Wear is an important factor in the long term success of total knee arthroplasty. Therefore, wear testing methods and machines become a standard in research and implant development. These methods are based on two simulation concepts which are defined in standards ISO 14243-1 and 14243-3. The difference in both concepts is the control mode. One is force controlled while the other has a displacement controlled concept. The aim of this study was to compare the
The meniscus is a fibrocartilaginous tissue that plays an important role in controlling the complex biomechanics of the knee. Many histological and mechanical studies about meniscal attachment have been carried out, and medial meniscus (MM) root repair is recommended to prevent subsequent cartilage degeneration following MM posterior root tear. However, there are only few studies about the differences between meniscus root and horn cells. The goal of this study was to clarify the differences between these two cells. Tissue samples were obtained from the medial knee compartments of 10 patients with osteoarthritis who underwent total knee arthroplasty. Morphology, distribution, and proliferation of MM root and horn cells, as well as gene and protein expression levels of Sry-type HMG box (SOX) 9 and type II collagen (COL2A1) were determined after cyclic tensile strain (CTS) treatment. Horn cells had a triangular morphology, whereas root cells were fibroblast-like. The number of horn cells positive for SOX9 and COL2A1 was considerably higher than that of root cells. Although root and horn cells showed similar levels of proliferation after 48, 72, or 96 h of culture, more horn cells than root cells were lost following 2-h CTS (5% and 10% strain). SOX9 and COL2A1 mRNA expression levels were significantly enhanced in horn cells compared with those in root cells after 2- and 4-h CTS (5%) treatment. This study demonstrates that MM root and horn cells have distinct characteristics and show different cellular phenotypes. Our results suggest that physiological tensile strain is important for activating extracellular matrix production in horn cells. Restoring physiological
Military personnel operating on high speed marine craft are exposed to Whole-Body Vibration (WBV). Additionally planing craft operate at speeds with minimal contact of the hull with warer making the crew vulnerable to mechanical shock. An association between Low Back Pain (LBP) and exposure to WBV has been extensively reported in civilian literature. LBP is reported by military personnel operating on planing craft leading to downgrades and potential discharge. There is a clear need to understand the impact prolonged exposure has on our population operating these craft. We performed a bibliographical search of the PubMed database for records using a combination of keywords. Abstracts were screened for relevance and references cited in retrieved papers reviewed. There is no consensus in the literature on the potentially pivotal pathological process behind the association. Evidence from professional driving suggests current safe operating exposure levels require review to protect against long-term damage however with little evidence concerning the unique environment in which boats crews operate, the parity of these environments require investigation to allow direct comparison. Due to the prevalence of LBP in this population a need exists to establish the pathological process and add to the evidence base driving safe operating exposure levels.
Introduction. Mechanical loading has been hypothesized to play an important role in the development, remodeling and in diseases of many skeletal tissues, including cartilage. In order to study the metabolic response of cartilage to physical forces, in vitro systems have often been used because of the precise control with which mechanical loads can be applied. We developed a new mechanical loading system, in which we were able to load the intact femoral condyle in order to preserve the native cartilage/subchondral bone structure. This system represents a more ‚in vivo‘ situation than cartilage explants or chondrocyte cell culture systems. Our approach focused on changes in mRNA expression of type II collagen, type VI collagen, and aggrecan in loaded versus adjacent unloaded cartilage in order to analyse the early response of chondrocytes to well-defined
A recently developed parametric geometrical finite element model (p-FEM) was adapted to the specific hip geometric measurements of a group of patients with slipped capital femoral epiphysis (SCFE). The objective was to analyze the stress distribution in the growth plate of these patients and to evaluate differences for those patients who developed bilateral disease. Different geometric parameters were measured in the healthy proximal femur of 18 adolescents (mean age, 12,1 yr) with unilateral SCFE and in 23 adolescents matched in age without hip disease (control group). Five patients developed SCFE in the contralateral side during follow-up. Different geometric measurements were taken from hip conventional X-ray studies. The p-FEM of the proximal femur permits modifications of different geometrical parameters, therefore the X-ray measurements taken from each patient were applied to the model obtaining a subject-specific model for each case. In each model, different mechanical situations such as walking, stairs climbing and sitting were simulated by applying loads on the femoral head corresponding to each own weight. The risk for growth plate failure was estimated by the Tresca, von Misses and Rankine stresses. In summary, the models shows important differences between the stresses computed at the healthy femurs of patients with unilateral SCFE and femurs that further underwent bilateral SCFE. So, the 95% confidence interval of the percentage of volume of the growth plate subjected to stresses higher than 2MPa was almost similar for the control group and patients with unilateral SCFE. However, those patients who developed bilateral disease had statistically significant large physeal areas with more than 2.0 MPa (p<
0.005). Stresses were also strongly dependent on the geometry of the proximal femur, especially on the posterior sloping angle of the physis and the physeal sloping angle. In spite of simplifications of the developed p-FEM, this tool has been able to show the influence of femur geometry in growth plate stresses and to predict the sites where growth plate starts to fail.
