A multi-platform approach for the comprehensive analysis of per- and polyfluoroalkyl substances (PFAS) and fluorine mass balance in commercial ski wax products.

The unique properties of per- and polyfluoroalkyl substances (PFAS) have led to their extensive use in consumer products, including ski wax. Based on the risks associated with PFAS, and to align with PFAS regulations, the international ski federation (FIS) implemented a ban on products containing "C8 fluorocarbons/perfluorooctanoate (PFOA)" at all FIS events from the 2021/2022 season, leading manufactures to shift their formulations towards short-chain PFAS chemistries. To date, most studies characterising PFAS in ski waxes have measured a suite of individual substances using targeted analytical approaches. However, the fraction of total fluorine (TF) in the wax accounted for by these substances remains unclear. In this study, we sought to address this question by applying a multi-platform, fluorine mass balance approach to a total of 10 commercially available ski wax products. Analysis of TF by combustion ion chromatography (CIC) revealed concentrations of 1040-51700 µg F g-1 for the different fluorinated waxes. In comparison, extractable organic fluorine (EOF) determined in methanol extracts by CIC (and later confirmed by inductively-coupled plasma-mass spectrometry and 19F- nuclear magnetic resonance spectroscopy) ranged from 92 to 3160 µg g-1, accounting for only 3-8.8 % of total fluorine (TF). Further characterisation of extracts by cyclic ion mobility-mass spectrometry (IMS) revealed 15 individual PFAS with perfluoroalkyl carboxylic acid concentrations up to 33 µg F g-1, and 3 products exceeding the regulatory limit for PFOA (0.025 µg g-1) by a factor of up to 100. The sum of all PFAS accounted for only 0.01-1.0 % of EOF, implying a high percentage of unidentified PFAS, thus, pyrolysis gas chromatography-mass spectrometry was used to provide evidence of the nature of the non-extractable fluorine present in the ski wax products.

Determination of total extractable organofluorine (EOF) in food contact materials and target and non-target analysis of per- and polyfluoroalkyl substances using LC-MS/MS and LC-HRMS simultaneously coupled to ICP-MS.

Food contact materials (FCMs) from three countries were analysed for all extractable organofluorines (EOFs) from the materials and subsequently by target and non-target analysis for per- and polyfluoroalkyl substances (PFAS). The EOF varied by two orders of magnitude for FCM from UK and Saudi Arabia ranging between 2.14 and 483 ng cm-2 (0.2-48 ng g-1) showing that one quarter of all samples were above the Danish regulation for PFAS in FCM. Target PFAS showed high variability in composition and accounted for less than 1% of the EOF. Non-target PFAS screening using HPLC-ICP-MS and coupled simultaneously to HRMS showed the occurrence of organofluorines which were identified by neither LC-MS/MS nor LC-HRMS. This illustrates that the current target PFAS approaches fail to identify EOFs from FCM, which would be a problem with the new EU proposal to ban all PFAS.

Analysis of per- and polyfluoroalkyl substances (PFAS) in raw materials intended for the production of paper-based food contact materials - evaluating LC-MS/MS versus total fluorine and extractable organic fluorine.

