Successful kinetic impact into an asteroid for planetary defence.

Although no known asteroid poses a threat to Earth for at least the next century, the catalogue of near-Earth asteroids is incomplete for objects whose impacts would produce regional devastation. Several approaches have been proposed to potentially prevent an asteroid impact with Earth by deflecting or disrupting an asteroid. A test of kinetic impact technology was identified as the highest-priority space mission related to asteroid mitigation.

Complete blood platelet and lymphocyte ratios increase diagnostic accuracy of periprosthetic joint infection following total hip arthroplasty.

Introduction: Systemically, changes in serum platelet to lymphocyte ratio (PLR), platelet count to mean platelet volume ratio (PVR), neutrophil to lymphocyte ratio (NLR) and monocyte to lymphocyte (MLR) represent primary responses to early inflammation and infection. This study aimed to determine whether PLR, PVR, NLR, and MLR can be useful in diagnosing periprosthetic joint infection (PJI) in total hip arthroplasty (THA) patients.

Methods: A total of 464 patients that underwent revision THA with calculable PLR, PVR, NLR, and MLR in 2 groups was evaluated: 1) 191 patients with a pre-operative diagnosis of PJI, and 2) 273 matched patients treated for revision THA for aseptic complications.

Elevated ESR and CRP Prior to Second-Stage Reimplantation Knee Revision Surgery for Periprosthetic Joint Infection Are Associated with Increased Reinfection Rates.

Although two-stage revision surgery is considered as the most effective treatment for managing chronic periprosthetic joint infection (PJI), there is no current consensus on the predictors of optimal timing to second-stage reimplantation. This study aimed to compare clinical outcomes between patients with elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) prior to second-stage reimplantation and those with normalized ESR and CRP prior to second-stage reimplantation. We retrospectively reviewed 198 patients treated with two-stage revision total knee arthroplasty for chronic PJI.

The Effect of Joint Line Elevation on In Vivo Knee Kinematics in Bicruciate Retaining Total Knee Arthroplasty.

Prior studies have reported a negative effect on both clinical outcomes and patient-reported outcome measures (PROMS) following joint line elevation (JLE) in cruciate-retaining (CR) total knee arthroplasty (TKA) and posterior stabilized (PS) TKA designs. This experimental study was aimed to quantify the effect of JLE on in vivo knee kinematics in patients with bicruciate retaining (BCR) TKA during strenuous activities. Thirty unilateral BCR TKA patients were evaluated during single-leg deep lunge and sit-to-stand using a validated combined computer tomography and dual fluoroscopic imaging system.

Outcomes and Risk Factors Associated With Failures of Debridement, Antibiotics, and Implant Retention in Patients With Acute Hematogenous Periprosthetic Joint Infection.

Background: Acute hematogenous periprosthetic joint infections (PJI) accounts for 20% to 35% of all PJI cases. Treatment options include débridement, antibiotics, and implant retention (DAIR) or implant revision (single-stage/two-stage revision). Because the reported success rates of DAIR for acute PJIs as reported in the literature varies widely, this study aimed to investigate (1) the outcome of DAIR as revision surgery procedure and (2) the potential risk factors for treatment failure of DAIR in patients with acute hematogenous PJI.

Lumbar Spine Fusion Before Revision Total Hip Arthroplasty Is Associated With Increased Dislocation Rates.

Background: The aim of this study was to determine whether timing of lumbar spinal fusion (LSF) before revision total hip arthroplasty (THA) would impact dislocation and rerevision rates.

Methods: This retrospective analysis includes a total of 505 patients who underwent revision THA with concomitant diagnosis of degenerative lumbar spinal stenosis with spondylolisthesis. Patients were stratified into the following two cohorts: (1) 328 patients who underwent revision THA with previous LSF and (2) 177 patients who underwent revision THA, followed by LSF.

MRI Characteristics of Adverse Local Tissue Reactions Associated With Intraoperative Tissue Damage and Poor Revision Surgery Outcomes: A Systematic Review.

Background: Metal artifact reductions sequence (MARS) MRI has been established as a cross-sectional imaging modality for diagnosis of adverse local tissue reaction (ALTR). This study aims to evaluate the current literature regarding the characteristics of MARS MRI associated with intraoperative tissue necrosis and postoperative complications in patients undergoing revision THA because of ALTR.

Methods: We systematically searched the literature that included reporting MRI characteristics of ALTR in failed THA and their correlation with intraoperative findings and postoperative outcomes.

Gait and Knee Flexion In Vivo Kinematics of Asymmetric Tibial Polyethylene Geometry Cruciate Retaining Total Knee Arthroplasty.

The preservation of the posterior cruciate ligament in cruciate retaining (CR) total knee arthroplasty (TKA) designs has the potential to restore healthy knee biomechanics; however, concerns related to kinematic asymmetries during functional activities still exist in unilateral TKA patients. As there is a limited data available regarding the ability of the contemporary CR TKA design with concave medial and convex lateral tibial polyethylene bearing components to restore healthy knee biomechanics, this study aimed to investigate in vivo three-dimensional knee kinematics in CR TKA patients during strenuous knee flexion activities and gait. Using a combined computer tomography and dual fluoroscopic imaging system approach, in vivo kinematics of 15 unilateral CR TKA patients (comparison of replaced and contralateral nonreplaced knee) were evaluated during sit-to-stand, step-ups, single-leg deep lunge, and level walking.

