Comparison of 90-Day Adverse Events Associated With Aspirin and Potent Anticoagulation Use for Venous Thromboembolism Prophylaxis: A Cohort Study of 72,288 Total Knee and 35,142 Total Hip Arthroplasty Patients.

BACKGROUND: While aspirin is acceptable for venous thromboembolism (VTE) prophylaxis following total joint arthroplasty in most patients, more potent agents are used in patients considered higher risk for VTE. We evaluated the efficacy and safety of aspirin versus potent anticoagulation agents following total knee arthroplasty (TKA) and total hip arthroplasty (THA). METHODS: A cohort study of 72,288 TKA and 35,142 THA from the Kaiser Permanente Total Joint Replacement Registry was performed (2009 to 2019). Identified medications were aspirin, factor Xa inhibitors, low-molecular-weight heparin (LMWH), and warfarin. A validated VTE risk score was assigned to each patient. Propensity score-weighted logistic regressions were used to evaluate 90-day VTEs. Noninferiority testing was performed with a margin of 1.25 using the upper bound (UB) of the 1-sided 95% CI. RESULTS: For TKA, aspirin was not inferior to LMWH (odds ratio [OR] = 0.77, UB = 1.09) and warfarin (OR = 0.64, UB = 0.90); there was no evidence to support noninferiority of aspirin compared to factor Xa inhibitors. Findings were consistent for THA (LMWH: OR = 0.59, UB = 0.75; warfarin: OR = 0.69, UB = 0.89). TKA was considered higher risk for VTE, whereas aspirin use demonstrated noninferiority compared to warfarin (OR = 0.54, UB = 0.81), we lacked evidence of noninferiority when compared to LMWH and factor Xa inhibitors. We lacked evidence of noninferiority of aspirin versus any potent anticoagulation in higher-risk THA. CONCLUSION: Aspirin was found to be effective and safe for VTE prevention in primary total joint arthroplasty, including in patients considered higher risk for VTE. LEVEL OF EVIDENCE: III.

The Utility of Obtaining Postmobilization Imaging in Nonsurgical Pelvic Ring Injuries.

INTRODUCTION: Pelvic fractures are diverse injuries with varying degrees of severity. Treatment recommendations are determined by the associated instability. For likely stable patterns, postmobilization imaging is used to assess for occult instability. This study assesses the utility of postmobilization images and determines how often they alter the recommendations for treatment. METHODS: Records at a single level 1 trauma center from January 2007 through December 2014 were reviewed, and patients with Current Procedural Terminology codes and International Classification of Diseases, Ninth Revision codes for pelvic and acetabular fractures were identified. For those chosen for nonsurgical treatment at presentation, a detailed chart review was performed to identify patients who had postmobilization radiographs and to determine whether this imaging led to a change in treatment recommendations. RESULTS: Inclusion criteria were met by 762 patients whose average age was 50 years. Of 331 patients planned for nonsurgical treatment at presentation, 168 (51%) had postmobilization images. The postmobilization radiographs did not alter treatment recommendations in any of these patients; however, three of these patients underwent surgical stabilization based on the patients' report of pain with attempted mobilization. DISCUSSION: Routine postmobilization imaging has limited value for patients with pelvic injuries and a low likelihood for instability, such as those with incomplete sacral fractures. Eliminating this step would reduce cost and decrease radiation exposure. The need for change in treatment plan or further imaging should be based on the patient's clinical progress with weight bearing. LEVEL OF EVIDENCE: Level 4.

Flexion contracture due to cyclops lesion after bicruciate-retaining total knee arthroplasty.

Flexion contracture may develop after total knee arthroplasty (TKA) and is usually associated with soft tissue contracture in the posterior compartment or hamstrings. A cyclops lesion is a soft tissue mass which can form in the anterior compartment usually after anterior cruciate ligament reconstruction and has been observed after bicruciate-retaining TKA. We have treated a patient who developed progressive loss of full extension from 0° to 20° after bicruciate-retaining TKA. A large fibrous tissue mass (cyclops lesion) was identified in the anterior compartment during arthrotomy 1 year after TKA. Excision of the mass resulted in complete resolution of the flexion contracture.

Corrigendum to "Delayed diagnosis of catastrophic ceramic liner failure with resultant pelvic discontinuity and massive metallosis" [ARTD 3 (2017) 77-82].

[This corrects the article DOI: 10.1016/j.artd.2016.11.002.].

"Monocept": A Brief Report of Congenital Absence of the Long Head of the Biceps Tendon and Literature Review.

