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S4. E-cadherin induces E- to N-cadherin switching in sarcoma cells.

CDH1 (also known as E-cadherin), an epithelial-specific cell–cell adhesion molecule, plays multiple roles in maintaining adherens junctions, regulating migration and invasion, and mediating intracellular signaling. Downregulation of E-cadherin is a hallmark of epithelial-to-mesenchymal transition (EMT) and correlates with poor prognosis in multiple carcinomas. Conversely, upregulation of E-cadherin is prognostic for improved survival in sarcomas. Yet, despite the prognostic benefit of E-cadherin expression in sarcoma, the mechanistic significance of E-cadherin in sarcomas remains poorly understood. Here, by combining mathematical models with wet-bench experiments, we identify the core regulatory networks mediated by E-cadherin in sarcomas, and decipher their functional consequences. Unlike carcinomas, E-cadherin overexpression in sarcomas does not induce a mesenchymal-to-epithelial transition (MET). However, E-cadherin acts to reduce both anchorage-independent growth and spheroid formation of sarcoma cells. Ectopic E-cadherin expression acts to downregulate phosphorylated CREB1 (p-CREB) and the transcription factor, TBX2, to inhibit anchorage-independent growth. RNAi-mediated knockdown of TBX2 phenocopies the effect of E-cadherin on CREB levels and restores sensitivity to anchorage-independent growth in sarcoma cells. Beyond its signaling role, E-cadherin expression in sarcoma cells can also strengthen cell–cell adhesion and restricts spheroid growth through mechanical action. Together, our results demonstrate that E-cadherin inhibits sarcoma aggressiveness by preventing anchorage-independent growth.Implications:We highlight how E-cadherin can restrict aggressive behavior in sarcomas through both biochemical signaling and biomechanical effects.

Supplementary Data

Introduction: Continuous compression implants (CCI) are a fixation device formed from nitinol, a shape memory alloy. This alloy is durable enough to augment fixation and combined with its small footprint, versatile enough to insert into areas that are too small for K wires or lag screws to hold a provisional fixation. Case Report: We used CCIs to successfully stabilize the transverse segments in three posterior column with posterior wall fractures. Conclusion: CCIs can be used to provisionally reduce posterior column with posterior wall acetabular fractures and stabilize small pelvic bone fragments that may be difficult to hold with lag screws. These cases highlight a novel augmentation of the surgical treatment of posterior column with posterior wall fractures.

The incidence of anterior cruciate ligament (ACL) reconstruction is increasing in the United States, particularly in the older athlete. Patients who undergo ACL reconstruction are at higher risk for undergoing total knee arthroplasty (TKA) later in life. TKA in patients with prior ACL reconstruction has been associated with longer operative time due in-part to difficulty with exposure and retained hardware. Outcomes after TKA in patients with prior ACL reconstruction are not well defined, with some reports showing increased rate of complications and higher risk of reoperation compared with routine primary TKA, but these results are based on small and nonrandomized cohorts. Future research is needed to determine whether graft choice or fixation technique for ACL reconstruction influences outcomes after subsequent TKA. Furthermore, whether outcomes are affected by choice of TKA implant design for patients with prior ACL reconstruction warrants further study. This review analyzes the epidemiology, operative considerations, and outcomes of TKA following ACL reconstruction.

Background Alcohol use disorder (AUD) is the most prevalent substance use disorder in the United States. However, the current literature on AUD as a preoperative risk factor for Total Shoulder Arthroplasty (TSA) outcomes is limited. The purpose of this study was to identify the association of AUD with revision rates and 90-day postoperative complications in TSA. Methods A retrospective study was conducted using the PearlDiver database. Patients diagnosed with AUD were identified. Patients in remission or with underlying cirrhosis were excluded. Outcomes included 2-year revision, 90-day readmission, 90-day emergency, and 90-day post-operative medical complications. Analysis was performed with univariate chi-squared tests followed by multivariable logistic regression. Results A total of 59,261 patients who underwent TSA for osteoarthritis were identified, with 1522 patients having a diagnosis of AUD. Multivariable logistic regression showed that patients with AUD were more likely to undergo 2-year all-cause revision (OR = 1.49, p = 0.007), 2-year aseptic revision (OR = 1.47, p = 0.014), 90-day hospital readmission (OR = 1.57, p = 0.015), and 90-day transient mental disorder (OR = 2.13, p = 0.026). Conclusions AUD is associated with increased rates of 2-year revision surgery, as well as 90-day readmission and 90-day transient mental disorder following primary TSA for osteoarthritis. These findings may assist orthopedic surgeons in counseling patients with AUD during the pre-operative course.