Per- and polyfluoroalkyl substances (PFAS) analysis has become crucial due to their presence in the environment, their persistence and potential health risks. These compounds are commonly used in food contact materials (FCM) as a coating to provide water and grease-repellent properties. One of the pathways for PFAS to enter the human body is either through direct consumption of contaminated food or indirectly through migration from FCM into food. The purpose of this study was to investigate where the initial contamination of paper FCM occurs. We analysed paper material consisting of fresh fibre and secondary materials, intended to produce food packaging for the presence of PFAS. The samples were extracted and analysed for 23 different PFAS substances using the targeted approach with LC tandem mass spectrometry (LC-MS/MS). This analytical technique detects specific, easily ionisable PFAS with high sensitivity. However, one drawback of this approach is that it allows the identification of less than 1% of the PFAS known today. For this reason, we used combustion ion chromatography (CIC) to determine the content of extractable organic fluorine compounds (EOF) and compare it to the total fluorine content. The targeted analysis using LC-MS/MS measured an average sum concentration of PFAS of 0.17 ng g-1 sample. Our research shows that the primary PFAS contamination happens during the recycling process since all of the samples in which the targeted PFAS were measured belonged to the secondary material. The most frequently detected analytes were PFOA and PFOS, detected in 90% and 62% of the samples, respectively, followed by PFBS (in 29% of the samples). CIC showed that measured PFAS via LC-MS/MS amount to an average of 2.7 × 10-4% of total fluorine content, whereas the EOF was under the LOD in all of the measured samples. This result highlights the complexity of the accurate determination of PFAS compounds, displaying what kind of information the chosen methods provide.

Fluorine mass balance analysis in wild boar organs from the Bohemian Forest National Park.

Wild boars have been reported as bioindicators for per- and polyfluoroalkyl substances (PFAS) in a variety of studies. However, data about PFAS levels in wild boars from sites with limited industrial and general human activity is scarce. In this study, wild boar (Sus scrofa) organs from the Bohemian Forest National Park (Czech Republic) were used as bioindicators for PFAS pollution. In this work, 29 livers and 24 kidneys from 30 wild boars (0.5-5 years) were investigated using a fluorine mass balance approach. For this, the samples were measured using high performance liquid chromatography with electrospray ionisation tandem mass spectrometry (HPLC-ESI-MS/MS), targeting 30 PFAS, including legacy and replacement PFAS, direct total oxidisable precursor assay (dTOPA) and combustion ion chromatography (CIC). Perfluorocarboxylic acids (PFCAs) from C7 to C14 and perfluorooctanesulfonic acid (PFOS) were detected in >50 % of samples. In the livers, PFCAs dominated the profile with median concentrations of 230 µg/kg for perfluorononanoic acid (PFNA) and 75 µg/kg perfluorooctanoic acid (PFOA). PFOA and PFNA concentrations in the livers were one order of magnitude higher than in livers from wild boars caught in rural NE Germany considered as background concentration. PFOS in liver contributed only 30 % to the Σc(PFASTarget) with a median concentration of 170 µg/kg. Kidneys and livers contain an average of 2460 µg F/kg and 6800 µg F/kg extractable organic fluorine (EOF) respectively. Σc(PFASTarget) add up to a maximum of 10 % of the extractable organic fluorine. After oxidisation of the samples, PFOA, PFNA and Σc(PFASdTOPA) increased in livers, but could not explain the EOF. The elevated concentration of PFOA and PFNA may indicate differences in biomagnification for different habitats or an unidentified PFAS source in proximity to the national park.

GenX uptake by wheat and rice in flooded and non-flooded soils: a greenhouse experiment.

GenX (hexafluoropropylene oxide dimer acid) belongs to the group of per- and poly-fluoroalkyl substance (PFAS) compounds introduced to replace perfluorooctanoic acid (PFOA), which has been phased out in industrial and consumer product formulations. While GenX has been investigated in lab animals, there is limited information available regarding its uptake and translocation in wheat and rice. This study reports on a greenhouse experiment in which wheat and rice grown under flooded and non-flooded conditions were exposed to two GenX concentrations in the soil (0.4 mg kg-1 and 2 mg kg-1). GenX was analysed in the soil, porewater and shoots using targeted liquid chromatography-tandem mass spectroscopy (LC-MS/MS) analysis. Extractable organic fluorine (EOF) was determined using high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-GFMAS) instrument. Results showed that different species took up different amounts of GenX. The GenX concentration in rice shoots was found to be 2.34 (± 0.45) and 4.11 (± 0.87) µg g-1 under flooded and non-flooded conditions, respectively, at a low exposure level. At high exposure, the GenX concentrations in flooded and non-flooded rice shoots increased threefold to 10.4 (± 0.41) and 13.4 (± 0.72) µg g-1, respectively. Wheat shoots showed similar concentrations and increases between low- and high-level exposure. The translocation factor was significantly higher (P = 0.013) in non-flooded rice compared to flooded rice. The GenX bioaccumulation behaviours under the same culture conditions (e.g. temperature, humidity, light, same GenX concentration in the soil) were significantly different in non-flooded and flooded rice (P < 0.001). Non-flooded rice plants displayed a higher level of GenX bioaccumulation than flooded ones. Following exposure to GenX, flooded rice plants showed a reduction in biomass (25%) compared to the control plants (P < 0.014). Our findings indicate that GenX is a bioaccumulative compound, the presence of which likely inhibits the growth of plants.

