Journal of Orthopaedic Research®最新文献

The field of bone regeneration has primarily focused on investigating fracture healing and nonunion in isolated musculoskeletal injuries. Compared to isolated fractures, which frequently heal well, fractures in patients with multiple bodily injuries (polytrauma) may exhibit impaired healing. While some papers have reported the overall cytokine response to polytrauma conditions, significant gaps in our understanding remain in how fractures heal differently in polytrauma patients. We aimed to characterize fracture healing and the temporal local and systemic immune responses to polytrauma in a murine model of polytrauma composed of a femur fracture combined with isolated chest trauma. We collected serum, bone marrow from the uninjured limb, femur fracture tissue, and lung tissue over 3 weeks to study the local and systemic immune responses and cytokine expression after injury. Immune cell distribution was assessed by flow cytometry. Fracture healing was characterized using microcomputed tomography (microCT), histological staining, immunohistochemistry, mechanical testing, and small angle X-ray scattering. We detected more innate immune cells in the polytrauma group, both locally at the fracture site and systemically, compared to other groups. The percentage of B and T cells was dramatically reduced in the polytrauma group 6 h after injury and remained low throughout the study duration. Fracture healing in the polytrauma group was impaired, evidenced by the formation of a poorly mineralized and dysregulated fracture callus. Our data confirm the early, dysregulated inflammatory state in polytrauma that correlates with disorganized and impaired fracture healing.

A major barrier that hampers our understanding of the precise anatomic distribution of pain sensing nerves in and around the joint is the limited view obtained from traditional two dimensional (D) histological approaches. Therefore, our objective was to develop a workflow that allows examination of the innervation of the intact mouse knee joint in 3D by employing clearing-enabled light sheet microscopy. We first surveyed existing clearing protocols (SUMIC, PEGASOS, and DISCO) to determine their ability to clear the whole mouse knee joint, and discovered that a DISCO protocol provided the optimal transparency for light sheet microscopy imaging. We then modified the DISCO protocol to enhance binding and penetration of antibodies used for labeling nerves. Using the pan-neuronal PGP9.5 antibody, our protocol allowed 3D visualization of innervation in and around the mouse knee joint. We then implemented the workflow in mice intra-articularly injected with nerve growth factor (NGF) to determine whether changes in the nerve density can be observed. Both 3D and 2D analytical approaches of the light sheet microscopy images demonstrated quantifiable changes in midjoint nerve density following 4 weeks of NGF injection in the medial but not in the lateral joint compartment. We provide, for the first time, a comprehensive workflow that allows detailed and quantifiable examination of mouse knee joint innervation in 3D.

Aseptic loosening remains one of the top causes of revision surgery of total knee arthroplasty (TKA). Radiostereometric analysis (RSA) is used in research to measure implant migration, however limitations prevent its clinical use. New methods have allowed the same measurements as RSA to be performed with computed tomography (CT) scanners (CT-RSA). The objective of this study is to determine inducible displacement measurements from weight-bearing computed tomography (WBCT) and conventional RSA to assess implant stability. Participants (n = 17) completed RSA exams in the supine and standing position, and WBCT exams in the seated (leg extended) and standing position. Double examinations were performed in the seated (WBCT) or supine (RSA) positions. Inducible displacements were measured with model-based RSA (MBRSA) for RSA exams, and a novel CT-RSA software, V3MA, for WBCT exams. Precision of each technique was calculated between double examinations. Precision data for tibial component total translations and rotations were 0.05 mm and 0.118°, respectively with WBCT-RSA, and were 0.108 mm and 0.269°, respectively with MBRSA. MTPM precision was 0.141 mm with WBCT-RSA and was 0.168 mm with MBRSA. Inducible displacement MTPM of the tibial component was 0.244 ± 0.220 mm with WBCT-RSA and 0.662 ± 0.257 mm with MBRSA. Inducible displacement measurements with MBRSA were significantly different from WBCT-RSA for tibial component anterior tilt (p = 0.0002). WBCT-RSA demonstrated comparable precision to MBRSA, and both techniques measured inducible displacements consistent with stable components. Clinical Significance: As the availability of WBCT increases, its use as an alternative to MBRSA is supported to measure the instantaneous fixation of implant components.

