We investigated the effects of a Tankyrase (TNKS-1/2) inhibitor on mechanical stress-induced gene expression in human chondrocytes and examined TNKS-1/2 expression in human osteoarthritis (OA) cartilage. Cells were seeded onto stretch chambers and incubated with or without a TNKS-1/2 inhibitor (XAV939) for 12 h. Uni-axial cyclic tensile strain (CTS) (0.5 Hz, 8% elongation, 30 min) was applied and the gene expression of type II collagen a1 chain (COL2A1), aggrecan (ACAN), SRY-box9 (SOX9), TNKS-1/2, a disintegrin and metalloproteinase with thrombospondin motifs-5 (ADAMTS-5), and matrix metalloproteinase-13 (MMP-13) were examined by real-time PCR. The expression of ADAMTS-5, MMP-13, nuclear translocation of nuclear factor-κB (NF-κB), and β-catenin were examined by immunocytochemistry and Western blotting. The concentration of IL-1β in the supernatant was examined by enzyme-linked immunosorbent assay (ELISA). TNKS-1/2 expression was assessed by immunohistochemistry in human OA cartilage obtained at the total knee arthroplasty. TNKS-1/2 expression was increased after CTS. The expression of anabolic factors were decreased by CTS, however, these declines were abrogated by XAV939. XAV939 suppressed the CTS-induced expression of catabolic factors, the release of IL-1β, as well as the nuclear translocation of NF-κB and β-catenin. TNKS-1/2 expression increased in mild and moderate OA cartilage. Our results demonstrated that XAV939 suppressed mechanical stress-induced expression of catabolic proteases by the inhibition of NF-κB and activation of β-catenin, indicating that TNKS-1/2 expression might be associated with OA pathogenesis.

We investigated the roles of low-density lipoprotein receptor-related protein (LRP) 4 and its ligand Agrin in the pathophysiology of cartilage degeneration. Immunohistochemical analysis of human normal articular cartilage and cartilage tissues from patients with osteoarthritis (OA) obtained during surgery of the knee joint showed marked LRP4 expression in the early stages of OA, which then decreased with cartilage degeneration, whereas Agrin was consistently increased with cartilage degeneration. In normal human articular chondrocytes (NHACs), mild cyclic tensile strain (CTS) (0.5 Hz, 5% elongation, 2 h) increased the expression of LRP4 and aggrecan (ACAN), while intense CTS (0.5 Hz, 10% elongation, 6 h) increased the expression of Agrin without affecting LRP4 expression. Treatment with recombinant human (rh) Agrin downregulated the mRNA expression of LRP4 and ACAN, but upregulated the expression of LRP5/6, SRY-box transcription factor 9 (SOX9), Runt-related transcription factor 2 (RUNX2), and a disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS-4). Immunocytochemistry and Western blot analysis showed that rhAgrin treatment upregulated the expression of β-catenin and SOX9. Agrin knockdown by siAGRN transfection partially reduced the nuclear protein expression of β-catenin, which was increased with intense CTS. LRP4 knockdown by siLRP4 transfection increased the expression of LRP5/6, SOX9, RUNX2, ADAMTS-4, and Agrin. These results suggested that intense CTS increases the expression of Agrin, which might interfere with the role of LRP4 in the inhibition of LRP5/6 and their downstream β-catenin signaling, leading to cartilage degeneration.

Background/Objectives: Launched in Japan in 2022, ozoralizumab (OZR) is a novel, anti-tumour necrosis factor (TNF)-α inhibitor for treating rheumatoid arthritis (RA) that is refractory to conventional therapies. However, there is a lack of evidence regarding its perioperative management. Methods: This retrospective case series included nine patients with RA who underwent a total of 12 either RA-related (n = 9) or unrelated (n = 3) orthopaedic procedures. We reviewed patient demographics, surgical procedures, perioperative OZR discontinuation periods, and postoperative complications. Results: The mean preoperative OZR discontinuation period was 15.8 days (range, 2–25 days). Sutures were removed at a mean of 12.8 days postoperatively (range, 11–14 days) after adequate wound healing had been confirmed. The mean total discontinuation period was 34.9 days (range, 27–43 days). No cases of surgical site infection (SSI) or delayed wound healing (DWH) were observed during a minimum follow-up period of three months. One patient experienced a disease flare before OZR was restarted. Conclusions: Preoperative OZR discontinuation for up to four weeks appeared to be safe in this cohort. These findings may assist orthopaedic surgeons in determining an appropriate perioperative discontinuation strategy for OZR that minimises SSI and DWH risk while reducing the likelihood of RA flare.

Purpose: Fragility fractures of the pelvis (FFP) classified as Rommens-Hoffman type IVb are associated with spinopelvic dissociation and are generally considered to require surgical intervention. This study aimed to clarify the localization patterns of FFP type IVb and compare the biomechanical stability of different internal fixation techniques. Methods: In this retrospective study, morphologic mapping of sacral fracture lines was performed in 36 patients with FFP type IVb. Based on the mapping results, a finite element (FE) model of FFP type IVb was developed to evaluate the biomechanical stability of ilio-sacral screw (ISS) fixation, trans-sacral screw (TSS) fixation, spinopelvic fixation (SPF; On each side, L5 pedicle screw was connected to two iliac screws with a rod, and the bilateral constructs were linked using a cross-connector.), and bilateral triangular fixation (one TSS at S1 combined with SPF mentioned above) using finite element analysis (FEA). Results: Morphologic mapping showed that the sacrum fracture transverse line tended to pass between the S1-2 transverse lines. Although bilateral triangular fixation and SPF provided the highest stability in both U-type and H-type fractures, a TSS for U-type and two TSSs for H-type also demonstrated comparable levels of stability. ISS-based methods showed greater displacements. Conclusion: TSS-based fixation may provide stability comparable to bilateral triangular fixation and SPF in FFP type IVb, with less invasiveness when anatomy permits. Further studies are needed to optimize treatment strategies for this complex injury.