Complex Material and Surface Analysis of Anterolateral Distal Tibial Plate of 1.4441 Steel

Nickel-based austenitic stainless steels are still common for manufacture of implants intended for acute hard tissue reinforcement or stabilization, but the risk of negative reactions due to soluble nickel-rich corrosion products must be considered seriously. Corrosion processes may even be accelerated by the evolution of microstructure caused by excessive heat during machining, etc. Therefore, this study also deals with the investigation of microstructure and microhardness changes near the threaded holes of the anterolateral distal tibial plate containing approx. 14wt.% Ni by composition. There were only insignificant changes of microhardness, grain size, or microstructure orientation found close to the area of machining. In addition, wettability measurements of surface energy demonstrated only minor differences for bulk material and areas close to machining. The cyclic potentiodynamic polarization tests were performed in isotonic physiological solution. The first cycle was used for the determination of corrosion characteristics of the implant after chemical passivation, the second cycle was used to simulate real material behavior under the condition of previous surface damage by excessive pitting corrosion occurring during previous polarization. It was found that the damaged and spontaneously repassived surface showed a three-time higher standard corrosion rate than the “as received” chemically passivated surface. One may conclude that previous surface damage may decrease the lifetime of the implant significantly and increase the amount of nickel-based corrosion products distributed into surrounding tissues.

A Locking Plate Designed With Cluster of Head Screws Would Be Biomechanically Superior Than Conventional Buttress Plate For The Fixation of Posteromedial Tibial Plateau Fractures: A Computational Assessment

Background: Dealing with high-energy fractures of the tibial plateau remains a challenge despite advances in implants, surgical approaches, and imaging methods. Posterior buttress plate is most commonly used implant but the fixation stability is still a challenge. Recently, a newly designed tibial locking plate was introduced that aims to provide better fixation strength for tibial plateau split fracture. This study compared the biomechanical strength of three different posteromedial tibial plateau split fracture fixation methods. Methods: The tibial plateau fractures were simulated using a human tibiae model. Each fracture model was virtually implanted with one of the three following constructs, proximal medial tibial plate (PMT), proximal posterior medial tibial plate (PPMT), and posterior T-shaped buttress plate (TBP). Posteromedial fragment vertical subsidence was measured under 2000 N joint contact force. The maximum Equivalent stress on the bone plate and bone screw and the construct stiffness were determined.Results: The proximal medial tibial plate (PMT) allowed the least posteromedial fragment subsidence and produced higher construct stiffness than each of the other two constructs. However, the proximal posterior medial tibial plate (PPMT) showed higher stiffness than the T-shaped buttress plate (TBP). The maximum Equivalent stress was the smallest for the proximal medial tibial plate (PMT).Conclusion: This study showed that the proximal medial tibial locking plate or proximal posterior medial tibial locking plate were biomechanically more stable fixation methods for posteromedial split tibial plateau fractures.

Biomechanical Evaluation of a New Anatomic Locking Buttress Plate for Posteromedial Tibial Plateau Fixation.

Background: Dealing with high-energy fractures of the tibial plateau remains a challenge despite advances in implants, surgical approaches, and imaging methods. Posterior buttress plate is most commonly used implant but the fixation stability is still a challenge. Recently, a newly designed tibial locking plate was introduced that aims to provide better fixation strength for tibial plateau split fracture. This study compared the biomechanical strength of three different posteromedial tibial plateau split fracture fixation methods. Methods: The tibial plateau fractures were simulated using a human tibiae model. Each fracture model was virtually implanted with one of the three following constructs, proximal medial tibial plate (PMT), proximal posterior medial tibial plate (PPMT), and posterior T-shaped buttress plate (TBP). Posteromedial fragment vertical subsidence was measured under 2000 N joint contact force. The maximum Equivalent stress on the bone plate and bone screw and the construct stiffness were determined.Results: The proximal medial tibial plate (PMT) allowed the least posteromedial fragment subsidence and produced higher construct stiffness than each of the other two constructs. However, the proximal posterior medial tibial plate (PPMT) showed higher stiffness than the T-shaped buttress plate (TBP). The maximum Equivalent stress was the smallest for the proximal medial tibial plate (PMT).Conclusion: This study showed that the proximal medial tibial locking plate or proximal posterior medial tibial locking plate were biomechanically more stable fixation methods for posteromedial split tibial plateau fractures.

Biomechanical Comparison of a Novel Implant and Commercial Fixation Devices for AO/OTA 43-C1 Type Distal Tibial Fracture

This study compares the novel Asia Distal Lateral Tibial Locking Plate mechanical stability to that of the current anterolateral and medial tibial plates based on finite element analysis. Four-part fracture fragment model of the distal tibia was reconstructed using CAD software. A load was applied to simulate the swing phase of gait. The implant stress and the construct stiffness were compared. The results of the anterolateral plate and the medial plate were similar and the displacement values were determined lower than those in the medial plate. In the simulated distal tibia fracture, the Aplus Asia Distal Lateral Tibial Locking Plate and medial distal tibial plate tibia fixations will lead to a stiffer bone-implant construct compared to the anterolateral distal tibial plate. Moreover, the stress in the Aplus Asia Distal Lateral Tibial Locking Plate was lower than those for the medial distal tibial plate and anterolateral bone plates. The Aplus Asia Distal Lateral Tibial Locking Plate has better stabilization and is an anterolateral plate that avoids more soft tissue damage than other bone plates. The Aplus Asia Distal Lateral Tibial Locking Plate could be one of a suitable design in tibia distal fracture fixation.

