Effect of Remnant-Preserving Reconstruction of Acute Anterior Cruciate Ligament Injuries in a Rabbit Model: Histological and Biomechanical Analysis

Acute anterior cruciate ligament (ACL) is a key structure that stabilizes knee joints. The objective of this research is to investigate the influence of ligament remnants preserved on the tendon-bone healing following ACL reconstruction and to examine postoperative articular cartilage degeneration in rabbit as a model animal. Sixty New Zealand rabbits are randomly divided into an ACL reconstruction without remnant preservation group (Group A; n = 30) or ACL reconstruction with remnant preservation group (Group B; n = 30). The expression of HIF-1α, VEGF, and micro vessel density (MVD) in the transplanted tendon was detected by immunohistochemical staining at week 6 and 12 after the operation. The signal intensity of the transplanted tendon was observed by MRI scanning, and the width of the bone tunnel was measured by CT scanning at week 6 and 12 after the operation. The graft biomechanics was tested 12 weeks after the operation. The JNK and MMP-13 expression levels were compared to analyze the cartilage degeneration of the knee at week 12 after the operation. The experimental results were analyzed and showed that the remnant-preserving ACL reconstruction is beneficial for bone healing of the tendon in rabbits, but ACL reconstruction with or without ligament remnants preserved will not affect knee articular cartilage degeneration post-surgery.

Implantation of Various Cell-Free Matrixes Does Not Contribute to the Restoration of Hyaline Cartilage within Full-Thickness Focal Defects

Articular cartilage is a highly organized tissue that has a limited ability to heal. Tissue engineering is actively exploited for joint tissue reconstruction in numerous cases of articular cartilage degeneration associated with trauma, arthrosis, rheumatoid arthritis, and osteoarthritis. However, the optimal scaffolds for cartilage repair are not yet identified. Here we have directly compared five various scaffolds, namely collagen-I membrane, collagen-II membrane, decellularized cartilage, a cellulose-based implant, and commercially available Chondro-Gide® (Geistlich Pharma AG, Wolhusen, Switzerland) collagen membrane. The scaffolds were implanted in osteochondral full-thickness defects, formed on adult Wistar rats using a hand-held cutter with a diameter of 2.0 mm and a depth of up to the subchondral bone. The congruence of the articular surface was almost fully restored by decellularized cartilage and collagen type II-based scaffold. The most vivid restoration was observed 4 months after the implantation. The formation of hyaline cartilage was not detected in any of the groups. Despite cellular infiltration into scaffolds being observed in each group except cellulose, neither chondrocytes nor chondro-progenitors were detected. We concluded that for restoration of hyaline cartilage, scaffolds have to be combined either with cellular therapy or morphogens promoting chondrogenic differentiation.

Improvement of clinical and radiological outcomes of root repair patients with advanced articular cartilage degeneration and osteoarthritis

Purpose The main purpose of this study was to investigate clinical and radiological outcomes of medial meniscus posterior root tear (MMPRT) repair in knees with advanced articular cartilage degeneration and osteoarthritis compared to those with minimal degenerative change. Methods Thirty-three knees underwent MMPRT repair using an arthroscopic pullout repair tibial tunnel technique. Clinical scores including Lysholm Score, International Knee Documentation Committee (IKDC) Score and Knee injury and Osteoarthritis Outcome (KOOS) Score were collected preoperatively and sequentially at 6 months, 12 months and mean final follow-up of 39.4 months. Kellgren-Lawrence (K-L) osteoarthritis grade, Outerbridge classification of cartilage degeneration and the presence of bone marrow oedema on MRI were also evaluated. Results All clinical scores improved at final follow-up for knees with K-L grade ≥ 2 osteoarthritis (p < 0.001), with no significant difference compared to K-L 0/1. Patients with Outerbridge class 3/4 cartilage degeneration also reported improvements in clinical scores, albeit lower than those with class 2 degeneration (p < 0.05). During recovery, the majority of patients reported clinical improvements by 6 months, and six patients further improved by at least 15 points in IKDC score between 6 and 12 months. Osteoarthritis progressed in 10 of 31 knees (32%), with an overall mean pre-operative K-L grade of 1.6 ± 0.9 compared to 2.0 ± 0.9 at final follow-up (n.s.). No knees progressed to K-L 4 or underwent re-operation. Pre-operative bone marrow oedema was present in 17 knees (52%), all of which had signal localised to the medial tibia or femur. Oedema had resolved in all but 5 knees post-operatively (p < 0.01). Conclusion Arthroscopic repair of medial meniscus posterior root tears is associated with improved outcomes in knees with advanced cartilage degeneration and osteoarthritis. Meaningful improvements in clinical outcomes can be achieved beyond 6 months, thus success of the operation is best determined at the 12-month mark. Oedema signal significantly improved post-operatively, however a relatively high proportion of knees had K-L progression. Level of evidence IV – Case Series.

