Spinal Anesthesia or General Anesthesia for Hip Surgery in Older Adults.

BACKGROUND: The effects of spinal anesthesia as compared with general anesthesia on the ability to walk in older adults undergoing surgery for hip fracture have not been well studied. METHODS: We conducted a pragmatic, randomized superiority trial to evaluate spinal anesthesia as compared with general anesthesia in previously ambulatory patients 50 years of age or older who were undergoing surgery for hip fracture at 46 U.S. and Canadian hospitals. Patients were randomly assigned in a 1:1 ratio to receive spinal or general anesthesia. The primary outcome was a composite of death or an inability to walk approximately 10 ft (3 m) independently or with a walker or cane at 60 days after randomization. Secondary outcomes included death within 60 days, delirium, time to discharge, and ambulation at 60 days. RESULTS: A total of 1600 patients were enrolled; 795 were assigned to receive spinal anesthesia and 805 to receive general anesthesia. The mean age was 78 years, and 67.0% of the patients were women. A total of 666 patients (83.8%) assigned to spinal anesthesia and 769 patients (95.5%) assigned to general anesthesia received their assigned anesthesia. Among patients in the modified intention-to-treat population for whom data were available, the composite primary outcome occurred in 132 of 712 patients (18.5%) in the spinal anesthesia group and 132 of 733 (18.0%) in the general anesthesia group (relative risk, 1.03; 95% confidence interval [CI], 0.84 to 1.27; P = 0.83). An inability to walk independently at 60 days was reported in 104 of 684 patients (15.2%) and 101 of 702 patients (14.4%), respectively (relative risk, 1.06; 95% CI, 0.82 to 1.36), and death within 60 days occurred in 30 of 768 (3.9%) and 32 of 784 (4.1%), respectively (relative risk, 0.97; 95% CI, 0.59 to 1.57). Delirium occurred in 130 of 633 patients (20.5%) in the spinal anesthesia group and in 124 of 629 (19.7%) in the general anesthesia group (relative risk, 1.04; 95% CI, 0.84 to 1.30). CONCLUSIONS: Spinal anesthesia for hip-fracture surgery in older adults was not superior to general anesthesia with respect to survival and recovery of ambulation at 60 days. The incidence of postoperative delirium was similar with the two types of anesthesia. (Funded by the Patient-Centered Outcomes Research Institute; REGAIN ClinicalTrials.gov number, NCT02507505.).

Significant Reduction in Short-Term Complications Following Unicompartmental Versus Total Knee Arthroplasty: A Propensity Score Matched Analysis.

BACKGROUND: Total knee arthroplasty (TKA) is a gold standard surgical treatment for end-stage arthritis and unicompartmental knee arthroplasty (UKA) is an alternative for localized disease in appropriate patients. Both have been shown to have equivalent complications in the short-term period. We aimed to explore the differences in 30-day complication rates between UKA and TKA using recent data. METHODS: Current Procedural Terminology codes identified patients in the American College of Surgeons National Surgical Quality Improvement Program database who underwent primary TKA or UKA from 2014 to 2018. Propensity score matching addressed demographic differences. Rate of any adverse event (AAE) and complications were compared. RESULTS: We identified 279,852 patients with 270,786 and 9,066 undergoing TKA and UKA. No significant difference was observed in baseline demographics after matching. The AAE rate differed significantly between TKA (5.07%) and UKA (2.38%) cohorts (P < .001). TKA group experienced more wound dehiscence, cerebrovascular accident, postoperative blood transfusion, deep vein thrombosis, and requirement for postoperative intubation. Rate of extended length of stay differed between the TKA (11.35%) and UKA (4.89%) cohorts (P < .001). Accounting for all other variables, preoperative corticosteroid use, bleeding disorder, and chronic obstructive pulmonary disease increased the risk for AAE for both groups. Increasing American Society of Anesthesiologists class also increased the odds for complication proportionally with increasing age and operative time. CONCLUSION: Contrary to previous data, we found a significantly higher 30-day complication rate in TKA patients. TKA patients had a higher likelihood of having an extended length of stay. Multivariable analysis identified preoperative steroid use, bleeding disorder, and chronic obstructive pulmonary disease as risk factors for developing adverse events for both groups. LEVEL OF EVIDENCE: Level III.