Outcomes and Risk Factors Associated With 2-Stage Reimplantation Requiring an Interim Spacer Exchange for Periprosthetic Joint Infection.

Background: Patients undergoing a 2-stage revision for periprosthetic joint infection (PJI) often require a repeat spacer in the interim due to persistent infection. This study aims to report outcomes for patients with repeat spacer exchange and to identify risk factors associated with interim spacer exchange in 2-stage revision arthroplasty.

Methods: A total of 256 consecutive 2-stage revisions for chronic infection of total hip arthroplasty and total knee arthroplasty with reimplantation and minimum 2-year follow-up were investigated.

Development of a Preoperative Risk Calculator for Reinfection Following Revision Surgery for Periprosthetic Joint Infection.

Background: A recent systematic review demonstrated that reinfection rates following eradication of hip and knee periprosthetic joint infection (PJI) may be as high as 29%. This study aimed to develop a preoperative risk calculator for assessing patient's individual risk associated with reinfection following treatment of PJI in total joint arthroplasty (TJA).

Methods: A total of 1081 consecutive patients who underwent revision TJA for PJI were evaluated.

Staged vs Concurrent Hardware Removal During Conversion Total Knee Arthroplasty.

Background: Conversion total knee arthroplasty (TKA) in the presence of periarticular hardware can be associated with increased resource utilization, complications, and revisions. However, little guidance exists on the optimal approach to hardware removal. The purpose of this study is to compare outcomes of conversion TKA with hardware removal performed in either a staged or concurrent manner.

Total knee arthroplasty following intramedullary tibial nailing.

Introduction/purpose: Total knee arthroplasty (TKA) in the setting of previous periarticular hardware increases resource utilization, readmissions, complications, and revision rates. Despite the frequency of intramedullary nail (IMN) fixation for tibial fractures, little guidance exists on the management of these patients and no series have reported on outcomes of patients undergoing TKA in the setting of a retained or removed IMN.

Methods: This is a retrospective case series of patients who underwent TKA after IMN fixation of tibial fractures.

Outcome of Dual Mobility Constructs for Adverse Local Tissue Reaction Associated Abductor Deficiency in Revision Total Hip Arthroplasty.

Background: Treatment of adverse local tissue reaction (ALTR) is challenging owing to high complications and poor outcomes after a revision surgery. As dislocation is the most common cause of reoperation, it is often necessary to use advanced articulations such as dual mobility. This study aims to evaluate the outcome and complication rates after revision surgery with dual mobility constructs, compared to constrained and conventional articulations in the setting of significant abductor deficiency due to ALTR.

S2 Alar Iliac Fixation in Long Segment Constructs, a Two- to Five-Year Follow-up.

Study Design: Retrospective review of patients having undergone S2 alar-iliac (S2AI) fixation for long fusions with a minimum two-year follow-up.

Objectives: To report on fusion rates, complications, technique-specific complications of patients having undergone S2AI fixation.

Summary Of Background Data: Sacropelvic fixation continues to be a challenge when performing long fusions to the pelvis.

Comparing hospital outcomes between open and closed tibia fractures treated with intramedullary fixation.

Introduction: Tibial shaft fractures comprise a large portion of operatively treated long bone fractures, and present with the highest rate of open injuries. Intramedullary fixation has become the standard of care for both open and closed injuries. The rates of short term complications and hospital length of stay for open and closed fractures treated with intramedullary fixation is not fully known.

Acute exercise prevents the development of neuropathic pain and the sprouting of non-peptidergic (GDNF- and artemin-responsive) c-fibers after spinal cord injury.

Spinal cord injury (SCI) impaired sensory fiber transmission leads to chronic, debilitating neuropathic pain. Sensory afferents are responsive to neurotrophic factors, molecules that are known to promote survival and maintenance of neurons, and regulate sensory neuron transduction of peripheral stimuli. A subset of primary afferent fibers responds only to the glial cell-line derived neurotrophic factor (GDNF) family of ligands (GFLs) and is non-peptidergic.

PHYRN: a robust method for phylogenetic analysis of highly divergent sequences.

Both multiple sequence alignment and phylogenetic analysis are problematic in the "twilight zone" of sequence similarity (≤ 25% amino acid identity). Herein we explore the accuracy of phylogenetic inference at extreme sequence divergence using a variety of simulated data sets. We evaluate four leading multiple sequence alignment (MSA) methods (MAFFT, T-COFFEE, CLUSTAL, and MUSCLE) and six commonly used programs of tree estimation (Distance-based: Neighbor-Joining; Character-based: PhyML, RAxML, GARLI, Maximum Parsimony, and Bayesian) against a novel MSA-independent method (PHYRN) described here.