Identification of miR-338-5p and miR-4776-3p as mediators of articular cartilage degeneration

Purpose Osteoarthritis is one of the most common chronic diseases nowadays, and can cause serious physical illness and economic burden. Cartilage degeneration is one of primary reasons for osteoarthritis, but there were not thorough studies on cartilage lesions. Methods miR-338-5p and miR-4776-3p were overexpressed and knocked down in SW1353 cells. Dual luciferase assay is used to detect the binding of miR-338-5p, miR-4776-3p and SOX6. The expression of MMP13, TNFA, IL6, MCP1, PARP, Runx2, ALP, OPN, WNT4, WNT16, TRACP and CTSK was quantified by qPCR. And the expression of WNT4 at the protein level was quantified by WB. Results In this study, we found miR-338-5p and miR-4776-3p showed significantly high expression on cartilage in osteoarthritis through bioinformatics methods, and verified miR-338-5p and miR-4776-3p can improve catabolism, and trigger biological processes such as inflammation and apoptosis. Meanwhile we validated miR-338-5p and miR-4776-3p may play negative regulation in the process of bone biology. Conclusions Our study showed that miR-338-5p and miR-4776-3p can be regarded as medium of articular cartilage degeneration, and it provided new biomarker of early diagnosis in cartilage disease and osteoarthritis.

NGF Expression and Elevation in Hip Osteoarthritis Patients with Pain and Central Sensitization

Osteoarthritis (OA) is a chronic degenerative musculoskeletal disease that causes articular cartilage degeneration and chronic pain. Research into OA animal models suggests that elevated NGF levels in the synovium contribute to pain and central sensitization (CS). However, it is unclear whether synovial NGF contributes to CS in patients with OA. We investigated the association between synovial NGF expression and clinical assessments of pain and CS in hip OA (hOA) patients. We also aimed to identify which cells in the synovium of hOA patients express NGF. Sixty-six patients who received total hip replacement and a diagnosis of hOA were enrolled. We measured NGF mRNA expression in synovial samples obtained from 50 patients using qPCR and analyzed the correlation of NGF expression with the CS inventory (CSI) score and Japanese Orthopaedic Association (JOA) score, a clinical scoring system for OA. To identify the synovial cells expressing NGF, we analyzed NGF mRNA expression in CD14+ and CD14- cells, which represent macrophage-rich and fibroblast-rich fractions, respectively, extracted from 8 patients. To further identify which macrophage subtypes express NGF, we examined NGF mRNA expression in CD14high and CD14low cells sorted from 8 patients. Synovial NGF mRNA expression was negatively correlated with JOA score but positively correlated with CSI score (JOA pain, r = − 0.337 , P = 0.017 ; CSI score, r = 0.358 , P = 0.011 ). Significantly greater levels of NGF were observed in CD14- cells compared to CD14+ cells ( P = 0.036 ) and in CD14high cells compared to CD14low cells ( P = 0.008 ). In conclusion, synovial NGF expression is correlated with the degree of pain and CS in hOA patients. NGF is predominantly expressed in synovial fibroblasts. Further, CD14high synovial macrophages expressed higher levels of NGF. Our results may provide a novel NGF-targeted therapeutic strategy for hOA pain.