Per and polyfluoroalkylated substances (PFAS) target and EOF analyses in ski wax, snowmelts, and soil from skiing areas.

Per and polyfluoroalkylated substances (PFAS) are common additives in ski waxes for their water repellent characteristic. Abrasion of ski wax leaves PFAS on the snow surface, however, little is known about the distribution and concentration of PFAS in snow and soil due to skiing. In this study we analysed different ski waxes, snowmelts and soil from family skiing areas from Alpine locations using targeted high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) to understand more about PFAS distribution in the environment. In general, we found a very diverse PFAS pattern in the analysed media. PFAS level was higher in skiing areas compared to the non-skiing ones that were used as control. ∑target PFAS ranged between <1.7 ng L-1 and 143 ng L-1 in snowmelt, <0.62 ng g-1 and 5.35 ng g-1 in soil and <1.89 and 874 ± 240 ng g-1 in ski wax samples. Snowmelt was dominated by short-chained PFAS, while soil and wax contained both short and long-chained PFAS. Extractable organic fluorine (EOF) was several orders of magnitude higher for waxes (0.5-2 mg g-1) than for soils (up to 0.3 µg g-1), while total fluorine (TF) content of the waxes was even higher, up to 31 210 ± 420 µg g-1. We also showed that the ∑ target PFAS accounts for up to 1.5% in EOF content, showing that targeted LC-MS/MS gives a limited measure of the pollution originated from ski waxes and non-targeted analysis and EOF is necessary for a better overview on PFAS distribution.

Fluorine mass balance analysis of PFAS in communal waters at a wastewater plant from Austria.

Wastewater treatment plants are a major source of per and polyfluoroalkyl substances (PFAS) in the environment; moreover, long chain PFAS are known to accumulate in sewage sludge. Although publications on PFAS in wastewater are available from around the globe, little information is available from Central Europe. In this study influent, effluent, and sludge from two wastewater treatment plants from Austria were analysed for target PFAS compounds with HPLC MS/MS and extractable organic fluorine (EOF) content with combustion ion chromatography (CIC). The sum of 31 target PFAS increased from 22 to 47 ng L-1 in influent to 140 - 213 ng L-1 in effluent and around 10 ng g-1 in sludge, while EOF were found to be consistent (2.3 - 3.5 µg F L-1) in influent/effluent and 280 ng F g-1 in sludge. Mass balance analysis showed an increase in the identified PFAS compounds in the effluent compared to the influent (from 0.9% - 1.3% to 3.6% - 6.1%), suggesting biotransformation of non-targeted PFAS precursor compounds. In conclusion, wastewater treatment plants transform some PFAS, and wastewater effluent is a source of PFAS contamination in surface water.

Apheresis for chimeric antigen receptor T-cell production in adult lymphoma patients.