Abstract. Source of Study: London, United Kingdom. This intervention study was conducted to assess two developing protocols for quadriceps and hamstring rehabilitation: Blood Flow Restriction (BFR) and Neuromuscular Electrical Stimulation Training (NMES). BFR involves the application of an external compression cuff to the proximal thigh. In NMES training a portable electrical stimulation unit is connected to the limb via 4 electrodes. In both training modalities, following device application, a standardised set of exercises were performed by all participants. BFR and NMES have been developed to assist with rehabilitation following lower limb trauma and surgery. They offer an alternative for individuals who are unable to tolerate the high
Low back pain is the single most common cause for disability in individuals aged 45 years or younger, it carries tremendous weight in socioeconomic considerations. Degenerative aging of the structural components of the spine can be associated with genetic aspects, lifetime of tissue exposure to
Varus malalignment increases the susceptibility of cartilage to mechanical overloading, which stimulates catabolic metabolism to break down the extracellular matrix and lead to osteoarthritis (OA). The altered mechanical axis from the hip, knee to ankle leads to knee joint pain and ensuing cartilage wear and deterioration, which impact millions of the aged population. Stabilization of the remaining damaged cartilage, and prevention of further deterioration, could provide immense clinical utility and prolong joint function. Our previous work showed that high tibial osteotomy (HTO) could shift the
Hip instability is one of the most common complications after total hip arthroplasty (THA). Among the possible techniques to treat and prevent hip dislocation, the use of constrained liners is a well-established option. However, there is concern regarding the longevity of these devices due to higher
Biomechanical analysis is important to evaluate the effect of orthopaedic surgeries. CT-image based finite element method (CT-FEM) is one of the most important techniques in the computational biomechanics field. We have been applied CT-FEM to evaluate resorptive bone remodeling, secondary to stress shielding, after total hip arthroplasty (THA). We compared the equivalent stress and strain energy density to postoperative BMD (bone mineral density) change in the femur after THA, and a significant correlation was observed between the rate of changes in BMD after THA and equivalent stress. For periacetabular osteotomy cases, we investigated
Introduction. The low-contact stress (LCS) knee prosthesis is a mobile-bearing design with modifications to the tibial component that allow for meniscal-bearing (MB) or rotating-platform (RP). The MB design had nonconstrained anteroposterior and rotational movement, and the RP design has only nonconstrained rotational movement. The anterior soft tissues, including patellar tendon (PT), prevent anterior dislocation of the MB. The PT may consistently be exposed to overstressing. Therefore, we hypothesized that the PT thickness and width in MB prosthesis revealed more morphological changes than those of RP prosthesis due to degeneration of the PT induced by much
Introduction and Objective. Anterior cruciate ligament reconstruction (ACLR) with tendon autografts is the “gold standard” technique for surgical treatment of ACL injuries. Common tendon graft choices include patellar tendon (PT), semitendinosus/gracilis “hamstring” tendon (HT), or quadriceps tendon (QT). Healing of the graft after ACLR may be affected by graft type since the tissue is subjected to
Background. Medical applications of nanotechnology are promising because it allows the surface of biomaterial to be tailored to optimise the interfacial interaction between the biomaterial and its biological environment. Such interfaces are of interest in the domain of orthopaedic surgery as they could have anti-bacterial functions or could be used as drug delivery systems. The development of orthopaedics is moving towards better integration of biology in implants and surgical techniques, but the mechanical properties of implanted materials are still important for orthopaedic applications. During clinical implantation, implants are subjected to large
Introduction: Two second generation highly crosslinked UHMWPEs have been cleared by the FDA for clinical use in the United States: sequentially crosslinked UHMWPE (X3™ UHMWPE, Stryker Inc., Mahwah, NJ, USA) and α-tocopherol stabilized UHMWPE (E-Poly™ UHMWPE, Biomet, Inc., Warsaw, IN, USA). Both have been shown to be oxidatively stable under standardized aging methods (ASTM F2003); however, these conventional aging methods did not consider the effect of mechanical loading on the oxidative behavior of the materials. By coupling the adverse effects of thermal aging and
