Search

Tibial plateau fractures are mostly complex and surgically demanding joint fractures, which require a comprehensive understanding of the fracture morphology, ligamentous and neurovascular injuries, as well as the diagnostic and therapeutic options for an optimal clinical outcome. Therefore, a standardised and structured approach is required. The success of the treatment of tibial plateau fractures relies on the interdisciplinary cooperation between surgical and conservative physicians in an outpatient and inpatient setting, physical therapists, patients and service providers (health insurance companies, statutory accident insurance, pension providers). On behalf of the German Society for Orthopaedics and Trauma Surgery (DGOU), the German Trauma Society (DGU) and the Society for Arthroscopy and Joint Surgery (AGA), under the leadership of the Fracture Committee of the German Knee Society (DKG), a guideline for tibial plateau fractures was created, which was developed in several voting rounds as part of a Delphi process. Based on the current literature, this guideline is intended to make clear recommendations and outline the most important treatment steps in diagnostics, therapy and follow-up treatment. Additionally, 25 statements were revised by the authors in several survey rounds using the Likert scale in order to reach a final consensus., Competing Interests: Die Autorinnen/Autoren geben an, dass kein Interessenkonflikt besteht., (Thieme. All rights reserved.)

Purpose: The study aims to investigate the influence of patient- and fracture-specific factors on the occurrence of complications after osteosynthesis of patella fractures and to compare knee joint function, activity, and subjective pain levels after a regular postoperative course and after complications in the medium term., Methods: This retrospective, multicenter cohort study examined patients who received surgery for patella fracture at level 1 trauma centers between 2013 and 2018. Patient demographics and fracture-specific variables were evaluated. Final follow-up assessments included patient-reported pain scores (NRS), subjective activity and knee function scores (Tegner Activity Scale, Lysholm score, IKDC score), complications, and revisions., Results: A total of 243 patients with a mean follow-up of 63.4 ± 21.3 months were included. Among them, 66.9% of patients underwent tension band wiring (TBW), 19.0% received locking plate osteosynthesis (LPO), and 14.1% underwent screw osteosynthesis (SO). A total of 38 patients (15.6%) experienced complications (TBW: 16.7%; LPO: 15.2%; SO: 11.8%). Implant-related complications of atraumatic fragment dislocation and material insufficiency/dislocation, accounted for 50% of all complications, were significantly more common after TBW than LPO (p = 0.015). No patient-specific factor was identified as a general cause for increased complications. Overall, particularly following complications such as limited range of motion or traumatic refracture, functional knee scores were significantly lower and pain levels were significantly higher at the final follow-up when a complication occurred. Implant-related complications, however, achieved functional scores comparable to a regular postoperative course without complications after revision surgery., Conclusion: The present study demonstrated that implant-related complications occurred significantly more often after TBW compared to LPO. The complication rates were similar in all groups., (© 2024. The Author(s).)

Unnatural base pairs (UBPs) augment the chemical diversity of artificial nucleic acids and can thus enable the generation of new aptamers and catalytic nucleic acids by in vitro selection. However, owing to a lack of methodologies, the reverse transcription of UBPs, a key step in RNA aptamer selection, has not been sufficiently characterized. Here, we present a series of versatile assays to investigate the reverse transcription of the TPT3:NaM base pair as a representative for hydrophobic unnatural base pairs. We determine the fidelity and retention of the UBP for four different reverse transcriptases (RT) in the context of RNA in vitro evolution. The retention of the TPT3:NaM pair during the RNA in vitro selection process was investigated using a novel click-chemistry based electromobility shift assay. Real-time monitoring of reverse transcription kinetics revealed considerable differences in polymerase activity processing the TPT3:NaM base pair. Our findings identified SuperScript IV RT as the most efficient RT for processing the TPT3:NaM pair. Our approach can be applied universally to study newly developed UBPs, not only at the reverse transcription level, but also during PCR and in vitro transcription., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The preparation of highly modified mRNAs and visualization of their cellular distribution are challenging. We report in-cell application of in vitro transcribed mRNA containing natural base modifications and site-specifically introduced artificial nucleotides. Click chemistry on mRNA allows visualization in cells with excellent signal intensities. While non-specific introduction of reporter groups often leads to loss in mRNA functionality, we combined the benefits from site-specificity in the 3'-UTR incorporated unnatural nucleotides with the improved translation efficiency of the natural base modifications Ψ and 5mC. A series of experiments is described to observe, quantify and verify mRNA functionality. This approach represents a new way to visualize mRNA delivery into cells and monitor its spread on a cellular level and translation efficiency. We observed increased protein expression from this twofold chemically modified, artificial mRNA counterbalancing a reduced transfection rate. This synergetic effect can be exploited as a powerful tool for future research on mRNA therapeutics., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Introduction: The aim of this study was to evaluate the effects of increasing posttraumatic step-offs after lateral tibial plateau fracture reduction on the intra-articular pressure., Materials and Methods: In eight fresh-frozen human cadaveric knees with intact menisci, a standardized sagittal osteotomy of the lateral tibial condyle was performed as an OTA/AO type 41-B1 fracture-model. The fragment was fixed by a customized sled including an angular stable tibia plate to evaluate step-offs from 0 mm to 8 mm in 1mm increments. In a servo-hydraulic testing machine, an axial force was applied to the tibial plateau in 0° (700N), 15° (700N), 30° (700N), 60° (350N), and 90 ° (350N) of flexion while the joint pressure was recorded by two pressure sensors., Results: A 1mm step-off did not result in an increased joint pressure. At 60° of flexion a 2mm step-off increased the lateral joint pressure by 61.84kPa (P = 0.0027). In 30° of flexion, a 3mm step raised the lateral joint pressure by 66.80kPa (p = 0.0017), whereas in 0°, 15° and 90° of flexion, a 4mm step increased the pressure by >50kPa (P < 0.05). Concomitant medial joint pressure increments were lower than those in the lateral plateau. A significant increase of 19-24kPa in the medial joint pressure was detected in 90° of flexion with a 1mm lateral step (P = 0.0075), in 15° and 60° of flexion with a 2mm step (P < 0.05), in 0° of flexion with a 4mm step (P = 0.0215) and in 30° of flexion with a 7mm step (P = 0.0487)., Conclusion: Lateral fracture step-offs of 2mm or larger should be reduced intraoperatively to avoid large increases in lateral joint pressure., Competing Interests: Declaration of Competing Interest The authors declare they have no conflicts of interest., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Purpose: The purpose of this study was to examine the length change patterns of the native medial structures of the knee and determine the effect on graft length change patterns for different tibial and femoral attachment points for previously described medial reconstructions., Methods: Eight cadaveric knee specimens were prepared by removing the skin and subcutaneous fat. The sartorius fascia was divided to allow clear identification of the medial ligamentous structures. Knees were then mounted in a custom-made rig and the quadriceps muscle and the iliotibial tract were loaded, using cables and hanging weights. Threads were mounted between tibial and femoral pins positioned in the anterior, middle, and posterior parts of the attachment sites of the native superficial medial collateral ligament (sMCL) and posterior oblique ligament (POL). Pins were also placed at the attachment sites relating to two commonly used medial reconstructions (Bosworth/Lind and LaPrade). Length changes between the tibiofemoral pin combinations were measured using a rotary encoder as the knee was flexed through an arc of 0-120°., Results: With knee flexion, the anterior fibres of the sMCL tightened (increased in length 7.4% ± 2.9%) whilst the posterior fibres slackened (decreased in length 8.3% ± 3.1%). All fibre regions of the POL displayed a uniform lengthening of approximately 25% between 0 and 120° knee flexion. The most isometric tibiofemoral combination was between pins placed representing the middle fibres of the sMCL (Length change = 5.4% ± 2.1% with knee flexion). The simulated sMCL reconstruction that produced the least length change was the Lind/Bosworth reconstruction with the tibial attachment at the insertion of the semitendinosus and the femoral attachment in the posterior part of the native sMCL attachment side (5.4 ± 2.2%). This appeared more isometric than using the attachment positions described for the LaPrade reconstruction (10.0 ± 4.8%)., Conclusion: The complex behaviour of the native MCL could not be imitated by a single point-to-point combination and surgeons should be aware that small changes in the femoral MCL graft attachment position will significantly effect graft length change patterns. Reconstructing the sMCL with a semitendinosus autograft, left attached distally to its tibial insertion, would appear to have a minimal effect on length change compared to detaching it and using the native tibial attachment site. A POL graft must always be tensioned near extension to avoid capturing the knee or graft failure., (© 2021. The Author(s).)

