Modified frailty index can help predict complications following tibial plateau fracture fixation: a NSQIP study involving 2213 patients.

PURPOSE: The 5-item modified frailty index (mFI-5) has been established as a reliable indicator of poor postoperative outcomes following a variety of orthopaedic procedures. This study aims to determine whether the mFI-5 can be used by surgeons to predict the likelihood of postoperative complications in patients undergoing open reduction internal fixation (ORIF) for tibial plateau fractures. METHODS: From 2006 to 2019, patients aged 50 years or older undergoing ORIF for tibial plateau fracture were identified in the National Surgical Quality Improvement Program database. The mFI-5 was calculated based on the sum of the presence of 5 conditions: diabetes, congestive heart failure, hypertension, chronic obstructive pulmonary disease, and dependent functional status. Chi-squared tests and multivariable regression analysis were used to evaluate the association of different mFI-5 scores with postoperative complications. RESULTS: The study analyzed 2213 patients with an average age of 63 years. Multivariable regression analysis demonstrated that in comparison to patients with a mFI-5 score of 0, those with a score of 1 had an increased risk of prolonged hospital stay (OR 1.31) and discharge to a non-home location (OR 1.50) while those with a score of 2 or greater were at an increased risk of readmission (OR 2.30), wound complication (OR 5.37), pulmonary complication (OR 4.56), urinary tract infection (OR 4.79), prolonged hospital stay (OR 1.89), and discharge to a non-home location (OR 3.01). CONCLUSION: The mFI-5 is a reliable instrument for determining the likelihood of postoperative complications following ORIF for tibial plateau fracture repair. LEVEL OF EVIDENCE: III.

Sickle Cell Disease Has No Impact on 10-Year Cumulative Incidence and Indications for Revision Lumbar Fusion.

STUDY DESIGN: Retrospective Cohort Study. OBJECTIVES: Patients with sickle cell disease (SCD) experience distinct physiological challenges that may alter surgical outcomes. There has been no research establishing 10-year lumbar fusion (LF) implant survivorship rates among individuals with SCD. This study aims to determine the 10-year cumulative incidence and indications for revision LF between patients with and without SCD. METHODS: A national database was queried to identify patients with and without SCD who underwent primary LF. SCD patients undergoing LF were propensity-score matched in a 1:4 ratio by age, gender, and Charlson Comorbidity Index (CCI) to a matched LF control. In total, 246 SCD patients were included along with 981 and 100,000 individuals in the matched and unmatched control cohorts, respectively. Kaplan-Meier survival analysis was utilized to determine the 10-year cumulative incidence rates of revision LF. Furthermore, multivariable analysis using Cox proportional hazard modeling was performed to compare indications for revisions and surgical complications between cohorts including hardware removal, drainage and evacuation, pseudoarthrosis, and mechanical failure. RESULTS: No significant differences were found in the cumulative incidence of 10-year all-cause revision LF between patients in the SCD cohort and either of the control cohorts (P > .05 for each). Additionally, there were no significant differences between the SCD cohort and either of the control cohorts in regards to the indications for revision or surgical complications in LF (P > .05 for each). CONCLUSIONS: This study indicates that SCD patients do not have increased risk for revision LF, nor any of its indications.

A National Database Analysis: Does Cold Weather Affect the Surgical Intervention Rate for Developmental Dysplasia of the Hip in Children Under Five Years?

Background Cold weather in the first few months of life may increase the risk of a late diagnosis of developmental dysplasia of the hip (DDH). Early detection of DDH can often be treated non-surgically. The purpose of this study is to observe whether the rates of surgical intervention for DDH differ based on average outdoor temperatures in the winter months. Methods A retrospective observational study of DDH patients diagnosed from 2010 to 2021 was conducted using a national administrative database. Five geographic regions were defined based on the average temperatures in the coldest quarter of the year. The rates of DDH-related surgeries were compared across these temperature regions. Results A total of 55,911 patients ≤5 years old with a DDH diagnosis from 2010 to 2021 were identified in the database. When compared to the warmest region (Group 5), the coldest region (Group 1) had higher rates of open reduction (4.59% vs. 2.06%, p<0.001), adductor tenotomy (6.95% vs. 2.91%, p<0.001), femoral osteotomy (5.75% vs. 2.04%, p<0.001), pelvic osteotomy (5.27% vs. 2.04%, p<0.001), and total DDH surgeries (11.42% vs. 5.03%, p<0.001). Conclusion Children living in states with an average winter temperature of -6.17°C had an increased likelihood of requiring surgical intervention for DDH within the first five years of life.

