Modifiable Risk Factors in Primary Joint Arthroplasty Increase 90-Day Cost of Care.

Background: Risk factors in demographics and health status have been identified that increase the risk of complications after joint arthroplasty, necessitating additional care and incurring additional charges. The purpose of this study was to identify the number of patients in a hospital network database who had one or more predefined modifiable risk factors and determine their impact on average length of stay, need for additional care during the 90-day postoperative period, and the 90-day charges for care.

Methods: An electronic hospital record query of 6968 lower extremity joint arthroplasty procedures under Diagnosis-Related Group 469/470 performed in 2014-2015 was reviewed, and total 90-day charges were calculated.

Hip Fracture Does Not Belong in the Elective Arthroplasty Bundle: Presentation, Outcomes, and Service Utilization Differ in Fracture Arthroplasty Care.

Background: Center for Medicare and Medicaid Services reimbursement is the same for hip arthroplasty performed electively for arthritis and urgently for femoral neck fracture.

Methods: An analytic report of hip arthroplasty for a 5-hospital network identified 2362 cases performed from January 2014 to May 2016. Resource utilization was determined using 90-day charges.

Functional Outcomes After Total Knee Arthroplasty Correlate With Spine Disability.

Background: Despite pain resolution in most patients after total knee arthroplasty (TKA), poor function persists in approximately 20% of patients and frequently is associated with patient dissatisfaction. Lumbar spine problems are a leading cause of functional disability. This study sought to determine the association between lower knee function scores and history of spine disability.

Does Extended-Release Liposomal Bupivacaine Better Control Pain Than Bupivacaine After Total Knee Arthroplasty (TKA)? A Prospective, Randomized Clinical Trial.

Liposomal bupivacaine periarticular injection (PAI) offers sustained bupivacaine release after TKA, but few prospective independent studies exist. In this prospective, blinded study, liposomal bupivacaine was randomized against bupivacaine and incorporated into a comprehensive multimodal pain management protocol. 111 primary TKAs were randomized to receive PAI: 58 patients received 266 mg (20cc) liposomal bupivacaine mixed with 75 mg (30cc) 0.

The Oxford unicompartmental knee fails at a high rate in a high-volume knee practice.

Background: The Oxford knee is a unicompartmental implant featuring a mobile-bearing polyethylene component with excellent long-term survivorship results reported by the implant developers and early adopters. By contrast, other studies have reported higher revision rates in large academic practices and in national registries. Registry data have shown increased failure with this implant especially by lower-volume surgeons and institutions.

Structural changes in isometrically contracting insect flight muscle trapped following a mechanical perturbation.

The application of rapidly applied length steps to actively contracting muscle is a classic method for synchronizing the response of myosin cross-bridges so that the average response of the ensemble can be measured. Alternatively, electron tomography (ET) is a technique that can report the structure of the individual members of the ensemble. We probed the structure of active myosin motors (cross-bridges) by applying 0.

Structural basis for myopathic defects engendered by alterations in the myosin rod.

While mutations in the myosin subfragment 1 motor domain can directly disrupt the generation and transmission of force along myofibrils and lead to myopathy, the mechanism whereby mutations in the myosin rod influences mechanical function is less clear. Here, we used a combination of various imaging techniques and molecular dynamics simulations to test the hypothesis that perturbations in the myosin rod can disturb normal sarcomeric uniformity and, like motor domain lesions, would influence force production and propagation. We show that disrupting the rod can alter its nanomechanical properties and, in vivo, can drive asymmetric myofilament and sarcomere formation.

Benefits of prolonged postoperative cyclooxygenase-2 inhibitor administration on total knee arthroplasty recovery: a double-blind, placebo-controlled study.

A double-blind, placebo-controlled study of a selective cyclooxygenase (COX)-2 inhibitor administered in 107 patients for 6 weeks after total knee arthroplasty was done to determine any benefits. All patients received celecoxib preoperatively and during hospitalization. At hospital discharge, patients were randomized to receive celecoxib or placebo for 6 weeks.

A mighty small heart: the cardiac proteome of adult Drosophila melanogaster.