Background: The treatment of patella fractures is technically demanding. Although the radiological results are mostly satisfactory, this often does not correspond to the subjective assessment of the patients. The classical treatment with tension band wiring with K‑wires has several complications. Fixed-angle plate osteosynthesis seems to be biomechanically advantageous., Objective: Who is treating patella fractures in Germany? What is the current standard of treatment? Have modern forms of osteosynthesis become established? What are the most important complications?, Material and Methods: The members of the German Society for Orthopedics and Trauma Surgery and the German Knee Society were asked to participate in an online survey., Results: A total of 511 completed questionnaires were evaluated. Most of the respondents are specialized in trauma surgery (51.5%), have many years of professional experience and work in trauma centers. Of the surgeons 50% treat ≤5 patella fractures annually. In almost 40% of the cases preoperative imaging is supplemented by computed tomography. The classical tension band wiring with K‑wires is still the preferred form of osteosynthesis for all types of fractures (transverse fractures 52%, comminuted fractures 40%). In the case of comminuted fractures 30% of the surgeons choose fixed-angle plate osteosynthesis. If the inferior pole is involved a McLaughlin cerclage is used for additional protection in 60% of the cases., Discussion: The standard of care for patella fractures in Germany largely corresponds to the updated S2e guidelines. Tension band wiring is still the treatment of choice. Further (long-term) clinical studies are needed to verify the advantages of fixed-angle plates., (© 2020. The Author(s).)

Background: The goal of this study was to analyze trends in Foot and Ankle surgery in Germany during the past ten years., Methods: Data of the German Federal Statistical Office from 2008 until 2018 were screened. We focused on the analysis of fusions and total joint replacements., Results: The total amount of the surgeries increased (+39.5%). Especially fusions like arthrodesis of the ankle (+31%) and of the MTP-1 joint (+77%) were on the rise. In 2017 60% of ankle arthrodesis were conducted in men, while 69% of MTP-1 arthrodesis were performed in women. The amount of joint replacements showed a decline during the last decade, in TAR (-39%) and in the MTP-1 (-48%). Regarding the patients age while undergoing a TAR, we observed a shift of the peak age group from 65 to 70 years in 2008 towards 55-60 years in 2017., Conclusion: Our study represents actual health care reality in Germany and shows a constant increase of ankle arthritis surgeries in the last decade, while there was a massive shift regarding the ratio of TAR in favour of fusion procedures., (Copyright © 2020 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.)

Purpose: This study aimed to compare the biomechanical properties of the popliteus bypass against the Larson technique for the reconstruction of a combined posterolateral corner and posterior cruciate ligament injury., Methods: In 18 human cadaver knees, the kinematics for 134 N posterior loads, 10 Nm varus loads, and 5 Nm external rotational loads in 0°, 20°, 30°, 60,° and 90° of knee flexion were measured using a robotic and optical tracking system. The (1) posterior cruciate ligament, (2) meniscofibular/-tibial fibers, (3) popliteofibular ligament (PFL), (4) popliteotibial fascicle, (5) popliteus tendon, and (6) lateral collateral ligament were cut, and the measurements were repeated. The knees underwent posterior cruciate ligament reconstruction, and were randomized into two groups. Group PB (Popliteus Bypass; n = 9) underwent a lateral collateral ligament and popliteus bypass reconstruction and was compared to Group FS (Fibular Sling; n = 9) which underwent the Larson technique., Results: Varus angulation, posterior translation, and external rotation increased after dissection (p < 0.01). The varus angulation was effectively reduced in both groups and did not significantly differ from the intact knee. No significant differences were found between the groups. Posterior translation was reduced by both techniques (p < 0.01), but none of the groups had restored stability to the intact state (p < 0.02), with the exception of group PB at 0°. No significant differences were found between the two groups. The two techniques revealed major differences in their abilities to reduce external rotational instability. Group PB had less external rotational instability compared to Group FS (p < 0.03). Only Group PB had restored rotational instability compared to the state of the intact knee (p < 0.04) at all degrees of flexion., Conclusion: The popliteus bypass for posterolateral reconstruction has superior biomechanical properties related to external rotational stability compared to the Larson technique. Therefore, the popliteus bypass may have a positive influence on the clinical outcome. This needs to be proven through clinical trials.

Purpose: Given that tibial plateau fractures (TPF) are rare, they may pose a challenge to the treating surgeon due to their variety of complex fracture patterns. Numerous studies have identified potential fracture-specific, surgery-related, and patient-related risk factors for impaired patient outcomes. However, reports on the influence of bone metabolism on functional outcomes are missing., Methods: In a retrospective multicenter cohort study, 122 TPF of 121 patients were analyzed with respect to radiological and clinical outcomes (Rasmussen) with a mean follow-up of 35.7 ± 24.9 months. The risk factor assessment included bone metabolism-affecting comorbidities and medication., Results: The findings showed that 95.9% of the patients reported a good-to-excellent clinical outcome, and 97.4% reported a good-to-excellent radiological outcome. Logistic regression revealed that potentially impaired bone metabolism (IBM) was an independent risk factor for the clinical (p = 0.016) but not the radiological outcome (Table 4). Patients with 41-type B fractures and a potential IBM had a seven times higher risk to present a fair-to-poor clinical outcome [OR 7.45, 95 CI (4.30, 12.92)]. The most common objective impairment was a limited range of motion in 16.4% of the patients, especially in 41-type C fractures (p = 0.06). The individual failure analysis additionally identified surgery-related options for improvement., Conclusion: This study demonstrated that potential IBM was an independent risk factor for a poor-to-fair clinical outcome.