BACKGROUND: To date, in-depth analysis of leukapheresis products as starting material for CAR T-cell manufacturing, specifically Tisagenlecleucel production, are scarce. In this study, we report on lymphapheresis data for production of Tisagenlecleucel for elderly and pretreated lymphoma patients. STUDY DESIGN AND METHODS: Spectra Optia from Terumo BCT, Lakewood, CO, was employed for apheresis using the cMNC program. Apheresis success was defined as meeting a target total nucleated cell (TNC) count of ≥2 × 109 , a CD3-positive lymphocyte count of ≥1 × 109 and an overall viability of ≥70% in the lymphapheresis product. RESULTS: Twenty-three patients (age 37-77 years) and 24 apheresis runs were evaluated. The median CD3-positive lymphocyte count in peripheral blood at the beginning of apheresis was 565 cells/µl (range: 70-1345 cells/µl). Circulating lymphoma cells were detected in one patient prior to apheresis. Target criteria were met in 21 of 23 patients. The median TNC count in the apheresate was 11.2 × 109 (range: 2.9 × 109 -47.4 × 109 ). The median CD3-positive lymphocyte count in the apheresate was 2.55 × 109 (range: 0.370 × 109 -6.915 × 109 ), which resulted in a median collection efficiency for CD3-positive lymphocytes of 63.7% (range: 9.56%-93.6%). No adverse events associated with the apheresis process were observed. CONCLUSIONS: Lymphapheresis with the Spectra Optia cMNC program provided a sufficient quantity of CD3-positive lymphocytes for CAR T-cell manufacturing for the majority of patients despite their heavy pretreatment and advanced age. Moreover, we are the first to advocate early pre-emptive lymphocyte collection in DLBCL-NOS patients intended to undergo treatment with Tisagenlecleucel.

Increasing temperature and flooding enhance arsenic release and biotransformations in Swiss soils.

Reductive dissolution is one of the main causes for arsenic (As) mobilisation in flooded soils while biomethylation and biovolatilisation are two microbial mechanisms that greatly influence the mobility and toxicity of As. Climate change results in more extreme weather events such as flooding and higher temperatures, potentially leading to an increase in As release and biotransformations. Here, we investigated the effects of flooding and temperature on As release, biomethylation and biovolatilisation from As-rich soils with different pH and source of As (one acidic and anthropogenic (Salanfe) and one neutral and geogenic (Liesberg)). Flooded soils incubated at 23 °C for two weeks showed a ~ 3-fold (Liesberg site) and ~ 7-fold (Salanfe site) increase in the total As concentration of soil solution compared to those incubated at 18 °C. Methyl- and thio-As species were found in the acidic soil and soil solution. High temperatures enhanced thiolation and methylation although inorganic As was predominant. We also show that volatile As fluxes increased more than 4-fold between treatments, from 18 ± 5 ng/kg/d at 18 °C to 75 ± 6 ng/kg/d at 23 °C from Salanfe soil. Our results suggest that high As soils with acidic pH can become an important source of As to the surrounding environment according to realistic climatic scenarios, and that biovolatilisation is very sensitive to increases in temperature. This study provides new data and further justifies further investigations into climate-induced changes on As release and speciation and its links to important factors such as microbial ecology and sulfate or iron biogeochemistry. SYNOPSIS: In the studied Swiss soils, elevated temperature increases arsenic mobility through volatilisation and methylation.

[Sleep behavior and problems in children and adolescents of a psychiatric day clinic sample: results and requirements for systematic diagnostic]. / Schlafverhalten und -auffälligkeiten von Kindern und Jugendlichen einer teilstationären kinder- und jugendpsychiatrischen Inanspruchnahmepopulation: Ergebnisse und Anforderungen an eine systematische Diagnostik.

