecutive 437 shoulders (11 cases were bilateral) underwent arthroscopic repair for full-thickness rotator cuff tear at the authors’ institution. The breakage of needles was recorded. Finite elements analysis and mechanical test were utilized to compare stress distribution, puncture performance, and loaded puncture performance between the broken needle and the intact needle.Results: We identified 19 consecutive patients for whom the needle tip of the TruePass™ suture passer was broken in the 437 shoulder surgeries. Based on the finite element analysis of Abaqus, around the tip and the notch of the intact needle was a large stress concentration. The average puncture force required by intact needle tip and the broken tip is 61.78N and 78.23N respectively. While the intact tip with notch is easier to break than the broken tip.Conclusions: The notch of the needle is a weak point in mechanics. The broken needle without the notch still has good tendon piercing and thread passing ability. The notch of needle may be not necessary, and the tip of the needle should be modified.

The tendon-bone junction (TBJ) is a graded structure consisting of tendons, nonmineralised, and mineralised fibrocartilage and bone. Given the complex gradient of the TBJ structure, TBJ healing is particularly challenging. Injuries to the TBJ such as anterior cruciate ligament (ACL) tears and rotator cuff injuries are common and serious sports injuries, affecting more than 250,000 patients annually in the United States, particularly people older than 50 years. ACL reconstruction and rotator cuff repair are the commonly performed TBJ repair surgeries. However, the re-tear rate is high post-operation. In recent years, studies on improving TBJ healing have focused on promoting tendon-bone integration at tendon sites. This process includes the use of periosteum, hydrogels, scaffolds, growth factors, stem cells or other reconstruction materials that promote bone growth or ligament attachment. In this study, we will highlight the utilisation of the unique properties of biomaterial coating in promoting tendon-bone healing and discuss recent advances in understanding their role in TBJ healing. Furthermore, we aim to provide a systematic and comprehensive review of approaches to promoting TBJ healing.

Objective. To reduce the pain of quadriceps during knee flexion after total knee arthroplasty and increase range motion of knee flexion. Design. Three-month prospective before/after quality improvement project. Setting. Department of Bone and Joint Surgery. Participants. A total of 80 patients who met the surgical indications were admitted to the outpatient department for surgery. They were randomly grouped by computer in advance, and the patients were divided into two groups according to the time of admission, each with 40 cases. Intervention. The intervention group performed routine rehabilitation exercises and received quadriceps acupoint massages for 20 minutes twice a day for two consecutive weeks. The control group performed routine rehabilitation exercises, such as gentle quadriceps massage for 20 minutes twice a day for two consecutive weeks. Main Outcome Measures. PPT (pressure pain threshold) of quadriceps femoris/VAS (visual analog scale) of knee flexion and motion of knee flexion. Results. The VAS score, range of motion, and tenderness threshold during flexion were significantly better in the intervention group than in the control group at 1, 2, and 4 weeks after surgery. But the VAS score, range of motion, and tenderness threshold did not significantly differ between groups at 12 weeks after surgery. Conclusion. Acupoint massage of the quadriceps femoris can relieve early flexion pain in patients after total knee arthroplasty. The trial was registered at clinical trials.gov.