We present herein a novel nitroxide spin label-containing RNA triphosphate TPT3 NO and its application for site-specific spin-labeling of RNA through in vitro transcription using an expanded genetic alphabet. Our strategy allows the facile preparation of spin-labeled RNAs with sizes ranging from short RNA oligonucleotides to large, complex RNA molecules with over 370 nucleotides by standard in vitro transcription. As a proof of concept, inter-spin distance distributions are measured by pulsed electron paramagnetic resonance (EPR) spectroscopy in short self-complementary RNA sequences and in a well-studied 185 nucleotide non-coding RNA, the B. subtilis glmS ribozyme. The approach is then applied to probe for the first time the folding of the 377 nucleotide A-region of the long non-coding RNA Xist, by PELDOR., (© 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

Background: Anterior cruciate ligament (ACL) repair has once again become a focus of research because of the development of new techniques., Purpose/hypothesis: The purpose was to compare the functional results and recurrent instability rates in patients undergoing ACL repair with dynamic intraligamentary stabilization (DIS) versus primary ACL reconstruction (ACLR) for acute isolated ACL tears. The hypothesis was that functional results and knee joint stability after ACL repair with DIS would be comparable with that after ACLR., Study Design: Randomized clinical trial; Level of evidence, 1., Methods: A total of 85 patients with acute ACL tears were randomized to undergo either ACL repair with DIS or primary ACLR. The preinjury activity level and function were recorded. Follow-up examinations were performed at 6 weeks and 6, 12, and 24 months postoperatively. Anterior tibial translation (ATT) was evaluated using Rolimeter testing. The Tegner activity scale, International Knee Documentation Committee (IKDC) subjective form, and Lysholm knee scoring scale scores were obtained. Clinical failure was defined as ΔATT >3 mm in combination with subjective instability. Recurrent instability and other complications were recorded., Results: There were 83 patients (97.6%) who were successfully followed until 2 years. ATT was significantly increased in the DIS group compared with the ACLR group (ΔATT, 1.9 vs 0.9 mm, respectively; P = .0086). A total of 7 patients (16.3%) in the DIS group had clinical failure and underwent single-stage revision. In the ACLR group, 5 patients (12.5%) had failure of the reconstruction procedure; 4 of these patients required 2-stage revision. The difference in the failure rate was not significant ( P = .432). There were 4 patients (3 in the DIS group and 1 in the ACLR group) who showed increased laxity (ΔATT >3 mm) without subjective instability and did not require revision. Recurrent instability was associated with young age (<25 years) and high Tegner scores (>6) in both groups. No significant differences between ACL repair with DIS and ACLR were found for the Tegner, IKDC, and Lysholm scores at any time., Conclusion: Whereas ATT measured by Rolimeter testing was significantly increased after ACL repair with DIS, clinical failure was similar to that after ACLR. In addition, functional results after ACL repair with DIS for acute tears were comparable with those after ACLR. The current study supports the use of ACL repair with DIS as an option to treat acute ACL tears., Registration: DRKS00015466 (German Clinical Trials Register).

The clinical examination of the knee joint represents a great challenge as well as a great opportunity. In particular, ligamentous injuries are understood better despite their complexity and thus treated in a more differentiated way. A purely radiologically based diagnosis is only possible to a limited extent, especially for chronic injuries. Therefore, complex ligament injuries can be diagnosed with the aid of a differentiated clinical examination. This article gives an overview of the most important examination techniques of the knee joint, with which the decisive analysis of acute or chronic injuries and overuse syndromes of the knee can be carried out. Particularly in the field of ligament instability, this article provides a practical guide for the differentiated examination of complex rotational instability of the knee joint. In addition, the most important patellar and meniscal examination techniques are described.

Purpose: To evaluate the effects of different stitching methods and suture diameters on the graft fixation of soft tissue human quadriceps tendon grafts for anterior cruciate ligament (ACL) reconstruction., Methods: The Krackow locking stitch (K), whipstitch (W), and baseball stitch (B) were combined with either a 2× no. 2 (#2) or a 1× no. 5 (#5) braided composite suture for graft fixation of 36 human quadriceps tendons in 6 groups. Biomechanical testing was performed using a cyclic protocol with loads between 0 and 100 N. The maximum load until failure, cyclic elongation, and failure mode were recorded., Results: The highest mean maximum load to failure was observed in the 2 Krackow stitch groups. The K#2 group had significantly higher load to failure values compared with those of the W#2 and B#2 groups (K#2, 553 ± 82 N vs W#2, 392 ± 107 N, P = .0349; K#2 vs B#2 366 ± 118 N, P = .0129). The mean cyclic elongation was lowest in the Krackow groups (K#2, 10.59 ± 2.63 mm; K#5, 13.66 ± 2.3 mm). The regular failure mode was the rupture of the suture for the Krackow stitch (8 of 12) and suture pullout for the whipstitch (11 of 12) and baseball stitch groups (12 of 12)., Conclusions: The double Krackow stitch with no. 2 braided composite suture exhibits a high maximum load to failure combined with a low amount of elongation in a biomechanical study for human quadriceps tendon soft tissue graft fixation. Unlike the whipstitch and the baseball stitch, it can solidly prevent suture pullout., Clinical Relevance: A safe soft tissue graft fixation technique is especially important for quadriceps tendon grafts with their laminar anatomical structure and physiologically varying diameter. Unlike other grafts for ACL replacement, it fully relies on the soft tissue suture fixation to resist the pullout force., (Copyright © 2019 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Purpose: Despite good initial pullout strength, it is unclear whether adjustable button (AB) devices for anterior cruciate ligament (ACL) soft-tissue graft fixation, which are based on the Chinese finger trap technique, resist cyclic loading. Furthermore, they have never been tested in a cyclic protocol including complete unloading. It was hypothesized, that the displacement of AB devices with the Chinese finger trap technique would be greater than that of continuous suture loop devices and other available AB mechanisms in a cyclic loading with complete unloading protocol., Methods: ACL reconstruction was performed in a porcine knee model using three different types of cortical fixation devices: two different AB devices that use the Chinese finger trap design, one AB device that uses a locked suture loop mechanism and two different continuous loop devices as control groups (n = 40). Specimens were mounted in a material-testing machine (Instron Inc.) that permitted 2500 loading and complete unloading cycles to a maximum of 250 N, as well as continuous elongation recording. A one-way ANOVA was performed for statistical analysis., Results: The displacement of ABs with a Chinese finger trap loop (mean 8.1; SD 1.5 mm and mean 6.1; SD 1.4 mm) was significantly greater than that of AB with a locked suture loop (mean 4.7; SD 1.0 mm; p < 0.05) and devices with a continuous loop (mean 4.1; SD 0.5 mm and mean 4.4, SD 0.3 mm; p < 0.01). No significant differences were detected between the ABs with a locked suture loop and the continuous loops., Conclusion: Cyclic loading and unloading of AB using the Chinese finger trap technique leads to significantly greater construct lengthening compared with other devices. Complete unloading of the ACL is very likely to occur during rehabilitation after ACL reconstruction. Lengthening of the AB device due to cyclic loading might be a potential mode of failure of the ACL graft fixation. Therefore, when using an AB femoral fixation technique, a locked suture loop design or a careful rehabilitation protocol should be considered.