Sleep behavior and problems in children and adolescents of a psychiatric day clinic sample: results and requirements for systematic diagnostic Abstract. Sleep disorders are common in adults as well as children and adolescents. Children and adolescents in psychiatric treatment (CAP) are especially affected by sleep problems. Cognitive behavioral therapy represents the first-line treatment, preceded by a standardized procedure for sleep diagnostics. To date, no study has investigated sleep behavior in CAP day clinics in Germany. In this study, N = 46 children/adolescents receiving CAP treatment in a day clinic completed a sleep diary (7 days) and a sleep anamnesis scheme with the help of their parents, and their sleep behavior was assessed by a clinician. Furthermore, a parent- and a self-report questionnaire plus a clinical assessment of the mental disorders in the children/adolescents were collected. 52 % of the children/ adolescents exhibited sleep disorders or sleep abnormalities (= sleep disorder symptoms in the context of comorbid disorders), in particular problems falling asleep or to falling asleep and sleeping through the night (26 %). In addition, 33 % reported having nightmares. Their sleep behavior correlated significantly with their external behavior problems (r = .38 .61, p = .02-.04); their sex (female: p = .01-≤ .001, |d| = 1.57-2.50) and their age (older: p = .05, |d| = .78) also significantly influenced sleep behavior. Particularly external behavior problems were associated with sleep problems in this day-care population. In summary, a multi-method-multi-informant procedure should be established for the systematic diagnostics of sleep abnormalities, together with individualized cognitive-behavioral therapy of sleep problems, especially in patients with external behavior problems.

Diurnal variations in flow density measured using optical coherence tomography angiography and the impact of heart rate, mean arterial pressure and intraocular pressure on flow density in primary open-angle glaucoma patients.

PURPOSE: To determine the diurnal variations in peripapillary and macular flow density (FD), as measured using optical coherence tomography angiography (OCTA) and to elaborate on the relationship between diurnal FD, circulatory parameters and intraocular pressure (IOP) variations in primary open-angle glaucoma (POAG). METHODS: Forty eyes of 40 POAG patients were drawn into this cross-sectional study. The retinal microvasculature of the macula (superficial and deep layers) and optic nerve [radial peripapillary capillary (RPC)] was examined by OCTA (AngioVue® , Optovue). Optical coherence tomography angiography (OCTA) measurements were conducted at 08:00, 11:00, 15:00 and 20:00 over the course of two consecutive days. Intraocular pressure (IOP) and circulatory parameters were assessed accordingly. Diurnal variations in FD were analysed using linear mixed models. RESULTS: While superficial macular FD and RPC FD revealed not to be affected by diurnal variations (p = 0.492, p = 0.319), FD in the deep layer of the macula increased throughout the day (p < 0.001). Superficial macular FD was influenced significantly by mean arterial pressure (MAP) (p = 0.006) and heart rate (HR) (p = 0.033), whereas FD in the RPC layer was significantly affected by HR (p = 0.010). No statistically significant effect of IOP fluctuations on FD was observed. CONCLUSION: This study shows diurnal fluctuations of deep macular FD measured by OCTA and outlines the relationship between FD and hemodynamic parameters (MAP/HR) in POAG patients.

Predicting attention deficit hyperactivity disorder using pregnancy and birth characteristics.

PURPOSE: The aim of this study was to evaluate maternal, prenatal, perinatal, and postpartum parameters as risk factors for the later development of an attention deficit hyperactivity disorder (ADHD) in the child. METHODS: Women who had given birth at Erlangen University Hospital between 1996 and 1999 were sent a questionnaire in 2009. The results of the questionnaire were correlated with the prospectively collected data for the births in 1996-1999. RESULTS: A total of 573 mother and child pairs were analyzed. Forty-four of the mothers reported that their child had ADHD (7.7%). No significant associations were found for the following parameters: mother's age; mother's educational level; number of the pregnancy; maternal weight before and at the end of pregnancy; mother's height; alcohol consumption during pregnancy; mode of delivery; gestational week; birthweight; umbilical artery blood values; Apgar score at 5 and 10 min; or breastfeeding. The parameters of smoking in pregnancy and an Apgar score lower than 7 after 1 min were significantly associated with a risk for later development of ADHD. CONCLUSIONS: This analysis of maternal, prenatal, perinatal, and postnatal parameters found that smoking in pregnancy and a low Apgar score 1 min after birth are associated with a significantly greater risk for the development of ADHD. Beyond the question of the causal mechanism involved, this is a relevant finding, since smoking during pregnancy is a preventable risk factor.

