Journal of Orthopaedic Research : Official Publication of the Orthopaedic Research Society

Although the Achilles tendon is the largest and strongest tendon in the body, healing of the Achilles tendon is the most common injury, and this process is difficult due to poor tendon circulation; moreover, the underlying mechanism has not been fully elucidated. In our study, we aimed to investigate the effects of pentoxifylline and alpha-tocopherol administered separately or in combination on rats with Achilles tendon injury. Forty-eight male Wistar rats weighing 230 ± 30 g were used in the study...

The study aimed to examine matrix metalloproteinase-2 (MMP-2) expression in a rat ligamentum flavum (LF) hypertrophy model in vivo, and the effect of elastin-derived peptides (EDPs) on MMP-2 and tissue inhibitors of metalloproteinases (TIMPs) in rat LF cells in vitro. Surgical destabilization was performed at the rat spinal L3/4 level to induce increased mechanical stress. Rats were killed at 6- and 12-weeks postsurgery for histological staining, immunohistochemical staining, RT-qPCR and western blot. 100 µg/mL EDPs were applied to isolated normal rat LF cells, with or without pretreatment of elastin receptor complex (ERC) inhibitors, to assess the expression of MMP-2, TIMP-1, and TIMP-2...

Segmental bone defects, often clinically treated with nondegradable poly(methylmethacrylate) (PMMA) in multistage surgeries, present a significant clinical challenge. Our study investigated the efficacy of 3D printed biodegradable polycaprolactone fumarate (PCLF)/PCL spacers in a one-stage surgical intervention for these defects, focusing on early bone regeneration influenced by spacer porosities. We compared nonporous PCLF/PCL and PMMA spacers, conventionally molded into cylinders, with porous PCLF/PCL spacers, 3D printed to structurally mimic segmental defects in rat femurs for a 4-week implantation study...

Osteoarthritis (OA) is a common degenerative joint disease, and subchondral osteosclerosis is an important pathological change that occurs in its late stages. Cardamonin (CD) is a natural flavonoid isolated from Alpinia katsumadai that has anti-inflammatory activity. The objectives of this study were to investigate the therapeutic effects and potential mechanism of CD in regulating OA subchondral osteosclerosis at in vivo and in vitro settings. Eight-week-old male C57BL/6J mice were randomly divided into four groups: sham operation, anterior cruciate ligament transection (ACLT)-induced OA model, low-dose and high-dose CD treated ACLT-OA model groups...

Porous metallic prosthesis components can now be manufactured using additive manufacturing techniques, and may prove beneficial for promoting bony ingrowth, for accommodating drug delivery systems, and for reducing stress shielding. Using finite element modeling techniques, 36 scenarios (three porous stems, three bone densities, and four held arm positions) were analysed to assess the viability of porous humeral stems for use in total shoulder arthroplasty, and their resulting mechanobiological impact on the surrounding humerus bone...

Limb lengthening relies on the process of distraction osteogenesis. The active periosteal bone formation has been detected in clinical practice with a lengthening and then nail (LATN) technique but has not been confirmed by experimental studies to date. The aim of this study is to compare the tissue regeneration of the distraction regenerate during tibial lengthening in rabbits using a LATN technique. This study was performed on 54 mature rabbits of the Soviet Chinchilla breed, which were divided into three groups of 18 animals...

Pannexin 3 (Panx3) is a glycoprotein that forms mechanosensitive channels expressed in chondrocytes and annulus fibrosus cells of the intervertebral disc (IVD). Evidence suggests Panx3 plays contrasting roles in traumatic versus aging osteoarthritis (OA) and intervertebral disc degeneration (IDD). However, whether its deletion influences the response of joint tissue to forced use is unknown. The purpose of this study was to determine if Panx3 deletion in mice causes increased knee joint OA and IDD after forced treadmill running...

The mechanical resilience of the knee meniscus is provided by a group of structural proteins in the extracellular matrix. Aging can alter the quantity and molecular structure of these proteins making the meniscus more susceptible to debilitating tears. In this study, we determined the effect of aging on the quantity of structural proteins and collagen crosslinks in human lateral meniscus, and examined whether the quantity of these molecules was predictive of tensile toughness (area under the stress-strain curve)...

In large animal studies, the mechanical reintegration of the bone fragments is measured using postmortem physical testing, but these assessments can only be performed once, after sacrifice. Image-based virtual mechanical testing is an attractive alternative because it could be used to monitor healing longitudinally. However, the procedures and software required to perform finite element analysis (FEA) on subject-specific models for virtual mechanical testing can be time consuming and costly. Accordingly, the goal of this study was to determine whether a simpler image-based geometric measure-the torsion constant, sometimes known as polar moment of inertia-can be reliably used as a surrogate measure of bone healing in large animals...