Background: Little is known about the dynamic restraints of the semimembranosus muscle (SM)., Purpose and Hypothesis: The goal of the present study was to elucidate the role of (1) passive and (2) active restraints to medial-side instability and to analyze (3) the corresponding tightening of the posteromedial structures by loading the SM. It was hypothesized that points 1 to 3 will significantly restrain medial knee instability. This will aid in understanding the synergistic effect of the semimembranosus corner., Study Design: Controlled laboratory study., Methods: Nine knees were tested in a 6 degrees of freedom robotic setup and an optical tracking system. External rotation (ER; 4 N·m), internal rotation (4 N·m), anteromedial rotation (4-N·m ER and 89-N anterior tibial translation), and valgus rotation (8 N·m) were applied at 0°, 30°, 60°, and 90°, with and without an SM load of 75 N. Sequential cutting of the medial collateral ligament and posterior oblique ligament was then performed. At the intact state of the knee and after each cut, the aforementioned simulated laxity tests were performed., Results: The medial collateral ligament was found to be the main passive stabilizer to ER and anteromedial rotation, resulting in 9.3° ± 6.8° ( P < .05), 8.1° ± 3.6° ( P < .05), and 7.6° ± 4.2° ( P < .05) at 30°, 60°, and 90°, respectively. Conversely, after the posterior oblique ligament was cut, internal rotation instability increased significantly at early flexion angles (9.3° ± 3.2° at 0° and 5.2° ± 1.1 at 30°). Loading the SM had an overall effect on restraining ER ( P < .001) and anteromedial rotation ( P < .001). This increased with flexion angle and sectioning of the medial structures and resulted in a pooled 2.8° ± 1.7° (not significant), 5.4° ± 2° ( P < .01), 7.5° ± 2.8° ( P < .001), and 8.3° ± 4.4° ( P < .001) at 0°, 30°, 60°, and 90° when compared with the unloaded state., Conclusion: The SM was found to be a main active restraint to ER and anteromedial rotation, especially at higher flexion angles and in absence of the main passive medial restraints. The calculated tensioning effect was small in all flexion angles for all simulated laxity tests., Clinical Relevance: A complete semimembranosus avulsion may indicate severe medial knee injury, and refixation should be considered in multiligament injury.

The site-specific introduction of spin labels into RNA for distance measurements by EPR gives insight into its solution structure. We here present a method for spin labeling of in vitro transcribed RNA. Distance distributions between two nitroxide spin labels are determined by PELDOR in a self-complementary RNA duplex.

Human faces are among the most salient visual stimuli and act both as socially and emotionally relevant signals. Faces and especially faces with emotional expression receive prioritized processing in the human brain and activate a distributed network of brain areas reflected, e.g., in enhanced oscillatory neuronal activity. However, an inconsistent picture emerged so far regarding neuronal oscillatory activity across different frequency-bands modulated by emotionally and socially relevant stimuli. The individual level of anxiety among healthy populations might be one explanation for these inconsistent findings. Therefore, we tested the hypothesis whether oscillatory neuronal activity is associated with individual anxiety levels during perception of faces with neutral and fearful facial expressions. We recorded neuronal activity using magnetoencephalography (MEG) in 27 healthy participants and determined their individual state anxiety levels. Images of human faces with neutral and fearful expressions, and physically matched visual control stimuli were presented while participants performed a simple color detection task. Spectral analyses revealed that face processing and in particular processing of fearful faces was characterized by enhanced neuronal activity in the theta- and gamma-band and decreased activity in the beta-band in early visual cortex and the fusiform gyrus (FFG). Moreover, the individuals' state anxiety levels correlated positively with the gamma-band response and negatively with the beta response in the FFG and the amygdala. Our results suggest that oscillatory neuronal activity plays an important role in affective face processing and is dependent on the individual level of state anxiety. Our work provides new insights on the role of oscillatory neuronal activity underlying processing of faces., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Purpose: Dynamic intraligamentary stabilization (DIS) has been introduced as a new technique to repair the torn anterior cruciate ligament (ACL) and to restore knee joint kinematics after an acute ACL tear. Aim of the present study was to compare the early post-operative activity, restoration of gait pattern and functional results after DIS in comparison with primary ACL reconstruction (ACLR) for acute ACL tears. It was hypothesized that functional results, post-operative activity and changes in gait pattern after DIS are comparable to those after ACLR., Methods: Sixty patients with acute ACL tears were included in this study and underwent either DIS or ACLR with an anatomic semitendinosus autograft in a randomized manner. Patients were equipped with an accelerometric step counter for the first 6 weeks after surgery in order to monitor their early post-operative activity. 3D gait analysis was performed at 6 weeks and 6 months after surgery. Temporal-spatial, kinematic and kinetic parameters were extracted and averaged for each subject. Functional results were recorded at 6 weeks, 6 months and 12 months after surgery using the Tegner activity scale, International Knee Documentation Committee score and Lysholm score., Results: Patients who underwent DIS showed an increased early post-operative activity with significant differences at week 2 and 3 (p = 0.0241 and 0.0220). No significant differences between groups were found for knee kinematic and kinetic parameters or the functional scores at any time of the follow-up. Furthermore, the difference in anterior tibial translation was not significantly different between the two groups (n.s.)., Conclusion: Early functional results and changes in gait pattern after DIS are comparable to those of primary ACLR. Therefore, ACL repair may be an alternative to ACLR in this cohort of patients., Level of Evidence: I.

Background: Since 2005, when the Diagnosis-Related Group (DRG) system was introduced, an increasing number of surgical procedures have been reported in Germany. In particular, the numbers of elective arthroplasty and spinal surgery procedures have been controversial., Objectives: The focus of this study was analyzing the development of spinal surgery, arthroplasty, and fracture management., Materials and Methods: We analyzed the database for all musculoskeletal operating procedure codes (OPS codes 5‑78 to 5‑86) from 2005 to 2013 collected by the German Federal Statistical Office., Results: With an increase in total patient numbers of 12.8%, there was a rise in in-patient musculoskeletal procedures of 43.5%; the highest increase in procedures was found in spinal surgery (130%). Despite an ageing population, the numbers of hip- and knee arthroplasty procedures initially decreased after 2011 and after 2009 respectively. The number of osteosyntheses showed a slight increase (16%), whereas the number of (elective) implant removals declined (-7%). An increase in novel techniques was noticeable, such as locked plate osteosynthesis (251%), shoulder arthroplasty (402%) or the use of bone substitutes in spinal surgery (+2,011%)., Conclusions: Despite generally increasing volume growth, the numbers of hip and knee arthroplasty cases decreased. In addition to an ageing population and potential economic incentives, technical innovations and new implant systems should be considered when discussing increasing case numbers.