The long head of the biceps tendon plays an important role in shoulder stability and its functional absence has been shown to contribute to glenohumeral instability. Congenital absence of the long head to the biceps tendon is rare, although described in the literature. We report the case of an 18-year-old recreational athlete with recurrent shoulder instability and congenital absence of the long head of the biceps tendon (which we term "monocept") and mild ipsilateral upper extremity hemimelia. The patient was treated surgically with posterior capsular shift with anterior Bankart repair without complication. At 16-month follow-up the patient has returned to recreational activity and has had an 11.37-point improvement in his DASH score. The authors suggest that patients with this uncommon anatomic anomaly and clinical shoulder instability are more likely to require surgical treatment.

Delayed diagnosis of catastrophic ceramic liner failure with resultant pelvic discontinuity and massive metallosis.

With newer-generation ceramic components used in total hip arthroplasty, component fracture is a rare complication. However rare, when ceramic component fracture does occur, prompt identification and revision is necessary as delay can lead to dramatic failure with resultant metallosis as the extremely hard ceramic debris abrades remaining components. We present a case of a 70-year-old woman with ceramic liner fracture and an estimated 10-year delay in intervention with failure resulting in pelvic discontinuity and massive metallosis with associated cutaneous manifestation. She was treated with a complex revision and reconstruction and is 2 years postrevision without major complication.

Resistance to venous flow: A mathematical description and implications for compartment syndromes.

BACKGROUND: The object of this work was to describe resistance to flow within a vein in a closed compartment. METHODS: A vein is mathematically modeled as a collapsible cylinder with fixed perimeter exposed to extraluminal hydrostatic pressure within a closed compartment of the body. The principle of minimization of energy is used to determine the cross-sectional area and resistance to flow through such a cylinder in various states of collapse. RESULTS: A mathematical expression for the cross-sectional area of a partially collapsed tube is derived. Resistance to flow is calculated within the tube in various states of collapse and compared with the resistance to flow in an annular tube of identical cross-sectional area. Resistance increases very rapidly in the first 5% of collapse and remains greater than that in an annular vessel of identical cross-sectional area through all further collapse. Resistance to flow closely follows a logarithmic gain as the tube undergoes collapse from extraluminal pressure until opposite sides of the vein make contact. CONCLUSION: Within a closed compartment in which there is rising pressure, resistance to flow through a vein is predicted to increase as a logarithmic function of the vein's cross-sectional area. This rapid rise in resistance and hence decline in flow are consistent with the position that in compartment syndromes of all anatomic locations, the venous contribution to resistance of flow is of paramount importance to the pathophysiology.

Induction of the unfolded protein response drives enhanced metabolism and chemoresistance in glioma cells.

The unfolded protein response (UPR) is an endoplasmic reticulum (ER)-based cytoprotective mechanism acting to prevent pathologies accompanying protein aggregation. It is frequently active in tumors, but relatively unstudied in gliomas. We hypothesized that UPR stress effects on glioma cells might protect tumors from additional exogenous stress (ie, chemotherapeutics), postulating that protection was concurrent with altered tumor cell metabolism. Using human brain tumor cell lines, xenograft tumors, human samples and gene expression databases, we determined molecular features of glioma cell UPR induction/activation, and here report a detailed analysis of UPR transcriptional/translational/metabolic responses. Immunohistochemistry, Western and Northern blots identified elevated levels of UPR transcription factors and downstream ER chaperone targets in gliomas. Microarray profiling revealed distinct regulation of stress responses between xenograft tumors and parent cell lines, with gene ontology and network analyses linking gene expression to cell survival and metabolic processes. Human glioma samples were examined for levels of the ER chaperone GRP94 by immunohistochemistry and for other UPR components by Western blotting. Gene and protein expression data from patient gliomas correlated poor patient prognoses with increased expression of ER chaperones, UPR target genes, and metabolic enzymes (glycolysis and lipogenesis). NMR-based metabolomic studies revealed increased metabolic outputs in glucose uptake with elevated glycolytic activity as well as increased phospholipid turnover. Elevated levels of amino acids, antioxidants, and cholesterol were also evident upon UPR stress; in particular, recurrent tumors had overall higher lipid outputs and elevated specific UPR arms. Clonogenicity studies following temozolomide treatment of stressed or unstressed cells demonstrated UPR-induced chemoresistance. Our data characterize the UPR in glioma cells and human tumors, and link the UPR to chemoresistance possibly via enhanced metabolism. Given the role of the UPR in the balance between cell survival and apoptosis, targeting the UPR and/or controlling metabolic activity may prove beneficial for malignant glioma therapeutics.