Prior Fragility Fractures are Associated With Higher Risk of Bone Health-Related Complications Within 8-Years Following Lumbar Fusion.

STUDY DESIGN: Retrospective study. OBJECTIVE: To determine the 8-year risk of revision lumbar fusion, pseudoarthrosis, mechanical failure, fragility fracture, and vertebral compression fracture in patients with a prior fragility fracture compared to those without. SUMMARY OF BACKGROUND DATA: Osteoporosis is a known modifiable risk factor for revision following lumbar fusion due to inadequate fixation. Patients with prior fragility fractures have been shown to have increased bone health-related complications following various orthopedic surgeries, however there is a paucity of literature that identifies these complications in patients undergoing lumbar fusion. METHODS: Patients aged 50 years and older who underwent elective lumbar fusion were identified in a large national database and stratified based on whether they sustained a fragility fracture within 3 years prior to fusion. These patients were propensity-score matched to a control based on age, gender, and Charlson Comorbidity Index (CCI) using a 1:1 ratio. Kaplan-Meier and Cox Proportional Hazards analyses were used to observe the cumulative incidences and risk of complications within 8-years of index surgery. RESULTS: After matching, 8,805 patients were included in both cohorts. Patients who sustained a prior fragility fracture had a higher risk of revision (Hazard Ratio [HR]: 1.46; 95% Confidence Interval [CI]: 1.26-1.69; P<0.001), pseudoarthrosis (HR: 1.31; 95% CI: 1.17-1.48; P<0.001), mechanical failure (HR: 2.08; 95% CI: 1.78-2.45; P<0.001), secondary fragility fracture (HR: 6.36; 95% CI: 5.86-6.90; P<0.001), and vertebral compression fracture (HR: 7.47; 95% CI: 7.68-8.21; P<0.001) when compared to the control cohort. CONCLUSION: Patients who sustain a fragility fracture prior to lumbar fusion have an increased risk of revision, pseudoarthrosis, and mechanical failure within 8 years. Surgeons should be aware of this high-risk patient population and consider bone health screening and treatment to reduce these preventable complications.

Self-sustained nonlinear waves in traffic flow.

In analogy to gas-dynamical detonation waves, which consist of a shock with an attached exothermic reaction zone, we consider herein nonlinear traveling wave solutions to the hyperbolic ("inviscid") continuum traffic equations. Generic existence criteria are examined in the context of the Lax entropy conditions. Our analysis naturally precludes traveling wave solutions for which the shocks travel downstream more rapidly than individual vehicles. Consistent with recent experimental observations from a periodic roadway [Y. Sugiyama, N. J. Phys. 10, 033001 (2008)], our numerical calculations show that nonlinear traveling waves are attracting solutions, with the time evolution of the system converging toward a wave-dominated configuration. Theoretical principles are elucidated by considering examples of traffic flow on open and closed roadways.

DST in healthy volunteers and after sleep deprivation.

The dexamethasone suppression test (DST) was performed in 46 healthy volunteers and repeated in nine of them following total sleep deprivation (TSD). While only 2 postdexamethasone cortisol values were insufficiently suppressed (greater than 5 micrograms %) in control DSTs, 5 postdexamethasone cortisol values were above 5 micrograms % following TSD. The mean postdexamethasone value was increased from 1.55 +/- 1.06 to 4.47 +/- 5.86 micrograms % following TSD at 8.00 h. The authors conclude that sleep deprivation as a therapeutic approach and prolonged sleeplessness may bias DST results.

Postdexamethasone prolactin and cortisol: a biological state variable in depression.

In 70 inpatients with major depressive disorder postdexamethasone cortisol and prolactin, but not baseline cortisol and prolactin, was found to correlate significantly with various state variables of depression. Postdexamethasone prolactin appeared to be a more specific state variable of depression compared with postdexamethasone cortisol. While prolactin was decreased following dexamethasone in controls and nonendogenous depressed patients, in endogenous depressed patients prolactin was increased by 30%. Due to this inverse prolactin response to dexamethasone, the sensitivity of this test should be considerably increased by using a higher dexamethasone dosage. The DST failed to be a diagnostic marker for any subgroup of depression.