Drosophila melanogaster is emerging as a powerful model system for the study of cardiac disease. Establishing peptide and protein maps of the Drosophila heart is central to implementation of protein network studies that will allow us to assess the hallmarks of Drosophila heart pathogenesis and gauge the degree of conservation with human disease mechanisms on a systems level. Using a gel-LC-MS/MS approach, we identified 1228 protein clusters from 145 dissected adult fly hearts.

Electron tomography of cryofixed, isometrically contracting insect flight muscle reveals novel actin-myosin interactions.

Background: Isometric muscle contraction, where force is generated without muscle shortening, is a molecular traffic jam in which the number of actin-attached motors is maximized and all states of motor action are trapped with consequently high heterogeneity. This heterogeneity is a major limitation to deciphering myosin conformational changes in situ.

Methodology: We used multivariate data analysis to group repeat segments in electron tomograms of isometrically contracting insect flight muscle, mechanically monitored, rapidly frozen, freeze substituted, and thin sectioned.

Methods for identifying and averaging variable molecular conformations in tomograms of actively contracting insect flight muscle.

During active muscle contraction, tension is generated through many simultaneous, independent interactions between the molecular motor myosin and the actin filaments. The ensemble of myosin motors displays heterogeneous conformations reflecting different mechanochemical steps of the ATPase pathway. We used electron tomography of actively contracting insect flight muscle fast-frozen, freeze substituted, Araldite embedded, thin-sectioned and stained, to obtain 3D snapshots of the multiplicity of actin-attached myosin structures.

Phosphorylation and the N-terminal extension of the regulatory light chain help orient and align the myosin heads in Drosophila flight muscle.

X-ray diffraction of the indirect flight muscle (IFM) in living Drosophila at rest and electron microscopy of intact and glycerinated IFM was used to compare the effects of mutations in the regulatory light chain (RLC) on sarcomeric structure. Truncation of the RLC N-terminal extension (Dmlc2(Delta2-46)) or disruption of the phosphorylation sites by substituting alanines (Dmlc2(S66A, S67A)) decreased the equatorial intensity ratio (I(20)/I(10)), indicating decreased myosin mass associated with the thin filaments. Phosphorylation site disruption (Dmlc2(S66A, S67A)), but not N-terminal extension truncation (Dmlc2(Delta2-46)), decreased the 14.

The Yb protein defines a novel organelle and regulates male germline stem cell self-renewal in Drosophila melanogaster.

Yb regulates the proliferation of both germline and somatic stem cells in the Drosophila melanogaster ovary by activating piwi and hh expression in niche cells. In this study, we show that Yb protein is localized as discrete cytoplasmic spots exclusively in the somatic cells of the ovary and testis. These spots, which are different from all known cytoplasmic structures in D.

Isokinetic strength testing of minimally invasive total knee arthroplasty recovery.

Fifty patients underwent isokinetic muscle strength testing before surgery and at 6 weeks, 3 months, 6 months, and 1 year after unilateral total knee arthroplasty using the minisubvastus surgical technique. Quadriceps muscle strength returned to preoperative levels by 3 months postoperatively and was 17% stronger at 6 months and 30% stronger at 1 year than preoperative levels (P < .05).

Effects of increased surgical volume on total knee arthroplasty complications.

The effect of increased total knee arthroplasty (TKA) surgical volume on the incidence of knee complications within a single surgeon's practice was determined. Data were collected prospectively on 600 primary TKAs. Major complications required knee reoperation.

Similarities and differences between frozen-hydrated, rigor acto-S1 complexes of insect flight and chicken skeletal muscles.

The structure and function of myosin crossbridges in asynchronous insect flight muscle (IFM) have been elucidated in situ using multiple approaches. These include generating "atomic" models of myosin in multiple contractile states by rebuilding the crystal structure of chicken subfragment 1 (S1) to fit IFM crossbridges in lower-resolution electron microscopy tomograms and by "mapping" the functional effects of genetically substituted, isoform-specific domains, including the converter domain, in chimeric IFM myosin to sequences in the crystal structure of chicken S1. We prepared helical reconstructions (approximately 25 A resolution) to compare the structural characteristics of nucleotide-free myosin0 S1 bound to actin (acto-S1) isolated from chicken skeletal muscle (CSk) and the flight muscles of Lethocerus (Leth) wild-type Drosophila (wt Dros) and a Drosophila chimera (IFI-EC) wherein the converter domain of the indirect flight muscle myosin isoform has been replaced by the embryonic skeletal myosin converter domain.