A Biomechanical Comparison of the Effect of Baseplate Design and Bone Marrow Fat Infiltration on Tibial Baseplate Pullout Strength.

BACKGROUND: Early clinical results of a new total knee arthroplasty (TKA) implant design show promise for improved outcomes and patellofemoral function scores. However, reports of early tibial component-cement interface debonding requiring revision have been published. This study investigated the biomechanical properties of three different tibial baseplates to understand potential causes of failure. METHODS: PFC Sigma (control), Attune (1st generation) and Attune S+ (2nd generation) tibial baseplates were implanted into 4th generation sawbone tibia models using a standardized technique. Three of each baseplate were cemented with and without additional bovine bone marrow fat. All models were tested to failure with measured axial distraction force. Implant type, presence or absence of bovine marrow and load to failure were all recorded and compared. Two-way ANOVA followed by post-hoc pairwise comparisons were used to determine statistical significance, which was set to P < .05. RESULTS: The 2nd generation tibial baseplates required significantly more force to failure. The presence of bovine marrow significantly reduced the pullout force of the implant designs overall. No significant difference was detected between the 1st generation and control baseplates. Failure mode for each model was also noted to be different irrespective of the presence or absence of bone marrow fat. CONCLUSION: The 2nd generation baseplates required significantly more force to failure compared with older designs. The presence of bone marrow during cementation of a tibial base plate significantly decreased axial pullout strength of a tibial baseplate in this laboratory model. All 1st generation baseplates exhibited debonding at the cement-implant interface.

Exacerbated Staphylococcus aureus Foot Infections in Obese/Diabetic Mice Are Associated with Impaired Germinal Center Reactions, Ig Class Switching, and Humoral Immunity.

Obese patients with type 2 diabetes (T2D) are at an increased risk of foot infection, with impaired immune function believed to be a critical factor in the infectious process. In this study, we test the hypothesis that humoral immune defects contribute to exacerbated foot infection in a murine model of obesity/T2D. C57BL/6J mice were rendered obese and T2D by a high-fat diet for 3 mo and were compared with controls receiving a low-fat diet. Following injection of Staphylococcus aureus into the footpad, obese/T2D mice had greater foot swelling and reduced S. aureus clearance than controls. Obese/T2D mice also had impaired humoral immune responses as indicated by lower total IgG levels and lower anti-S. aureus Ab production. Within the draining popliteal lymph nodes of obese/T2D mice, germinal center formation was reduced, and the percentage of germinal center T and B cells was decreased by 40-50%. Activation of both T and B lymphocytes was similarly suppressed in obese/T2D mice. Impaired humoral immunity in obesity/T2D was independent of active S. aureus infection, as a similarly impaired humoral immune response was demonstrated when mice were administered an S. aureus digest. Isolated splenic B cells from obese/T2D mice activated normally but had markedly suppressed expression of Aicda, with diminished IgG and IgE responses. These results demonstrate impaired humoral immune responses in obesity/T2D, including B cell-specific defects in Ab production and class-switch recombination. Together, the defects in humoral immunity may contribute to the increased risk of foot infection in obese/T2D patients.

Preoperative Risk Factor Screening Protocols in Total Joint Arthroplasty: A Systematic Review.

BACKGROUND: Preoperative optimization protocols targeting potentially modifiable risk factors could prove beneficial in reducing the rate of complications in lower extremity total joint arthroplasty (LE-TJA). We aimed to summarize the evidence on preoperative screening protocols targeting modifiable risk factors to assess their effect on postoperative outcomes following primary LE-TJA. METHODS: A literature search of MEDLINE, EMBASE, CINAHL, and Cochrane Library databases was performed in August 2019. The bibliographies of relevant publications were searched for further applicable studies. Included studies were required to report at least one outcome including prosthetic joint infection/surgical site infection (PJI/SSI), hospital length of stay (LOS), disposition, 90-day emergency department visits, or hospital readmissions after implementation of an evidence-based preoperative optimization protocol targeting modifiable risk factors. Methodological quality of included studies was assessed using the methodological index for non-randomized studies (MINORS) criteria. RESULTS: A total of 8 retrospective cohort studies including 9915 patients were reviewed. Implementation of preoperative optimization protocols were associated with reductions in SSI (0.56% vs. 2.60%; RR 0.21 [95% CI 0.12 to 0.37]; P < .00001), hospital LOS, mean cost of care, and hospital readmission rates. The mean MINORS score for comparative studies was 16.285. CONCLUSIONS: Implementation and compliance with evidence-based preoperative protocols for optimization of modifiable risk factors is associated with overall improved outcomes following LE-TJA. SSI, hospital LOS, average total cost of care, and hospital readmission rates were favorable in those cohorts subjected to a preoperative intervention protocol. Future prospective studies are necessary for further refinement of preoperative optimization protocols and referral algorithms, without compromising patients' access to surgery. LEVEL OF EVIDENCE: III, Systematic Review.