In carpometacarpal osteoarthritis (CMC OA) of the thumb, to what extent treatments should be directed by radiographic disease severity versus pain-based indicators remains an open question. To address this gap, this study investigated the relative impact of disease severity and pain severity on the range of motion in participants with CMC OA. We hypothesized larger differences would exist between extremes in the pain severity cohort than the disease severity cohort, suggesting pain modulates movement to a greater extent than joint degradation...

The shape of the talus, its internal structure, and its mechanical properties are important in determining talar behavior during loading, which may be significant for the design of surgical tools and implants. Although recent studies using statistical shape modeling have described quantitative talar external shape variation, no similar quantitative study exists to describe the density distribution of internal talar structure. The goal of this study is to quantify statistical variation in talar shape and density to benefit the design of talar implants...

Measuring the healing status of a bone fracture is important to determine the clinical care a patient receives. Implantable devices can directly and continuously assess the healing status of fracture fixation constructs, while subject-specific virtual biomechanical tests can noninvasively determine callus structural integrity at single time points. Despite their potential for objectification, both methods are not yet integrated into clinical practice with further evidence of their benefits required. This study correlated continuous data from an implantable sensor assessing healing status through implant load monitoring with computer tomography (CT) based longitudinal finite element (FE) simulations in a large animal model...

Lateral platform collapse in fixations of lateral tibial plateau fractures (TPFs) using either double-lag screws fixation (DSF) or locking-plate fixation (LPF) is not rare. This study aimed to explore the effect of enhancing the interfragmentary compression force (IFCF) on fixation stability in lateral TPFs in normal and osteoporotic bones using finite element analysis. Finite element models of DSF in normal bone and LPF in normal and osteoporotic bones were established to simulate the fixations of lateral TPF...

Substantial research on complete Achilles tendon ruptures is available, but guidance on partial ruptures is comparatively sparse. Conservative management is considered acceptable in partial tendon ruptures affecting less than 50% of the tendon's width, but supporting experimental evidence is currently lacking. Using a previously validated finite element model of the Achilles tendon, this study aimed to assess whether loading conditions simulating an early functional rehabilitation protocol could elicit progression to a complete rupture in partial ruptures of varying severity...

In unstable shoulders, excessive anteroinferior position of the humeral head relative to the glenoid can lead to a dislocation. Measuring humeral head position could therefore be valuable in quantifying shoulder laxity. The aim of this study was to measure (1) position of the humeral head relative to the glenoid and (2) joint space thickness during passive motion in unstable shoulders caused by traumatic anterior dislocations and in contralateral uninjured shoulders. A prospective cross-sectional CT-study was performed in patients with unilateral anterior shoulder instability...

Established risk factors for osteoarthritis (OA) include obesity, joint injury, age, race, and genetics. However, the relationship between cigarette smoking and OA has yet to be established. In the present study, we have employed the use of cigarette smoke extract (CSE), the water-soluble vapor phase of cigarette smoke, with porcine cartilage explants to investigate the effects of cigarette smoking on cartilage catabolism at the tissue level. Articular cartilage explants were first exposed to 2.5%, 5%, and 10% CSE to assess its effects on cartilage homeostasis...

The need for additional fibular osteotomy (FO) when performing supramalleolar osteotomy (SMO) in the varus ankle arthritis (VAA) is controversial. Some cadaveric studies have been performed to prove this; however, it is difficult to implement deformities including talar tilting and translation in cadavers. In this study, we created a model of VAA with the tilting and translation using three-dimensional (3-D) finite element (FE) analysis and analyzed the results of SMO with or without FO depending on the types of VAA...

The aim of the present study was to investigate the association between chondrogenic differentiation and Wnt signal expression in the degenerative process of the human meniscus. Menisci were obtained from patients with and without knee osteoarthritis (OA), and degeneration was histologically assessed using a grading system. Immunohistochemistry, real-time polymerase chain reaction (PCR), and Western blot analysis were performed to examine the expressions of chondrogenic markers and of the components of Wnt signaling...

Large osteochondral defects are a major challenge in orthopedics, for which osteochondral allograft (OCA) transplantation is nowadays considered as an option, especially in young patients. However, a major issue with OCA is the need for graft storage, which ensures adequate cartilage integrity over time. The aim of this study was to test how long a Ringer-based storage solution can provide good graft quality after explantation and thus meet the requirements for OCA. For this purpose, human osteochondral allografts of the knee and ankle were analyzed...

The ideal cell source for articular cartilage repair remains elusive. Using developmentally inspired differentiation protocols, we induced human pluripotent stem cells (hPSCs) toward articular chondrocytes capable of joint cartilage repair in rodent models, which were distinct from growth plate chondrocytes, fated to be replaced by bone in vivo. Working toward clinical translation, we demonstrated controlled differentiation into chondrocytes by comprehensive gene expression analysis at each step of the differentiation...