Trampoline-related proximal tibia impaction fractures in children: a population-based approach to epidemiology and radiographic findings between 2006 and 2017

Purpose Proximal tibia impaction fractures are specific injuries, usually caused by trampolining. They may associate with later growth disturbances. There is sparse understanding about their recent epidemiology, in particular the changing incidence. Their typical radiographic findings are not completely known. Methods All children, aged < 16 years, who had suffered from proximal tibia fracture in Oulu Arc and Oulu between 2006 and 2017 were enrolled (n = 101). Their annual incidence was determined using the official population-at-risk, obtained from the Statistics Finland. The specific characteristics and risk factors of the patients and their fractures were evaluated. Radiographic findings were analyzed, in particular the anterior tilting of the proximal growth plate, due to impaction. Results The annual incidence increased two-fold from 9.5 per 100 000 children (2006 to 2009) to 22.0 per 100 000 (2014 to 2017) (difference: 12.5; 95% confidence interval 5.1 to 20.3 per 100 000; p = 0.0008). The mean annual incidence of trampoline impaction leg fractures was 15.4 per 100 000 children. In 80% of the cases multiple children had been jumping together on the trampoline. Anterior tilting (mean 7.3°, SD 2.5°, 6.1° to 19.1°) ) of the proximal tibial plate was seen in 68.3% of the patients. Satisfactory bone union was found in 92.7% during follow-up. Isolated patients presented delayed bone healing. Conclusion The incidence of trampoline leg fractures has increased 130% during the 12 years of the study period. Many of these injuries could have been prevented by avoiding having several jumpers on the trampoline at the same time. Anterior tilting of the growth plate was a common finding and should be recognized in the primary radiographs. Level of evidence IV

Three-Dimensional Virtual Model Used to Analyze a Normal and Prosthetic Human Joint

Prosthetic alignment is one of the most important factors, both in terms of the correct functioning of neoarticulation and the survival duration of knee arthroplasty. Significant changes in the alignment of prosthetic components affect the distribution of stress in the knee joint. These changes may also affect the distribution of stresses on the contact surface, soft knee joints, and the subjacent bone remodeling under these forces. The malposition of the components and, in particular, the tibial component in the varus, which in practice is the most common situation alongside the malrotation of the femoral component, leads to the excessive intimal tension of the internal tibial plate by the summing of the additional stresses at this level with its physiological loading from during the unipodal support phase during the walk. Although valuable, all of these studies have no capacity to assess these changes in the kinetics of in vivo knee arthroplasty. Two methods are used for this: telemetry and mathematical models. Traditionally, telemetry has been used to determine the forces acting on the hip, and more recently, on the knee. It values ​​very precisely the value of the axial rotation forces as well as the moments of bending; however, this method is little used, because the necessary equipment is very expensive. Taking this into account, the most used method is the finite element method. The objective of this study was to investigate the effect of malpositioning in the valgus and varus of the tibial component on tension developed in polyethylene as well as in the subjacent bone. Obviously, other situations have also been analyzed. In this direction a series of original numerical models of the anatomical elements (tibia, fibula, femur) of the knee were constructed to simulate the biomechanical phenomena occurring in the normal and prosthetic joint during physical activities, in order to evaluate the factors that influence the duration operation of total knee prostheses.

A rapid prototyping-based methodology for patient-specific contouring of osteotomy plates

Purpose An important challenge of the osteotomy procedures, particularly in the case of large and complex corrections, is the fixation of the osteotomy site. The purpose of this study is to propose a practical and cost-effect methodology for the plate adapting problem of osteotomy surgery. Design/methodology/approach A novel patient-specific plate contouring methodology, based on rapid prototyping (RP) and multi-point forming (MPF) techniques, was developed and evaluated. In this methodology, a female mold is fabricated by RP, based on the geometry of the osteotomy site and estimation of the plate spring back. The mold is then used to configure a MPF die, which is then used for press forming of the factory-made locking plate. The applicability of the methodology was assessed in two case studies. Findings The results of implementing the methodology on a femoral and a tibial locking plate indicated very good conformity with the underlying bone, in both the frontal and sagittal planes. The surgical application of the pre-operatively contoured tibial plate facilitated the plate locating and screw inserting procedures, and provided a secure fixation for bone fragments. Practical implications The results are promising and provide a proof of concept for the feasibility and applicability of the proposed methodology in clinical practice, as a complementary to the existing surgical preplanning and patient-specific instrument preparations. Originality/value The advantageous features of RP and the MPF were used to provide a solution for the plate adapting problem of osteotomy surgery.

Analiza przyczyn uszkodzeń płytki blokowanej kompresyjnej stabilizującej złamanie końca dalszego i części dalszej trzonu kości piszczelowej

Wstęp: Uszkodzenia implantów są jedną z przyczyn powikłań w leczeniu złamań.Opis przypadku: W pracy przedstawiono przypadek 59-letniego chorego, u którego po leczeniu operacyjnym wieloodłamowego złamania końca dalszego i części dalszej trzonu kości goleni (wg klasyfikacji AO 43C3) doszło do uszkodzenia implantu nie tylko z powodu braku współpracy chorego, ale również w wyniku powstania zjawiska karbu i złamania zmęczeniowego płytki blokowanej kompresyjnej (locking compression plate – medial distal tibial plate), prawdopodobnie z powodu błędu technologicznego (analiza makroskopowa i metoda elementów skończonych).Wniosek: Przedstawiony przypadek dowodzi konieczności współpracy z chorym w trakcie leczenia złamań oraz konieczności wyeliminowania błędów konstrukcyjnych i produkcyjnych używanych implantów.