Vitamin C and inflammatory cytokine levels in elective total knee arthroplasty.

BACKGROUND: Vitamin C levels are decreased in arthritis patients and reduced levels following surgery may impair adequate healing. AIM: This study measured changes in vitamin C and inflammatory markers in patients undergoing total knee arthroplasty (TKA). METHODS: Venous blood samples were collected from 10 patients during the preoperative to postoperative period. Vitamin C, interleukin-1ß, interleukin-6 (IL-6), and C-reactive protein (CRP) levels were measured using various assays. RESULTS: No significant changes in vitamin C levels were measured. However, all participants had suboptimal preoperative vitamin C levels and 90% had suboptimal levels postoperatively. IL-6 and CRP levels significantly increased during the immediate postoerative period. CONCLUSION: There was a rise in inflammation following TKA while vitamin C levels did not significantly change during this short study period. Of note, every patient had suboptimal vitamin C levels prior to surgery and 90% continued with suboptimal levels two days postoperatively.

Development and challenges in setting up an international bone infection registry.

INTRODUCTION: Osteomyelitis is an increasing burden on the society especially due to the emergence of multiple drug-resistant organisms. The lack of a central registry that prospectively collects data on patient risk factors, laboratory test results, treatment modalities, serological analysis results, and outcomes has hampered the research effort that could have improved and provided guidelines for treatments of bone infections. The current manuscript describes the lessons learned in setting up a multi-continent registry. MATERIALS AND METHODS: This multicenter, international registry was conducted to prospectively collect essential patient, clinical, and surgical data with a 1-year follow-up period. Patients 18 years or older with confirmed S. aureus long bone infection through fracture fixation or arthroplasty who consented to participate in the study were included. The outcomes using the Short Form 36 Health Survey Questionnaire (version 2), Parker Mobility Score, and Katz Index of Independence in Activities of Daily Living were assessed at baseline and at 1 month, 6 months, and 12 months. Serological samples were collected at follow-ups. RESULTS: Contract negotiation with a large number of study sites was difficult; obtaining ethics approvals were time-consuming but straightforward. The initial patient recruitment was slow, leading to a reduction of target patient number from 400 to 300 and extension of enrollment period. Finally, 292 eligible patients were recruited by 18 study sites (in 10 countries of 4 continents, Asia, North and South America, and Central Europe). Logistical and language barriers were overcome by employing courier service and local monitoring personnel. CONCLUSIONS: Multicenter registry is useful for collecting a large number of cases for analysis. A well-defined data collection practice is important for data quality but challenging to coordinate with the large number of study sites.

General treatment principles for fracture-related infection: recommendations from an international expert group.

