Análise da deformação na prótese femoral não cimentada do quadril pelo método de elementos finitos – Influência da variabilidade do posicionamento angular do implante

Resumo Objetivo Avaliar a influência da variação do posicionamento da prótese femoral do quadril na tensão e na deformação produzidas neste implante. Métodos Utilizou-se a análise de tensão e de deformação da prótese femoral (Taper, Víncula, Rio Claro, SP, Brasil) pelo método de elementos finitos (MEF) de acordo com a norma ISO 7206-6 Implants for surgery - Partial and total hip joint prostheses–Part 6: Endurance properties testing and performance requirements of neck region of stemmed femoral components. A análise propôs uma ramificação do ensaio físico, com variação da angulação de +/− 5° sobre a proposta normativa das variáveis α e β. Resultados Ao comparar com a deformação controle, houve significância estatística com a angulação isolada de +/− 5° do ângulo α, bem como com a associação de +/− 5° nas angulações α e β (p = 0,027 e 0,021, respectivamente). Já com a variação apenas do ângulo β, não houve variação significativa na deformação da prótese (p = 0,128). A posição da haste com maior deformação no implante foi com α = 5° e β = 14° (p = 0,032). Conclusão A variabilidade de posicionamento da haste femoral protética de +/− 5° no plano coronal e/ou a associação da angulação de +/− 5° nos planos coronal e sagital interferiu de forma significativa na deformação do implante.

Design of bionic active–passive hybrid-driven prosthesis based on gait analysis and simulation of compound control method

Purpose The purpose of this paper is to design a prosthetic limb that is close to the motion characteristics of the normal human ankle joint. Methods In this study, combined with gait experiments, based on a dynamic ankle joint prosthesis, an active–passive hybrid-driven prosthesis was designed. On this basis, a real-time control algorithm based on the feedforward compensation angle outer loop is proposed. To test the effectiveness of the control method, a multi-body dynamic model and a controller model of the prosthesis were established, and a co-simulation study was carried out. Results A real-time control algorithm based on the feedforward compensation angle outer loop can effectively realize the gait angle curve measured in the gait test, and the error is less than the threshold. The co-simulation result and the test result have a high close rate, which reflects the real-time nature of the control algorithm. The use of parallel springs can improve the energy efficiency of the prosthetic system. Conclusions Based on the motion characteristics of human ankle joint prostheses, this research has completed an effective and feasible design of active and passive ankle joint prostheses. The use of control algorithms improves the controllability of the active and passive ankle joint prostheses.

About biological hip joint prostheses and the biomechanical behavior of implanted femur

Biofidel femur Models with finite elements were developed using a specific segmentation combination with computed tomography and solid modeling tools capable of representing bone physiology and structural behavior. These biofidel Finite Element Models (FEM) are used to evaluate the change in the physiological distribution of stress in the prosthesis femur and to evaluate the new design criteria for biopsy biopsy biopsy biopsy. The proposed belief patterns allowed us to adequately take into account the non-isotropic features of the proximal femoral epiphysis and isotropic behavior in diaphysis to explain the critical changes in stress distribution in a femur resected after the implantation of a traditional articular prosthesis. It has been shown that a wide range of femoral diaphyses is completely protected by rigid prostheses that significantly alter the physiological distribution of stress, which should guarantee healthy growth and bone regeneration.

Combination of musculoskeletal and wear models to investigate the effect of daily living activities on wear of hip prostheses

Numerical wear predictions are gaining increasing interest in many engineering applications, as they allow to simulate complex operative conditions not easily replicable in the laboratory. As far as hip prostheses are concerned, most of the wear models in the literature are based on the simulation of gait (recommended also in experimental wear tests), since gait is considered the most frequent and important motor task to recover after arthroplasty. However, since joint prostheses have been increasingly implanted in younger people, high loads and potentially severe conditions, e.g. due to sporting activities, should also be considered for a more reliable wear assessment of these implants. In this study, we propose a profitable combination of musculoskeletal and analytical wear modelling for the prediction of wear caused by common daily activities in metal-on-plastic hip arthroplasties. Several motion analysis data available in the literature (walking, fast walking, lunge, squat, stair negotiation) were selected and the effects of such motor tasks on prosthesis wear were investigated, both separately and in combination. Additionally, for comparative purposes, wear prediction for simplified gait conditions prescribed by the ISO 14242 standard, were also considered. Results suggest that this latter case produces lower wear depth and volume with respect to a relatively demanding combination of the selected daily activities. The preliminary results of the present study represent a first step towards the auspicious goal of validating the proposed procedure for in silico trials of hip arthroplasties.

Rotation-hinged knee prosthesis for the treatment of Charcot arthropathy: a case report and literature review

Charcot arthropathy is a type of destructive osteoarthropathy characterized by neurotrophic and sensory disorders. The condition is relatively rare, with an insidious onset, and it is easily misdiagnosed. Total knee arthroplasty (TKA) can cause excessive joint wear, continuous inflammatory stimulation of the prosthesis, postoperative residual cavity, prosthesis loosening and subsidence, peripheral fracture, infection, and other complications. Furthermore, these complications are more likely to occur in patients with Charcot arthropathy because of disease-specific pathological characteristics, when TKA is performed. Therefore, Charcot arthropathy was once a contraindication to TKA. Recently, with the optimization of joint prostheses and the maturity of surgical techniques, more studies have reported successful cases of TKA in patients with Charcot arthropathy. We report a case of Charcot arthropathy in our hospital, and describe the patient’s medical history, clinical symptoms, signs, imaging findings, diagnosis, and the entire TKA process, to explore the TKA strategy and prosthesis selection in a patient with Charcot arthropathy.