Resorbable and running suture for stable fixation of amniotic membrane multilayers: A useful modification in deep or perforating sterile corneal ulcers.

PURPOSE: To present a modified technique for secure tightening and fixing of multilayer amniotic membranes in deep or perforating corneal ulcers. OBSERVATIONS: The modified procedure for application and fixation of multilayer amniotic membranes is retrospectively described step by step, and the results of three patients treated with this technique were retrospectively analysed and presented.The modification consists basically in fixing the inlays with one mini-overlay that is sutured intracorneally with resorbable and running Vicryl 10.0, before a corneoscleral overlay is fixed on top conjunctivally with a running nylon 10.0 suture. The resorbable Vicryl suture is left in place permanently. CONCLUSIONS AND IMPORTANCE: The method described avoids any risk of destroying or displacing the inlays by removing sutures later. In each of the three patients demonstrated as case reports the cornea remained stable throughout the 3- to 5-month follow-up period. This modified technique represents a very useful auxiliary means of treating deep or perforating non-infectious corneal ulcers.

Changes in Flow Density Measured Using Optical Coherence Tomography Angiography after iStent Insertion in Combination with Phacoemulsification in Patients with Open-Angle Glaucoma.

PURPOSE: To evaluate changes in flow density after the implantation of a trabecular microbypass stent (iStent) in combination with cataract surgery. METHODS: A total of 48 eyes of 48 patients, who underwent either cataract surgery alone (cataract group) or cataract surgery with implantation of two iStent inject devices (iStent group), were prospectively included in this study. Intraocular pressure (IOP) and flow density data before and after surgery were extracted and analyzed. RESULTS: In the iStent group, the mean IOP was 18.2 ± 3.3 mmHg prior to surgery and 13.2 ± 2.3 at follow-up, and this difference was statistically significant (p < 0.001). The mean IOP in the cataract group also improved significantly after surgery (before: 17.1 ± 2.4; after: 15.1 ± 2.7 p = 0.003). The flow density (whole en face) in the superficial and deep retinal OCT angiogram of the macula (superficial: p = 0.002; deep: p = 0.034) and in the ONH (p = 0.011) improved significantly after surgery in the iStent group. The differences in the cataract group were not significant. CONCLUSIONS: Flow density of the macula and ONH, as measured by OCTA, improved significantly after cataract surgery with iStent. Noninvasive quantitative analyses of flow density provide a new parameter, which can help for the monitoring of therapy success after glaucoma surgery.

Correlation of flow density, as measured using optical coherence tomography angiography, with structural and functional parameters in glaucoma patients.

PURPOSE: To evaluate the correlation between flow density, as measured by optical coherence tomography angiography (OCTA), and structural and functional parameters in patients with open-angle glaucoma. METHODS: Thirty-four eyes of 34 patients with open-angle glaucoma and 35 eyes of 35 healthy subjects were prospectively included in this study. OCTA was performed using RTVue XR Avanti with AngioVue. The macula was imaged with a 3 × 3 mm scan and the optic nerve head (ONH) with a 4.5 × 4.5 mm scan. Visual field parameters [mean deviation (MD), pattern standard deviation (PSD) and visual field index (VFI)], Bruch's membrane opening minimal rim width (BMO-MRW), retinal nerve fiber layer thickness (RNFLT) and the stereometric parameters rim area, cup/disc area (HRT III, Heidelberg Retina Tomograph, Heidelberg Engineering) were tested for correlation with flow density data. RESULTS: The flow density (whole en face) in the retinal OCT angiograms (superficial: p = 0.01; deep: p = 0.005), in the radial peripapillary capillary network (p < 0.001) and in the OCT angiograms of the optic nerve head (p = 0.004) were significantly lower in the glaucoma group when compared with the control group. The flow density in the RPC network correlated significantly with all functional and structural parameters tested. The strongest correlation was found between the RPC flow density (inside disc) and the BMO-MRW (Spearman's correlation coefficient = 0.912, p < 0.001). CONCLUSIONS: Glaucoma patients showed a reduced ONH and macular perfusion when compared with healthy controls. The flow density as measured by OCTA correlated with structural damage and visual field loss in glaucoma patients. Non-invasive quantitative analyses of flow density using OCTA provide a new parameter describing a different aspect of glaucoma, which could be useful in clinical practice.