Fracture-related infection (FRI) remains a challenging complication that creates a heavy burden for orthopaedic trauma patients, their families and treating physicians, as well as for healthcare systems. Standardization of the diagnosis of FRI has been poor, which made the undertaking and comparison of studies difficult. Recently, a consensus definition based on diagnostic criteria for FRI was published. As a well-established diagnosis is the first step in the treatment process of FRI, such a definition should not only improve the quality of published reports but also daily clinical practice. The FRI consensus group recently developed guidelines to standardize treatment pathways and outcome measures. At the center of these recommendations was the implementation of a multidisciplinary team (MDT) approach. If such a team is not available, it is recommended to refer complex cases to specialized centers where a MDT is available and physicians are experienced with the treatment of FRI. This should lead to appropriate use of antimicrobials and standardization of surgical strategies. Furthermore, an MDT could play an important role in host optimization. Overall two main surgical concepts are considered, based on the fact that fracture fixation devices primarily target fracture consolidation and can be removed after healing, in contrast to periprosthetic joint infection were the implant is permanent. The first concept consists of implant retention and the second consists of implant removal (healed fracture) or implant exchange (unhealed fracture). In both cases, deep tissue sampling for microbiological examination is mandatory. Key aspects of the surgical management of FRI are a thorough debridement, irrigation with normal saline, fracture stability, dead space management and adequate soft tissue coverage. The use of local antimicrobials needs to be strongly considered. In case of FRI, empiric broad-spectrum antibiotic therapy should be started after tissue sampling. Thereafter, this needs to be adapted according to culture results as soon as possible. Finally, a minimum follow-up of 12 months after cessation of therapy is recommended. Standardized patient outcome measures purely focusing on FRI are currently not available but the patient-reported outcomes measurement information system (PROMIS) seems to be the preferred tool to assess the patients' short and long-term outcome. This review summarizes the current general principles which should be considered during the whole treatment process of patients with FRI based on recommendations from the FRI Consensus Group.Level of evidence: Level V.

Evidence Review Conducted for the Agency for Healthcare Research and Quality Safety Program for Improving Surgical Care and Recovery: Focus on Anesthesiology for Total Knee Arthroplasty.

Enhanced recovery after surgery (ERAS) has rapidly gained popularity in a variety of surgical subspecialities. A large body of literature suggests that ERAS leads to superior outcomes, improved patient satisfaction, reduced length of hospital stay, and cost benefits, without affecting rates of readmission after surgery. These patterns have been described for patients undergoing elective total knee arthroplasty (TKA); however, adoption of ERAS to orthopedic surgery has lagged behind other surgical disciplines. The Agency for Healthcare Research and Quality, in partnership with the American College of Surgeons and the Johns Hopkins Medicine Armstrong Institute (AI) for Patient Safety and Quality, has developed the Safety Program for Improving Surgical Care and Recovery. The program comprises a national effort to incorporate best practice in perioperative care and improve patient safety, for over 750 hospitals and multiple procedures over the next 5 years, including orthopedic surgery. We have conducted a full evidence review of anesthetic interventions to derive anesthesiology-related components of an evidence-based ERAS pathway for TKA. A PubMed search was performed for each protocol component, focusing on the highest levels of evidence in the literature. Search findings are summarized in narrative format. Anesthesiology components of care were identified and evaluated across the pre-, intra-, and postoperative phases. A summary of the best available evidence, together with recommendations for inclusion in ERAS protocols for TKA, is provided. There is extensive evidence in the literature, and from society guidelines to support the Agency for Healthcare Research and Quality Safety Program for Improving Surgical Care and Recovery goals for TKA.

Evidence Review Conducted for the Agency for Healthcare Research and Quality Safety Program for Improving Surgical Care and Recovery: Focus on Anesthesiology for Total Hip Arthroplasty.

Successes using enhanced recovery after surgery (ERAS) protocols for total hip arthroplasty (THA) are increasingly being reported. As in other surgical subspecialties, ERAS for THA has been associated with superior outcomes, improved patient satisfaction, reduced length of hospital stay, and cost savings. Nonetheless, the adoption of ERAS to THA has not been universal. The Agency for Healthcare Research and Quality, in partnership with the American College of Surgeons and the Johns Hopkins Medicine Armstrong Institute for Patient Safety and Quality, has developed the Safety Program for Improving Surgical Care and Recovery. We have conducted an evidence review to select anesthetic interventions that positively influence outcomes and facilitate recovery after THA. A literature search was performed for each intervention, and the highest levels of available evidence were considered. Anesthesiology-related interventions for pre- (carbohydrate loading/fasting, multimodal preanesthetic medications), intra- (standardized intraoperative pathway, regional anesthesia, ventilation, tranexamic acid, fluid minimization, glycemic control), and postoperative (multimodal analgesia) phases of care are included. We have summarized the best available evidence to recommend the anesthetic components of care for ERAS for THA. There is evidence in the literature and from society guidelines to support the Agency for Healthcare Research and Quality Safety Program for Improving Surgical Care and Recovery goals for THA.