Knockdown of LSD1 alleviates the IL-1β-induced chondrocyte apoptosis, inflammation and ECM degradation via TRIM32-mediated autophagy

Osteoarthritis (OA) is a common joint disease with characteristics of chronic inflammation and articular cartilage degeneration. It has been proved that LSD1 was up-regulated in OA cartilage tissues, but its role and regulatory mechanism in OA are unclear. Herein, interleukin 1 beta (IL-1β)-treated human chondrocytes was performed as a cell model of OA. Then, LSD1 expression was found that up-regulated in OA cartilage tissues and IL-1β-induced chondrocytes. Knockdown of LSD1 increased cell viability, while decreased apoptosis rate and inflammatory cytokines secretion levels in IL-1β-induced chondrocytes. In addition, knockdown of LSD1 reduced the expression of catabolic proteins (MMP-13 and ADAMTS-5) and enhanced the expression of anabolic proteins (Collagen II and Aggrecan) in chondrocytes after IL-1β stimulation. Moreover, overexpression of TRIM32 repressed chondrocyte viability, while promoted IL-1β-induced chondrocyte apoptosis, inflammation and ECM degradation. The expression of LSD1 and TRIM32 in OA cartilage was positively correlated, and knockdown of LSD1 down-regulated TRIM32 expression of chondrocytes. Our data further indicated that LSD1 regulated autophagy of chondrocytes through modulating TRIM32. Overexpression of TRIM32 reduced the effect of LSD1 knockdown on IL-1β-induced chondrocytes, while activating autophagy by Rapamycin further reversed this reduction. Therefore, our study shows that knockdown of LSD1 inhibited IL-1β-induced chondrocyte apoptosis, inflammation and ECM degradation via TRIM32-mediated autophagy.

Effect of differences in mechanical stress in vivo on the onset and progression of knee osteoarthritis

Objective: The effect of the type of mechanical stress on OA onset has not been clarified. The aim of this study was to establish a new model that reproduces the type and increase and decrease of mechanical stress in vivo and to clarify the differences in the mechanism of knee OA onset and progression among the models. Design: To reproduce the difference in mechanical stress, we used the anterior cruciate ligament transection (ACL-T) model and the destabilization of the medial meniscus (DMM) model. In addition, we created a controlled abnormal tibial translation (CATT) model and a controlled abnormal tibial rotation (CATR) model that suppressed the joint instability of the ACL-T and DMM model, respectively. These four models reproduced the increase and decrease in shear force due to joint instability and compressive stress due to meniscal dysfunction. We performed joint instability analysis with soft X-ray, micro computed tomography analysis, histological analysis, and immunohistological analysis in 4 and 6 weeks. Results: Joint instability decreased in the CATT and CATR groups. The meniscus deviated in the DMM and CATR groups. Chondrocyte hypertrophy increased in the ACL-T and DMM groups with joint instability. In the subchondral bone, bone resorption was promoted in the ACL-T and CATT groups, and bone formation was promoted in the DMM and CATR groups. Conclusions: Increased shear force causes articular cartilage degeneration and osteoclast activation in the subchondral bone. In contrast, increased compressive stress promotes bone formation in the subchondral bone earlier than articular cartilage degeneration occurs.

Effect of Suppression of Rotational Joint Instability on Cartilage and Meniscus Degeneration in Mouse Osteoarthritis Model

Objective: Joint instability and meniscal dysfunction contribute to the onset and progression of knee osteoarthritis (OA). In the destabilization of the medial meniscus (DMM) model, secondary OA occurs due to the rotational instability and increases compressive stress resulting from the meniscal dysfunction. We created a new controlled abnormal tibial rotation (CATR) model that reduces the rotational instability that occurs in the DMM model. So, we aimed to investigate whether rotational instability affects articular cartilage degeneration using the DMM and CATR models, as confirmed using histology and immunohistochemistry. Design: Twelve-week-old male mice were randomized into 3 groups: DMM group, CATR group, and INTACT group (right knee of the DMM group). After 8 and 12 weeks, we performed the tibial rotational test, safranin-O/fast green staining, and immunohistochemical staining for TNF-α and MMP-13. Results: The rotational instability in the DMM group was significantly higher than that of the other groups. And articular cartilage degeneration was higher in the DMM group than in the other groups. However, meniscal degeneration was observed in both DMM and CATR groups. The TNF-α and MMP-13 positive cell rates in the articular cartilage of the CATR group were lower than those in the DMM group. Conclusions: We found that the articular cartilage degeneration was effectively suppressed by controlling the rotational instability caused by meniscal dysfunction. These findings suggest that suppression of rotational instability in the knee joint is an effective therapeutic measure for preventing OA progression.