Periprosthetic joint infection (PJI) after total joint arthroplasty is a known risk factor for infection in subsequent joint arthroplasty. The purpose of this study was to determine whether prior nonshoulder PJI contributes to the increased risk of infectious complications, greater healthcare utilization, and increased revision surgery after primary total shoulder arthroplasty (TSA).Patients who underwent primary TSA for osteoarthritis with prior nonshoulder PJI were identified in a national database (PearlDiver Technologies) using Current Procedural Terminology and International Classification of Diseases codes. These patients were propensity matched based on age, sex, Charlson Comorbidity Index, smoking status, and obesity (body mass index30 kg/m2) to a control cohort of patients who underwent primary TSA for osteoarthritis without any prior PJI. Primary outcomes include 1- and 2-year revision rates. Secondary outcomes include healthcare-specific outcomes of readmission, emergency department visits, length of stay, and mortality. Bivariate analysis was conducted using chi-square tests to compare all outcomes and complications between both cohorts.Compared with patients without prior PJI, those with prior PJI had a significantly higher risk of 90-day surgical site infection (7.61% versus 0.56%) and sepsis (1.79% versus 0.56%) after TSA (P0.05 for both). Patients with prior PJI also had a higher risk of 90-day readmission compared with those without prior PJI (3.36% versus 1.23%, P = 0.008). In terms of surgical complications, patients with prior PJI had significantly higher risk of 2-year revision surgery compared with patients without prior PJI (3.36% versus 1.57%, P = 0.034).Prior nonshoulder PJI of any joint increases rates of 90-day surgical site infection, sepsis, and hospital readmission, as well as 2-year all-cause revision after TSA. These results are important for risk-stratifying patients undergoing TSA with prior history of PJI.III.

To compare 90-day postoperative complications, health care use, 2-year and 5-year rates of reoperation and manipulation under anesthesia, and costs at the 30-day, 90-day, and 1-year postoperative intervals following open and arthroscopic rotator cuff repair (RCR).Patients who underwent an open or arthroscopic RCR with minimum 5-year follow-up were identified in a national database (PearlDiver Technologies) using Common Procedural Terminology andIn total, 3,266 patients who underwent open RCR were matched with 3,266 patients who underwent arthroscopic RCR. Compared with patients who underwent arthroscopic RCR, patients who underwent open RCR were at significantly increased risk of 90-day surgical-site infection (0.89% vs 0.34%,Patients undergoing open RCR were at increased risk of 90-day surgical-site infection and MUA both within 2 years and within 5 years of surgery in this study cohort.Level III, retrospective cohort study.

Background Recurrent shoulder instability is a debilitating condition that can lead to chronic pain, decreased function, and inability to return to activities or sport. This retrospective epidemiology study was performed to report 90-day postoperative complications and costs of Latarjet, anterior bone block reconstruction, arthroscopic, and open Bankart repair for shoulder instability. Methods Patients 18 years and older who underwent four primary shoulder surgeries from 2010 to 2019 were identified using national claims data. Patient demographics, comorbidities, and 90-day postoperative complications were analyzed using univariate analysis and multivariable logistic regression. Total and itemized 90-day reimbursements were determined for each procedure. Results The 90-day medical and surgery-specific complication rates were highest for anterior bone block reconstruction, followed by Latarjet. Arthroscopic Bankart repair had the highest 90-day costs and primary procedure costs compared to other procedures. Conclusion Anterior bone block reconstruction and Latarjet procedures were associated with the highest rates of 90-day medical and surgery-specific complications, while arthroscopic Bankart repair was associated with the highest costs.

Background: Stabilization methods for distal tibiofibular syndesmotic injuries present risk of malreduction. We compared reduction accuracy and biomechanical properties of a new syndesmotic reduction and stabilization technique using 2 suture buttons placed through a sagittal tunnel in the fibula and across the tibia just proximal to the incisura with those of the conventional method. Methods: Syndesmotic injury was created in 18 fresh-frozen cadaveric lower leg specimens. Nine ankles were repaired with the conventional method and 9 with the new technique. Reduction for the conventional method was performed using thumb pressure under direct visualization and for the new method by tightening both suture buttons passed through the fibular and tibial tunnels. Computed tomography was used to assess reduction accuracy. Torsional resistance, fibular rotation, and fibular translation were evaluated during biomechanical testing. Results: The new technique showed less lateral translation of the fibula on CT measurements after reduction (0.06 ± 0.06 mm) than the conventional method (0.26 ± 0.31 mm), P = .02. The new technique produced less fibular rotation during internal rotation after 0 cycles (new –2.4 ± 1.4 degrees; conventional –5.0 ± 1.2 degrees, P = .001), 100 cycles (new –2.1 ± 1.9 degrees; conventional –4.6 ± 1.4 degrees, P = .01), and 500 cycles (new –2.2 ± 1.6 degrees; conventional –5.3 ± 2.5 degrees, P = .01) and during external rotation after 100 cycles (new 3.9 ± 3.3 degrees; conventional 5.9 ± 3.5 degrees, P = .02) and 500 cycles (new 3.3 ± 3.2 degrees; conventional 6.3 ± 2.6 degrees, P = .03). Fixation failed in 3 specimens. Conclusion: The new syndesmotic reduction and fixation technique resulted in more accurate reduction of the fibula in the tibial incisura in the coronal plane and better rotational stability compared with the conventional method. Clinical Relevance: This new technique of syndesmosis reduction and stabilization may be a reliable alternative to current methods.