Evidence Review Conducted for the Agency for Healthcare Research and Quality Safety Program for Improving Surgical Care and Recovery: Focus on Anesthesiology for Hip Fracture Surgery.

Enhanced recovery after surgery (ERAS) protocols represent patient-centered, evidence-based, multidisciplinary care of the surgical patient. Although these patterns have been validated in numerous surgical specialities, ERAS has not been widely described for patients undergoing hip fracture (HFx) repair. As part of the Agency for Healthcare Research and Quality Safety Program for Improving Surgical Care and Recovery, we have conducted a full evidence review of interventions that form the basis of the anesthesia components of the ERAS HFx pathway. A literature search was performed for each protocol component, and the highest levels of evidence available were selected for review. Anesthesiology components of care were identified and evaluated across the perioperative continuum. For the preoperative phase, the use of regional analgesia and nonopioid multimodal analgesic agents is suggested. For the intraoperative phase, a standardized anesthetic with postoperative nausea and vomiting prophylaxis is suggested. For the postoperative phase, a multimodal (primarily nonopioid) analgesic regimen is suggested. A summary of the best available evidence and recommendations for inclusion in ERAS protocols for HFx repair are provided.

Adaptive Upregulation of Clumping Factor A (ClfA) by Staphylococcus aureus in the Obese, Type 2 Diabetic Host Mediates Increased Virulence.

Obesity and associated type 2 diabetes (T2D) are important risk factors for infection following orthopedic implant surgery. Staphylococcus aureus, the most common pathogen in bone infections, adapts to multiple environments to survive and evade host immune responses. Whether adaptation of S. aureus to the unique environment of the obese/T2D host accounts for its increased virulence and persistence in this population is unknown. Thus, we assessed implant-associated osteomyelitis in normal versus high-fat-diet obese/T2D mice and found that S. aureus infection was more severe, including increases in bone abscesses relative to nondiabetic controls. S. aureus isolated from bone of obese/T2D mice displayed marked upregulation of four adhesion genes (clfA, clfB, bbp, and sdrC), all with binding affinity for fibrin(ogen). Immunostaining of infected bone revealed increased fibrin deposition surrounding bacterial abscesses in obese/T2D mice. In vitro coagulation assays demonstrated a hypercoagulable state in obese/T2D mice that was comparable to that of diabetic patients. S. aureus with an inactivating mutation in clumping factor A (clfA) showed a reduction in bone infection severity that eliminated the effect of obesity/T2D, while infections in control mice were unchanged. In infected mice that overexpress plasminogen activator inhibitor-1 (PAI-1), S. aureusclfA expression and fibrin-encapsulated abscess communities in bone were also increased, further linking fibrin deposition to S. aureus expression of clfA and infection severity. Together, these results demonstrate an adaptation by S. aureus to obesity/T2D with increased expression of clfA that is associated with the hypercoagulable state of the host and increased virulence of S. aureus.

Increased numbers of CD23(+) CD21(hi) Bin-like B cells in human reactive and rheumatoid arthritis lymph nodes.

A unique population of CD23(+) CD21(high) B cells in inflamed nodes (Bin) has been shown to accumulate in lymph nodes (LNs) draining inflamed joints of TNF-transgenic (TNF-tg) mice. Bin cells contribute to arthritis flare in mice by distorting node architecture and hampering lymphatic flow, but their existence in human inflamed LNs has not yet been described. Here, we report the characterization of resident B-cell populations in fresh popliteal lymph nodes (PLNs) from patients with severe lower limb diseases (non-RA) and rheumatoid arthritis (RA) patients, and from banked, cryopreserved reactive and normal human LN single cell suspension samples. Bin-like B cells were shown to be significantly increased in reactive LNs, and strikingly elevated (>30% of total) in RA samples. Histopathology and immunofluorescence analyses were consistent with B follicular hyperplasia and histological alterations in RA vs. non-RA PLNs. This is the first description of Bin-like B cells in human inflamed LNs. Consistent with published mouse data, this population appears to be associated with inflammatory arthritis and distortion of LN architecture. Further analyses are necessary to assess the role of CD23(+) CD21(hi) Bin-like B cells in RA pathogenesis and arthritic flare.