Diclofenac etalhyaluronate (DF-HA) sustained diclofenac release with the effects of hyaluronic acid (HA), offering long-term analgesia in osteoarthritis. In this study, the effects of DF-HA on pain improvement and osteoarthritis were evaluated in a rat knee monoiodoacetate-induced osteoarthritis model compared to HA. Eight rats per group had been injected with monoiodoacetate (2.0 mg) or saline in the right knee for 4 weeks and were injected with either DF-HA (1.25 mg/kg; 0.5 mg), HA (0.5 mg), vehicle which was a substrate without DF-HA (50 μL), or saline and followed for 4 weeks. Mechanical plantar skin sensitivity was assessed weekly using the von Frey assay. Osteoarthritis changes were monitored with Larsen scores via CT imaging at every 2 weeks. The articular cartilage was analyzed using OARSI scores through H&E, Safranin-O staining at 8 weeks. The percentage of Iba-1 positive microglia in the spinal dorsal horn and of FG + CGRP-labeled cells among FG-positive cells in the dorsal root ganglion were evaluated by immunohistochemical staining. TNF-α and IL-6 mRNA expression levels in the knee synovium were evaluated by PCR. The DF-HA showed significantly improved pain hypersensitivity compared with the HA at 6–8 weeks. The percentage of Iba-1-positive microglia was significantly lower than that in the vehicle and the percentage of FG + CGRP/FG was significantly lower than that in the HA. OARSI scores did not differ among treatment groups, Larsen scores indicated lower in the DF-HA than in the vehicle. DF-HA was as effective as HA in joint protection and significantly improved inflammatory pain compared to HA.

Bone fracture healing is a complex physiological process influenced by biomechanical and biomolecular factors. Mechanical stability is crucial for successful healing, and disruptions can lead to delayed healing or nonunion. Bone commonly heals itself through secondary fracture healing, which is governed by the mechanical strain at the fracture site. To investigate these phenomena, a validated methodology for capturing the mechanoregulatory process in specimen-specific models of fracture healing could provide insight into the healing process. This study implemented a prognostic healing simulation framework to predict healing trajectories based on mechanical stimuli. Sixteen sheep were subjected to a 3 mm transverse tibial mid-shaft osteotomy, stabilized with a custom plate, and equipped with displacement transducer sensors to measure interfragmentary motion over 8 weeks. Computed tomography scans were used to create specimen-specific bone geometries for finite element analysis. Virtual mechanical testing was performed iteratively to calculate strains in the callus region, which guided tissue differentiation and consequently, healing. The predicted healing outcomes were compared to continuous in vivo sensor data, providing a unique validation data set. Healing times derived from the in vivo sensor and in silico sensor showed no significant differences, suggesting the potential for these predictive models to inform clinical assessments and improve nonunion risk evaluations. This study represents a crucial step towards establishing trustworthy computational models of bone healing and translating these to the preclinical and clinical setting, enhancing our understanding of fracture healing mechanisms.

Clinical significance: Prognostic bone fracture healing simulation could assist in non-union diagnosis and prediction.

The low friction nature of articular cartilage has been attributed to the synergistic interaction between lubricin and hyaluronic acid in the synovial fluid (SF). Lubricin is a mucinous glycoprotein that lowers the boundary mode coefficient of friction of articular cartilage in a dose-dependent manner. While there have been multiple attempts to produce recombinant lubricin and lubricin mimetic cartilage lubricants over the last two decades, these materials have not found clinical use due to challenges associated with large scale production, manufacturing, and purification. Recently, a novel method using codon scrambling was developed to produce a stable, full-length bioengineered equine lubricin (eLub) in large reproducible quantities. While preliminary frictional analysis of eLub and other recombinantly produced forms revealed they can lubricate cartilage, a complete tribological characterization is lacking, with previous studies evaluating the friction coefficient only at a single dose or a single speed. The objective of this study was to analyze the dose-dependent tribological properties of eLub using the Stribeck framework of tribological analysis. Recombinantly produced eLub at doses greater than 1.5 mg/mL exhibits friction coefficients on par with healthy bovine SF, and a maximal 5 mg/mL dose exhibits a nearly 50% lower friction coefficient than healthy SF. eLub also modulates the shift in lubrication mode of the cartilage from the high friction boundary mode to the low friction minimum mode at high concentrations.

Heterotopic ossification (HO) in Achilles tendon often arises due to endochondral ossification during the healing process following trauma. Retinoic acid receptor γ (RARγ) plays a critical role in this phenomenon. This study aims to elucidate the therapeutic effects of CD1530, an RARγ selective agonist, along with the contributing cells, in Achilles tendon healing, utilizing a cell lineage tracing system. Local injection of CD1530 facilitated histological tendon healing by inhibiting chondrification in a mouse Achilles rupture model. Resident Scleraxis (Scx)⁺ cells in Achilles tendon were not found to be actively involved in HO or　tendon healing following injury. Instead, these processes were primarily driven by tendon stem/progenitor cells (TSPC)-like cells. Furthermore, an in vitro assay revealed that CD1530 attenuated inflammation in injured Achilles tendon-derived tendon fibroblasts (iATF) and inhibited the chondrogenesis of iATF. This dual effect suggests the potential of CD1530 in effectively modulating the healing environment during tendon healing. Together, the present study demonstrated that the local administration of CD1530 accelerated tendon healing by modulating the healing environment, including reducing chondrification via targeting TSPC-like cells in a mouse Achilles tendon rupture model. These results suggest that CD1530 may have the potential to be a novel tendon therapy that offers benefits via the inhibition of chondrogenesis.