Association of increased knee flexion and patella clunk syndrome after mini-subvastus total knee arthroplasty.

This study reviewed 747 consecutive posterior stabilized total knee arthroplasty (TKA) to explain the increased incidence of patella clunk syndrome that occurred when the surgeon switched from a medial parapatellar arthrotomy to a mini-subvastus (MIS) TKA technique. The incidence of patella clunk syndrome increased with increased postoperative knee flexion. Six weeks after surgery, knees that developed patella clunk had a mean flexion of 124 degrees vs 117 degrees for knees that did not develop this syndrome (P = .

Surgical accuracy with the mini-subvastus total knee arthroplasty a computer tomography scan analysis of postoperative implant alignment.

A total of 50 total knee arthroplasty (TKA) patients, 25 traditional and 25 minimally invasive surgical (MIS), underwent computed tomography scans to determine if a loss of accuracy in implant alignment occurred when a surgeon switched from a traditional medial parapatellar arthrotomy to a mini-subvastus surgical technique. Surgical accuracy was determined by comparing the computed tomography measured implant alignment with the surgical alignment goals. There was no loss in accuracy in the implantation of the tibial component with the mini-subvastus technique.

Signal sequence- and translation-independent mRNA localization to the endoplasmic reticulum.

The process of mRNA localization typically utilizes cis-targeting elements and trans-recognition factors to direct the compartmental organization of translationally suppressed mRNAs. mRNA localization to the endoplasmic reticulum (ER), in contrast, occurs via a co-translational, signal sequence/signal recognition particle (SRP)-dependent mechanism. We have utilized cell fractionation/cDNA microarray analysis, shRNA-mediated suppression of SRP expression, and mRNA reporter construct studies to define the role of the SRP pathway in ER-directed mRNA localization.

Mini-subvastus approach for total knee arthroplasty.

The mini-subvastus surgical technique avoids both quadriceps arthrotomy and patella eversion. Since March 2003, this quad-sparing minimally invasive surgical (MIS) technique has been applied to more than 98% of our primary total knee arthroplasty (TKA) patients. This study compares our first 150 MIS TKA patients to our previous 150 traditional TKA patients.

Applicability of the mini-subvastus total knee arthroplasty technique: an analysis of 725 cases with mean 2-year follow-up.

Recent total knee arthroplasty (TKA) studies suggest a more rapid functional recovery with minimally invasive surgical (MIS) techniques. These studies often fail to disclose the percentage of primary TKA that underwent the MIS technique, raising the concern that positive clinical outcomes are a result of patient selection. This study evaluates the applicability of the mini-subvastus technique in one surgeon's consecutive primary TKA patients.

Morphology and ultrastructure of differentiating three-dimensional mammalian skeletal muscle in a collagen gel.

Because previous studies of three-dimensional skeletal muscle cultures have shown limited differentiation, the goal of this study was to establish conditions that would produce mature sarcomeres in a mammalian-derived skeletal muscle construct. We evaluated the differentiation of bioartificial muscles generated from C(2)C(12) myoblasts in a collagen gel cultured under steady, passive tension for up to 36 days. Staining for alpha-actinin, myosin, and F-actin indicated the presence of striated fibers as early as 6 days post-differentiation.

Electron tomography of swollen rigor fibers of insect flight muscle reveals a short and variably angled S2 domain.

Subfragment 2 (S2), the segment that links the two myosin heads to the thick filament backbone, may serve as a swing-out adapter allowing crossbridge access to actin, as the elastic component of crossbridges and as part of a phosphorylation-regulated on-off switch for crossbridges in smooth muscle. Low-salt expansion increases interfilament spacing (from 52 nm to 67 nm) of rigor insect flight muscle fibers and exposes a tethering segment of S2 in many crossbridges. Docking an actoS1 atomic model into EM tomograms of swollen rigor fibers identifies in situ for the first time the location, length and angle assignable to a segment of S2.