The Utility of Postoperative Radiographs 2 Years After Primary Total Knee Arthroplasty.

BACKGROUND: Radiographs are routinely used to evaluate patients postoperatively after total knee arthroplasty, but no evidence-based guidelines exist regarding their use. The purpose of this study is to quantify the use of radiographs within 2 years of primary total knee arthroplasty by one surgeon and to determine if routine studies in asymptomatic patients altered patient management. METHODS: Patients undergoing consecutive primary total knee arthroplasties between 2008 and 2010 were identified. Patients undergoing revision or additional simultaneous procedures or those with less than 6 months of radiographic follow-up were excluded. Operative and clinic notes, radiographs, and radiology reports were reviewed. RESULTS: A total of 263 patients were identified; each patient had an average of 13.5 ± 3.8 individual radiographs obtained in 6.5 ± 1.7 series. Twelve radiographic series were noted to have abnormal findings by either the attending surgeon or by radiology report. Three of these patients underwent reoperation directly related to the findings; 2 for deep infections and 1 for extensor mechanism disruption. All 3 patients had reported abnormal symptoms when their films were obtained. The remaining 9 abnormal radiographic findings included focal lucencies or osteolysis, asymmetric spacer wear, a healing stress fracture, an inferior patellar avulsion fracture, and heterotopic ossification. No patient had symptoms attributable to these findings when the radiographs were obtained, and in no case was the management altered based on these finding. CONCLUSION: This study suggests that the observed frequency of routine postoperative radiographs in asymptomatic patients may not be necessary in the first 2 years after primary total knee arthroplasty.

A humoral immune defect distinguishes the response to Staphylococcus aureus infections in mice with obesity and type 2 diabetes from that in mice with type 1 diabetes.

Obesity and diabetes are among the greatest risk factors for infection following total joint arthroplasty. However, the underlying mechanism of susceptibility is unclear. We compared orthopedic implant-associated Staphylococcus aureus infections in type 1 (T1D) versus type 2 (T2D) diabetic mouse models and in patients with S. aureus infections, focusing on the adaptive immune response. Mice were fed a high-fat diet to initiate obesity and T2D. T1D was initiated with streptozotocin. Mice were then given a trans-tibial implant that was precoated with bioluminescent Xen36 S. aureus. Although both mouse models of diabetes demonstrated worse infection severity than controls, infection in T2D mice was more severe, as indicated by increases in bioluminescence, S. aureus CFU in tissue, and death within the first 7 days. Furthermore, T2D mice had an impaired humoral immune response at day 14 with reduced total IgG, decreased S. aureus-specific IgG, and increased IgM. These changes were not present in T1D mice. Similarly, T2D patients and obese nondiabetics with active S. aureus infections had a blunted IgG response to S. aureus. In conclusion, we report the first evidence of a humoral immune deficit, possibly due to an immunoglobulin class switch defect, in obesity and T2D during exacerbated S. aureus infection which may contribute to the increased infection risk following arthroplasty in patients with T2D and obesity.

A Diagnostic Serum Antibody Test for Patients With Staphylococcus aureus Osteomyelitis.