Background Identifying preoperative risk factors for complications following total shoulder arthroplasty (TSA) has both clinical and financial implications. The purpose of this study was to determine the influence of different degrees of preoperative INR elevation on complications following TSA. Methods Patients undergoing primary TSA from 2007 to 2018 were identified in a national database. Patients were stratified into 4 cohorts: INR of 1.0 to 1.25, INR of >1.25 to 1.5, and INR of >1.5. Postoperative complications were assessed. Multivariate logistic regressions were performed to adjust for differences in demographics and comorbidities among the INR groups. Results Following adjustment and relative to patients with an INR of 1.0–1.25, >1.25–1.5, and >1.5 had 1.6-times, 2.4-times, and 2.8-times higher odds of having postoperative bleeding requiring transfusion, respectively (p 1.25–1.5 and INR of >1.5 had 7.8-times and 7.0-times higher odds of having pulmonary complications, respectively (p Discussion With increasing INR levels, there is an independent and step-wise increase in odd ratios for postoperative complications. Current guidelines for preoperative INR thresholds may need to be adjusted for more predictive risk-stratification for TSA. Level of Evidence III

CDH1 (also known as E-cadherin), an epithelial-specific cell–cell adhesion molecule, plays multiple roles in maintaining adherens junctions, regulating migration and invasion, and mediating intracellular signaling. Downregulation of E-cadherin is a hallmark of epithelial-to-mesenchymal transition (EMT) and correlates with poor prognosis in multiple carcinomas. Conversely, upregulation of E-cadherin is prognostic for improved survival in sarcomas. Yet, despite the prognostic benefit of E-cadherin expression in sarcoma, the mechanistic significance of E-cadherin in sarcomas remains poorly understood. Here, by combining mathematical models with wet-bench experiments, we identify the core regulatory networks mediated by E-cadherin in sarcomas, and decipher their functional consequences. Unlike carcinomas, E-cadherin overexpression in sarcomas does not induce a mesenchymal-to-epithelial transition (MET). However, E-cadherin acts to reduce both anchorage-independent growth and spheroid formation of sarcoma cells. Ectopic E-cadherin expression acts to downregulate phosphorylated CREB1 (p-CREB) and the transcription factor, TBX2, to inhibit anchorage-independent growth. RNAi-mediated knockdown of TBX2 phenocopies the effect of E-cadherin on CREB levels and restores sensitivity to anchorage-independent growth in sarcoma cells. Beyond its signaling role, E-cadherin expression in sarcoma cells can also strengthen cell–cell adhesion and restricts spheroid growth through mechanical action. Together, our results demonstrate that E-cadherin inhibits sarcoma aggressiveness by preventing anchorage-independent growth. Implications: We highlight how E-cadherin can restrict aggressive behavior in sarcomas through both biochemical signaling and biomechanical effects.