A case report on a IV-degree thermal crush injury of right upper arm：The application of functional prosthesis implantation technology

Severe IV-degree thermal crush injury of limbs involved the subcutaneous fascia, muscle and bone, which may lead to amputation and has a great impact on the patient's quality of life. We can repair wounds with pedicle flaps or even free flaps, However, there are still huge challenges in bone defect of extremities and functional reconstruction. In recent years, with the development of functional prostheses, we have reconstructed limb functions in many patients helping them to complete their daily lives. We report a case where the right upper arm was injured by thermal crush, leading severe burns to the skin, fascia, muscle and bone. We applied a pedicled latissimus dorsi flap and a free anterolateral thigh flap to repair the wound, and realized the function of limb salvage and movement of the right upper arm by implanting 3D printed scapula, upper arm and elbow joint prostheses. This case illustrates that IV-degree burns involving bones have new technologies to repair and achieve mobility now.

Traumatic Dorsal Hand Reconstruction through A free Anterolateral Thigh Flap, Induced Membrane Technique, Toe Joint Transfer, and Joint Prosthesis

Introduction:This study presents a case of post-traumatic dorsal hand reconstruction by describing the surgical technique in several stages and the outcome. Case report:It involves a patient with loss of cutaneous tissue, loss of bone, and tendon in the dorsal hand and fingers following a car accident. He was treated on a four-stage hand salvage and reconstruction. Stage one fulfilled in emergency involved K-wire and osseous filling through acrylic cement, hunter tendon rods, and a free anterolateral thigh flap. The second stage at 2 months involved osseous grafts and finger joint prostheses. The third stage time at 7 months involved a toe joint transfer. The last stage at 11 months involved extensor tendons graft reconstruction. The functional outcome at 2 years is acceptable. Conclusion:The post-traumatic dorsal hand reconstruction requires several techniques to reconstruct the losses of substances observed and this in several stages. It allowed to have an acceptable hand function. Keywords:Hand injuries, induced membrane, finger joint prosthesis, tendon transfer.

Rheological Properties and Its Effect on the Lubrication Mechanism of PVP K30 and PVP 40-50 G as Artificial Synovial Fluids

The effect of polyvinylpyrrolidone (PVP) on the rheological properties of joint prostheses is still unclear, despite its good lubricity and biocompatibility. In the present work, PVP K30 and PVP 40-50 G solutions at different concentrations were analyzed for rheological and lubrication properties. The rheological properties of the samples were measured at a shear rate range of 0–1800 s−1 (advanced air bearing rheometer Bohlin Gemini 2 and Plate MCR 72/92 rheometer for PVP30 and PVP 40-50 G, respectively). It was found that both the viscosity and shear stress of the samples reduced with a shear rate increase. PVP 40-50 G/sterile water showed higher viscosity as compared to the PVP K30/sterile water sample at a lower shear rate. However, at a higher shear rate, the PVP K30 sample produced better results. Further numerical study results showed the pressure and molecular viscosity distributions. The inclusion of PVP improved the load caring capacity and hence, it is a promising lubrication additive for artificial joints.

Staphylococcus aureus Strain-Dependent Biofilm Formation in Bone-Like Environment

Staphylococcus aureus species is an important threat for hospital healthcare because of frequent colonization of indwelling medical devices such as bone and joint prostheses through biofilm formations, leading to therapeutic failure. Furthermore, bacteria within biofilm are less sensitive to the host immune system responses and to potential antibiotic treatments. We suggested that the periprosthetic bone environment is stressful for bacteria, influencing biofilm development. To provide insights into S. aureus biofilm properties of three strains [including one methicillin-resistant S. aureus (MRSA)] under this specific environment, we assessed several parameters related to bone conditions and expected to affect biofilm characteristics. We reported that the three strains harbored different behaviors in response to the lack of oxygen, casamino acids and glucose starvation, and high concentration of magnesium. Each strain presented different biofilm biomass and live adherent cells proportion, or matrix production and composition. However, the three strains shared common responses in a bone-like environment: a similar production of extracellular DNA and engagement of the SOS response. This study is a step toward a better understanding of periprosthetic joint infections and highlights targets, which could be common among S. aureus strains and for future antibiofilm strategies.

In Vitro Analysis of Wearing of Hip Joint Prostheses Composed of Different Contact Materials

Cobalt-chromium-molybdenum alloy (CoCrMo) and ceramic are the two most common materials for the femoral head in hip joint prostheses, and the acetabular liner is typically made from ultra-high molecular weight polyethylene (UHMWPE), highly cross-linked polyethylene (XLPE), or highly cross-linked polyethylene blended with Vitamin E (VEXLPE). The selection of suitable materials should consider both wear performance and cost-effectiveness. This study compared the wear rate between different friction pairs using a hip joint simulator and then recommended a suitable prosthesis based on the corresponding processing technology and cost. All wear simulations were performed in accordance with ISO 14242, using the same hip joint simulator and same test conditions. This study found that when using the same material for the femoral head, the XLPE and VEXLPE liners had a lower wear rate than the UHMWPE liners, and the wear rate of the XLPE liners increased after blending with Vitamin E (VEXLPE). There was no significant difference in the wear rate of XLPE when using a CoCrMo or ceramic head. Considering the wear rate and cost-effectiveness, a CoCrMo femoral head with an accompanying XLPE liner is recommended as the more suitable combination for hip prostheses.