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Background: With an increasing number of primary anterior cruciate ligament reconstructions (ACLRs), the burden of revision ACLR (rACLR) has also increased. Graft choice for rACLR is complicated by patient factors and the remaining available graft options. Purpose: To examine the association between graft type at the time of rACLR and the risk of repeat rACLR (rrACLR) in a large US integrated health care system registry while accounting for patient and surgical factors at the time of revision surgery. Study Design: Cohort study; Level of evidence, 3. Methods: Data from the Kaiser Permanente ACLR registry were used to identify patients who underwent a primary isolated ACLR between 2005 and 2020 and then went on to have rACLR. Graft type used at rACLR, classified as autograft versus allograft, was the exposure of interest. Multivariable Cox proportional hazard regression was used to evaluate the risk of rrACLR, with ipsilateral and contralateral reoperation as secondary outcomes. Models included factors at the time of the rACLR (age, sex, body mass index, smoking status, staged revision, femoral fixation, tibial fixation, femoral tunnel method, lateral meniscal injury, medial meniscal injury, and cartilage injury) and a factor from the primary ACLR (activity at injury) as covariates. Results: A total of 1747 rACLR procedures were included. The crude cumulative rrACLR incidence at 8-year follow-up was 13.9% for allograft and 6.0% for autograft. Cumulative ipsilateral reoperation incidence at 8-year follow-up was 18.3% for allograft and 18.9% for autograft; contralateral reoperation cumulative incidence was 4.3% for allograft and 6.8% for autograft. With adjustment for covariates, a 70% lower risk for rrACLR was observed for autograft compared with allograft (hazard ratio [HR], 0.30; 95% CI, 0.18-0.50; P < .0001). No differences were observed for ipsilateral reoperation (HR, 1.05; 95% CI, 0.73-1.51; P = .78) or contralateral reoperation (HR, 1.33; 95% CI, 0.60-2.97; P = .48). Conclusion: The use of autograft at rACLR was associated with a 70% lower risk of rrACLR compared with allograft in this cohort from the Kaiser Permanente ACLR registry. When accounting for all reoperations outside of rrACLR after rACLR, the authors found no significant difference in risk between autograft and allograft. To minimize the risk of rrACLR, surgeons should consider using autograft for rACLR when possible.

Excessive fracture site collapse and shortening in intertrochanteric femur fractures alter hip biomechanics and patient outcomes. The purpose of the study was to compare extent of collapse in cephalomedullary nails with blades or lag screws. We hypothesized that there would be no difference in collapse between helical blades and lag screws. Retrospective cohort study. Single U.S. Level I Trauma Center. 171 consecutive patients treated with cephalomedullary nails with either lag screw or blade for AO/OTA 31A1-3 proximal femur fractures and minimum 3-month follow-up. Lag screw or helical blade in a cephalomedullary nail. The primary outcome was fracture site collapse at 3 months. There was a significantly higher proportion of reverse-oblique and transverse intertrochanteric femur fractures (31-A3) in the lag screw group (15/42 vs 25/129). A3 patterns were associated with more collapse. There was significantly less collapse in the blade group (median 4.7 mm, inter-quartile range 2.5–7.8 mm) than the screw group (median 8.4 mmm, inter-quartile range 3.7–11.2 mm, p 0.006). Median collapse was no different between blades and screws when comparing stable and unstable patterns. However, blades were independently associated with 2.5 mm less collapse (95%CI − 4.2, − 0.72 mm, p 0.006) and lower likelihood of excessive collapse (> 10 mm at 3 months, OR 0.3, 95% CI 0.13–0.74, p 0.007), regardless of fracture pattern. Helical blades are independently associated with significantly less collapse than lag screws in intertrochanteric proximal femur fractures, after adjusting for unstable fracture patterns. In fracture patterns at risk for collapse, surgeons can consider use of a helical blade due to its favorable sliding properties compared to screws.