For many cancer types, survival is improved when patients receive management at treatment centers that encounter high numbers of patients annually. This correlation may be more important with less common malignancies such as sarcoma. Existing evidence, however, is limited and inconclusive as to whether facility volume may be associated with survival in soft tissue sarcoma.The purpose of this study was to examine the association between facility volume and overall survival in patients with soft tissue sarcoma of the extremities. In investigating this aim, we sought to (1) examine differences in the treatment characteristics of high- and low-volume facilities; (2) estimate the 5-year survival by facility volume; and (3) examine the association between facility volume and of traveling a further distance to a high-volume center and overall survival when controlling for confounding factors.The largest sarcoma patient registry to date is contained within the National Cancer Database (NCDB) and captures70% of new cancer diagnoses annually. We retrospectively analyzed 25,406 patients with soft tissue sarcoma of the extremities in the NCDB from 1998 through 2012. Patients were stratified based on per-year facility sarcoma volume and we used univariate comparisons and multivariate proportional hazards analyses to correlate survival measures with facility volume and various other patient-, tumor-, and treatment-related factors. First, we evaluated long-term survival for all variables using the Kaplan-Meier method with statistical comparisons based on the log-rank test. Multiple patient, tumor, and treatment characteristics were compared between the two facility-volume groups and then included them in the multivariate proportional hazards model. Of the 25,406 patients analyzed, 3310 were treated at high-volume centers (≥ 20 patients annually) and 22,096 were treated at low-volume centers. Patient demographics were generally not different between both patient cohorts, although patients treated at high-volume centers were more likely to have larger and higher grade tumors (64% versus 56% size ≥ 5 cm, 28% versus 14% undifferentiated grade, p0.001).When controlling for patient, tumor, and treatment characteristics in a multivariate proportional hazards analysis, patients treated at high-volume facilities had an overall lower risk of mortality than those treated at low-volume centers (hazard ratio, 0.81 [0.75-0.88], p0.001). Patients treated at high-volume centers were also less likely to have positive margins (odds ratio [OR], 0.59 [0.52-0.68], p0.001) and in patients who received radiation, those treated at high-volume centers were more likely to have radiation before surgery (40.5% versus 21.7%, p0.001); there was no difference in the type of surgery performed (resection versus amputation) (OR, 1.01 [0.84-1.23], p = 0.883).With the largest patient cohort to date, this database review suggests that certain patients with soft tissue sarcoma of the extremities, particularly those with large high-grade tumors, may benefit from treatment at high-volume centers. Further investigation is necessary to help improve the referral of appropriate patients to high-volume sarcoma centers and to increase the treatment capacity of and access to such centers.Level III, therapeutic study.

Bordetella pertussis is the causative agent of whooping cough. This pathogenic bacterium can obtain the essential nutrient iron using its native alcaligin siderophore and by utilizing xeno-siderophores such as desferrioxamine B, ferrichrome, and enterobactin. Previous genome-wide expression profiling identified an iron repressible B. pertussis gene encoding a periplasmic protein (FbpABp). A previously reported crystal structure shows significant similarity between FbpABp and previously characterized bacterial iron binding proteins, and established its iron-binding ability. Bordetella growth studies determined that FbpABp was required for utilization of not only unchelated iron, but also utilization of iron bound to both native and xeno-siderophores. In this in vitro solution study, we quantified the binding of unchelated ferric iron to FbpABp in the presence of various anions and importantly, we demonstrated that FbpABp binds all the ferric siderophores tested (native and xeno) with μM affinity. In silico modeling augmented solution data. FbpABp was incapable of iron removal from ferric xeno-siderophores in vitro. However, when FbpABp was reacted with native ferric-alcaligin, it elicited a pronounced change in the iron coordination environment, which may signify an early step in FbpABp-mediated iron removal from the native siderophore. To our knowledge, this is the first time the periplasmic component of an iron uptake system has been shown to bind iron directly as Fe(3+) and indirectly as a ferric siderophore complex.

Haptoglobin (Hp) is an abundant and conserved plasma glycoprotein, which binds acellular adult hemoglobin (Hb) dimers with high affinity and facilitates their rapid clearance from circulation after hemolysis. Humans possess three main phenotypes of Hp, designated Hp 1-1, Hp 2-1, and Hp 2-2. These variants exhibit diverse structural configurations and have been reported to be functionally nonequivalent. We have investigated the functional and redox properties of Hb-Hp complexes prepared using commercially fractionated Hp and found that all forms exhibit similar behavior. The rate of Hb dimer binding to Hp occurs with bimolecular rate constants of ~0.9 μM(-1) s(-1), irrespective of the type of Hp assayed. Although Hp binding does accelerate the observed rate of HbO2 autoxidation by dissociating Hb tetramers into dimers, the rate observed for these bound dimers is three- to fourfold slower than that of Hb dimers free in solution. Co-incubation of ferric Hb with any form of Hp inhibits heme loss to below detectable levels. Intrinsic redox potentials (E1/2) of the ferric/ferrous pair of each Hb-Hp complex are similar, varying from +54 to +59 mV (vs NHE), and are essentially the same as reported by us previously for Hb-Hp complexes prepared from unfractionated Hp. All Hb-Hp complexes generate similar high amounts of ferryl Hb after exposure to hydrogen peroxide. Electron paramagnetic resonance data indicate that the yields of protein-based radicals during this process are approximately 4 to 5% and are unaffected by the variant of Hp assayed. These data indicate that the Hp fractions examined are equivalent to one another with respect to Hb binding and associated stability and redox properties and that this result should be taken into account in the design of phenotype-specific Hp therapeutics aimed at countering Hb-mediated vascular disease.