The structure and extracellular matrix composition of the interface are complex and allow for a gradual
In recent years, novel therapies for intervertebral disc (IVD) regeneration have been developed that are based on the delivery of cells, biomaterials or bioactive molecules. The efficacy of these biological therapies depends on the type and degree of IVD degeneration. Whole organ culture bioreactors provide an attractive platform for pre-clinical testing of IVD therapeutics, since the cells are maintained within their native extracellular matrix, and the endplate remains intact to fulfil its function. Moreover, defined regimes of
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Introduction: In a photoelasticimetric model Ondrouch suggested a correlation between stress in arthritic joints, microfractures and bone cysts. Other authors believe in a causative role of access of joint ßuid to bone in periarticular osteolysis. In our opinion
Anterior cruciate ligament (ACL) reconstruction is the current standard of care for ACL tears. However, the results are not consistently successful, autografts or allografts have certain disadvantages, and synthetic grafts have had poor clinical results. The aim of this study was to determine the efficacy of tissue engineering decellularized tibialis tendons by recellularization and culture in a dynamic tissue bioreactor. To determine if recellularization of decellularized tendons combined with mechanical stimulation in a bioreactor could replicate the mechanical properties of the native ACL and be successfully used for ACL reconstruction in vivo. Porcine tibialis tendons were decellularized and then recellularized with human adult bone marrow-derived stem cells. Tendons were cultured in a tissue bioreactor that provided biaxial cyclic loading for up to 7 days. To reproduce
The amount of bone loss due to implant failure, loosening, or osteolysis can vary greatly and can have a major impact on reconstructive options during revision total knee arthroplasty (TKA). Massive bone loss can threaten ligamentous attachments in the vicinity of the knee and may require use of components with additional constraint to compensate for associated ligamentous instability. Classification of bone defects can be helpful in predicting the complexity of the reconstruction required and in facilitating preoperative planning and implant selection. One very helpful classification of bone loss associated with TKA is the Anderson Orthopaedic Research Institute (AORI) Bone Defect Classification System as it provides the means to compare the location and extent of femoral and tibial bone loss encountered during revision surgery. In general, the higher grade defects (Type IIb or III) on both the femoral and tibial sides are more likely to require stemmed components, and may require the use of either structural graft or large augments to restore support for currently available modular revision components. Custom prostheses were previously utilised for massive defects of this sort, but more recently have been supplanted by revision TKA component systems with or without special metal augments or structural allograft. Options for bone defect management are: 1) Fill with cement; 2) Fill with cement supplemented by screws or K-wires; 3) Morselised bone grafting (for smaller, especially contained cavitary defects); 4) Small segment structural bone graft; 5) Impaction grafting; 6) Porous metal cones or sleeves 7) Massive structural allograft-prosthetic composites; 8) Custom implants. Of these, use of uncemented highly porous metal metaphyseal cones in combination with an initial cemented or partially cemented implant has been shown to provide versatile and highly durable results for a range of bone defects including those previously requiring structural bone graft. The hybrid fixation combination of both cement and cementless fixation of an individual tibial or femoral component has emerged as a frequent and often preferred technique. Initial secure and motionless interfaces are provided by the cemented portions of the construct, while subsequent bone ingrowth to the cementless porous metal portions is the key to long term stable fixation. As bone grows into the porous portions there is off loading and protection of the cemented interfaces from