[Parenting stress and the reliability of parental information in the diagnostics of children and adolescents with symptoms of psychiatric and behavioral disorders]. / Elterliche Belastung und die Zuverlässigkeit von Elternangaben in der Diagnostik psychisch und verhaltensauffälliger Kinder und Jugendlicher.

Objective: Information from parents is regularly used in the diagnostic process of children and adolescents with psychiatric symptoms. But the reliability of this information is debatable, because the parents' own stress can distort their perceptions of the child's symptoms. Method: For each of N = 68 children and adolescents (11­18 years) who were using mental health services for the first time, we evaluated the ratings of a parent and a professional clinician (internalizing, externalizing symptoms, total-problem score). In addition, parenting stress was scored on the Eltern-Belastungs-Inventars (EBI, Tröster, 2011), which measures both child-related stress and parent-related stress as well as total stress. Results: Highly stressed parent ratings differed more from the clinicians' ratings than the ratings of less stressed parents. Additionally, correlations showed that higher parenting stress resulted in larger differences between the parent's and the clinician's assessments. Multiple regressions proved the predictive value of child-caused parenting stress for these differences. These results apply for internalizing symptoms, externalizing symptoms, and total-problem score. Conclusions: Parenting stress should be evaluated systematically in order to carefully assess the value of the information from parents and to determine how it should be included in diagnostic and therapeutical decisions.

Influence of Different Tibial Fixation Techniques on Initial Stability in Single-Stage Anterior Cruciate Ligament Revision With Confluent Tibial Tunnels: A Biomechanical Laboratory Study.

PURPOSE: To kinematically and biomechanically compare 4 different types of tibial tunnel management in single-stage anterior cruciate ligament (ACL) revision reconstruction with the control: primary ACL reconstruction using a robotic-based knee testing setup. METHODS: Porcine knees and flexor tendons were used. One hundred specimens were randomly assigned to 5 testing groups: (1) open tibial tunnel, (2) bone plug technique, (3) biodegradable interference screw, (4) dilatation technique, and (5) primary ACL reconstruction. A robotic/universal force-moment sensor testing system was used to simulate the KT-1000 (MEDmetric, San Diego, CA) and pivot-shift tests. Cyclic loading and load-to-failure testing were performed. RESULTS: Anterior tibial translation increased significantly with all of the techniques compared with the intact ACL (P < .05). In the simulated KT-1000 test, groups 2 and 3 achieved results equal to those of primary ACL reconstruction (P > .05). The open tunnel and dilated tunnel techniques showed significantly greater anterior tibial translation (P < .05). The results of the simulated pivot-shift test were in accordance with those of the KT-1000 test. No significant differences could be observed regarding stiffness or maximum load to failure. However, elongation was significantly lower in the primary ACL reconstruction group compared with groups 1 and 3 (P = .02 and P = .03, respectively). CONCLUSIONS: Filling an incomplete and incorrect tibial tunnel with a press-fit bone plug or a biodegradable interference screw in a standardized laboratory situation provided initial biomechanical properties and knee stability comparable with those of primary ACL reconstruction. In contrast, the dilatation technique or leaving the malplaced tunnel open did not restore knee kinematics adequately in this model. Backup extracortical fixation should be considered because the load to failure depends on the extracortical fixation when an undersized interference screw is used for aperture fixation. CLINICAL RELEVANCE: Our biomechanical results could help orthopaedic surgeons to optimize the results of primary ACL revision with incomplete, incorrect tunnel placement.