Fy phenotype and gender determine plasma levels of monocyte chemotactic protein.

BACKGROUND: In vitro studies indicate that the Fy blood group system antigens serve as receptors for chemokines such as monocyte chemotactic protein-1 (MCP-1) and RANTES. However, it is unclear whether subjects with the Fy(a-b-) phenotype exhibit altered clearance and hence altered plasma levels of chemo-kines, because they still express Fy on endothelial cells. STUDY DESIGN AND METHODS: To clarify a possible in vivo role of Fy on RBCs in the regulation of chemo-kine levels, healthy young volunteers of common Fy phenotypes were compared in a cross-sectional study. RESULTS: More than 90 percent of the 34 subjects of African origin were Fy(a-b-), one black volunteer was Fy(a+b-), and two were Fy(a-b+). As expected, all 65 white volunteers were positive for either Fy(a) and/or Fy(b). Unexpectedly, persons expressing either Fy(a) and/or Fy(b) had significantly higher plasma levels of MCP-1 than Fy(a-b-) volunteers (women: 154 vs. 110 ng/L, p<0.01; men: 179 vs. 169 ng/L, p = 0.03). Surprisingly, plasma levels of MCP-1 were found to be sex-dependent: median MCP-1 levels averaged 180 ng per L in men but only 139 ng per L in women (p<0.001). Further, MCP-1 levels decreased significantly throughout the menstrual cycle of 18 women studied longitudinally. CONCLUSION: MCP-1 levels are about 30 percent higher in men than in premenopausal women, and MCP-1 levels are also higher in persons with RBCs expressing Fy antigens than in Fy(a-b-) persons. These findings have direct implications for the concept and interpretation of clinical studies measuring MCP-1 levels; the role of the observed differences in MCP-1 levels for the pathogenesis of MCP-1-dependent diseases, such as atherosclerosis, merits further investigation.

4-Hydroxybenzoate hydroxylase from Pseudomonas sp. CBS3. Purification, characterization, gene cloning, sequence analysis and assignment of structural features determining the coenzyme specificity.

4-Hydroxybenzoate hydroxylase from Pseudomonas sp. CBS3 was purified by five consecutive steps to apparent homogeneity. The enrichment was 50-fold with a yield of about 20%. The enzyme is a homodimeric flavoprotein monooxygenase with each 44-kDa polypeptide chain containing one FAD molecule as a rather weakly bound prosthetic group. In contrast to other 4-hydroxybenzoate hydroxylases of known primary structure, the enzyme preferred NADH over NADPH as electron donor. The pH optimum for catalysis was pH 8.0 with a maximum turnover rate around 45 degrees C. Chloride ions were inhibitory, and competitive with respect to NADH. 4-Hydroxybenzoate hydroxylase from Pseudomonas sp. CBS3 has a narrow substrate specificity. In addition to the transformation of 4-hydroxybenzoate to 3,4-dihydroxybenzoate, the enzyme converted 2-fluoro-4-hydroxybenzoate, 2-chloro-4-hydroxybenzoate, and 2,4-dihydroxybenzoate. With all aromatic substrates, no uncoupling of hydroxylation was observed. The gene encoding 4-hydroxybenzoate hydroxylase from Pseudomonas sp. CBS3 was cloned in Escherichia coli. Nucleotide sequence analysis revealed an open reading frame of 1182 bp that corresponded to a protein of 394 amino acid residues. Upstream of the pobA gene, a sequence resembling an E. coli promoter was identified, which led to constitutive expression of the cloned gene in E. coli TG1. The deduced amino acid sequence of Pseudomonas sp. CBS3 4-hydroxybenzoate hydroxylase revealed 53% identity with that of the pobA enzyme from Pseudomonas fluorescens for which a three-dimensional structure is known. The active-site residues and the fingerprint sequences associated with FAD binding are strictly conserved. This and the conservation of secondary structures implies that the enzymes share a similar three-dimensional fold. Based on an isolated region of sequence divergence and site-directed mutagenesis data of 4-hydroxybenzoate hydroxylase from P. fluorescens, it is proposed that helix H2 is involved in determining the coenzyme specificity.