Purpose: To determine the static stabilizing effects of different anatomical structures of the posterolateral corner (PLC) of the knee in the lateral collateral ligament (LCL)-intact state., Methods: Thirteen fresh-frozen human cadaveric knees were dissected and tested using an industrial robot with an optical tracking system. Kinematics were determined for 134 N anterior/posterior loads, 10 N m valgus/varus loads, and 5 N m internal/external rotatory loads in 0°, 20°, 30°, 60°, and 90° of knee flexion. The PLC structures were dissected and consecutively released: (I) intact knee joint, (II) with released posterior cruciate ligament (PCL), (III) popliteomeniscal fibers, (IV) popliteofibular ligament, (V) arcuat and popliteotibial fibers, (VI) popliteus tendon (PLT), and (VII) LCL. Repeated-measures analysis of variance was performed with significance set at P < .05., Results: After releasing the PCL, posterior tibial translation increased by 5.2 mm at 20° to 9.4 mm at 90° of joint flexion (P < .0001). A mild 1.8° varus instability was measured in 0° of flexion (P = .0017). After releasing the PLC structures, posterior tibial translation further increased by 2.9 mm at 20° to 5.9 mm at 90° of flexion (P < .05) and external rotation angle increased by 2.6° at 0° to 7.9° at 90° of flexion (P < .05, vs II). Varus stability did not decrease. Mild differences between states V and VI were found in 60° and 90° external rotation tests (2.1° and 3.1°; P < .05)., Conclusions: The connecting ligaments/fibers to the PLT act as a primary static stabilizer against external rotatory loads and a secondary stabilizer against posterior tibial loads (when PCL is injured). After releasing these structures, most static stabilizing function of the intact PLT is lost. The PLC has no varus-stabilizing function in the LCL-intact knee., Clinical Relevance: Anatomy and function of these structures for primary and secondary joint stability should be considered for clinical diagnostics and when performing surgery in the PLC., (Copyright © 2017 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Purpose: To analyze the ultimate failure load, yield load, stiffness, and cyclic resistance of different anterior cruciate ligament (ACL) soft tissue graft fixation techniques in osteopenic bone., Methods: In this study, 24 fresh-frozen human cadaveric tibiae (mean age 82.6 years; range 56-96; 6 male and 6 female donors) were used. Quantitative computed tomography was performed to match bone density. Looped porcine flexor tendon grafts were chosen as ACL graft substitutes for tibial graft fixation techniques (n = 8 each): (1) hybrid fixation with an interference screw and extracortical button fixation; (2) extracortical button fixation; and (3) interference screw fixation. In single cycle mode, constructs were loaded to failure to evaluate stiffness, yield load, and maximum load. In cyclic testing, 2,000 cycles (25-100 N) were applied followed by loading to failure. A 1-way analysis of variance was performed with significance set at P = .05., Results: Hybrid fixation resulted in significantly higher yield load (283.4 ± 86.19 N; P = .0037) and maximum load (407.9 ± 102.3 N; P = .0026) than interference screw fixation (yield load 176.4 ± 26.03, max load 231.8 ± 94.06 N) in elderly bone. Yield load after extracortical button fixation (252.9 ± 41.97 N; P = .0286) was also higher than that after interference screw fixation, but stiffness (18.98 ± 9.154 N/mm; P = .0041) was less than that after hybrid fixation (37.28 ± 13.53 N/mm). Of 8 specimens in the interference screw group, 7 did not survive 2,000 cycles and failed by graft slippage, whereas all other specimens in both other groups survived., Conclusions: Tibial hybrid fixation of ACL soft tissue grafts provides less vertical graft movement than extracortical button fixation and higher primary failure loads than interference screw fixation in elderly bone., Clinical Relevance: In this elderly human joint in vitro model, tibial hybrid fixation provides biomechanical advantages over other techniques. Graft fixation with only an interference screw should be avoided in osteopenic bone., (Copyright © 2017 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Introduction: In Germany most surgical procedures of the ligaments of the knee and correcting osteotomies of the knees are performed within an inpatient setting. The purpose of this study was to analyze the available data to assess epidemiological trends and incidences in inpatient knee joint surgery., Materials and Methods: Approximately 154 million anonymized DRG inpatient records were collected by the German Federal Statistical Office between 2005 and 2013. These data were screened and analyzed for knee joint surgical ligamental procedures and osteotomies., Results: Anterior cruciate ligament reconstruction (ACLR) or repair had a high incidence (46 per 100,000 persons/year). In addition, the most frequent grafts included hamstring tendon (90%) and the patellar tendon (6.3%) autografts (2013). Peak age group for ACLR was 15-20 years (14.5%) for female and 20-25 years (23.6%) for male patients, while there was a second peak in the age group 45-50 years (13.8%) for female patients. Male patients had a higher risk for receiving ACLR (RR 1.96; 95% CI 1.92-2.00) and for receiving valgizing high tibial osteotomy (RR 2.43; 95% CI 2.27-2.61). Females had a higher risk for receiving varizing distal femur osteotomy (RR 1.89; 95% CI 1.58-2.26)., Conclusion: There are growing trends for joint- and activity-preserving procedure in the middle-aged patients. The knowledge of the trends and incidences related to these procedures may help to validate and discuss the results of clinical and register studies.

Partial tibial plateau fractures may occur as a consequence of either valgus or varus trauma combined with a rotational and axial compression component.High-energy trauma may result in a more complex and multi-fragmented fracture pattern, which occurs predominantly in young people. Conversely, a low-energy mechanism may lead to a pure depression fracture in the older population with weaker bone density.Pre-operative classification of these fractures, by Müller AO, Schatzker or novel CT-based methods, helps to understand the fracture pattern and choose the surgical approach and treatment strategy in accordance with estimated bone mineral density and the individual history of each patient.Non-operative treatment may be considered for non-displaced intra-articular fractures of the lateral tibial condyle. Intra-articular joint displacement ⩾ 2 mm, open fractures or fractures of the medial condyle should be reduced and fixed operatively. Autologous, allogenic and synthetic bone substitutes can be used to fill bone defects.A variety of minimally invasive approaches, temporary osteotomies and novel techniques (e.g. arthroscopically assisted reduction or 'jail-type' screw osteosynthesis) offer a range of choices for the individual and are potentially less invasive treatments.Rehabilitation protocols should be carefully planned according to the degree of stability achieved by internal fixation, bone mineral density and other patient-specific factors (age, compliance, mobility). To avoid stiffness, early functional mobilisation plays a major role in rehabilitation. In the elderly, low-energy trauma and impression fractures are indicators for the further screening and treatment of osteoporosis. Cite this article: EFORT Open Rev 2017;2. DOI: 10.1302/2058-5241.2.160067. Originally published online at www.efortopenreviews.org., Competing Interests: ICMJE Conflict of Interest Statement: None.

The synthesis of sequence-specifically modified long RNA molecules, which cannot entirely be prepared via solid phase synthesis methods is experimentally challenging. We are using a new approach based on an expanded genetic alphabet preparing site-specifically modified RNA molecules via standard in vitro transcription. In this report, the site-specific labeling of functional RNAs, in particular ribozymes and a long non-coding RNA with cyclopropene moieties, is presented. We provide detailed instructions for RNA labeling via in vitro transcription and include required analytical methods to verify production and identity of the transcript. We further present post-transcriptional inverse electron demand Diels-Alder cycloaddition reactions on the cyclopropene-modified sequences and discuss applications of the genetic alphabet expansion transcription for in vitro preparation of labeled functional RNAs with complex foldings. In detail, the glmS and CPEB3 ribozymes were site-specifically decorated with methyl cyclopropene moieties using the unnatural TPT3 CP triphosphate and were proven to be still functional. In addition, the structurally complex A region of the Xist lncRNA (401nt) was site-specifically modified with methyl cyclopropene and detected by fluorescence after cycloaddition reaction with a tetrazine-BODIPY conjugate., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Purpose: The structural properties of hamstring tendon grafts were evaluated in a porcine model, after processing it to a flat shape, to better replace or augment anatomic flat structures (e.g. ACL, MPFL or MCL)., Methods: In this biomechanical study, porcine flexor tendons were used which have a comparable shape to semitendinosus and gracilis tendons. One part of the tendon was prepared to a flat tendon construct by splitting the tendon longitudinally with a knife to half of the diameter of the tendon. The semi-split tendon was scratched out to a flat shape. The other matched part was tested in its original round shape. The tendons (n = 40) have been fixed in a uniaxial testing machine (Zwick/Roell) by cryo-clamps after preparing the fixed ends by 2-0 polyester sutures (2-0 Ethibond ® EXCEL, Ethicon, Somerville, NJ). In every specimen, there was a free 60-mm tendon part between both clamps. The tendons have been loaded to failure to evaluate typical biomechanical parameters such as stiffness, yield load and maximum load., Results: No statistically significant differences (n.s.) regarding stiffness, yield load and maximum load between natively round and processed flat tendons could be detected., Conclusion: A prepared flat-shaped tendon does not show any different structural properties compared with an original round tendon. Therefore, a flat tendon seems to be a biomechanical stable graft option for anatomic reconstruction or augmentation of injured natively flat-shaped structures such as MCL, MPFL or ACL.