BACKGROUND: Because immunity against Staphylococcus aureus has not been fully elucidated, there is no diagnostic test to gauge how robust a patient's host response is likely to be. Therefore, we aimed to develop a test for specific antibodies in serum with diagnostic and prognostic potential. QUESTIONS/PURPOSES: We describe the development and validation of a multiplex immunoassay for characterizing a patient's immune response against 14 known S aureus antigens, which we then used to answer four questions: (1) Do certain antigens predominate in the immune response against S aureus? (2) Is there a predominant pattern of antigens recognized by patients and mice with infections? (3) Is the immunoglobulin G (IgG) response to any single antigen a useful predictor of ongoing S aureus infection? (4) Does measurement of the combined response against all 14 antigens provide a better predictor of ongoing infection? METHODS: A case-control study was performed. Sera were collected from 35 consecutive patients with S aureus culture-confirmed (methicillin-sensitive S aureus or methicillin-resistant S aureus) musculoskeletal infections (deep implant-associated, osteomyelitis, and cases of established septic arthritis). Patients were excluded only if they did not give informed consent for participation. Twenty-four patients had implant infections after total joint replacements, five had fracture implant infections, four had native knee infections, and two had chronic osteomyelitis without an implant. Control patients were chosen from a group of healthy, medically optimized patients scheduled to undergo elective arthroplasty. Control patients were matched for age (± 3 years), BMI (± 3 kg/m(2)), and sex as closely as possible to patients with infections. Sera from patients with S aureus infections and murine S aureus tibial implant infections were used to evaluate a multiplex immunoassay for immunoglobulin titers against 14 recombinant S aureus antigens. All patients were treated with organism-targeted antibiotic therapy and appropriate, timely surgery. Treatment response was monitored with clinical examination, erythrocyte sedimentation rate, C-reactive protein, and resampling of the infection site for the pathogen as needed. Elevated inflammatory markers or persistent positive culture results were considered evidence of ongoing infection. Treatment provided was considered standard-of-care therapy in our medical center and all patients were treated jointly with a board-certified infectious disease specialist. RESULTS: Four antigens elicited more than 65% of the measurable IgG, the most dominant being against iron-regulated surface determinant protein B (IsdB). Patients with infections had different patterns of elevated IgG titers, so that no single titer was elevated in more than 50% of patients with infections (area under the curve [AUC] ≤ 0.80). Multivariate analysis of IgG titers yielded greater predictive power of S aureus infection (AUC = 0.896). Patients with infections who had high titers against IsdB (median of survivors, 7.28 [25%-75% range, 2.22-21.26] vs median of patients with infection-related death, 40.41 [25%-75% range, 23.57-51.37], difference of medians, 33.13; p = 0.043) and iron-regulated surface determinant protein A (IsdA) median of survivors, 2.21 [25%-75% range, 0.79-9.11] vs median of patients with infection-related death, 12.24 [25%-75% range, 8.85-15.95], difference of medians, 10.03; p = 0.043) were more likely to die from infections than those who did not have high titers of IsdB. CONCLUSIONS: Measurement of the host antibody response is a predictor of ongoing infection that may prove to have prognostic value. Future studies will seek to enlarge the patient population with infections to allow us to reduce the number of antigens required to achieve a stronger predictive power. CLINICAL RELEVANCE: Measurement of the immune response against S aureus with this diagnostic tool may help guide future studies on prophylaxis and therapy in an era of personalized medicine and pathogen-specific therapies.

Hospital readmission after hip fracture.

INTRODUCTION: Readmission to the hospital following a hip fracture is common, often involves an adverse event, and strains an already overburdened health care system. OBJECTIVES: To assess the rate of 30-day readmission to the hospital after discharge for care of hip fracture. A secondary objective was measurement of the 30-day mortality rate for those patients readmitted versus those patients not readmitted to the hospital after discharge. MATERIALS AND METHODS: Study design was a retrospective review of registry data comparing readmitted patients to those not readmitted after hip fracture. Setting was a university affiliated level 3 trauma center. PARTICIPANTS: 1,081 patients aged 65 and older. MEASUREMENTS: rate of readmission, rate of mortality, predictors of readmission. RESULTS: 129 patients (11.9 %) were readmitted to the hospital within 30 days of their initial discharge date. The primary causes of readmission were surgical in nature for 24/129 (18.6 %) patients and 105/129 (81.4 %) were readmitted for medical or other reasons. Twenty-four (18.6 %) patients who were readmitted died during readmission. The one-year mortality rate for patients readmitted within 30 days was 56.2 vs. a 21.8 % 1-year mortality rate for those patients not readmitted (p < 0.0001). Independent predictors of readmission were age >85 (OR = 1.52; p = 0.03), time to surgery >24 h (OR = 1.50; p = 0.05), Charlson score ≥4 (OR = 1.70; p = 0.04), delirium (OR = 1.65; p = 0.01), dementia (OR = 1.61; p = 0.01), history of arrhythmia with pacemaker placement (OR = 1.75; p = 0.02), and presence of a pre-op arrhythmia (OR = 1.62; p = 0.02). CONCLUSION: Readmission after hip fracture is harmful and undesirable-18.6 % of readmitted patients died during their readmission and the average length of stay was 8.7 days. Approximately one of every six readmissions was identified as potentially preventable with interventions.