Objectives: With the rising utilization of primary anterior cruciate ligament reconstruction (ACLR), the burden of revision ACLR (rACLR) has also increased. Graft choice for rACLR is complicated by patient factors and the remaining available graft options. This study examines the relationship between graft type at the time of rACLR and the risk of repeat rACLR (rrACLR). Methods: We conducted a cohort study from a US integrated healthcare system’s ACLR registry. The study population included patients with a primary isolated ACLR, between 2005-2020, who then went on to have an aseptic rACLR. Graft type used at revision surgery, classified as autograft versus allograft, was the exposure of interest. Multivariable Cox proportional hazard regression was used to evaluate the risk of aseptic rrACLR with ipsilateral and contralateral reoperation as secondary outcomes. Models included factors at the time of the revision procedure (age, gender, body mass index, smoking status, staged revision, femoral fixation, tibial fixation, femoral tunnel method, lateral meniscus injury, medial meniscus injury, and cartilage injury) and a factor from the primary ACLR (activity at injury) as covariates. Results: 1747 rACLR procedures were included. The crude cumulative aseptic rrACLR incidence at 8-years follow-up was 13.9% for allograft and 6.0% for autografts (Figure 1). Cumulative ipsilateral reoperation incidence at 8-years follow-up was 18.3% for allograft and 18.9% for autograft; contralateral reoperation cumulative incidence was 4.3% for allograft and 6.8% for autograft. With adjustment for covariates, a lower aseptic rrACLR risk was observed for autografts compared with allografts (HR=0.30, 95% CI=0.18-0.50, p Conclusions: The use of autograft at rACLR was associated with a 70% reduced risk of rrACLR compared to allograft in this large integrated health care system registry. When accounting for all reoperations after rACLR, we found no significant difference in risk between autograft and allograft. In order to minimize the risk of rrACLR, surgeons should consider using autograft for rACLR when possible. [Figure: see text]

Introduction: Bridge plating of distal femur fractures with lateral locking plates is susceptible to varus collapse, fixation failure, and nonunion. While medial and lateral dual plating has been described in clinical series, the biomechanical effects of dual plating of distal femur fractures have yet to be clearly defined. The purpose of this study was to compare dual plating to lateral locked bridge plating alone in a cadaveric distal femur gap osteotomy model. Materials and Methods: Gap osteotomies were created in eight matched pairs of cadaveric female distal femurs (average age: 64 yrs (standard deviation ± 4.4 yrs); age range: 57–68 yrs;) to simulate comminuted extraarticular distal femur fractures (AO/OTA 33A). Eight femurs underwent fixation with lateral locked plates alone and were matched with eight femurs treated with dual plating: lateral locked plates with supplemental medial small fragment non-locking fixation. Mechanical testing was performed on an ElectroPuls E10000 materials testing system using a 10 kN/100 Nm biaxial load cell. Specimens were subject to 25,000 cycles of cyclic loading from 100-1000 N at 2 Hz. Results: Two (2/8) specimens in the lateral only group failed catastrophically prior to completion of testing. All dual plated specimens survived the testing regimen. Dual plated specimens demonstrated significantly less coronal plane displacement (median 0.2 degrees, interquartile range [IQR], 0.0–0.5 degrees) compared to 2.0 degrees (IQR 1.9-3.3, p = 0.02) in the lateral plate only group. Dual plated specimens demonstrated greater bending stiffness compared to the lateral plated group (median 29.0 kN/degree, IQR 1.5–68.2 kN/degree vs median 0.50 kN/degree, IQR 0.23–2.28 kN/degree, p = 0.03). Conclusion: Contemporary fixation methods with a distal femur fractures are susceptible to mechanical failure and nonunion with lateral plates alone. Dual plate fixation in a cadaveric model of distal femur fractures underwent significantly less displacement under simulated weight bearing conditions and demonstrated greater stiffness than lateral plating alone. Given the significant clinical failure rates of lateral bridge plating in distal femur fractures, supplemental fixation should be considered, and dual plating of distal femurs augments mechanical stability in a clinically relevant magnitude.

Excessive fracture site collapse and shortening in intertrochanteric femur fractures alter hip biomechanics and patient outcomes. The purpose of the study was to compare extent of collapse in cephalomedullary nails with blades or lag screws. We hypothesized that there would be no difference in collapse between helical blades and lag screws.Retrospective cohort study.Single U.S. Level I Trauma Center.171 consecutive patients treated with cephalomedullary nails with either lag screw or blade for AO/OTA 31A1-3 proximal femur fractures and minimum 3-month follow-up.Lag screw or helical blade in a cephalomedullary nail.The primary outcome was fracture site collapse at 3 months.There was a significantly higher proportion of reverse-oblique and transverse intertrochanteric femur fractures (31-A3) in the lag screw group (15/42 vs 25/129). A3 patterns were associated with more collapse. There was significantly less collapse in the blade group (median 4.7 mm, inter-quartile range 2.5-7.8 mm) than the screw group (median 8.4 mmm, inter-quartile range 3.7-11.2 mm, p 0.006). Median collapse was no different between blades and screws when comparing stable and unstable patterns. However, blades were independently associated with 2.5 mm less collapse (95%CI - 4.2, - 0.72 mm, p 0.006) and lower likelihood of excessive collapse ( 10 mm at 3 months, OR 0.3, 95% CI 0.13-0.74, p 0.007), regardless of fracture pattern.Helical blades are independently associated with significantly less collapse than lag screws in intertrochanteric proximal femur fractures, after adjusting for unstable fracture patterns. In fracture patterns at risk for collapse, surgeons can consider use of a helical blade due to its favorable sliding properties compared to screws.

