MicroPort Orthopedics (Netherlands)

A fiber array manufacturing method based on a novel micro-actuator is presented. The micro-actuator consists of a comb of cantilevers capable of aligning densely spaced fibers with 250μm pitch, independently and simultaneously. The horizontal and vertical position of the tip of every fiber can be controlled with a tuning range of several micrometers and with nanometer-scale resolution. The fibers are actively aligned to a high-accuracy reference device and permanently blocked within a glass ferrule by UV-adhesive curing. Active alignment is performed to achieve a core-positioning accuracy smaller than ±100nm, for all the fibers.

The present study aimed to identify the optimal design of the unicompartmental femoral component through parameter analysis and stability evaluation. A finite element (FE) analysis was applied to analyse and adjust the parameter combinations of the anterior tilt angle of the posterior condyle resection surface, the position of the peg, the length of the pegand the inclination angle of the peg, resulting in 10 different FE models. Setting three knee flexion angles of 8.4° (maximum load state during walking), 40° (maximum load state during stair climbing)and 90° (maximum load state during squatting exercise), quantitatively analysing the micromotion values of the bone-prosthesis interfaceand defining a weighted scoring formula to evaluate the stability of different FE models. The validity of the FE analysis was verified using the Digital Image Correlation (DIC) device. The errors between the FE analysis and the DIC test at three flexion angles were 5.6%, 1.7%and 11.1%. The 10 different femoral component design models were measured separately. The FE analysis demonstrated that the design with a 0° anterior tilt angle of the posterior condyle resection surface, both pegs placed on the distal resection surface, lengthened 5 mm pegsand a 10° peg inclination angle provided the best stability. The current study proposed a method for evaluating the stability of the femoral component design. The optimal intersurface stability design of the unicompartmental femoral component was achieved with two pegs placed on the distal resection surface, a 5-mm peg length incrementand a 10° peg inclination. These results might provide a reference for the selection of unicompartmental femoral components in clinical practice and therefore improve the survival rate of future unicompartmental knee arthroplasty. Level III.

Grundsätzlich ist zu beachten, dass gemäß den gesetzlichen Bestimmungen (Strahlenschutzverordnung, StrlSchV) alle Untersuchungen mit der Anwendung von Röntgenstrahlen am Menschen nur dann erlaubt sind, wenn eine Ärztin oder ein Arzt mit der erforderlichen Fachkunde im Strahlenschutz hierfür die rechtfertigende Indikation patientenindividuell gestellt hat. Das bedeutet, dass die vorliegende Empfehlung nicht verbindlich sein kann, sondern der jeweilige Untersuchende immer im Einzelfall die rechtfertigende Indikation prüfen muss. Im Folgenden soll erläutert werden, wann auch bei beschwerdearmen bzw. beschwerdefreien Patientinnen und Patienten radiologische Verlaufskontrollen nach primären Hüft- und Knieendoprothesen durch wissenschaftlich bekannte Versagensmechanismen und Versagenszeitpunkte sinnvoll sind und die rechtfertigende Indikation damit gegeben wäre.

Leadless Cardiac Pacemakers (LCP) have the potential to revolutionize Cardiac Rhythm Management (CRM). Current LCPs can only pace a single location of the heart limiting their use to patients requiring single-chamber stimulation. A Multi-node system of synchronized LCPs could be used in a significantly larger patient population. Synchronization using standard communication techniques involves high power consumption decreasing the longevity of the device. In this work, we investigate Galvanic Intra Body Communication (IBC) as a method to synchronize multi-node LCP systems. First, an accurate computational torso model was used for quasi-static simulations to estimate channel pathloss in the frequency range [40 kHz-20 MHz]. The model was then verified with in-vivo measurements using a novel experimental setup, where two LCP devices were placed in the right atrium, right ventricle and left ventricle. All channels involved in a potential multi-node LCP system were characterized. The orientation of the transducers relative to each other had a great impact on the results, with the attenuation level ranging between 55dB and 70dB between the best and worst orientations. The best results were achieved in the MHz range. Coupled with the fact that it does not require additional electrodes, this study suggests Galvanic IBC be superior to conventional communication methods for LCP devices. This analysis defines a methodology for galvanic IBC channel characterization for LCP systems, which is an important step for the design of efficient transceivers for IBC applications. More experiments with larger datasets are needed to bring this method to practice.

Antibiotic-laden bone cement (ALBC) has a number of different uses in primary and revision total joint arthroplasty. However, considerable controversy remains regarding how and when it is best used. The prophylactic use of low-dose ALBC in primary cemented total hip arthroplasty is well supported by the literature, conferring both clinical and economic benefits. In contrast, conclusive evidence on the clinical efficacy or economic benefit of the routine use of ALBC in primary total knee arthroplasty remains elusive. Given the currently available evidence, we cannot determine definitively whether the routine use of ALBC in primary total knee arthroplasty is justified, although selective use in patients with a high risk of infection seems warranted. The routine use of ALBC in revision total joint arthroplasty is well accepted, with good supporting evidence in studies of both aseptic and first-stage revision procedures. Although limited clinical evidence exists on the use of ALBC at the time of definitive component reimplantation after septic revision, the rationale for its use is strong.

Interference screw fixation is a standard procedure in anterior cruciate ligament (ACL) replacement. Aim of this study was to evaluate the degradation process of Poly-D-L-lactide (PDLLA) interference screws used for tibial ACL graft fixation. We evaluated magnetic resonance imaging (MRI) scans of 18 patients who underwent ACL revision surgery at different time points after anatomic ACL reconstruction. At primary surgery, a tibial hybrid fixation was performed with a degradable interference (IF) screw made of PDLLA (Megafix(®)) and a button. MRI revealed three different phases of degradation of the PDLLA screw. 6-8 months after surgery the IF screw was clearly visible as a well-defined structure on MRI and CT scan. After 12-16 months, the screws appeared less defined with central ingrowths' of connective tissue. In some cases only fragmented screw material was visible. At these time points, there was a slight edema surrounding the tunnel visible on MRI. After 22 months and later, the mean screw site densities were comparable with the surrounding bone density. There was no edema or signs of inflammation around the bone tunnels visible. Presence of cystic or osteolytic changes was not detected. After 22 months, a PDLLA screw may not interfere with ACL revision surgery. Regarding the degradation process of PDLLA screws, we noted three different phases. Furthermore, the degradation process observed by MRI resembles to that described by animal studies. The PDLLA screws fully absorb and are partially replaced by bone. The degradation process in humans seems to be longer than that described in animals.

The VISIONAIRE™ (Smith & Nephew) patient-specific instrumentation is based on a magnetic resonance imaging (MRI) scan of the knee and a whole-leg standing radiogram for calculation of the axes. The preoperative planning is based on the surgeon’s individual preferences and can still be changed during the planning process. The surgeon can more easily control the whole-leg standing radiogram measurements than the axes that are calculated from computed tomography (CT) or MRI data. VISIONAIRETM instruments already include the cutting slots and are fully compatible with conventional instruments, in case the surgeon wishes to change any parameters during surgery.