Purpose: Dynamic intraligamentary stabilization (DIS) has been introduced for the repair of acute anterior cruciate ligament (ACL) tears as an alternative to delayed reconstruction. The aim of the present study was to compare knee joint kinematics after DIS to those of the ACL-intact and ACL-deficient knee under simulated Lachman/KT-1000 and pivot-shift tests. We hypothesized that DIS provides knee joint kinematics equivalent to an intact ACL., Methods: With the use of a robotic knee simulator, knee kinematics were determined in simulated Lachman/KT-1000 and pivot-shift tests at 0°, 15°, 30°, 60°, and 90° of flexion in eight cadaveric knees under the following conditions: (1) intact ACL, (2) ACL deficiency, (3) DIS with a preload of 60 N, and (4) DIS with a preload of 80 N. Statistical analyses were performed using two-factor repeated-measures analysis of variance. The significance level was set at a p value of <0.05., Results: After DIS with a preload of either 60 N or 80 N, the anterior translation was significantly reduced in the simulated Lachman/KT-1000 and pivot-shift tests when compared to the ACL-deficient knee (p < 0.05). No significant differences were observed between the DIS reconstruction with a preload of 80 N and the intact ACL with regard to anterior laxity in either test. However, DIS with a preload of only 60 N was not able to restore knee joint kinematics to that of an intact knee in all degrees of flexion., Conclusion: DIS with a preload of 80 N restores knee joint kinematics comparable to that of an ACL-intact knee and is therefore capable of providing knee joint stability during ACL healing. DIS therefore provides a new technique for primary ACL repair with superior biomechanical properties in comparison with other techniques that have been described previously, although further clinical studies are required to determine its usefulness in clinical settings.

Background: Semitendinosus and gracilis muscles are frequently harvested for autologous tendon grafts for cruciate ligament reconstruction. This study investigated the joint-stabilizing effects of these hamstring muscles in cases of insufficiency of the medial collateral ligament (MCL)., Hypotheses: First, both the semitendinosus and gracilis muscles can actively stabilize the joint against valgus moments in the MCL-deficient knee. Second, the stabilizing influence of these muscles decreases with an increasing knee flexion angle., Study Design: Controlled laboratory study., Methods: The kinematics was examined in 10 fresh-frozen human cadaveric knees using a robotic/universal force moment sensor system and an optical tracking system. The knee kinematics under 5- and 10-N·m valgus moments were determined in the different flexion angles of the (1) MCL-intact and (2) MCL-deficient knee using the following simulated muscle loads: (1) 0-N (idle) load, (2) 200-N semitendinosus (ST) load, and (3) 280-N (200/80-N) combined semitendinosus/gracilis (STGT) load., Results: Cutting the MCL increased the valgus angle under all tested conditions and angles compared with the MCL-intact knee by 4.3° to 8.1° for the 5-N·m valgus moment and 6.5° to 11.9° for the 10-N·m valgus moment ( P < .01). The applied 200-N simulated ST load reduced the valgus angle significantly at 0°, 10°, 20°, and 30° of flexion under 5- and 10-N·m valgus moments ( P < .05). At 0°, 10°, and 20° of flexion, these values were close to those for the MCL-intact joint under the respective moments (both P > .05). The combined 280-N simulated STGT load significantly reduced the valgus angle in 0°, 10°, and 20° of flexion under 5- and 10-N·m valgus moments ( P < .05) to values near those for the intact joint (5 N·m: 0°, 10°; 10 N·m: 0°, 10°, 20°; P > .05). In 60° and 90° of flexion, ST and STGT loads did not decrease the resulting valgus angle of the MCL-deficient knee without hamstring loads ( P > .05 vs deficient; P = .0001 vs intact)., Conclusion: In this human cadaveric study, semitendinosus and gracilis muscles successfully stabilize valgus moments applied to the MCL-insufficient knee when the knee is near extension., Clinical Relevance: In the valgus-unstable knee, these data suggest that the hamstring muscles should be preserved in (multi-) ligament surgery when possible.

Background: Currently existing classifications of tibial plateau fractures do not help to guide surgical strategy. Recently, a segment-based mapping of the tibial plateau has been introduced in order to address fractures with a fracture-specific surgical approach. The goal of the present study was to analyze incidence and fracture specifics according to a new 10-segment classification of the tibial plateau., Methods: A total of 242 patients with 246 affected knees were included (124 females, 118 males, mean age 51.9±16.1years). Fractures were classified according to the OTA/AO classification. Fracture pattern was analyzed with respect to a 10-segment classification based on CT imaging of the proximal tibial plateau 3cm below the articular surface., Results: 161 Patients suffered an OTA/AO type 41-B and 85 patients an OTA/AO type 41-C tibial plateau fracture. Females had an almost seven times higher risk to suffer a fracture due to low-energy trauma (OR 6.91, 95% CI (3.52, 13.54), p<0.001) than males. In 34% of the patients with affection of the medial tibial plateau, a fracture comminution, primarily due to low-energy trauma (p<0.001), was observed. In type B fractures, the postero-latero-lateral (65.2%), the antero-latero-lateral (64.6%) and the antero-latero-central (60.9%) segment were most frequently affected. Every second type C fracture showed an unique fracture line and zone of comminution. The tibial spine was typically involved (89.4%). A typical fracture pattern of high-energy trauma demonstrated a zone of comminution of the lateral plateau and a split fracture in the medial plateau. The most frequently affected segments were the postero-latero-central (85.9%), postero-central (84.7%), and antero-latero-central (78.8%) segment., Conclusion: Posterior segments were the most frequently affected in OTA/AO type B and C fractures. Acknowledging the restricted visibility of posterior segments, whose reduction and fixation is crucial for long-term success, our findings implicate the use of posterior approaches more often in the treatment of tibial plateau fractures. Also, low-energy trauma was identified as an important cause for tibial plateau fractures., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Introduction: Porcine flexor tendons, bovine extensor tendons, and human (semitendinosus) tendons are frequently used as substitutes for human ACL grafts in biomechanical in vitro studies. This study compares the biomechanical properties and structural differences of these tendons., Materials and Methods: In this biomechanical study, fresh-frozen porcine flexor tendons, bovine extensor tendons, and human semitendinosus tendons were used (n = 36). The tendons were mounted in a uniaxial testing machine (Zwick/Roell) with cryo-clamps, leaving a 60 mm tendon part free between the two clamps. Specimens have been loaded to failure to evaluate the biomechanical parameters stiffness, yield load, and maximum load. A Total Collagen Assay Kit was used to detect differences in the total collagen type I concentration (n = 30). A one-way ANOVA was performed to detect differences in the means. The significance level was set at p < 0.05., Results: There were no significant differences in the stiffness between the groups (bovine 194 ± 43 N/mm, porcine 211 ± 63 N/mm, and human cadaveric 208 ± 58 N/mm). The yield and maximum loads were high (>1000 N) in all groups, but they were significantly increased in both animal specimens (means of 1681-1795 N) compared with human cadaveric specimen (means of 1289-1406 N; p < 0.01). No difference in the collagen type I concentration was detected (N.S.)., Conclusion: Porcine flexor and bovine extensor tendons are eligible substitutes with similar stiffness and high failure loads compared with human cadaveric semitendinosus tendons in in vitro studies.