The lag screw or helical blade of a cephalomedullary nail facilitates controlled collapse of intertrochanteric proximal femur fractures. However, excessive collapse results in decreased hip offset and symptomatic lateral implants. Countersinking the screw or helical blade past the lateral cortex may minimize subsequent prominence, but some surgeons are concerned that this will prevent collapse and result in failure through cutout. We hypothesized that patients with countersunk lag screws or helical blades do not experience higher rates of screw or blade cutout and have less implant prominence after fracture healing.A retrospective review of 175 consecutive patients treated with cephalomedullary nails for AO/OTA 31A1-3 proximal femur fractures and a minimum 3-month follow-up and 254 patients with a 6-week follow-up at a single US level I trauma center. Patients were stratified based on countersunk versus noncountersunk lag screw or helical blade in a cephalomedullary nail. The primary outcome was the cutout rate at minimum 3 months, and the secondary outcome was radiographic collapse at minimum 6 weeks.Cutout rates were no different in patients with countersunk and noncountersunk screws and blades, and countersinking was associated with less collapse and less implant prominence at 6 weeks.Surgeons can countersink the lag screw or blade when treating intertrochanteric proximal femur fractures with a cephalomedullary nail without increasing failure rates and with the potential benefits of less prominent lateral implants and decreased collapse.

We present measurements of azimuthal correlations of charged hadron pairs in sNN=200 GeV Au+Au collisions for the trigger and associated particle transverse-momentum ranges of 14GeV/c) correlations is suppressed compared with that of correlations measured in p+p collisions. At the lowest associated particle pT(0.5

Neutrinoless double beta decays in liquid xenon produce a significant amount of Cherenkov light, with a photon number and angular distribution that distinguishes these events from common backgrounds. A GEANT4 simulation was used to simulate Cherenkov photon production and measurement in a liquid xenon detector and a multilayer perceptron was used to analyze the resulting distributions to classify events based on their Cherenkov photons. Our results show that a modest improvement in the sensitivity of neutrinoless double beta decay searches is possible using this technique, but the kinematics of the neutrinoless double beta decay and electron scattering in liquid xenon substantially limit this approach., 13 pages, 8 figures, 2 tables

The MICROMEGAS (MICRO-MEsh GAseous Structure) charge amplification structure has found wide use in many detection applications, especially as a gain stage for the charge readout of Time Projection Chambers (TPCs). Here we report on the behavior of a MICROMEGAS TPC when operated in a high-energy (up to 800 MeV ) neutron beam. It is found that neutron-induced reactions can cause discharges in some drift gas mixtures that are stable in the absence of the neutron beam. The discharges result from recoil ions close to the MICROMEGAS that deposit high specific ionization density and have a limited diffusion time. For a binary drift gas, increasing the percentage of the molecular component (quench gas) relative to the noble component and operating at lower pressures generally improves stability.

Measurements of double-helicity asymmetries in inclusive hadron production in polarized p+p collisions are sensitive to helicity-dependent parton distribution functions, in particular to the gluon helicity distribution, {Delta}g. This study focuses on the extraction of hte double-helicity asymmetry in {eta} production (p+p{yields}{eta}+X), the {eta} cross section, and the {eta}/{pi}{sup 0} cross section ratio. The cross section and ratio measurements provide essential input for the extraction of fragmentation functions that are needed to acess the helicity-dependent parton distribution functions.

The Relativistic Heavy Ion Collider (RHIC), as the world's first and only polarized proton collider, offers a unique environment in which to study the spin structure of the proton. In order to study the proton's transverse spin structure, the PHENIX experiment at RHIC took data with transversely polarized beams in 2001-02 and 2005, and it has plans for further running with transverse polarization in 2006 and beyond. Results from early running as well as prospective measurements for the future will be discussed., Comment: 6 pages, 2 figures, presented at Transversity 2005, Como, Italy