An Alternative Macrophage Activation Pathway Regulator, CHIT1, May Provide a Serum and Synovial Fluid Biomarker of Periprosthetic Osteolysis.

BACKGROUND: Periprosthetic osteolysis (PPO) is a frequent indication for total hip replacement (THR) failure. Currently, PPO diagnosis occurs in advanced stages that often necessitate complex revisions due to bone loss. PPO biomarkers could facilitate earlier diagnosis. Alternative macrophage activation pathway regulators, chitotriosidase (CHIT1) and CC chemokine ligand 18 (CCL18), have increased periprosthetic expression in patients undergoing revision THR for osteolysis. We hypothesized that synovial fluid and serum levels of CHIT1 and CCL18 would be increased in patients undergoing revision THR for PPO versus controls without osteolysis. METHODS: In this prospective case-control study, 60 patients undergoing revision metal-on-polyethylene THR at Hospital for Special Surgery were screened preoperatively from January 2013 to December 2014. Twenty "osteolysis" patients who underwent revision for PPO (based on imaging and operative reports) and 10 "control" patients (with stable implants) who underwent revision for recurrent dislocation or a mechanical etiology were included. Among osteolysis and control patients, 11/20 and 4/10 were male; average age was 68 and 63 years, respectively; 9/20 and 3/10 had cemented femoral components; and average implant longevity was 15 and 5 years, respectively. Preoperative serum and intraoperative synovial fluid samples were collected. CHIT1 and CCL18 were quantified via enzyme-linked immunosorbent assay. Significance was assessed via nonparametric Mann-Whiney U test. RESULTS: CHIT1 was significantly increased in both synovial fluid (3727 versus 731 nanomoles [nM]) and serum (98 versus 39 nM) in the osteolysis versus control patients. CCL18 levels were also significantly increased in osteolysis versus control patients' synovial fluid (425 versus 180 nM) but not their serum. CONCLUSIONS: In this prospective case-control study, CHIT1 was identified as a novel synovial fluid and serum biomarker of PPO. CHIT1 expression is induced during macrophage activation in response to wear debris. CHIT1 monitoring may facilitate early diagnosis of THR PPO. Furthermore, CHIT1 may represent a novel therapeutic target for PPO.

The role of antibiotics in preventing totally implantable venous access device (TIVAD) infections; is there a population that would benefit?

PURPOSE: To assess the role for prophylactic antibiotics in preventing totally implantable venous access device (TIVAD) infections and identify populations that may benefit from antibiotics. METHODS: 1284 patients undergoing TIVAD placement were retrospectively reviewed to determine association between infection rate, prophylactic antibiotics, and clinical data including white blood cell (WBC) count, platelets, and coagulation profile. Patients were further sub-categorized based on hospital admission status and leukopenia. Patients who received antibiotics were compared to those who did not using chi-square test or Fisher's exact tests and Student's t-tests. Additionally, multivariable logistic regression analysis was used to determine factors associated with infections. RESULTS: A total of 7 infections were identified with an infection rate of 0.5%. 1010 patients received antibiotics (78.7%), and infection rate in these patients was 0.7% compared to 0% in patients who did not receive antibiotics. 21 patients were under the age of 18, eight of which received antibiotics. No infections occurred in the pediatric group. Upon multivariate analysis, developing TIVAD infection was significantly associated with inpatient placement (p < 0.0001, OR 29.1, 95% CI 3.1-272.1), while utilization of double lumen ports was not (OR 3.0, 95% CI 0.5-17.4). There were no significant associations between infections and antibiotic use (p = 0.36), leukopenia (p = 0.47), pediatric patients (p = 1) or other demographic or laboratory data. CONCLUSION: Routine use of prophylactic antibiotics with TIVAD placement should be avoided. Antibiotics may not benefit even those with greater risk for infection.

Evaluating the Diagnostic Yield of Computed Tomography-Guided Aspirations in Suspected Post-operative Spine Infections.

BACKGROUND: Early detection of surgical site infection (SSI) following spinal surgery would allow for prompt treatment and would improve overall outcome, yet early diagnosis is a challenge. Computed tomography (CT) guided aspiration of fluid collections may aid in diagnosis, as its diagnostic utility has previously been demonstrated in the setting of hip SSI, knee SSI, and spontaneous diskitis. There is no literature on its use in post-operative spinal SSIs. QUESTIONS/PURPOSES: The current study aims to (1) determine the diagnostic value of CT-guided aspiration in evaluating suspected SSI; (2) identify the characteristics of the clinical presentation that are predictive of SSI; and (3) identify characteristics of the hematologic workup that are predictive of SSI. METHODS: Thirty patients who underwent CT-guided aspiration of paraspinal post-operative fluid collections and culture of aspirate fluid over the 6-year period from 2006 to 2011 were retrospectively reviewed. Aspirate fluid culture results were compared to intraoperative cultures, which were used as the "gold standard" for diagnosing SSI. The diagnostic value was evaluated by determining the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of aspirate fluid cultures. Clinical presentation, patient demographics, comorbidities, and laboratory values were reviewed for association with infection risk. RESULTS: Eleven of thirty patients undergoing CT-guided aspiration were subsequently confirmed to have SSI through positive cultures. Wound drainage, wound erythema, elevated ESR, and cloudiness of aspirate fluid were associated with SSI. The sensitivity and specificity of aspirate cultures were 36.4 and 89.5%, respectively, and the respective positive predictive value (PPV) and negative predictive value (NPV) were 66.7 and 70.8%. CONCLUSIONS: Cloudy aspirate fluid was highly suggestive of infection, while wound erythema, drainage, and elevated ESR were also suggestive of SSI. CT-guided aspirations are a useful adjunct tool in evaluating for SSI but further studies are necessary before it can be considered a stand-alone diagnostic procedure.