Purpose: To analyze the ultimate failure load, yield load, stiffness, and cyclic elongation of 4 different fixation techniques for posterior cruciate ligament avulsion fractures under cyclic loading and load-to-failure conditions., Methods: In 40 porcine knees, a standardized bony avulsion of the posterior cruciate ligament was generated. The osseous avulsion was fixed by the following techniques through an open approach: (1) direct anterograde screw fixation (3.5 mm with washer), (2) retrograde screw fixation (3.5 mm with washer), (3) cortical suspension button fixation (with No. 2 braided suture), and (4) direct suture cerclage (with No. 2 braided suture). The constructs were cyclically loaded 500 times (10 to 100 N) to measure the maximum elongation. Subsequently, loading to failure was performed, and stiffness, yield load, and maximum load were measured. A 1-way analysis-of-variance test was performed with significance set at P < .05., Results: Button fixation resulted in lower elongation (1.25 ± 0.27 mm) than anterograde screw fixation (2.17 ± 0.74 mm, P = .0058) and the cerclage technique (2.02 ± 0.24 mm, P = .0290). The cerclage technique showed a lower yield load (493.55 ± 88.86 N) than anterograde screw fixation (720.39 ± 139.0 N, P = .0012) and retrograde screw fixation (668.58 ± 147.59 N, P = .0145); it also had lower stiffness and maximum load values (51.2 ± 6.11 N/mm and 631.22 ± 101.22 N, respectively) than the anterograde screw fixation technique (65.6 ± 12.74 N/mm, P = .041, for stiffness and 817.5 ± 145.9 N, P = .008, for maximum load). None of the other results were significantly different (P > .05)., Conclusions: The cortical suspension button and retrograde screw fixation techniques showed comparable structural properties to the direct screw fixation technique. The raw structural properties of suture cerclage still seem eligible enough to consider using this technique for fixation., Clinical Relevance: In this in vitro model, all techniques appear to constitute a biomechanically stable alternative to traditional anterograde screw fixation. In contrast to anterograde screw fixation, these techniques can be performed minimally invasively., (Copyright © 2016 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

We describe the multifactorial origins of catalysis by the twister ribozyme. We provide evidence that the adenine immediately 3' to the scissile phosphate (A1) acts as a general acid. Substitution of ring nitrogen atoms indicates that very unusually the N3 of A1 is the proton donor to the oxyanion leaving group. A1 is accommodated in a specific binding pocket that raises its pKa toward neutrality, juxtaposes its N3 with the O5' to be protonated, and helps create the in-line trajectory required for nucleophilic attack. A1 performs general acid catalysis while G33 acts as a general base. A 100-fold stereospecific phosphorothioate effect at the scissile phosphate is consistent with a significant stabilization of the transition state by the ribozyme, and functional group substitution at G33 indicates that its exocyclic N2 interacts directly with the scissile phosphate. A model of the ribozyme active site is proposed that accommodates these catalytic strategies.

Introduction: Aim of this study was to investigate the accuracy of a conventional over-the-top-guide (OTG) with a typically short offset to hit the center of the native femoral ACL footprint through the anteromedial portal in comparison to a specific medial-portal-aimer (MPA) with larger offset., Materials and Methods: In 20 matched human cadaveric knees, insertion sites of the ACL were marked in medial arthrotomy. An OTG with an offset of 5.5 mm, respectively, the MPA with 9 mm offset was used in a medial portal approach to locate the center of a single bundle ACL reconstruction tunnel with k-wires. Distances from the footprint center, the OTG drilling and the MPA drilling to the roof of the intercondylar notch and to the deep cartilage margin were determined. After positioning of radiological markers, radiographic analysis was performed according to the quadrant technique as described by Bernard and Hertel., Results: The distance from ACL origin to the roof of the notch was 10.3 (±2.1) mm, in the OTG group 6.7 (±1.5) mm and in the MPA group 9.6 (±1.9) mm. The distance to the deep cartilage margin was 9.5 (±1.7) mm from ACL origin, 4.8 (±1.3) mm with OTG and 8.7 (±1.4) mm with MPA. There were statistically significant differences between the distances of the footprint center and the OTG group after measuring and also after radiographic analysis (p < 0.0001). Using the MPA, no significant different distances in comparison to the anatomical ACL center were found (p > 0.0001). There was an increased risk for femoral blow (9/10 vs. 0/10) in the OTG group after overdrilling with a 9 mm drill., Conclusion: Short (5.5 mm) offset femoral aiming devices fail to locate the native ACL footprint center in medial portal approach with an increased risk for femoral blowout when overdrilling. The special medial-portal-aiming device with 9 mm offset hit the center reliably.

The influences and mechanisms of the physiology, rupture and reconstruction of the anterior cruciate ligament (ACL) on kinematics and clinical outcomes have been investigated in many biomechanical and clinical studies over the last several decades. The knee is a complex joint with shifting contact points, pressures and axes that are affected when a ligament is injured. The ACL, as one of the intra-articular ligaments, has a strong influence on the resulting kinematics. Often, other meniscal or ligamentous injuries accompany ACL ruptures and further deteriorate the resulting kinematics and clinical outcomes. Knowing the surgical options, anatomic relations and current evidence to restore ACL function and considering the influence of concomitant injuries on resulting kinematics to restore full function can together help to achieve an optimal outcome.

Background: Anatomic femoral tunnel placement in anterior cruciate ligament (ACL) reconstruction is considered to be a key to good primary stability of the knee. There is still no consensus on whether a centrally placed single bundle in the anatomical femoral footprint can compare with anatomic double-bundle (DB) reconstruction., Purpose/hypothesis: The purpose of this study was to determine knee kinematics after single-bundle ACL reconstruction via the medial portal technique using 2 different femoral tunnel positions and to compare results with those of the anatomic DB technique. The hypotheses were that (1) single-bundle reconstruction using the medial portal technique with a centrally placed femoral tunnel relative to the native footprint (SB-central technique) would more closely restore intact knee kinematics compared with the same reconstruction technique with an eccentric femoral tunnel drilled in the anteromedial bundle footprint (SB-AM technique) and (2) DB reconstruction would result in superior kinematics compared with the SB-central technique., Study Design: Controlled laboratory study., Methods: Knee kinematics was examined in 10 fresh-frozen human cadaveric knees using a robotic/universal force-moment sensor system. Kinematics in simulated pivot-shift and 134-N anterior tibial loading tests were determined in different conditions within the same specimen: (1) intact ACL, (2) deficient ACL, (3) SB-AM, (4) SB-central, and (5) DB., Results: All reconstruction techniques significantly reduced anterior tibial translation (ATT) compared with a deficient ACL at 0°, 15°, 30°, 60°, and 90° in the anterior tibial loading test (P < .01, repeated-measures analysis of variance) and at 0°, 15°, and 30° in the simulated pivot-shift test (P < .001). There were no significant differences in the SB-central group and the DB group compared with the intact ACL. Reconstruction in the SB-AM group resulted in significantly increased ATT compared with the intact ACL in near-to-extension angles in both tests (0°, 15°, and 30°; P < .01). SB-central and DB reconstructions both resulted in significantly reduced ATT, in some tests at ≤30°, compared with SB-AM reconstruction (P < .05). No significant differences between the SB-central and DB groups were found (P > .05)., Conclusion: The SB-central technique restored intact knee kinematics more closely than did SB-AM reconstruction at time zero. There were no differences in knee kinematics between the DB and SB-central techniques., Clinical Relevance: Anatomic single-bundle ACL reconstruction provides similar knee kinematics as anatomic double-bundle reconstruction., (© 2015 The Author(s).)

Purpose: To evaluate knee laxity after anatomic ACL reconstruction with additional suture repair of a medial meniscus tear., Methods: Kinematics of the intact knee were determined in 12 human cadaver specimens in response to a 134-N anterior tibial load (aTT) and a combined rotatory load of 10 Nm valgus and 4 Nm internal tibial rotation (aTTPS) using a robotic/universal force moment sensor testing system. Subsequently, the ACL was resected following the creation of a standardized tear of the medial meniscus, a standard meniscus repair and an ACL reconstruction using an anatomic single-bundle (6) or an anatomic double-bundle technique (6). Knee kinematics were determined following every sub-step., Results: Significant increase of aTT in the ACL-deficient knee was found (p ≤ 0.001) with a further increase in the ACL-deficient knee with additional medial meniscal rupture (p ≤ 0.001). ACL reconstructions significantly decreased aTT compared with the ACL and meniscus-ruptured knee. No significant differences were seen between the intact knee and the ACL-reconstructed knee with additional meniscal repair (p < 0.05). In response to a simulated pivot shift, aTTPS in the intact knee significantly increased in the ACL-deficient knee and meniscus-ruptured knee (p = 0.005). No significant differences in knee kinematics were found between SB as well as DB ACL reconstruction with additional medial meniscal repair compared with the intact knee. Comparison of SB versus DB ACL reconstruction did not reveal any significant differences in a simulated Lachman test or simulated pivot shift test (n.s.)., Conclusions: aTT as well as aTTPS significantly increased with ACL deficiency compared with the intact knee; additional medial meniscal rupture further increased aTT. Anatomic ACL reconstruction with medial meniscal repair did not reveal significant differences in knee kinematics compared with the intact knee. Comparison of anatomic SB versus DB ACL reconstruction with additional repair of the medial meniscus did not show significant differences neither in a simulated Lachman nor in a simulated pivot shift test.

Attention is an important factor that is able to strongly modulate the experience of pain. In order to differentiate cortical mechanisms underlying subject-driven (i.e., top-down) and stimulus-driven (bottom-up) modes of attentional pain modulation, we recorded electric brain activity in healthy volunteers during painful laser stimulation while spatial attention and stimulus intensity were systematically varied. The subjects' task was to evaluate the pain intensity at the attended finger, while ignoring laser stimuli delivered to the other finger. Top-down (attention) and bottom up (intensity) influences differed in their effects on oscillatory response components. Attention towards pain induced a decrease in alpha and an increase in gamma band power, localized in the insula. Pain intensity modulated delta, alpha, beta and gamma band power. Source localization revealed stimulus driven modulation in the cingulate gyrus (CG) and somatosensory areas for gamma power changes. Our results indicate that bottom-up and top-down modes of processing exert different effects on pain-induced slow and fast oscillatory activities. Future studies may examine pain-induced oscillations using this paradigm to test for altered attentional pain control in patients with chronic pain.

Inverse electron demand Diels-Alder cycloadditions have proven to be extremely useful for mild and additive-free orthogonal labeling of biomolecules, amongst others, for RNA labeling in vitro and in a cellular context. Here we present a method for site-specific introduction of an alkene modification into RNA via T7 in vitro transcription. For this, an unnatural, hydrophobic base pairing system developed by Romesberg and coworkers was modified introducing one or two norbornene moieties at predefined positions into RNA oligonucleotides in an in vitro transcription reaction. This allows post-transcriptional functionalization of these RNA molecules with tetrazine derivatives containing for instance fluorophores or biotin.

Objective: The aim of arthroscopically assisted treatment of tibial plateau fractures is to achieve minimally invasive reduction and internal fixation of the joint fracture of the tibial plateau. Using the arthroscopic procedure, both the approach morbidity and the control of the articular reduction can be optimized., Indications: Displaced tibia plateau fractures of AO type A1 and B1/2/3 or Tscherne P2., Contraindications: Strongly displaced tibial plateau fractures, which require an open surgical approach and stabilization with plate fixation (e.g., AO type C fractures or Moore type 5 fractures); 2nd and 3rd degree open fractures. Danger of compartment syndrome., Surgical Technique: Planning of the surgical approach and confirmation of the indication by CT imaging. Diagnostic arthroscopy of the knee joint with treatment of associated injuries and confirming the indications for arthroscopically assisted reduction. Under arthroscopic control, insertion of an ACL tibial aiming device. In the central portion of the dislocated fracture fragment, a 2.4 mm K-wire is placed with the help of the aiming device. Opening of the outer cortex using a cannulated drill (9-11 mm diameter), introduction of a cannulated plunger below the fracture resulting in reduction of the fracture and compression of the cancellous bone below the fracture. Simultaneously the reduction is controlled by arthroscopy. Finally, the fracture is fixed using minimally invasive screw fixation (3.5-7.3 mm cancellous screws with washers) or by plate osteosynthesis (e.g., support plate). The metaphyseal defect can optionally be filled with bone substitute material., Postoperative Management: Rehabilitation is dependent on the extent of the fracture. In arthroscopically treated fractures, partial weight bearing of 20 kg over a period of 6-12 weeks is usually necessary.

Background: The aim of this study was to analyze the structural properties of the original MPFL and to compare it to a MPFL-reconstruction-technique using a strip of quadriceps tendon., Methods: In 13 human cadaver knees the MPFLs were dissected protecting their insertion at the patellar border. The MPFL was loaded to failure after preconditioning with 10 cycles in a uniaxial testing machine evaluating stiffness, yield load and maximum load to failure. In the second part Quadriceps-MPFL-reconstruction was performed and tested in a uniaxial testing machine. Following preconditioning, the constructs were cyclically loaded 1000 times between 5 and 50 N measuring the maximum elongation. After cyclic testing, the constructs have been loaded to failure measuring stiffness, yield load and maximum load. For statistical analysis a repeated measures (RM) one-way ANOVA for multiple comparisons was used. The significance was set at P<0.05., Results: During the load to failure tests of the original MPFL the following results were measured: stiffness 29.4 N/mm (+9.8), yield load 167.8 N (+80) and maximum load to failure 190.7 N (+82.8). The results in the QT-technique group were as follows: maximum elongation after 1000 cycles 2.1 mm (+0.8), stiffness 33.6 N/mm (+6.8), yield load 147.1 N (+65.1) and maximum load to failure 205 N (+77.8). There were no significant differences in all tested parameters., Conclusions: In a human cadaveric model using a strip of quadriceps-tendon 10 mm wide and 3mm deep, the biomechanical properties match those of the original MPFL when tested as a reconstruction., Clinical Relevance: The tested QT-technique shows sufficient primary stability with comparable biomechanical parameters to the intact MPFL., (Copyright © 2014. Published by Elsevier B.V.)

Inverse electron demand Diels-Alder cycloadditions are extremely useful tools for orthogonal labeling of biomolecules such as proteins or small molecules in a cellular context. In-cell labeling of dienophile-modified RNA oligonucleotides using Diels-Alder cycloaddition reactions has not been demonstrated before. In this study we report site-specific labeling of RNA oligonucleotides modified with norbornene derivatives at a predefined sequence position within an RNA sequence in vitro and in mammalian cells using various tetrazine-fluorophore conjugates. The approach could in future be used as a chemical tool for the detection and investigation of RNA functions in cells minimizing the presumed distortion of RNA functions by a large chemical reporter group such as a fluorophore.